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libjansson (3lib)

Name

libjansson - Jansson Documentation This is the documentation for Jansson 2.7, last updated October 28, 2014.

Synopsis

Please see following description for synopsis

Description

LIBJANSSON(3lib)                    Jansson                   LIBJANSSON(3lib)



NAME
       jansson - Jansson Documentation

       This  is  the  documentation  for Jansson 2.7, last updated October 28,
       2014.

INTRODUCTION
       Jansson is a C library for encoding,  decoding  and  manipulating  JSON
       data. Its main features and design principles are:

       o Simple and intuitive API and data model

       o Comprehensive documentation

       o No dependencies on other libraries

       o Full Unicode support (UTF-8)

       o Extensive test suite

         Jansson  is licensed under the MIT license; see LICENSE in the source
         distribution for details.

         Jansson is used in production and its API  is  stable.  It  works  on
         numerous platforms, including numerous Unix like systems and Windows.
         It's suitable for use on any system, including desktop,  server,  and
         small embedded systems.

CONTENTS
   Getting Started
   Compiling and Installing Jansson
       The         Jansson         source        is        available        at
       http://www.digip.org/jansson/releases/.

   Unix-like systems (including MinGW)
       Unpack the source tarball and change to the source directory:

       bunzip2 -c jansson-2.7.tar.bz2 | tar xf -
       cd jansson-2.7

       The source uses GNU Autotools (autoconf, automake, libtool), so compil-
       ing and installing is extremely simple:

       ./configure
       make
       make check
       make install

       To  change  the  destination directory (/usr/local by default), use the
       --prefix=DIR argument to ./configure. See ./configure  --help  for  the
       list  of  all  possible  installation options. (There are no options to
       customize the resulting Jansson binary.)

       The command make check runs the test suite  distributed  with  Jansson.
       This  step is not strictly necessary, but it may find possible problems
       that Jansson has on your platform. If any problems  are  found,  please
       report them.

       If  you  obtained the source from a Git repository (or any other source
       control system), there's no ./configure script as it's not kept in ver-
       sion  control. To create the script, the build system needs to be boot-
       strapped. There are many ways to do this, but the easiest one is to use
       autoreconf:

       autoreconf -vi

       This  command creates the ./configure script, which can then be used as
       described above.

   CMake (various platforms, including Windows)
       Jansson can be built using CMake.  Create  a  build  directory  for  an
       out-of-tree  build, change to that directory, and run cmake (or ccmake,
       cmake-gui, or similar) to configure the project.

       See the examples below for more detailed information.

       NOTE: In the below examples .. is used as an argument for cmake.   This
       is simply the path to the jansson project root directory.  In the exam-
       ple it is assumed you've created a sub-directory build  and  are  using
       that. You could use any path you want.

   Unix (Make files)
       Generating make files on unix:

       bunzip2 -c jansson-2.7.tar.bz2 | tar xf -
       cd jansson-2.7

       mkdir build
       cd build
       cmake .. # or ccmake ..() for a GUI.

       Then to build:

       make
       make check
       make install

   Windows (Visual Studio)
       Creating Visual Studio project files from the command line:

       <unpack>
       cd jansson-2.7

       md build
       cd build
       cmake -G "Visual Studio 10" ..

       You will now have a Visual Studio Solution in your build directory.  To
       run the unit tests build the RUN_TESTS project.

       If you prefer a GUI the cmake line in the above example can be replaced
       with:

       cmake-gui ..

       For  command  line  help (including a list of available generators) for
       CMake simply run:

       cmake

       To list available CMake settings (and what they are currently  set  to)
       for the project, run:

       cmake -LH ..

   Mac OSX (Xcode)
       If  you prefer using Xcode instead of make files on OSX, do the follow-
       ing. (Use the same steps as for Unix):

       ...
       cmake -G "Xcode" ..

   Additional CMake settings
   Shared library
       By default the CMake project will generate build files for building the
       static library. To build the shared version use:

       ...
       cmake -DJANSSON_BUILD_SHARED_LIBS=1 ..

   Changing install directory (same as autoconf --prefix)
       Just as with the autoconf project you can change the destination direc-
       tory for make install. The equivalent for autoconfs ./configure  --pre-
       fix in CMake is:

       ...
       cmake -DCMAKE_INSTALL_PREFIX:PATH=/some/other/path ..
       make install

   Android
       Jansson can be built for Android platforms. Android.mk is in the source
       root directory. The configuration header file is located in the android
       directory in the source distribution.

   Other Systems
       On  non  Unix-like  systems,  you  may be unable to run the ./configure
       script. In this case, follow these steps. All the files  mentioned  can
       be found in the src/ directory.

       1. Create jansson_config.h (which has some platform-specific parameters
          that are normally filled in by the ./configure script).  Edit  jans-
          son_config.h.in,  replacing  all @variable@ placeholders, and rename
          the file to jansson_config.h.

       2. Make jansson.h and jansson_config.h available to  the  compiler,  so
          that they can be found when compiling programs that use Jansson.

       3. Compile  all  the  .c  files  (in the src/ directory) into a library
          file. Make the library available to the compiler, as in step 2.

   Building the Documentation
       (This subsection describes how to build the HTML documentation you  are
       currently reading, so it can be safely skipped.)

       Documentation   is   in   the   doc/   subdirectory.  It's  written  in
       reStructuredText with Sphinx annotations. To generate the HTML documen-
       tation, invoke:

       make html

       and  point  your  browser  to doc/_build/html/index.html. Sphinx 1.0 or
       newer is required to generate the documentation.

   Compiling Programs that Use Jansson
       Jansson involves one C header file, jansson.h, so it's  enough  to  put
       the line

       #include <jansson.h>

       in the beginning of every source file that uses Jansson.

       There's  also  just  one  library to link with, libjansson. Compile and
       link the program as follows:

       cc -I/usr/include/jansson -o prog prog.c -ljansson

       Starting from version 1.2, there's also support for pkg-config:

       cc -o prog prog.c `pkg-config --cflags --libs jansson`

   Upgrading from 1.x
       This chapter lists the backwards  incompatible  changes  introduced  in
       Jansson 2.0, and the steps that are needed for upgrading your code.

       The  incompatibilities are not dramatic. The biggest change is that all
       decoding functions now require and extra parameter. Most  programs  can
       be  modified  to work with 2.0 by adding a 0 as the second parameter to
       all calls of json_loads(), json_loadf() and json_load_file().

   Compatibility
       Jansson 2.0 is backwards incompatible with the  Jansson  1.x  releases.
       It  is  ABI  incompatible, i.e. all programs dynamically linking to the
       Jansson library need to be recompiled. It's also API incompatible, i.e.
       the source code of programs using Jansson 1.x may need modifications to
       make them compile against Jansson 2.0.

       All the 2.x releases are guaranteed to be backwards compatible for both
       ABI  and  API,  so  no  recompilation or source changes are needed when
       upgrading from 2.x to 2.y.

   List of Incompatible Changes
       Decoding flags
              For future needs, a flags parameter  was  added  as  the  second
              parameter   to   all   decoding  functions,  i.e.  json_loads(),
              json_loadf() and json_load_file(). All calls to these  functions
              need  to  be  changed  by adding a 0 as the second argument. For
              example:

              /* old code */
              json_loads(input, &error);

              /* new code */
              json_loads(input, 0, &error);

       Underlying type of JSON integers
              The underlying C type of JSON integers has been changed from int
              to  the widest available signed integer type, i.e.  long long or
              long, depending on whether long long is supported on your system
              or  not.  This makes the whole 64-bit integer range available on
              most modern systems.

              jansson.h has a typedef json_int_t  to  the  underlying  integer
              type.  int  should still be used in most cases when dealing with
              smallish JSON integers, as the compiler  handles  implicit  type
              coercion.  Only when the full 64-bit range is needed, json_int_t
              should be explicitly used.

       Maximum encoder indentation depth
              The maximum argument of the JSON_INDENT() macro has been changed
              from  255  to  31,  to  free up bits from the flags parameter of
              json_dumps(), json_dumpf() and json_dump_file().  If  your  code
              uses a bigger indentation than 31, it needs to be changed.

       Unsigned integers in API functions
              Version  2.0 unifies unsigned integer usage in the API. All uses
              of unsigned int  and  unsigned  long  have  been  replaced  with
              size_t.  This includes flags, container sizes, etc.  This should
              not require source  code  changes,  as  both  unsigned  int  and
              unsigned long are usually compatible with size_t.

   Tutorial
       In  this  tutorial, we create a program that fetches the latest commits
       of a repository in GitHub over the web. GitHub API uses  JSON,  so  the
       result can be parsed using Jansson.

       To  stick to the the scope of this tutorial, we will only cover the the
       parts of the program related to handling JSON data. For the  best  user
       experience,  the  full  source  code is available: github_commits.c. To
       compile it (on Unix-like systems with gcc), use the following command:

       gcc -o github_commits github_commits.c -ljansson -lcurl

       libcurl is used to communicate over the web, so it is required to  com-
       pile the program.

       The command line syntax is:

       github_commits USER REPOSITORY

       USER  is a GitHub user ID and REPOSITORY is the repository name. Please
       note that the GitHub API is rate limited, so if you run the program too
       many  times  within a short period of time, the sever starts to respond
       with an error.

   The GitHub Repo Commits API
       The GitHub Repo Commits API is used by sending HTTP  requests  to  URLs
       like  https://api.github.com/repos/USER/REPOSITORY/commits,  where USER
       and REPOSITORY are the GitHub user ID and the name  of  the  repository
       whose commits are to be listed, respectively.

       GitHub responds with a JSON array of the following form:

       [
           {
               "sha": "<the commit ID>",
               "commit": {
                   "message": "<the commit message>",
                   <more fields, not important to this tutorial...>
               },
               <more fields...>
           },
           {
               "sha": "<the commit ID>",
               "commit": {
                   "message": "<the commit message>",
                   <more fields...>
               },
               <more fields...>
           },
           <more commits...>
       ]

       In our program, the HTTP request is sent using the following function:

       static char *request(const char *url);

       It  takes  the  URL  as  a  parameter, preforms a HTTP GET request, and
       returns a newly allocated string that contains the  response  body.  If
       the request fails, an error message is printed to stderr and the return
       value is NULL. For full details, refer  to  the  code,  as  the  actual
       implementation is not important here.

   The Program
       First the includes:

       #include <string.h>
       #include <jansson.h>

       Like all the programs using Jansson, we need to include jansson.h.

