PATHCONF(2)                 BSD System Calls Manual                PATHCONF(2)

NAME
     fpathconf, pathconf -- get configurable pathname variables

SYNOPSIS
     #include <unistd.h>

     long
     fpathconf(int fildes, int name);

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

DESCRIPTION
     The pathconf() and fpathconf() functions provides 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 fildes 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.

     _PC_XATTR_SIZE_BITS
             Returns the number of bits used to store maximum extended
             attribute size in bytes.  For example, if the maximum attribute
             size supported by a file system is 128K, the value returned will
             be 18.  However a value 18 can mean that the maximum attribute
             size can be anywhere from (256KB - 1) to 128KB.  As a special
             case, the resource fork can have much larger size, and some file
             system specific extended attributes can have smaller and preset
             size; for example, Finder Info is always 32 bytes.

     _PC_MIN_HOLE_SIZE
             If a file system supports the reporting of holes (see lseek(2)),
             pathconf() and fpathconf() return a positive number that repre-
             sents the minimum hole size returned in bytes.  The offsets of
             holes returned will be aligned to this same value.  A special
             value of 1 is returned if the file system does not specify the
             minimum hole size but still reports holes.

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 variable
     value is returned.

ERRORS
     If any of the following conditions occur, the pathconf and fpathconf
     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.

     pathconf() will fail if:

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

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

     [ELOOP]         Too many symbolic links are encountered in translating
                     the pathname.  This is taken to be indicative of a loop-
                     ing symbolic link.

     [ENAMETOOLONG]  A component of a pathname exceeded 255 characters, or an
                     entire path name exceeded 1023 characters.

     [ENOENT]        The named file does not exist.

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

     fpathconf() will fail if:

     [EBADF]         fildes is not a valid open file descriptor.

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

SEE ALSO
     sysctl(3)

HISTORY
     The pathconf and fpathconf functions first appeared in 4.4BSD.

4th Berkeley Distribution        June 4, 1993        4th Berkeley Distribution