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pathconf(2)

NAME

     pathconf, fpathconf -- get configurable pathname variables

LIBRARY

     Standard C Library (libc, -lc)

SYNOPSIS

     #include <unistd.h>

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

     long
     fpathconf(int fd, int name);

DESCRIPTION

     The pathconf() and fpathconf() system calls provide a method for applica-
     tions to determine the current value of a configurable system limit or
     option variable associated with a pathname or file descriptor.

     For pathconf(), the path argument is the name of a file or directory.
     For fpathconf(), 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 privilege is required for the chown(2)
	     system call, otherwise 0.	IEEE Std 1003.1-2001 (``POSIX.1'')
	     requires appropriate privilege in all cases, but this behavior
	     was optional in prior editions of the standard.

     _PC_NO_TRUNC
	     Return greater than zero if attempts to use pathname components
	     longer than {NAME_MAX} will result in an [ENAMETOOLONG] error;
	     otherwise, such components will be truncated to {NAME_MAX}.  IEEE

     _PC_ASYNC_IO
	     Return 1 if asynchronous I/O is supported, otherwise 0.

     _PC_PRIO_IO
	     Returns 1 if prioritised I/O is supported for this file, other-
	     wise 0.

     _PC_SYNC_IO
	     Returns 1 if synchronised I/O is supported for this file, other-
	     wise 0.

     _PC_ALLOC_SIZE_MIN
	     Minimum number of bytes of storage allocated for any portion of a
	     file.

     _PC_FILESIZEBITS
	     Number of bits needed to represent the maximum file size.

     _PC_REC_INCR_XFER_SIZE
	     Recommended increment for file transfer sizes between
	     _PC_REC_MIN_XFER_SIZE and _PC_REC_MAX_XFER_SIZE.

     _PC_REC_MAX_XFER_SIZE
	     Maximum recommended file transfer size.

     _PC_REC_MIN_XFER_SIZE
	     Minimum recommended file transfer size.

     _PC_REC_XFER_ALIGN
	     Recommended file transfer buffer alignment.

     _PC_SYMLINK_MAX
	     Maximum number of bytes in a symbolic link.

     _PC_ACL_EXTENDED
	     Returns 1 if an Access Control List (ACL) can be set on the spec-
	     ified file, otherwise 0.

     _PC_ACL_PATH_MAX
	     Maximum number of ACL entries per file.

     _PC_CAP_PRESENT
	     Returns 1 if a capability state can be set on the specified file,
	     otherwise 0.

     _PC_INF_PRESENT
	     Returns 1 if an information label can be set on the specified
	     file, otherwise 0.

     _PC_MAC_PRESENT
	     Returns 1 if a Mandatory Access Control (MAC) label can be set on
	     the specified file, otherwise 0.

RETURN VALUES

     If the call to pathconf() or fpathconf() 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 vari-
     [EINVAL]		The implementation does not support an association of
			the variable name with the associated file.

     The pathconf() system call will fail if:

     [ENOTDIR]		A component of the path prefix is not a directory.

     [ENAMETOOLONG]	A component of a pathname exceeded {NAME_MAX} charac-
			ters (but see _PC_NO_TRUNC above), or an entire path
			name exceeded {PATH_MAX} characters.

     [ENOENT]		The named file does not exist.

     [EACCES]		Search permission is denied for a component of the
			path prefix.

     [ELOOP]		Too many symbolic links were encountered in translat-
			ing the pathname.

     [EIO]		An I/O error occurred while reading from or writing to
			the file system.

     The fpathconf() system call will fail if:

     [EBADF]		The fd argument is not a valid open file descriptor.

     [EIO]		An I/O error occurred while reading from or writing to
			the file system.

SEE ALSO

     sysctl(3)

HISTORY

     The pathconf() and fpathconf() system calls first appeared in 4.4BSD.

FreeBSD 5.4		       November 4, 2002 		   FreeBSD 5.4

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