       The following definitions are used to build the GitHub API request URL:

       #define URL_FORMAT   "https://api.github.com/repos/%s/%s/commits"
       #define URL_SIZE     256

       The  following  function is used when formatting the result to find the
       first newline in the commit message:

       /* Return the offset of the first newline in text or the length of
          text if there's no newline */
       static int newline_offset(const char *text)
       {
           const char *newline = strchr(text, '\n');
           if(!newline)
               return strlen(text);
           else
               return (int)(newline - text);
       }

       The main function follows. In the beginning, we first declare  a  bunch
       of variables and check the command line parameters:

       int main(int argc, char *argv[])
       {
           size_t i;
           char *text;
           char url[URL_SIZE];

           json_t *root;
           json_error_t error;

           if(argc != 3)
           {
               fprintf(stderr, "usage: %s USER REPOSITORY\n\n", argv[0]);
               fprintf(stderr, "List commits at USER's REPOSITORY.\n\n");
               return 2;
           }

       Then we build the request URL using the user and repository names given
       as command line parameters:

       snprintf(url, URL_SIZE, URL_FORMAT, argv[1], argv[2]);

       This uses the URL_SIZE and URL_FORMAT  constants  defined  above.   Now
       we're ready to actually request the JSON data over the web:

       text = request(url);
       if(!text)
           return 1;

       If  an  error occurs, our function request prints the error and returns
       NULL, so it's enough to just return 1 from the main function.

       Next we'll call json_loads() to decode  the  JSON  text  we  got  as  a
       response:

       root = json_loads(text, 0, &error);
       free(text);

       if(!root)
       {
           fprintf(stderr, "error: on line %d: %s\n", error.line, error.text);
           return 1;
       }

       We  don't  need the JSON text anymore, so we can free the text variable
       right after decoding it. If json_loads() fails,  it  returns  NULL  and
       sets  error information to the json_error_t structure given as the sec-
       ond parameter. In this case, our program prints the  error  information
       out and returns 1 from the main function.

       Now  we're  ready to extract the data out of the decoded JSON response.
       The structure of the response JSON was explained in section The  GitHub
       Repo Commits API.

       We check that the returned value really is an array:

       if(!json_is_array(root))
       {
           fprintf(stderr, "error: root is not an array\n");
           json_decref(root);
           return 1;
       }

       Then we proceed to loop over all the commits in the array:

       for(i = 0; i < json_array_size(root); i++)
       {
           json_t *data, *sha, *commit, *message;
           const char *message_text;

           data = json_array_get(root, i);
           if(!json_is_object(data))
           {
               fprintf(stderr, "error: commit data %d is not an object\n", i + 1);
               json_decref(root);
               return 1;
           }
       ...

       The function json_array_size() returns the size of a JSON array. First,
       we again declare some variables and then extract the  i'th  element  of
       the  root array using json_array_get().  We also check that the result-
       ing value is a JSON object.

       Next we'll extract the commit ID (a hexadecimal SHA-1 sum),  intermedi-
       ate  commit  info  object,  and the commit message from that object. We
       also do proper type checks:

           sha = json_object_get(data, "sha");
           if(!json_is_string(sha))
           {
               fprintf(stderr, "error: commit %d: sha is not a string\n", i + 1);
               json_decref(root);
               return 1;
           }

           commit = json_object_get(data, "commit");
           if(!json_is_object(commit))
           {
               fprintf(stderr, "error: commit %d: commit is not an object\n", i + 1);
               json_decref(root);
               return 1;
           }

           message = json_object_get(commit, "message");
           if(!json_is_string(message))
           {
               fprintf(stderr, "error: commit %d: message is not a string\n", i + 1);
               json_decref(root);
               return 1;
           }
       ...

       And finally, we'll print the first 8 characters of the  commit  ID  and
       the  first  line  of  the commit message. A C-style string is extracted
       from a JSON string using json_string_value():

           message_text = json_string_value(message);
           printf("%.8s %.*s\n",
                  json_string_value(id),
                  newline_offset(message_text),
                  message_text);
       }

       After sending  the  HTTP  request,  we  decoded  the  JSON  text  using
       json_loads(), remember? It returns a new reference to the JSON value it
       decodes. When we're finished with the value, we'll need to decrease the
       reference  count  using json_decref(). This way Jansson can release the
       resources:

       json_decref(root);
       return 0;

       For a detailed  explanation  of  reference  counting  in  Jansson,  see
       apiref-reference-count in apiref.

       The program's ready, let's test it and view the latest commits in Jans-
       son's repository:

       $ ./github_commits akheron jansson
       1581f26a Merge branch '2.3'
       aabfd493 load: Change buffer_pos to be a size_t
       bd72efbd load: Avoid unexpected behaviour in macro expansion
       e8fd3e30 Document and tweak json_load_callback()
       873eddaf Merge pull request #60 from rogerz/contrib
       bd2c0c73 Ignore the binary test_load_callback
       17a51a4b Merge branch '2.3'
       09c39adc Add json_load_callback to the list of exported symbols
       cbb80baf Merge pull request #57 from rogerz/contrib
       040bd7b0 Add json_load_callback()
       2637faa4 Make test stripping locale independent
       <...>

   Conclusion
       In this tutorial, we implemented a program that fetches the latest com-
       mits of a GitHub repository using the GitHub Repo Commits API.  Jansson
       was used to decode the JSON response and to extract the commit data.

       This tutorial only covered a small part of Jansson. For example, we did
       not  create  or  manipulate  JSON  values  at all. Proceed to apiref to
       explore all features of Jansson.

   RFC Conformance
       JSON is specified in RFC 4627, "The  application/json  Media  Type  for
       JavaScript Object Notation (JSON)".

   Character Encoding
       Jansson  only supports UTF-8 encoded JSON texts. It does not support or
       auto-detect any of the other encodings mentioned  in  the  RFC,  namely
       UTF-16LE,  UTF-16BE,  UTF-32LE or UTF-32BE. Pure ASCII is supported, as
       it's a subset of UTF-8.

   Strings
       JSON strings are mapped to C-style  null-terminated  character  arrays,
       and UTF-8 encoding is used internally.

       All  Unicode  codepoints  U+0000 through U+10FFFF are allowed in string
       values. However, U+0000 is not allowed in object keys  because  of  API
       restrictions.

       Unicode normalization or any other transformation is never performed on
       any strings (string values or object keys). When checking  for  equiva-
       lence  of  strings  or object keys, the comparison is performed byte by
       byte between the original UTF-8 representations of the strings.

   Numbers
   Real vs. Integer
       JSON makes no distinction between real  and  integer  numbers;  Jansson
       does.  Real  numbers  are mapped to the double type and integers to the
       json_int_t type, which is a typedef of long long or long, depending  on
       whether long long is supported by your compiler or not.

       A  JSON  number is considered to be a real number if its lexical repre-
       sentation includes one of e, E, or .; regardless if its actual  numeric
       value  is a true integer (e.g., all of 1E6, 3.0, 400E-2, and 3.14E3 are
       mathematical integers, but will be treated as real  values).  With  the
       JSON_DECODE_INT_AS_REAL decoder flag set all numbers are interpreted as
       real.

       All other JSON numbers are considered integers.

       When encoding to JSON, real values are always represented with a  frac-
       tional  part; e.g., the double value 3.0 will be represented in JSON as
       3.0, not 3.

   Overflow, Underflow & Precision
       Real numbers whose absolute values are too small to be represented in a
       C  double will be silently estimated with 0.0. Thus, depending on plat-
       form, JSON numbers very close to zero such as 1E-999 may result in 0.0.

       Real numbers whose absolute values are too large to be represented in a
       C  double  will  result  in  an overflow error (a JSON decoding error).
       Thus, depending on platform, JSON numbers like 1E+999  or  -1E+999  may
       result in a parsing error.

       Likewise,  integer  numbers  whose  absolute values are too large to be
       represented in the json_int_t type (see above) will result in an  over-
       flow  error  (a JSON decoding error). Thus, depending on platform, JSON
       numbers like 1000000000000000 may result in parsing error.

       Parsing JSON real numbers may result in a loss of precision. As long as
       overflow  does  not occur (i.e. a total loss of precision), the rounded
       approximate  value   is   silently   used.   Thus   the   JSON   number
       1.000000000000000005  may,  depending on platform, result in the double
       value 1.0.

   Signed zeros
       JSON makes no statement about what a number means;  however  Javascript
       (ECMAscript)  does  state  that  +0.0 and -0.0 must be treated as being
       distinct values, i.e. -0.0 != 0.0. Jansson  relies  on  the  underlying
       floating  point  library  in the C environment in which it is compiled.
       Therefore it is platform-dependent whether 0.0 and -0.0  will  be  dis-
       tinct values. Most platforms that use the IEEE 754 floating-point stan-
       dard will support signed zeros.

       Note that this only applies to floating-point; neither JSON, C, or IEEE
       support the concept of signed integer zeros.

   Types
       No  support  is  provided in Jansson for any C numeric types other than
       json_int_t and double. This excludes things  such  as  unsigned  types,
       long  double,  etc.  Obviously, shorter types like short, int, long (if
       json_int_t is long long) and float are implicitly handled via the ordi-
       nary  C  type  coercion rules (subject to overflow semantics). Also, no
       support or hooks are provided for any supplemental "bignum" type add-on
       packages.

   Portability
   Thread safety
       Jansson is thread safe and has no mutable global state. The only excep-
       tions are the hash function seed and memory allocation  functions,  see
       below.

       There's  no locking performed inside Jansson's code, so a multithreaded
       program must perform its own locking if JSON values are shared by  mul-
       tiple  threads.  Jansson's reference counting semantics may make this a
       bit harder than it seems, as it's possible to have  a  reference  to  a
       value  that's  also  stored inside a list or object. Modifying the con-
       tainer (adding or removing values) may  trigger  concurrent  access  to
       such  values,  as  containers  manage the reference count of their con-
       tained values. Bugs involving concurrent incrementing  or  decrementing
       of deference counts may be hard to track.

       The encoding functions (json_dumps() and friends) track reference loops
       by modifying the internal state of objects and arrays.  For  this  rea-
       son,  encoding functions must not be run on the same JSON values in two
       separate threads at the same time. As already  noted  above,  be  espe-
       cially  careful  if  two arrays or objects share their contained values
       with another array or object.

       If you want to make sure that two JSON value hierarchies do not contain
       shared values, use json_deep_copy() to make copies.

   Hash function seed
       To  prevent  an  attacker from intentionally causing large JSON objects
       with specially crafted keys to perform very  slow,  the  hash  function
       used by Jansson is randomized using a seed value. The seed is automati-
       cally  generated  on  the  first   explicit   or   implicit   call   to
       json_object(), if json_object_seed() has not been called beforehand.

       The  seed  is  generated by using operating system's entropy sources if
       they are available (/dev/urandom, CryptGenRandom()). The initialization
       is  done  in  as  thread safe manner as possible, by using architecture
       specific lockless operations if provided by the platform  or  the  com-
       piler.

       If  you're  using  threads,  it's recommended to autoseed the hashtable
       explicitly before spawning any threads by calling json_object_seed(0) ,
       especially  if  you're unsure whether the initialization is thread safe
       on your platform.

   Memory allocation functions
       Memory allocation functions should be set at most  once,  and  only  on
       program startup. See apiref-custom-memory-allocation.

   Locale
       Jansson works fine under any locale.

