man pages section 3: Basic Library Functions

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Updated: July 2014
 
 

getattrat(3C)

Name

fgetattr, fsetattr, getattrat, setattrat - get and set system attributes

Synopsis

#include <fcntl.h>
#include <sys/types.h>
#include <attr.h>
#include <sys/nvpair.h>

int fgetattr(int fildes, 
xattr_view_t view,nvlist_t **response);

int fsetattr(int
 fildes, xattr_view_t view,nvlist_t *
request)
int getattrat(int
 fildes, xattr_view_t view, const char *
filename,
     nvlist_t **response);
int setattrat(int
 fildes, xattr_view_t view, const char *
filename,
     nvlist_t *request);

Description

The fgetattr() function obtains an nvlist of system attribute information about an open file object specified by the file descriptor fildes, obtained from a successful open(2) , creat (2), dup(2), fcntl(2) , or pipe (2) function.

The getattrat() function first opens the extended attribute file specified by filename in the already opened file directory object specified by fildes. It then retrieves an nvlist of system attributes and their values from filename.

The response argument is allocated by either fgetattr() or getattrat(). The application must call nvlist_free (3NVPAIR) to deallocate the memory.

Upon successful completion, the nvlist will contain one nvpair for each of the system attributes associated with view. The list of views and the attributes associated with each view are listed below. Not all underlying file systems support all views and all attributes. The nvlist will not contain an nvpair for any attribute not supported by the underlying filesystem.

The fsetattr() function uses the nvlist pointed to by request to update one or more of the system attribute's information about an open file object specified by the file descriptor fildes, obtained from a successful open(), creat(), dup(), fcntl(), or pipe() function. The setattrat() function first opens the extended attribute file specified by filename in the already opened file directory object specified by fildes. It then uses the nvlist pointed to by request to update one or more of the system attributes of filename.

If completion is not successful then no system attribute information is updated.

The following chart lists the supported views, attributes, and data types for each view:

View
Attribute
Data type
XATTR_VIEW_READONLY
A_FSID
uint64_value
A_OPAQUE
boolean_value
A_AV_SCANSTAMP
uint8_array[]
XATTR_VIEW_READWRITE
A_READONLY
boolean_value
A_SENSITIVE
boolean_value
A_HIDDEN
boolean_value
A_SYSTEM
boolean_value
A_ARCHIVE
boolean_value
A_CRTIME
uint64_array[2]
A_NOUNLINK
boolean_value
A_IMMUTABLE
boolean_value
A_APPENDONLY
boolean_value
A_NODUMP
boolean_value
A_AV_QUARANTINED
boolean_value
A_AV_MODIFIED
boolean_value
A_OWNERSID
nvlist composed of uint32_value and string
A_GROUPSID
nvlist composed of uint32_value and string

Return Values

Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.

Errors

The fgetattr(), getattrat(), fsetattr(), and setattrat(), functions will fail if:

EBADF

The fildes argument is not a valid open file descriptor.

EINVAL

The underlying file system does not support extended file attributes.

EIO

An error occurred while reading from the file system.

The getattrat() and setattrat() functions will fail if:

EACCES

Search permission or write permission for filename is denied.

ENOENT

The filename argument does not name an existing file in the extended attribute directory represented by fildes.

EPERM

There are insufficient privileges to manipulate attributes.

Examples

Example 1 Obtain an nvlist of readonly system attributes for an open file object.

Use fgetattr() to obtain an nvlist of the readonly system attributes for the open file object represented by file descriptor fildes.

#include <fcntl.h>
#include <sys/types.h>
#include <attr.h>
#include <sys/nvpair.h>

nvlist_t *response;
nvpair_t *pair = NULL;

if (fgetattr(fildes, XATTR_VIEW_READONLY, &response)) {
             exit(1);
}
while (pair = nvlist_next_nvpair(response, pair)) {
    .
    .
    .
}
nvlist_free(response);

Example 2 Set the A_READONLY system attribute on an open file object.

Use fsetattr() to set the A_OPAQUE system attribute on the open file object represented by file descriptor fildes.

nvlist_t *request;
nvpair_t *pair = NULL;

if (nvlist_alloc(&request, NV_UNIQUE_NAME, 0) != 0) {
            exit(1);
}
if (nvlist_add_boolean_value(request, A_READONLY, 1) != 0) {
            exit(1);
}
if (fsetattr(fildes, XATTR_VIEW_READWRITE, request)) {
            exit(1);
}
Example 3 Obtain an nvlist of the read/write system attributes for a file.

Use getattrat() to obtain an nvlist of the read/write system attributes for the file named xattrfile in the extended attribute directory of the open file represented by file descriptor fildes.

nvlist_t *response;
nvpair_t *pair = NULL;

if (getattrat(fildes, XATTR_VIEW_READWRITE, "file", &response)) {
             exit(1);
}
while (pair = nvlist_next_nvpair(response, pair)) {
    .
    .
    .
}
nvlist_free(response);
Example 4 Set the A_APPENDONLY system attribute on a file.

Use setattrat() to set the A_APPENDONLY system attribute on the file named file in the extended attribute directory of the open file represented by file descriptor fildes.

nvlist_t *request;
nvpair_t *pair = NULL;

if (nvlist_alloc(&request, NV_UNIQUE_NAME, 0) != 0) {
            exit(1);
}
if (nvlist_add_boolean_value(request, A_APPENDONLY, 1) != 0) {
            exit(1);
}
if (setattrat(fildes, XATTR_VIEW_READWRITE, "file", request)) {
            exit(1);
     }

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
Committed
MT-Level
Safe

See Also

creat(2) , dup (2), fcntl(2) , fstat (2), fstatat(2) , open (2), pipe(2) , libnvpair (3LIB), attributes(5) , fsattr (5)