pathconf()

NAME

pathconf(), fpathconf() - get configurable pathname variables

SYNOPSIS 

#include <unistd.h>


long pathconf (const char *path, int name)
long fpathconf (int fd, int name)

DESCRIPTION

The pathconf(2) and fpathconf(2) functions provides a method for applications to determine the current value of a configurable system limit or option variable associated with a pathname or file descriptor.

For pathconf(2), the path argument is the name of a file or directory. For fpathconf(2), the fd argument is an open file descriptor. The name argument specifies the system variable to be queried. Symbolic constants for each name value are found in the include file <unistd.h>.

The available values are as follows:

_PC_LINK_MAX
The maximum file link count.
_PC_MAX_CANON
The maximum number of bytes in terminal canonical input line.
_PC_MAX_INPUT
The minimum maximum number of bytes for which space is available in a terminal input queue.
_PC_NAME_MAX
The maximum number of bytes in a file name.
_PC_PATH_MAX
The maximum number of bytes in a pathname.
_PC_PIPE_BUF
The maximum number of bytes which will be written atomically to a pipe.
_PC_CHOWN_RESTRICTED
Return 1 if appropriate privileges are required for the chown(2) system call, otherwise 0.
_PC_NO_TRUNC
Return 1 if file names longer than {KERN_NAME_MAX} are truncated.
_PC_VDISABLE
Returns the terminal character disabling value.

RETURN VALUES

If the call to pathconf(2) or fpathconf(2) is not successful, -1 is returned and errno is set appropriately. Otherwise, if the variable is associated with functionality that does not have a limit in the system, -1 is returned and errno is not modified. Otherwise, the current variable value is returned.

ERRORS

If any of the following conditions occur, the pathconf(2) and fpathconf(2) functions shall return -1 and set errno to the corresponding value.

[EINVAL]
The value of the name argument is invalid.
[EINVAL]
The implementation does not support an association of the variable name with the associated file.
The pathconf(2) call will fail if:
[EACCES]
Search permission is denied for a component of the path prefix.
[EIO]
An I/O error occurred while reading from or writing to the file system.
[ELOOP]
Too many symbolic links were encountered in translating the pathname.
[ENAMETOOLONG]
A component of a pathname exceeded {NAME_MAX} characters, or an entire pathname exceeded {PATH_MAX} characters.
[ENOENT]
The named file does not exist.
[ENOTDIR]
A component of the path prefix is not a directory.

The fpathconf(2) call will fail if:

[EBADF]
fd is not a valid open file descriptor.
[EIO]
An I/O error occurred while reading from or writing to the file system.