       However,  if  the host program is multithreaded and uses setlocale() to
       switch the locale in one thread while Jansson is currently encoding  or
       decoding  JSON  data  in another thread, the result may be wrong or the
       program may even crash.

       Jansson uses locale specific functions for certain  string  conversions
       in  the encoder and decoder, and then converts the locale specific val-
       ues to/from the JSON representation. This fails if the  locale  changes
       between  the  string conversion and the locale-to-JSON conversion. This
       can only happen in multithreaded programs that use setlocale(), because
       setlocale()  switches  the locale for all running threads, not only the
       thread that calls setlocale().

       If your program uses setlocale() as described above, consider using the
       thread-safe uselocale() instead.

   API Reference
   Preliminaries
       All declarations are in jansson.h, so it's enough to

       #include <jansson.h>

       in each source file.

       All  constants are prefixed with JSON_ (except for those describing the
       library version, prefixed with JANSSON_). Other  identifiers  are  pre-
       fixed with json_. Type names are suffixed with _t and typedef'd so that
       the struct keyword need not be used.

   Library Version
       The Jansson version is of the form A.B.C, where A is the major version,
       B is the minor version and C is the micro version. If the micro version
       is zero, it's omitted from the version string, i.e. the version  string
       is just A.B.

       When  a  new  release  only  fixes bugs and doesn't add new features or
       functionality, the micro version is incremented. When new features  are
       added  in  a backwards compatible way, the minor version is incremented
       and the micro version is set to zero. When there are  backwards  incom-
       patible changes, the major version is incremented and others are set to
       zero.

       The following preprocessor constants specify the current version of the
       library:

       JANSSON_MAJOR_VERSION, JANSSON_MINOR_VERSION, JANSSON_MICRO_VERSION
              Integers specifying the major, minor and micro versions, respec-
              tively.

       JANSSON_VERSION
              A string representation of the current version, e.g. "1.2.1"  or
              "1.3".

       JANSSON_VERSION_HEX
              A   3-byte  hexadecimal  representation  of  the  version,  e.g.
              0x010201 for version 1.2.1 and 0x010300 for version  1.3.   This
              is useful in numeric comparisions, e.g.:

              #if JANSSON_VERSION_HEX >= 0x010300
              /* Code specific to version 1.3 and above */
              #endif

   Value Representation
       The  JSON  specification  (RFC  4627) defines the following data types:
       object, array, string, number, boolean, and null. JSON types  are  used
       dynamically; arrays and objects can hold any other data type, including
       themselves. For this reason, Jansson's type system is also  dynamic  in
       nature.  There's  one  C  type  to  represent all JSON values, and this
       structure knows the type of the JSON value it holds.

       json_t This data structure is used throughout the library to  represent
              all  JSON  values. It always contains the type of the JSON value
              it holds and the value's reference count. The  rest  depends  on
              the type of the value.

              Objects  of  json_t are always used through a pointer. There are
              APIs for querying the type, manipulating  the  reference  count,
              and for constructing and manipulating values of different types.

              Unless  noted otherwise, all API functions return an error value
              if an error occurs. Depending on the function's  signature,  the
              error  value  is either NULL or -1. Invalid arguments or invalid
              input are apparent sources for errors. Memory allocation and I/O
              operations may also cause errors.

   Type
       The  type  of  a  JSON  value is queried and tested using the following
       functions:

       enum json_type
              The type of a JSON value. The following members are defined:

                                       +-------------+
                                       |JSON_OBJECT  |
                                       +-------------+
                                       |JSON_ARRAY   |
                                       +-------------+
                                       |JSON_STRING  |
                                       +-------------+
                                       |JSON_INTEGER |
                                       +-------------+
                                       |JSON_REAL    |
                                       +-------------+
                                       |JSON_TRUE    |
                                       +-------------+
                                       |JSON_FALSE   |
                                       +-------------+
                                       |JSON_NULL    |
                                       +-------------+

              These correspond to JSON object, array, string, number,  boolean
              and  null. A number is represented by either a value of the type
              JSON_INTEGER or of the type JSON_REAL. A true boolean  value  is
              represented  by  a  value  of  the type JSON_TRUE and false by a
              value of the type JSON_FALSE.

       int json_typeof(const json_t *json)
              Return the type of the JSON value (a  json_type  cast  to  int).
              json  MUST NOT be NULL. This function is actually implemented as
              a macro for speed.

       json_is_object(const json_t *json)

       json_is_array(const json_t *json)

       json_is_string(const json_t *json)

       json_is_integer(const json_t *json)

       json_is_real(const json_t *json)

       json_is_true(const json_t *json)

       json_is_false(const json_t *json)

       json_is_null(const json_t *json)
              These functions (actually macros)  return  true  (non-zero)  for
              values  of  the given type, and false (zero) for values of other
              types and for NULL.

       json_is_number(const json_t *json)
              Returns true for values of types JSON_INTEGER and JSON_REAL, and
              false for other types and for NULL.

       json_is_boolean(const json_t *json)
              Returns  true  for types JSON_TRUE and JSON_FALSE, and false for
              values of other types and for NULL.

       json_boolean_value(const json_t *json)
              Alias of json_is_true(), i.e. returns 1 for JSON_TRUE and 0 oth-
              erwise.

              New in version 2.7.


   Reference Count
       The reference count is used to track whether a value is still in use or
       not. When a value is created, it's reference count is set to  1.  If  a
       reference  to  a  value  is  kept (e.g. a value is stored somewhere for
       later use), its reference count is incremented, and when the  value  is
       no  longer  needed, the reference count is decremented. When the refer-
       ence count drops to zero, there are no references left, and  the  value
       can be destroyed.

       The following functions are used to manipulate the reference count.

       json_t *json_incref(json_t *json)
              Increment the reference count of json if it's not NULL.  Returns
              json.

       void json_decref(json_t *json)
              Decrement the reference count of json. As  soon  as  a  call  to
              json_decref()  drops  the  reference count to zero, the value is
              destroyed and it can no longer be used.

              Functions creating new JSON values set the reference count to 1.
              These  functions are said to return a new reference. Other func-
              tions returning (existing) JSON values do not normally  increase
              the  reference  count. These functions are said to return a bor-
              rowed reference. So, if the user will  hold  a  reference  to  a
              value   returned   as   a   borrowed  reference,  he  must  call
              json_incref(). As  soon  as  the  value  is  no  longer  needed,
              json_decref() should be called to release the reference.

              Normally,  all  functions  accepting a JSON value as an argument
              will manage the reference, i.e. increase and decrease the refer-
              ence  count  as needed. However, some functions steal the refer-
              ence, i.e. they have the same  result  as  if  the  user  called
              json_decref()  on the argument right after calling the function.
              These functions are suffixed with _new or have  _new_  somewhere
              in their name.

              For  example,  the  following  code creates a new JSON array and
              appends an integer to it:

              json_t *array, *integer;

              array = json_array();
              integer = json_integer(42);

              json_array_append(array, integer);
              json_decref(integer);

              Note how the caller has to release the reference to the  integer
              value  by  calling  json_decref(). By using a reference stealing
              function json_array_append_new() instead of json_array_append(),
              the code becomes much simpler:

              json_t *array = json_array();
              json_array_append_new(array, json_integer(42));

              In  this  case,  the user doesn't have to explicitly release the
              reference  to  the  integer  value,  as  json_array_append_new()
              steals the reference when appending the value to the array.

              In  the  following  sections  it is clearly documented whether a
              function will return a new or borrowed reference or steal a ref-
              erence to its argument.

   Circular References
       A circular reference is created when an object or an array is, directly
       or indirectly, inserted inside itself. The direct case is simple:

       json_t *obj = json_object();
       json_object_set(obj, "foo", obj);

       Jansson will refuse to do this,  and  json_object_set()  (and  all  the
       other  such functions for objects and arrays) will return with an error
       status. The indirect case is the dangerous one:

       json_t *arr1 = json_array(), *arr2 = json_array();
       json_array_append(arr1, arr2);
       json_array_append(arr2, arr1);

       In this example, the array arr2 is contained in  the  array  arr1,  and
       vice  versa.  Jansson  cannot  check for this kind of indirect circular
       references without a performance hit, so it's up to the user  to  avoid
       them.

       If  a  circular reference is created, the memory consumed by the values
       cannot be freed by json_decref(). The reference counts never  drops  to
       zero because the values are keeping the references to each other. More-
       over, trying to encode the values with any of  the  encoding  functions
       will fail. The encoder detects circular references and returns an error
       status.

   True, False and Null
       These three values are  implemented  as  singletons,  so  the  returned
       pointers won't change between invocations of these functions.

       json_t *json_true(void)
              Return value: New reference.

              Returns the JSON true value.

       json_t *json_false(void)
              Return value: New reference.

              Returns the JSON false value.

       json_t *json_boolean(val)
              Return value: New reference.

              Returns  JSON  false  if  val  is zero, and JSON true otherwise.
              This  is  a  macro,  and  equivalent  to  val  ?  json_true()  :
              json_false().

              New in version 2.4.


       json_t *json_null(void)
              Return value: New reference.

              Returns the JSON null value.

   String
       Jansson  uses UTF-8 as the character encoding. All JSON strings must be
       valid UTF-8 (or ASCII, as it's a subset of UTF-8).  All  Unicode  code-
       points   U+0000   through  U+10FFFF  are  allowed,  but  you  must  use
       length-aware functions if you wish to embed NUL bytes in strings.

       json_t *json_string(const char *value)
              Return value: New reference.

              Returns a new JSON string, or NULL on error.  value  must  be  a
              valid null terminated UTF-8 encoded Unicode string.

       json_t *json_stringn(const char *value, size_t len)
              Return value: New reference.

              Like  json_string(), but with explicit length, so value may con-
              tain null characters or not be null terminated.

       json_t *json_string_nocheck(const char *value)
              Return value: New reference.

              Like json_string(), but doesn't check that value is valid UTF-8.
              Use  this  function  only if you are certain that this really is
              the case (e.g. you have already checked it by other means).

       json_t *json_stringn_nocheck(const char *value, size_t len)
              Return value: New reference.

              Like json_string_nocheck(), but with explicit length,  so  value
              may contain null characters or not be null terminated.

       const char *json_string_value(const json_t *string)
              Returns  the  associated  value  of  string as a null terminated
              UTF-8 encoded string, or NULL if string is not a JSON string.

              The retuned value is read-only and must not be modified or freed
              by  the user. It is valid as long as string exists, i.e. as long
              as its reference count has not dropped to zero.

       size_t json_string_length(const json_t *string)
              Returns the length of string in its UTF-8 presentation, or  zero
              if string is not a JSON string.

       int json_string_set(const json_t *string, const char *value)
              Sets  the  associated  value of string to value. value must be a
              valid UTF-8 encoded Unicode string. Returns 0 on success and  -1
              on error.

       int json_string_setn(json_t *string, const char *value, size_t len)
              Like  json_string_set(),  but with explicit length, so value may
              contain null characters or not be null terminated.

       int json_string_set_nocheck(const json_t *string, const char *value)
              Like json_string_set(), but doesn't check that  value  is  valid
              UTF-8.  Use  this  function  only  if  you are certain that this
              really is the case (e.g. you have already checked  it  by  other
              means).

       int    json_string_setn_nocheck(json_t *string,    const   char *value,
       size_t len)
              Like json_string_set_nocheck(), but  with  explicit  length,  so
              value may contain null characters or not be null terminated.

