pathconf(2) - NetBSD Manual Pages

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PATHCONF(2)               NetBSD System Calls Manual               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() functions 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 <unistd.h> header.

     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 filename, not including a termi-
             nating null character.

     _PC_PATH_MAX
             The maximum number of bytes in a pathname, including the termi-
             nating null character.

     _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 0 if filenames longer than {NAME_MAX} are silently trun-
             cated, or non-zero if an error is generated when {NAME_MAX} is
             exceeded.

     _PC_VDISABLE
             Returns the terminal character disabling value.

     _PC_SYNC_IO
             Returns 1 if synchronized I/O is supported, otherwise 0.

     _PC_FILESIZEBITS
             If the maximum size file that could ever exist on the mounted
             file system is maxsize, then the returned value is 2 plus the
             floor of the base 2 logarithm of maxsize.

     _PC_SYMLINK_MAX
             The maximum number of bytes in a symbolic link.

     _PC_2_SYMLINKS
             When referring to a directory the system supports the creation of
             symbolic links within that directory; for nondirectory files, the
             meaning of {_PC_2_SYMLINKS} is undefined.


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, or 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 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 path name exceeded {PATH_MAX} characters.

     [ENOENT]        The named file does not exist.

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

     fpathconf() 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.


SEE ALSO

     sysctl(3)


STANDARDS

     The pathconf() and fpathconf() functions conform to ISO/IEC 9945-1:1990
     (``POSIX.1'').


HISTORY

     The pathconf and fpathconf functions first appeared in 4.4BSD.

NetBSD 10.1                      July 26, 2010                     NetBSD 10.1