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pathconf()

Return the value of a configurable limit

Synopsis:

#include <unistd.h>

long pathconf( const char* path, 
               int name );

Arguments:

path

The name of the file whose limit you want to get.

name

The name of the configurable limit; see below.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The pathconf() function returns a value of a configurable limit indicated by name, which is associated with the filename given in path.

Configurable limits are defined in <confname.h>, and include at least the following values:

_PC_LINK_MAX

Maximum value of a file's link count.

_PC_MAX_CANON

Maximum number of bytes in a terminal's canonical input buffer (edit buffer).

_PC_MAX_INPUT

Maximum number of bytes in a terminal's raw input buffer.

_PC_NAME_MAX

Maximum number of bytes in a file name (not including the terminating null).

_PC_PATH_MAX

Maximum number of bytes in a pathname (not including the terminating null).

_PC_PIPE_BUF

Maximum number of bytes that can be written atomically when writing to a pipe.

_PC_CHOWN_RESTRICTED

If defined (not -1), indicates that the use of the chown() function is restricted to a process with root privileges, and to changing the group ID of a file to the effective group ID of the process or to one of its supplementary group IDs.

_PC_NO_TRUNC

If defined (not -1), indicates that the use of pathname components longer than the value given by _PC_NAME_MAX will generate an error.

_PC_VDISABLE

If defined (not -1), this is the character value which can be used to individually disable special control characters in the termios control structure.

Returns:

The requested configurable limit, or -1 if an error occurs (errno is set).

Errors:

EACCES

Search permission is denied for a component of path.

EINVAL

The name argument is invalid, or the indicated limit isn't supported.

ELOOP

Too many levels of symbolic links or prefixes.

ENAMETOOLONG

The path argument, or a component of path, is too long.

ENOENT

The file doesn't exist.

ENOSYS

The pathconf() function isn't implemented for the filesystem specified in path.

ENOTDIR

A component of the path prefix isn't a directory.

Examples:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int main( void )
  {
    long value;

    value = pathconf( "/dev/con1", _PC_MAX_INPUT );
    printf( "Input buffer size is %ld bytes\n",
        value );
    return EXIT_SUCCESS;
  }

Classification:

POSIX 1003.1

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes

See also:

chown(), confstr(), errno, fpathconf(), sysconf(), termios

getconf in the Utilities Reference

Understanding System Limits chapter of the Neutrino User's Guide

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