   Number
       The  JSON specification only contains one numeric type, "number". The C
       programming language has distinct types for integer and  floating-point
       numbers,  so  for practical reasons Jansson also has distinct types for
       the two. They are called "integer" and "real", respectively.  For  more
       information, see rfc-conformance.

       json_int_t
              This is the C type that is used to store JSON integer values. It
              represents the widest integer type available on your system.  In
              practice  it's just a typedef of long long if your compiler sup-
              ports it, otherwise long.

              Usually, you can safely use plain int in  place  of  json_int_t,
              and  the  implicit  C  integer conversion handles the rest. Only
              when you know that you need the full 64-bit  range,  you  should
              use json_int_t explicitly.

       JSON_INTEGER_IS_LONG_LONG
              This  is  a  preprocessor  variable  that  holds  the value 1 if
              json_int_t is long long, and 0 if it's long. It can be  used  as
              follows:

              #if JSON_INTEGER_IS_LONG_LONG
              /* Code specific for long long */
              #else
              /* Code specific for long */
              #endif

       JSON_INTEGER_FORMAT
              This  is a macro that expands to a printf() conversion specifier
              that corresponds to json_int_t, without the leading % sign, i.e.
              either  "lld" or "ld". This macro is required because the actual
              type of json_int_t can be either long or long long, and printf()
              reuiqres different length modifiers for the two.

              Example:

              json_int_t x = 123123123;
              printf("x is %" JSON_INTEGER_FORMAT "\n", x);

       json_t *json_integer(json_int_t value)
              Return value: New reference.

              Returns a new JSON integer, or NULL on error.

       json_int_t json_integer_value(const json_t *integer)
              Returns  the  associated value of integer, or 0 if json is not a
              JSON integer.

       int json_integer_set(const json_t *integer, json_int_t value)
              Sets the associated value of integer to value. Returns 0 on suc-
              cess and -1 if integer is not a JSON integer.

       json_t *json_real(double value)
              Return value: New reference.

              Returns a new JSON real, or NULL on error.

       double json_real_value(const json_t *real)
              Returns  the  associated  value of real, or 0.0 if real is not a
              JSON real.

       int json_real_set(const json_t *real, double value)
              Sets the associated value of real to value. Returns 0 on success
              and -1 if real is not a JSON real.

              In addition to the functions above, there's a common query func-
              tion for integers and reals:

       double json_number_value(const json_t *json)
              Returns the associated value of the JSON integer  or  JSON  real
              json,  cast  to double regardless of the actual type. If json is
              neither JSON real nor JSON integer, 0.0 is returned.

   Array
       A JSON array is an ordered collection of other JSON values.

       json_t *json_array(void)
              Return value: New reference.

              Returns a new JSON array, or NULL on error. Initially, the array
              is empty.

       size_t json_array_size(const json_t *array)
              Returns  the  number of elements in array, or 0 if array is NULL
              or not a JSON array.

       json_t *json_array_get(const json_t *array, size_t index)
              Return value: Borrowed reference.

              Returns the element in array at position index. The valid  range
              for  index  is  from  0 to the return value of json_array_size()
              minus 1. If array is not a JSON array, if array is NULL,  or  if
              index is out of range, NULL is returned.

       int json_array_set(json_t *array, size_t index, json_t *value)
              Replaces the element in array at position index with value.  The
              valid range  for  index  is  from  0  to  the  return  value  of
              json_array_size() minus 1. Returns 0 on success and -1 on error.

       int json_array_set_new(json_t *array, size_t index, json_t *value)
              Like  json_array_set()  but steals the reference to value.  This
              is useful when value is newly created and  not  used  after  the
              call.

       int json_array_append(json_t *array, json_t *value)
              Appends  value to the end of array, growing the size of array by
              1. Returns 0 on success and -1 on error.

       int json_array_append_new(json_t *array, json_t *value)
              Like json_array_append() but steals the reference to value. This
              is  useful  when  value  is newly created and not used after the
              call.

       int json_array_insert(json_t *array, size_t index, json_t *value)
              Inserts value to array at position index, shifting the  elements
              at index and after it one position towards the end of the array.
              Returns 0 on success and -1 on error.

       int json_array_insert_new(json_t *array, size_t index, json_t *value)
              Like json_array_insert() but steals the reference to value. This
              is  useful  when  value  is newly created and not used after the
              call.

       int json_array_remove(json_t *array, size_t index)
              Removes the element in array at  position  index,  shifting  the
              elements  after  index  one  position  towards  the start of the
              array.  Returns 0 on success and  -1  on  error.  The  reference
              count of the removed value is decremented.

       int json_array_clear(json_t *array)
              Removes  all  elements from array. Returns 0 on sucess and -1 on
              error. The reference count of  all  removed  values  are  decre-
              mented.

       int json_array_extend(json_t *array, json_t *other_array)
              Appends  all  elements  in  other_array  to  the  end  of array.
              Returns 0 on success and -1 on error.

              The following macro can be used to iterate through all  elements
              in an array.

       json_array_foreach(array, index, value)
              Iterate  over  every element of array, running the block of code
              that follows each time with the proper values set  to  variables
              index  and  value,  of  types  size_t and json_t * respectively.
              Example:

              /* array is a JSON array */
              size_t index;
              json_t *value;

              json_array_foreach(array, index, value) {
                  /* block of code that uses index and value */
              }

              The items are returned in increasing index order.

              This macro expands to an ordinary for statement upon preprocess-
              ing,  so  its  performance is equivalent to that of hand-written
              code using the array access functions.  The  main  advantage  of
              this  macro  is that it abstracts away the complexity, and makes
              for shorter, more concise code.

              New in version 2.5.


   Object
       A JSON object is a dictionary of key-value pairs, where the  key  is  a
       Unicode string and the value is any JSON value.

       Even  though  NUL  bytes  are  allowed  in  string values, they are not
       allowed in object keys.

       json_t *json_object(void)
              Return value: New reference.

              Returns a new JSON object, or  NULL  on  error.  Initially,  the
              object is empty.

       size_t json_object_size(const json_t *object)
              Returns  the number of elements in object, or 0 if object is not
              a JSON object.

       json_t *json_object_get(const json_t *object, const char *key)
              Return value: Borrowed reference.

              Get a value corresponding to key from object.  Returns  NULL  if
              key is not found and on error.

       int json_object_set(json_t *object, const char *key, json_t *value)
              Set  the  value  of  key to value in object. key must be a valid
              null terminated UTF-8 encoded Unicode string. If  there  already
              is  a value for key, it is replaced by the new value.  Returns 0
              on success and -1 on error.

       int    json_object_set_nocheck(json_t *object,     const     char *key,
       json_t *value)
              Like  json_object_set(),  but  doesn't  check  that key is valid
              UTF-8. Use this function only  if  you  are  certain  that  this
              really  is  the  case (e.g. you have already checked it by other
              means).

       int json_object_set_new(json_t *object, const char *key, json_t *value)
              Like json_object_set() but steals the reference to  value.  This
              is  useful  when  value  is newly created and not used after the
              call.

       int   json_object_set_new_nocheck(json_t *object,   const    char *key,
       json_t *value)
              Like  json_object_set_new(), but doesn't check that key is valid
              UTF-8. Use this function only  if  you  are  certain  that  this
              really  is  the  case (e.g. you have already checked it by other
              means).

       int json_object_del(json_t *object, const char *key)
              Delete key from object if it exists. Returns 0 on success, or -1
              if  key  was not found. The reference count of the removed value
              is decremented.

       int json_object_clear(json_t *object)
              Remove all elements from object. Returns 0 on success and -1  if
              object  is not a JSON object. The reference count of all removed
              values are decremented.

       int json_object_update(json_t *object, json_t *other)
              Update object with the key-value pairs from  other,  overwriting
              existing keys. Returns 0 on success or -1 on error.

       int json_object_update_existing(json_t *object, json_t *other)
              Like  json_object_update(), but only the values of existing keys
              are updated. No new keys are created. Returns 0 on success or -1
              on error.

              New in version 2.3.


       int json_object_update_missing(json_t *object, json_t *other)
              Like  json_object_update(),  but only new keys are created.  The
              value of any existing key is not changed. Returns 0  on  success
              or -1 on error.

              New in version 2.3.


              The following macro can be used to iterate through all key-value
              pairs in an object.

       json_object_foreach(object, key, value)
              Iterate over every key-value pair of object, running  the  block
              of  code  that  follows  each time with the proper values set to
              variables key and value, of types const  char  *  and  json_t  *
              respectively. Example:

              /* obj is a JSON object */
              const char *key;
              json_t *value;

              json_object_foreach(obj, key, value) {
                  /* block of code that uses key and value */
              }

              The items are not returned in any particular order.

              This macro expands to an ordinary for statement upon preprocess-
              ing, so its performance is equivalent to  that  of  hand-written
              iteration  code using the object iteration protocol (see below).
              The main advantage of this macro is that it abstracts  away  the
              complexity behind iteration, and makes for shorter, more concise
              code.

              New in version 2.3.


              The following functions  implement  an  iteration  protocol  for
              objects,  allowing  to iterate through all key-value pairs in an
              object. The items are not returned in any particular  order,  as
              this  would require sorting due to the internal hashtable imple-
              mentation.

       void *json_object_iter(json_t *object)
              Returns an opaque iterator which can be used to iterate over all
              key-value pairs in object, or NULL if object is empty.

       void *json_object_iter_at(json_t *object, const char *key)
              Like   json_object_iter(),   but  returns  an  iterator  to  the
              key-value pair in object whose key is equal to key, or  NULL  if
              key  is  not  found  in  object. Iterating forward to the end of
              object only yields all key-value pairs of the object if key hap-
              pens to be the first key in the underlying hash table.

       void *json_object_iter_next(json_t *object, void *iter)
              Returns  an  iterator  pointing  to  the  next key-value pair in
              object after iter, or NULL if the whole object has been iterated
              through.

       const char *json_object_iter_key(void *iter)
              Extract the associated key from iter.

       json_t *json_object_iter_value(void *iter)
              Return value: Borrowed reference.

              Extract the associated value from iter.

       int json_object_iter_set(json_t *object, void *iter, json_t *value)
              Set  the  value of the key-value pair in object, that is pointed
              to by iter, to value.

       int json_object_iter_set_new(json_t *object, void *iter, json_t *value)
              Like json_object_iter_set(), but steals the reference to  value.
              This  is  useful  when value is newly created and not used after
              the call.

       void *json_object_key_to_iter(const char *key)
              Like json_object_iter_at(), but much faster. Only works for val-
              ues  returned  by  json_object_iter_key(). Using other keys will
              lead to segfaults. This function is used internally to implement
              json_object_foreach().

