pathconf(2) - NetBSD Manual Pages

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PATHCONF(2)               NetBSD Programmer's Manual               PATHCONF(2)


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() 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 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.

     _PC_SYNC_IO
             Returns 1 of 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.


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 re-
     turned 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:

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

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

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

     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 IEEE Std1003.1-1990
     (``POSIX'').


HISTORY

     The pathconf and fpathconf functions first appeared in 4.4BSD.

NetBSD 1.4                      March 21, 1999                               2