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man pages section 7: Standards, Environments, Macros, Character Sets, and Miscellany

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Updated: Wednesday, August 8, 2018
 
 

extendedFILE(7)

Name

extendedFILE - enable extended FILE facility usage

Synopsis

$ ulimit –n N_file_descriptors
$ LD_PRELOAD_32=/usr/lib/extendedFILE.so.1 application [arg...]

Description

The extendedFILE.so.1 is an obsolete, empty, library, kept for binary compatibility only.

Its old purpose, the use of file descriptors larger than 255 for 32 bit binaries, is now the default behavior in Oracle Solaris.

The libc library now handles the environment variables originally handled by extendedFILE.so.1

Environment Variables

The following environment variables control the behavior of the extended FILE facility.

_STDIO_BADFD

This variable takes an integer representing the lowest file descriptor, which will be made unallocatable. This action provides a protection mechanism so that applications that abuse interfaces do not experience silent data corruption. The value must be between 3 and 255 inclusive. By specifying none, the extended FILE facility is disabled.

_STDIO_BADFD_SIGNAL

This variable takes an integer or string representing any valid signal. See signal.h(3HEAD) for valid values or strings. This environment variable causes the specified signal to be sent to the application if certain exceptional cases are detected during the use of this facility. The default signal is SIGABRT.

Examples

Example 1 Limit the number of file descriptors and FILE standard I/O structures.

The following example limits the number of file descriptors and FILE standard I/O structures to 1000.

$ ulimit -n 1000
$ application [arg...]
Example 2 Enable the extended FILE facility.

The following example enables the extended FILE facility. See enable_extended_FILE_stdio(3C) for more examples.

$ ulimit -n 1000
$ _STDIO_BADFD=100 _STDIO_BADFD_SIGNAL=SIGABRT \
   application [arg ...]
Example 3 Set up the extended FILE environment and start the application.

The following shell script first sets up the proper extended FILE environment and then starts the application:

#!/bin/sh
if [ $# = 0 ]; then
   echo "usage: $0 application [arguments...]"
   exit 1
fi
ulimit -n 1000
# _STDIO_BADFD=196; export _STDIO_BADFD
# _STDIO_BADFD_SIGNAL=SIGABRT; export _STDIO_BADFD_SIGNAL
"$@"

Files

/usr/lib/extendedFILE.so.1

enabling library

Attributes

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

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Availability
system/library (32–bit)
Interface Stability
Committed
MT-Level
Safe

See Also

limit(1), open(2), enable_extended_FILE_stdio(3C), fdopen(3C), fopen(3C), popen(3C), stdio(3C), signal.h(3HEAD), attributes(7)

Warnings

The following displayed message

Application violated extended FILE safety mechanism.
Please read the man page for extendedFILE.
Aborting

is an indication that your application is modifying the internal file descriptor field of the FILE structure from standard I/O. Continued use of this extended FILE facility could harm your data. Do not use the extended FILE facility with your application.