              New in version 2.3.


              The iteration protocol can be used for example as follows:

              /* obj is a JSON object */
              const char *key;
              json_t *value;

              void *iter = json_object_iter(obj);
              while(iter)
              {
                  key = json_object_iter_key(iter);
                  value = json_object_iter_value(iter);
                  /* use key and value ... */
                  iter = json_object_iter_next(obj, iter);
              }

       void json_object_seed(size_t seed)
              Seed  the  hash function used in Jansson's hashtable implementa-
              tion.  The seed is used to randomize the hash function  so  that
              an attacker cannot control its output.

              If seed is 0, Jansson generates the seed itselfy by reading ran-
              dom data from the operating  system's  entropy  sources.  If  no
              entropy sources are available, falls back to using a combination
              of the current timestamp (with microsecond precision  if  possi-
              ble) and the process ID.

              If  called at all, this function must be called before any calls
              to json_object(), either explicit or implicit. If this  function
              is  not  called  by  the  user,  the first call to json_object()
              (either explicit or  implicit)  seeds  the  hash  function.  See
              portability-thread-safety for notes on thread safety.

              If  repeatable  results  are  required, for e.g. unit tests, the
              hash    function    can    be    "unrandomized"    by    calling
              json_object_seed()  with  a  constant  value on program startup,
              e.g.  json_object_seed(1).

              New in version 2.6.


   Error reporting
       Jansson uses a single struct type to  pass  error  information  to  the
       user.  See  sections apiref-decoding, apiref-pack and apiref-unpack for
       functions that pass error information using this struct.

       json_error_t

       char text[]
              The error message (in UTF-8), or an empty string if a message is
              not available.

       char source[]
              Source  of the error. This can be (a part of) the file name or a
              special identifier in angle brackers (e.g. <string>).

       int line
              The line number on which the error occurred.

       int column
              The column on which the error occurred. Note that  this  is  the
              character  column,  not  the byte column, i.e. a multibyte UTF-8
              character counts as one column.

       size_t position
              The position in bytes from the start of the input. This is  use-
              ful for debugging Unicode encoding problems.

              The  normal  use of json_error_t is to allocate it on the stack,
              and pass a pointer to a function. Example:

              int main() {
                  json_t *json;
                  json_error_t error;

                  json = json_load_file("/path/to/file.json", 0, &error);
                  if(!json) {
                      /* the error variable contains error information */
                  }
                  ...
              }

              Also note that if the call succeeded (json != NULL in the  above
              example),  the contents of error are generally left unspecified.
              The decoding functions write to the position member also on suc-
              cess. See apiref-decoding for more info.

              All  functions  also accept NULL as the json_error_t pointer, in
              which case no error information is returned to the caller.

   Encoding
       This sections describes the functions that can be used to encode values
       to  JSON.  By default, only objects and arrays can be encoded directly,
       since they are the only valid root values of a JSON  text.   To  encode
       any JSON value, use the JSON_ENCODE_ANY flag (see below).

       By  default,  the  output  has no newlines, and spaces are used between
       array and object elements for a readable output. This behavior  can  be
       altered  by  using  the  JSON_INDENT  and  JSON_COMPACT flags described
       below. A newline is never appended to the end of the encoded JSON data.

       Each function takes a flags parameter that controls some aspects of how
       the  data  is encoded. Its default value is 0. The following macros can
       be ORed together to obtain flags.

       JSON_INDENT(n)
              Pretty-print the result, using newlines between array and object
              items,  and  indenting  with  n spaces. The valid range for n is
              between 0 and 31 (inclusive), other values result  in  an  unde-
              fined  output. If JSON_INDENT is not used or n is 0, no newlines
              are inserted between array and object items.

              The JSON_MAX_INDENT constant  defines  the  maximum  indentation
              that can be used, and its value is 31.

              Changed in version 2.7: Added JSON_MAX_INDENT.


       JSON_COMPACT
              This  flag enables a compact representation, i.e. sets the sepa-
              rator between array and object items to "," and  between  object
              keys  and  values  to  ":". Without this flag, the corresponding
              separators are ", " and ": " for more readable output.

       JSON_ENSURE_ASCII
              If this flag is used, the output is guaranteed to  consist  only
              of  ASCII  characters.  This  is achived by escaping all Unicode
              characters outside the ASCII range.

       JSON_SORT_KEYS
              If this flag is used, all the objects in output  are  sorted  by
              key.   This  is useful e.g. if two JSON texts are diffed or vis-
              ually compared.

       JSON_PRESERVE_ORDER
              If this flag is used, object keys in the output are sorted  into
              the  same order in which they were first inserted to the object.
              For example, decoding a JSON text and then  encoding  with  this
              flag preserves the order of object keys.

       JSON_ENCODE_ANY
              Specifying  this flag makes it possible to encode any JSON value
              on its own. Without it, only objects and arrays can be passed as
              the root value to the encoding functions.

              Note:  Encoding  any  value may be useful in some scenarios, but
              it's generally discouraged as it  violates  strict  compatiblity
              with  RFC 4627. If you use this flag, don't expect interoperati-
              bility with other JSON systems.

              New in version 2.1.


       JSON_ESCAPE_SLASH
              Escape the / characters in strings with \/.

              New in version 2.4.


       JSON_REAL_PRECISION(n)
              Output all real numbers with at most n digits of precision.  The
              valid  range  for  n  is between 0 and 31 (inclusive), and other
              values result in an undefined behavior.

              By default, the precision is 17,  to  correctly  and  losslessly
              encode all IEEE 754 double precision floating point numbers.

              New in version 2.7.


              The  following  functions  perform the actual JSON encoding. The
              result is in UTF-8.

       char *json_dumps(const json_t *root, size_t flags)
              Returns the JSON representation of root as a string, or NULL  on
              error.  flags is described above. The return value must be freed
              by the caller using free().

       int json_dumpf(const json_t *root, FILE *output, size_t flags)
              Write the JSON representation of  root  to  the  stream  output.
              flags  is described above. Returns 0 on success and -1 on error.
              If an error occurs, something may have already been  written  to
              output.  In  this  case, the output is undefined and most likely
              not valid JSON.

       int json_dump_file(const json_t *json, const char *path, size_t flags)
              Write the JSON representation of root to the file path. If  path
              already  exists,  it  is  overwritten. flags is described above.
              Returns 0 on success and -1 on error.

       json_dump_callback_t
              A typedef for a function that's called by json_dump_callback():

              typedef int (*json_dump_callback_t)(const char *buffer, size_t size, void *data);

              buffer points to a buffer containing a chunk of output, size  is
              the  length  of  the  buffer,  and  data  is  the  corresponding
              json_dump_callback() argument passed through.

              On error, the function should return -1  to  stop  the  encoding
              process. On success, it should return 0.

              New in version 2.2.


       int  json_dump_callback(const  json_t *json, json_dump_callback_t call-
       back, void *data, size_t flags)
              Call callback repeatedly, passing a chunk of the JSON  represen-
              tation  of  root each time. flags is described above.  Returns 0
              on success and -1 on error.

              New in version 2.2.


   Decoding
       This sections describes the functions that can be used to  decode  JSON
       text to the Jansson representation of JSON data. The JSON specification
       requires that a JSON text is either a serialized array or  object,  and
       this  requirement  is  also  enforced  with the following functions. In
       other words, the top level value in the JSON text being decoded must be
       either   array   or   object.   To  decode  any  JSON  value,  use  the
       JSON_DECODE_ANY flag (see below).

       See rfc-conformance for a discussion on Jansson's  conformance  to  the
       JSON specification. It explains many design decisions that affect espe-
       cially the behavior of the decoder.

       Each function takes a flags parameter that can be used to  control  the
       behavior  of  the decoder. Its default value is 0. The following macros
       can be ORed together to obtain flags.

       JSON_REJECT_DUPLICATES
              Issue a decoding error if any JSON object in the input text con-
              tains  duplicate  keys. Without this flag, the value of the last
              occurence of each key ends up in the result. Key equivalence  is
              checked  byte-by-byte,  without special Unicode comparison algo-
              rithms.

              New in version 2.1.


       JSON_DECODE_ANY
              By default, the decoder expects an array or object as the input.
              With  this  flag  enabled,  the  decoder  accepts any valid JSON
              value.

              Note: Decoding any value may be useful in  some  scenarios,  but
              it's  generally  discouraged  as it violates strict compatiblity
              with RFC 4627. If you use this flag, don't expect  interoperati-
              bility with other JSON systems.

              New in version 2.3.


       JSON_DISABLE_EOF_CHECK
              By default, the decoder expects that its whole input constitutes
              a valid JSON text, and issues an error  if  there's  extra  data
              after  the  otherwise  valid JSON input. With this flag enabled,
              the decoder stops after decoding a valid JSON array  or  object,
              and thus allows extra data after the JSON text.

              Normally,  reading  will  stop  when the last ] or } in the JSON
              input  is  encountered.  If  both   JSON_DISABLE_EOF_CHECK   and
              JSON_DECODE_ANY  flags  are used, the decoder may read one extra
              UTF-8 code unit (up to 4 bytes of input). For example,  decoding
              4true correctly decodes the integer 4, but also reads the t. For
              this reason, if reading multiple consecutive values that are not
              arrays  or  objects,  they  should  be separated by at least one
              whitespace character.

              New in version 2.1.


       JSON_DECODE_INT_AS_REAL
              JSON defines only one number type. Jansson distinguishes between
              ints  and reals. For more information see real-vs-integer.  With
              this flag enabled the decoder interprets  all  numbers  as  real
              values. Integers that do not have an exact double representation
              will silently result in a loss of precision. Integers that cause
              a double overflow will cause an error.

              New in version 2.5.


       JSON_ALLOW_NUL
              Allow  \u0000 escape inside string values. This is a safety mea-
              sure; If you know your input can contain  NUL  bytes,  use  this
              flag.  If you don't use this flag, you don't have to worry about
              NUL bytes inside strings unless you explicitly create themselves
              by   using  e.g.  json_stringn()  or  s#  format  specifier  for
              json_pack().

              Object keys cannot have embedded NUL bytes even if this flag  is
              used.

              New in version 2.6.


              Each function also takes an optional json_error_t parameter that
              is filled with error information if decoding  fails.  It's  also
              updated on success; the number of bytes of input read is written
              to its position field. This  is  especially  useful  when  using
              JSON_DISABLE_EOF_CHECK to read multiple consecutive JSON texts.

              New  in version 2.3: Number of bytes of input read is written to
              the position field of the json_error_t structure.


              If no error or position information  is  needed,  you  can  pass
              NULL.

              The following functions perform the actual JSON decoding.

       json_t        *json_loads(const        char *input,       size_t flags,
       json_error_t *error)
              Return value: New reference.

              Decodes the JSON string input and returns the array or object it
              contains,  or  NULL on error, in which case error is filled with
              information about the error. flags is described above.

       json_t  *json_loadb(const  char *buffer,  size_t buflen,  size_t flags,
       json_error_t *error)
              Return value: New reference.

              Decodes  the  JSON  string  buffer,  whose length is buflen, and
              returns the array or object it contains, or NULL  on  error,  in
              which  case  error  is  filled with information about the error.
              This is similar to json_loads() except that the  string  doesn't
              need to be null-terminated. flags is described above.

              New in version 2.1.


       json_t *json_loadf(FILE *input, size_t flags, json_error_t *error)
              Return value: New reference.

              Decodes  the  JSON text in stream input and returns the array or
              object it contains, or NULL on error, in  which  case  error  is
              filled  with  information  about  the  error. flags is described
              above.

              This function will start reading the input from  whatever  posi-
              tion the input file was, without attempting to seek first. If an
              error occurs, the file position will be left  indeterminate.  On
              success,  the  file  position  will  be at EOF, unless JSON_DIS-
              ABLE_EOF_CHECK flag was used. In this case,  the  file  position
              will be at the first character after the last ] or } in the JSON
              input. This allows calling json_loadf() on the same FILE  object
              multiple times, if the input consists of consecutive JSON texts,
              possibly separated by whitespace.

       json_t      *json_load_file(const       char *path,       size_t flags,
       json_error_t *error)
              Return value: New reference.

              Decodes  the  JSON  text  in  file path and returns the array or
              object it contains, or NULL on error, in  which  case  error  is
              filled  with  information  about  the  error. flags is described
              above.

       json_load_callback_t
              A typedef for a function that's called  by  json_load_callback()
              to read a chunk of input data:

              typedef size_t (*json_load_callback_t)(void *buffer, size_t buflen, void *data);

              buffer  points to a buffer of buflen bytes, and data is the cor-
              responding json_load_callback() argument passed through.

              On success, the function should return the number of bytes read;
              a  returned  value of 0 indicates that no data was read and that
              the end of file has been reached. On error, the function  should
              return (size_t)-1 to abort the decoding process.

              New in version 2.4.


       json_t  *json_load_callback(json_load_callback_t callback,  void *data,
       size_t flags, json_error_t *error)
              Return value: New reference.

              Decodes the JSON text produced by repeated  calls  to  callback,
              and  returns  the array or object it contains, or NULL on error,
              in which case error is filled with information about the  error.
              data  is  passed  through  to  callback  on  each call. flags is
              described above.

              New in version 2.4.


   Building Values
       This section describes functions that help to create, or pack,  complex
       JSON  values,  especially  nested objects and arrays. Value building is
       based on a format string that is used to tell the functions  about  the
       expected arguments.

       For  example,  the  format string "i" specifies a single integer value,
       while the format string "[ssb]" or the equivalent "[s, s, b]" specifies
       an array value with two strings and a boolean as its items:

       /* Create the JSON integer 42 */
       json_pack("i", 42);

       /* Create the JSON array ["foo", "bar", true] */
       json_pack("[ssb]", "foo", "bar", 1);

       Here's  the  full  list  of  format specifiers. The type in parentheses
       denotes the resulting JSON type, and the  type  in  brackets  (if  any)
       denotes  the  C  type that is expected as the corresponding argument or
       arguments.

       s (string) [const char *]
              Convert a NULL terminated UTF-8 string to a JSON string.

       s# (string) [const char *, int]
              Convert a UTF-8 buffer of a given length to a JSON string.

              New in version 2.5.


       s% (string) [const char *, size_t]
              Like s# but the length argument is of type size_t.

              New in version 2.6.


       + [const char *]
              Like s, but concatenate to the previous string. Only valid after
              s, s#, + or +#.

              New in version 2.5.


       +# [const char *, int]
              Like  s#,  but  concatenate  to  the previous string. Only valid
              after s, s#, + or +#.

              New in version 2.5.


       +% (string) [const char *, size_t]
              Like +# but the length argument is of type size_t.

              New in version 2.6.


       n (null)
              Output a JSON null value. No argument is consumed.

       b (boolean) [int]
              Convert a C int to JSON boolean  value.  Zero  is  converted  to
              false and non-zero to true.

       i (integer) [int]
              Convert a C int to JSON integer.

       I (integer) [json_int_t]
              Convert a C json_int_t to JSON integer.

       f (real) [double]
              Convert a C double to JSON real.

       o (any value) [json_t *]
              Output  any  given JSON value as-is. If the value is added to an
              array or object, the reference to  the  value  passed  to  o  is
              stolen by the container.

       O (any value) [json_t *]
              Like o, but the argument's reference count is incremented.  This
              is useful if you pack into an array or object and want  to  keep
              the reference for the JSON value consumed by O to yourself.

       [fmt] (array)
              Build  an  array with contents from the inner format string. fmt
              may contain objects and arrays, i.e. recursive value building is
              supported.

       {fmt} (object)
              Build  an object with contents from the inner format string fmt.
              The first, third, etc. format specifier  represent  a  key,  and
              must be a string (see s, s#, + and +# above), as object keys are
              always strings. The second, fourth, etc. format specifier repre-
              sent  a  value. Any value may be an object or array, i.e. recur-
              sive value building is supported.

              Whitespace, : and , are ignored.

              The following functions compose the value building API:

       json_t *json_pack(const char *fmt, ...)
              Return value: New reference.

              Build a new JSON value according to the format string  fmt.  For
              each  format specifier (except for {}[]n), one or more arguments
              are consumed and used to build the corresponding value.  Returns
              NULL on error.

       json_t     *json_pack_ex(json_error_t *error,    size_t flags,    const
       char *fmt, ...)

       json_t    *json_vpack_ex(json_error_t *error,    size_t flags,    const
       char *fmt, va_list ap)
              Return value: New reference.

              Like  json_pack(), but an in the case of an error, an error mes-
              sage is written to error, if it's not NULL. The flags  parameter
              is currently unused and should be set to 0.

              As  only  the errors in format string (and out-of-memory errors)
              can be caught by the packer, these two functions are most likely
              only useful for debugging format strings.

              More examples:

              /* Build an empty JSON object */
              json_pack("{}");

              /* Build the JSON object {"foo": 42, "bar": 7} */
              json_pack("{sisi}", "foo", 42, "bar", 7);

              /* Like above, ':', ',' and whitespace are ignored */
              json_pack("{s:i, s:i}", "foo", 42, "bar", 7);

              /* Build the JSON array [[1, 2], {"cool": true}] */
              json_pack("[[i,i],{s:b}]", 1, 2, "cool", 1);

              /* Build a string from a non-NUL terminated buffer */
              char buffer[4] = {'t', 'e', 's', 't'};
              json_pack("s#", buffer, 4);

              /* Concatentate strings together to build the JSON string "foobarbaz" */
              json_pack("s++", "foo", "bar", "baz");

   Parsing and Validating Values
       This  section  describes functions that help to validate complex values
       and extract, or unpack, data from them. Like building values,  this  is
       also based on format strings.

       While a JSON value is unpacked, the type specified in the format string
       is checked to match that of the JSON value. This is the validation part
       of  the  process. In addition to this, the unpacking functions can also
       check that all items of arrays and objects are unpacked. This check  be
       enabled  with  the format specifier ! or by using the flag JSON_STRICT.
       See below for details.

       Here's the full list of format  specifiers.  The  type  in  parentheses
       denotes  the JSON type, and the type in brackets (if any) denotes the C
       type whose address should be passed.

       s (string) [const char *]
              Convert a JSON string to a pointer to a  NULL  terminated  UTF-8
              string.   The   resulting   string   is   extracted   by   using
              json_string_value() internally, so it exists as  long  as  there
              are still references to the corresponding JSON string.

       s% (string) [const char *, size_t *]
              Convert  a  JSON  string to a pointer to a NULL terminated UTF-8
              string and its length.

              New in version 2.6.


       n (null)
              Expect a JSON null value. Nothing is extracted.

       b (boolean) [int]
              Convert a JSON boolean value to a C int, so that  true  is  con-
              verted to 1 and false to 0.

       i (integer) [int]
              Convert a JSON integer to C int.

       I (integer) [json_int_t]
              Convert a JSON integer to C json_int_t.

       f (real) [double]
              Convert a JSON real to C double.

       F (integer or real) [double]
              Convert a JSON number (integer or real) to C double.

       o (any value) [json_t *]
              Store a JSON value with no conversion to a json_t pointer.

       O (any value) [json_t *]
              Like O, but the JSON value's reference count is incremented.

       [fmt] (array)
              Convert  each item in the JSON array according to the inner for-
              mat string. fmt may contain objects and arrays,  i.e.  recursive
              value extraction is supporetd.

       {fmt} (object)
              Convert each item in the JSON object according to the inner for-
              mat string fmt. The first, third, etc. format  specifier  repre-
              sent  a key, and must be s. The corresponding argument to unpack
              functions is read as the object key.  The  second  fourth,  etc.
              format specifier represent a value and is written to the address
              given as the corresponding argument. Note that every other argu-
              ment is read from and every other is written to.

              fmt  may  contain  objects  and arrays as values, i.e. recursive
              value extraction is supporetd.

              New in version 2.3: Any s representing a  key  may  be  suffixed
              with  a  ?  to  make  the key optional. If the key is not found,
              nothing is extracted. See below for an example.


       !      This special format specifier is used to enable the  check  that
              all  object  and array items are accessed, on a per-value basis.
              It must appear inside an array or  object  as  the  last  format
              specifier  before  the  closing  bracket or brace. To enable the
              check globally, use the JSON_STRICT unpacking flag.

       *      This special format specifier is  the  opposite  of  !.  If  the
              JSON_STRICT  flag  is  used, * can be used to disable the strict
              check on a per-value basis. It must appear inside  an  array  or
              object  as  the last format specifier before the closing bracket
              or brace.

              Whitespace, : and , are ignored.

              The following functions compose the parsing and validation API:

       int json_unpack(json_t *root, const char *fmt, ...)
              Validate and unpack the JSON value root according to the  format
              string fmt. Returns 0 on success and -1 on failure.

       int   json_unpack_ex(json_t *root,  json_error_t *error,  size_t flags,
       const char *fmt, ...)

       int  json_vunpack_ex(json_t *root,  json_error_t *error,  size_t flags,
       const char *fmt, va_list ap)
              Validate  and unpack the JSON value root according to the format
              string fmt. If an error occurs and  error  is  not  NULL,  write
              error information to error. flags can be used to control the be-
              haviour of the unpacker, see below for the flags. Returns  0  on
              success and -1 on failure.

              NOTE: The first argument of all unpack functions is json_t *root
              instead of const json_t *root, because the use of O format spec-
              ifier  causes  the reference count of root, or some value reach-
              able from root, to be increased. Furthermore, the o format spec-
              ifier may be used to extract a value as-is, which allows modify-
              ing the structure or contents of a value reachable from root.

              If the O and o format specifiers are not  used,  it's  perfectly
              safe  to  cast  a const json_t * variable to plain json_t * when
              used with these functions.

              The following unpacking flags are available:

       JSON_STRICT
              Enable the extra validation step checking that  all  object  and
              array  items  are  unpacked. This is equivalent to appending the
              format specifier ! to the end of every array and object  in  the
              format string.

       JSON_VALIDATE_ONLY
              Don't extract any data, just validate the JSON value against the
              given format string. Note that object keys must still be  speci-
              fied after the format string.

              Examples:

              /* root is the JSON integer 42 */
              int myint;
              json_unpack(root, "i", &myint);
              assert(myint == 42);

              /* root is the JSON object {"foo": "bar", "quux": true} */
              const char *str;
              int boolean;
              json_unpack(root, "{s:s, s:b}", "foo", &str, "quux", &boolean);
              assert(strcmp(str, "bar") == 0 && boolean == 1);

              /* root is the JSON array [[1, 2], {"baz": null} */
              json_error_t error;
              json_unpack_ex(root, &error, JSON_VALIDATE_ONLY, "[[i,i], {s:n}]", "baz");
              /* returns 0 for validation success, nothing is extracted */

              /* root is the JSON array [1, 2, 3, 4, 5] */
              int myint1, myint2;
              json_unpack(root, "[ii!]", &myint1, &myint2);
              /* returns -1 for failed validation */

              /* root is an empty JSON object */
              int myint = 0, myint2 = 0;
              json_unpack(root, "{s?i, s?[ii]}",
                          "foo", &myint1,
                          "bar", &myint2, &myint3);
              /* myint1, myint2 or myint3 is no touched as "foo" and "bar" don't exist */

   Equality
       Testing for equality of two JSON values cannot, in general, be achieved
       using the == operator. Equality in the terms of the == operator  states
       that the two json_t pointers point to exactly the same JSON value. How-
       ever, two JSON values can be equal not only if  they  are  exactly  the
       same value, but also if they have equal "contents":

       o Two  integer or real values are equal if their contained numeric val-
         ues are equal. An integer value is  never  equal  to  a  real  value,
         though.

       o Two  strings  are  equal  if their contained UTF-8 strings are equal,
         byte by byte. Unicode comparison algorithms are not implemented.

       o Two arrays are equal if they have the same  number  of  elements  and
         each element in the first array is equal to the corresponding element
         in the second array.

       o Two objects are equal if they have exactly  the  same  keys  and  the
         value  for  each key in the first object is equal to the value of the
         corresponding key in the second object.

       o Two true, false or null values have no "contents", so they are  equal
         if their types are equal. (Because these values are singletons, their
         equality can actually be tested with ==.)

         The following function can be used to test whether  two  JSON  values
         are equal.

       int json_equal(json_t *value1, json_t *value2)
         Returns  1 if value1 and value2 are equal, as defined above.  Returns
         0 if they are inequal or one or both of the pointers are NULL.

   Copying
       Because of reference  counting,  passing  JSON  values  around  doesn't
       require  copying  them.  But  sometimes a fresh copy of a JSON value is
       needed. For example, if you need to modify an array, but still want  to
       use the original afterwards, you should take a copy of it first.

       Jansson  supports  two  kinds  of copying: shallow and deep. There is a
       difference between these methods only for arrays and  objects.  Shallow
       copying  only  copies  the first level value (array or object) and uses
       the same child values in the copied value. Deep copying makes  a  fresh
       copy  of the child values, too. Moreover, all the child values are deep
       copied in a recursive fashion.

       json_t *json_copy(json_t *value)
              Return value: New reference.

              Returns a shallow copy of value, or NULL on error.

       json_t *json_deep_copy(const json_t *value)
              Return value: New reference.

              Returns a deep copy of value, or NULL on error.

   Custom Memory Allocation
       By default, Jansson uses malloc() and  free()  for  memory  allocation.
       These functions can be overridden if custom behavior is needed.

       json_malloc_t
              A typedef for a function pointer with malloc()'s signature:

              typedef void *(*json_malloc_t)(size_t);

       json_free_t
              A typedef for a function pointer with free()'s signature:

              typedef void (*json_free_t)(void *);

       void json_set_alloc_funcs(json_malloc_t malloc_fn, json_free_t free_fn)
              Use malloc_fn instead of malloc() and free_fn instead of free().
              This function has to be called before any  other  Jansson's  API
              functions  to  ensure  that  all  memory operations use the same
              functions.

              Examples:

              Circumvent problems with different CRT heaps on Windows by using
              application's malloc() and free():

              json_set_alloc_funcs(malloc, free);

              Use the Boehm's conservative garbage collector for memory opera-
              tions:

              json_set_alloc_funcs(GC_malloc, GC_free);

              Allow storing sensitive data (e.g. passwords or encryption keys)
              in JSON structures by zeroing all memory when freed:

              static void *secure_malloc(size_t size)
              {
                  /* Store the memory area size in the beginning of the block */
                  void *ptr = malloc(size + 8);
                  *((size_t *)ptr) = size;
                  return ptr + 8;
              }

              static void secure_free(void *ptr)
              {
                  size_t size;

                  ptr -= 8;
                  size = *((size_t *)ptr);

                  guaranteed_memset(ptr, 0, size + 8);
                  free(ptr);
              }

              int main()
              {
                  json_set_alloc_funcs(secure_malloc, secure_free);
                  /* ... */
              }

              For  more information about the issues of storing sensitive data
              in                          memory,                          see
              http://www.dwheeler.com/secure-programs/Secure-Programs-HOWTO/protect-secrets.html.
              The page also explains the guaranteed_memset() function used  in
              the example and gives a sample implementation for it.

   Changes in Jansson
   Version 2.7
       Released 2014-10-02

       o New features:

       o json_pack() and friends: Add format specifiers s% and +% for a size_t
         string length (#141).

       o json_unpack() and friends: Add format specifier s% for unpacking  the
         string length along with the string itself (#141).

       o Add    length-aware    string    constructors    json_stringn()   and
         json_stringn_nocheck(),      length-aware       string       mutators
         json_string_setn() and json_string_setn_nocheck(), and a function for
         getting string's length json_string_length() (#141, #143).

       o Support \u0000 escapes in the decoder. The support can be enabled  by
         using the JSON_ALLOW_NUL decoding flag (#141).

       o Add json_boolean_value() as an alias for json_is_true() (#146).

       o Add JSON_REAL_PRECISION encoding flag/macro for controlling real num-
         ber precision (#178).

       o Define the maximum indentation as JSON_MAX_INDENT (#191).

       o Bug fixes:

       o Some malformed \uNNNN escapes could crash the decoder with an  asser-
         tion failure.

       o Avoid  integer  overflows with very long strings in UTF-8 decoder and
         hashtable.

       o Check for NULL key in json_object_get() and json_object_del() (#151).

       o Enhance hashtable seeding on Windows (#162).

       o json_unpack(): Allow mixing JSON_STRICT  with  optional  keys  (#162,
         #163).

       o Fix int/int32 mismatch (#142).

       o Parse subnormal numbers correctly (#202).

       o Build:

       o Remove  VS2010  build  files. CMake should be used on Windows instead
         (#165).

       o Fix CMake build flags for MinGW (#193).

       o Add CMake config files for find_package.  Rename  config.h  to  jans-
         son_private_config.h (#157, #159).

       o Make Valgrind checks work with CMake (#160).

       o Fix feature checks to use correct __ATOMIC flags.

       o Fix CMake checks for uint16_t and uint8_t support (#177).

       o Make Jansson build on SmartOS/Solaris (#171).

       o Work around a GCC bug on Solaris (#175).

       o Fix autoreconf on Debian (#182).

       o Don't use GNU make specific export for global AM_CFLAGS (#203, #204).

       o Fix building on Android using the supplied Android.mk (#166, #174).

       o Android.mk: Add -DHAVE_STDINT_H to LOCAL_CFLAGS (#200).

       o Documentation:

       o Document JANSSON_BUILD_SHARED_LIBS CMake option (#187).

       o Tests:

       o Close file handles correctly (#198).

       o Other changes:

       o \uNNNN escapes are now encoded in upper case for better readability.

       o Enable usage of AddressSanitizer (#180).

   Version 2.6
       Released 2014-02-11

       o Security:

       o CVE-2013-6401: The hash function used by the hashtable implementation
         has been changed, and is automatically seeded with random  data  when
         the  first  JSON  object  is  created. This prevents an attacker from
         causing large  JSON  objects  with  specially  crafted  keys  perform
         poorly.

       o New features:

       o json_object_seed(): Set the seed value of the hash function.

       o Bug fixes:

       o Include CMake specific files in the release tarball.

       o Documentation:

       o Fix  tutorial  source  to  send  a  User-Agent  header,  which is now
         required by the GitHub API.

       o Set all memory to zero in secure_free() example.

   Version 2.5
       Released 2013-09-19

       o New features:

       o json_pack() and friends: Add format specifiers s#, + and +#.

       o Add JSON_DECODE_INT_AS_REAL decoding flag to  treat  all  numbers  as
         real in the decoder (#123).

       o Add json_array_foreach(), paralleling json_object_foreach() (#118).

       o Bug fixes:

       o json_dumps()   and   friends:   Don't  crash  if  json  is  NULL  and
         JSON_ENCODE_ANY is set.

       o Fix a theoretical integer overflow in jsonp_strdup().

       o Fix l_isxdigit() macro (#97).

       o Fix an off-by-one error in json_array_remove().

       o Build:

       o Support CMake in addition to GNU Autotools (#106, #107,  #112,  #115,
         #120, #127).

       o Support building for Android (#109).

       o Don't use -Werror by default.

       o Support building and testing with VPATH (#93).

       o Fix compilation when NDEBUG is defined (#128)

       o Tests:

       o Fix a refleak in test/bin/json_process.c.

       o Documentation:

       o Clarify the return value of json_load_callback_t().

       o Document how to circumvent problems with separate heaps on Windows.

       o Fix memory leaks and warnings in github_commits.c.

       o Use json_decref() properly in tutorial.

       o Other:

       o Make it possible to forward declare struct json_t.

   Version 2.4
       Released 2012-09-23

       o New features:

       o Add  json_boolean()  macro  that returns the JSON true or false value
         based on its argument (#86).

       o Add json_load_callback() that calls a callback function repeatedly to
         read the JSON input (#57).

       o Add  JSON_ESCAPE_SLASH  encoding  flag  to escape all occurences of /
         with \/.

       o Bug fixes:

       o Check for and reject NaN and Inf values  for  reals.  Encoding  these
         values resulted in invalid JSON.

       o Fix json_real_set() to return -1 on error.

       o Build:

       o Jansson  now  builds on Windows with Visual Studio 2010, and includes
         solution and project files in win32/vs2010/ directory.

       o Fix build warnings (#77, #78).

       o Add -no-undefined to LDFLAGS (#90).

       o Tests:

       o Fix the symbol exports test on Linux/PPC64 (#88).

       o Documentation:

       o Fix typos (#73, #84).

   Version 2.3.1
       Released 2012-04-20

       o Build issues:

       o Only use long long if strtoll() is also available.

       o Documentation:

       o Fix the names of library version constants in documentation. (#52)

       o Change the tutorial to use GitHub API v3. (#65)

       o Tests:

       o Make some tests locale independent. (#51)

       o Distribute the library exports test in the tarball.

       o Make test run on shells that don't support the export FOO=bar syntax.

   Version 2.3
       Released 2012-01-27

       o New features:

       o json_unpack() and friends: Add support for optional object keys  with
         the {s?o} syntax.

       o Add  json_object_update_existing()  and json_object_update_missing(),
         for updating only existing keys or only adding  missing  keys  to  an
         object. (#37)

       o Add json_object_foreach() for more convenient iteration over objects.
         (#45, #46)

       o When decoding JSON, write the number of bytes  that  were  read  from
         input to error.position also on success. This is handy with JSON_DIS-
         ABLE_EOF_CHECK.

       o Add support for decoding any JSON value, not just arrays or  objects.
         The  support  is  enabled with the new JSON_DECODE_ANY flag. Patch by
         Andrea Marchesini. (#4)

       o Bug fixes

       o Avoid problems with object's serial number  growing  too  big.  (#40,
         #41)

       o Decoding  functions  now  return  NULL if the first argument is NULL.
         Patch by Andrea Marchesini.

       o Include jansson_config.h.win32 in the distribution tarball.

       o Remove + and leading zeros from exponents in the encoder.  (#39)

       o Make Jansson build and work on MinGW. (#39, #38)

       o Documentation

       o Note that the same JSON values must not be  encoded  in  parallel  by
         separate threads. (#42)

       o Document MinGW support.

   Version 2.2.1
       Released 2011-10-06

       o Bug fixes:

       o Fix real number encoding and decoding under non-C locales. (#32)

       o Fix identifier decoding under non-UTF-8 locales. (#35)

       o json_load_file(): Open the input file in binary mode for maximum com-
         patiblity.

       o Documentation:

       o Clarify the lifecycle of the result of the s fromat of json_unpack().
         (#31)

       o Add some portability info. (#36)

       o Little clarifications here and there.

       o Other:

       o Some style fixes, issues detected by static analyzers.

   Version 2.2
       Released 2011-09-03

       o New features:

       o json_dump_callback():  Pass the encoder output to a callback function
         in chunks.

       o Bug fixes:

       o json_string_set(): Check that target is a string  and  value  is  not
         NULL.

       o Other:

       o Documentation typo fixes and clarifications.

   Version 2.1
       Released 2011-06-10

       o New features:

       o json_loadb(): Decode a string with a given size, useful if the string
         is not null terminated.

       o Add JSON_ENCODE_ANY encoding flag to allow encoding any  JSON  value.
         By default, only arrays and objects can be encoded. (#19)

       o Add JSON_REJECT_DUPLICATES decoding flag to issue a decoding error if
         any JSON object in the input contins duplicate keys. (#3)

       o Add JSON_DISABLE_EOF_CHECK decoding flag to  stop  decoding  after  a
         valid JSON input. This allows other data after the JSON data.

       o Bug fixes:

       o Fix  an  additional  memory  leak  when  memory  allocation  fails in
         json_object_set() and friends.

       o Clear errno before calling strtod() for better portability. (#27)

       o Building:

       o Avoid set-but-not-used warning/error in a test. (#20)

       o Other:

       o Minor clarifications to documentation.

   Version 2.0.1
       Released 2011-03-31

       o Bug fixes:

       o Replace a few malloc() and free() calls with their counterparts  that
         support custom memory management.

       o Fix object key hashing in json_unpack() strict checking mode.

       o Fix the parentheses in JANSSON_VERSION_HEX macro.

       o Fix json_object_size() return value.

       o Fix a few compilation issues.

       o Portability:

       o Enhance portability of va_copy().

       o Test framework portability enhancements.

       o Documentation:

       o Distribute doc/upgrading.rst with the source tarball.

       o Build documentation in strict mode in make distcheck.

   Version 2.0
       Released 2011-02-28

       This  release  is  backwards  incompatible with the 1.x release series.
       See the chapter "Upgrading from older versions"  in  documentation  for
       details.

       o Backwards incompatible changes:

       o Unify  unsigned  integer usage in the API: All occurences of unsigned
         int and unsigned long have been replaced with size_t.

       o Change JSON integer's underlying type to the  widest  signed  integer
         type  available,  i.e.  long  long if it's supported, otherwise long.
         Add a typedef json_int_t that defines the type.

       o Change the maximum indentation depth to 31 spaces  in  encoder.  This
         frees  up  bits  from  the  flags  parameter  of  encoding  functions
         json_dumpf(), json_dumps() and json_dump_file().

       o For future needs, add a flags parameter  to  all  decoding  functions
         json_loadf(), json_loads() and json_load_file().

       o New features

       o json_pack(),  json_pack_ex(),  json_vpack_ex():  Create  JSON  values
         based on a format string.

       o json_unpack(),  json_unpack_ex(),  json_vunpack_ex():  Simple   value
         extraction and validation functionality based on a format string.

       o Add column, position and source fields to the json_error_t struct.

       o Enhance error reporting in the decoder.

       o JANSSON_VERSION  et  al.:  Preprocessor  constants  that  define  the
         library version.

       o json_set_alloc_funcs(): Set custom memory allocation functions.

       o Fix many portability issues, especially on Windows.

       o Configuration

       o Add file jansson_config.h that contains site specific  configuration.
         It's created automatically by the configure script, or can be created
         by hand if the configure script  cannot  be  used.   The  file  jans-
         son_config.h.win32  can be used without modifications on Windows sys-
         tems.

       o Add a section to documentation describing how  to  build  Jansson  on
         Windows.

       o Documentation now requires Sphinx 1.0 or newer.

   Version 1.3
       Released 2010-06-13

       o New functions:

       o json_object_iter_set(),   json_object_iter_set_new():  Change  object
         contents while iterating over it.

       o json_object_iter_at(): Return an iterator that points to  a  specific
         object item.

       o New encoding flags:

       o JSON_PRESERVE_ORDER: Preserve the insertion order of object keys.

       o Bug fixes:

       o Fix  an  error that occured when an array or object was first encoded
         as empty, then populated with some data, and then re-encoded

       o Fix the situation like above, but when the first encoding resulted in
         an error

       o Documentation:

       o Clarify the documentation on reference stealing, providing an example
         usage pattern

   Version 1.2.1
       Released 2010-04-03

       o Bug fixes:

       o Fix reference counting on true, false and null

       o Estimate real number underflows in decoder with 0.0 instead of  issu-
         ing an error

       o Portability:

       o Make int32_t available on all systems

       o Support compilers that don't have the inline keyword

       o Require Autoconf 2.60 (for int32_t)

       o Tests:

       o Print test names correctly when VERBOSE=1

       o test/suites/api: Fail when a test fails

       o Enhance tests for iterators

       o Enhance tests for decoding texts that contain null bytes

       o Documentation:

       o Don't remove changes.rst in make clean

       o Add a chapter on RFC conformance

   Version 1.2
       Released 2010-01-21

       o New functions:

       o json_equal(): Test whether two JSON values are equal

       o json_copy()  and  json_deep_copy():  Make  shallow and deep copies of
         JSON values

       o Add a version of all functions taking a string argument that  doesn't
         check       for       valid       UTF-8:       json_string_nocheck(),
         json_string_set_nocheck(),                 json_object_set_nocheck(),
         json_object_set_new_nocheck()

       o New encoding flags:

       o JSON_SORT_KEYS: Sort objects by key

       o JSON_ENSURE_ASCII: Escape all non-ASCII Unicode characters

       o JSON_COMPACT:  Use  a compact representation with all unneeded white-
         space stripped

       o Bug fixes:

       o Revise and unify whitespace usage  in  encoder:  Add  spaces  between
         array and object items, never append newline to output.

       o Remove    const    qualifier    from    the   json_t   parameter   in
         json_string_set(), json_integer_set() and json_real_set().

       o Use int32_t internally for representing Unicode code points  (int  is
         not enough on all platforms)

       o Other changes:

       o Convert  CHANGES  (this file) to reStructured text and add it to HTML
         documentation

       o The test system has been refactored. Python is no longer required  to
         run the tests.

       o Documentation can now be built by invoking make html

       o Support for pkg-config

   Version 1.1.3
       Released 2009-12-18

       o Encode  reals  correctly,  so that first encoding and then decoding a
         real always produces the same value

       o Don't export private symbols in libjansson.so

   Version 1.1.2
       Released 2009-11-08

       o Fix a bug where an error message was not produced if the  input  file
         could not be opened in json_load_file()

       o Fix  an assertion failure in decoder caused by a minus sign without a
         digit after it

       o Remove an unneeded include of stdint.h in jansson.h

   Version 1.1.1
       Released 2009-10-26

       o All documentation files were not distributed with v1.1;  build  docu-
         mentation in make distcheck to prevent this in the future

       o Fix v1.1 release date in CHANGES

   Version 1.1
       Released 2009-10-20

       o API additions and improvements:

       o Extend array and object APIs

       o Add functions to modify integer, real and string values

       o Improve argument validation

       o Use unsigned int instead of uint32_t for encoding flags

       o Enhance documentation

       o Add getting started guide and tutorial

       o Fix some typos

       o General clarifications and cleanup

       o Check for integer and real overflows and underflows in decoder

       o Make singleton values thread-safe (true, false and null)

       o Enhance circular reference handling

       o Don't define -std=c99 in AM_CFLAGS

       o Add C++ guards to jansson.h

       o Minor performance and portability improvements

       o Expand test coverage

   Version 1.0.4
       Released 2009-10-11

       o Relax Autoconf version requirement to 2.59

       o Make Jansson compile on platforms where plain char is unsigned

       o Fix API tests for object

   Version 1.0.3
       Released 2009-09-14

       o Check for integer and real overflows and underflows in decoder

       o Use  the Python json module for tests, or simplejson if the json mod-
         ule is not found

       o Distribute changelog (this file)

   Version 1.0.2
       Released 2009-09-08

       o Handle EOF correctly in decoder

   Version 1.0.1
       Released 2009-09-04

       o Fixed broken json_is_boolean()

   Version 1.0
       Released 2009-08-25

       o Initial release

       o genindex

       o search


AUTHOR
       Petri Lehtinen

COPYRIGHT
       2009-2014, Petri Lehtinen



ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | library/jansson  |
       +---------------+------------------+
       |Stability      | Volatile         |
       +---------------+------------------+
NOTES
       This    software    was    built    from    source     available     at
       https://github.com/oracle/solaris-userland.    The  original  community
       source was downloaded from  http://www.digip.org/jansson/releases/jans-
       son-2.10.tar.gz

       Further information about this software can be found on the open source
       community website at http://www.digip.org/jansson.



2.7                            October 28, 2014               LIBJANSSON(3lib)