fpathconf(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

FPATHCONF(3)            Linux Programmer's Manual           FPATHCONF(3)

NAME         top

       fpathconf, pathconf - get configuration values for files

SYNOPSIS         top

       #include <unistd.h>

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

DESCRIPTION         top

       fpathconf() gets a value for the configuration option name for
       the open file descriptor fd.

       pathconf() gets a value for configuration option name for the
       filename path.

       The corresponding macros defined in <unistd.h> are minimum
       values; if an application wants to take advantage of values which
       may change, a call to fpathconf() or pathconf() can be made,
       which may yield more liberal results.

       Setting name equal to one of the following constants returns the
       following configuration options:

       _PC_LINK_MAX
              The maximum number of links to the file.  If fd or path
              refer to a directory, then the value applies to the whole
              directory.  The corresponding macro is _POSIX_LINK_MAX.

       _PC_MAX_CANON
              The maximum length of a formatted input line, where fd or
              path must refer to a terminal.  The corresponding macro is
              _POSIX_MAX_CANON.

       _PC_MAX_INPUT
              The maximum length of an input line, where fd or path must
              refer to a terminal.  The corresponding macro is
              _POSIX_MAX_INPUT.

       _PC_NAME_MAX
              The maximum length of a filename in the directory path or
              fd that the process is allowed to create.  The
              corresponding macro is _POSIX_NAME_MAX.

       _PC_PATH_MAX
              The maximum length of a relative pathname when path or fd
              is the current working directory.  The corresponding macro
              is _POSIX_PATH_MAX.

       _PC_PIPE_BUF
              The maximum number of bytes that can be written atomically
              to a pipe of FIFO.  For fpathconf(), fd should refer to a
              pipe or FIFO.  For fpathconf(), path should refer to a
              FIFO or a directory; in the latter case, the returned
              value corresponds to FIFOs created in that directory.  The
              corresponding macro is _POSIX_PIPE_BUF.

       _PC_CHOWN_RESTRICTED
              This returns a positive value if the use of chown(2) and
              fchown(2) for changing a file's user ID is restricted to a
              process with appropriate privileges, and changing a file's
              group ID to a value other than the process's effective
              group ID or one of its supplementary group IDs is
              restricted to a process with appropriate privileges.
              According to POSIX.1, this variable shall always be
              defined with a value other than -1.  The corresponding
              macro is _POSIX_CHOWN_RESTRICTED.

              If fd or path refers to a directory, then the return value
              applies to all files in that directory.

       _PC_NO_TRUNC
              This returns nonzero if accessing filenames longer than
              _POSIX_NAME_MAX generates an error.  The corresponding
              macro is _POSIX_NO_TRUNC.

       _PC_VDISABLE
              This returns nonzero if special character processing can
              be disabled, where fd or path must refer to a terminal.

RETURN VALUE         top

       The return value of these functions is one of the following:

       *  On error, -1 is returned and errno is set to indicate the
          cause of the error (for example, EINVAL, indicating that name
          is invalid).

       *  If name corresponds to a maximum or minimum limit, and that
          limit is indeterminate, -1 is returned and errno is not
          changed.  (To distinguish an indeterminate limit from an
          error, set errno to zero before the call, and then check
          whether errno is nonzero when -1 is returned.)

       *  If name corresponds to an option, a positive value is returned
          if the option is supported, and -1 is returned if the option
          is not supported.

       *  Otherwise, the current value of the option or limit is
          returned.  This value will not be more restrictive than the
          corresponding value that was described to the application in
          <unistd.h> or <limits.h> when the application was compiled.

ERRORS         top

       EACCES (pathconf()) Search permission is denied for one of the
              directories in the path prefix of path.

       EBADF  (fpathconf()) fd is not a valid file descriptor.

       EINVAL name is invalid.

       EINVAL The implementation does not support an association of name
              with the specified file.

       ELOOP  (pathconf()) Too many symbolic links were encountered
              while resolving path.

       ENAMETOOLONG
              (pathconf()) path is too long.

       ENOENT (pathconf()) A component of path does not exist, or path
              is an empty string.

       ENOTDIR
              (pathconf()) A component used as a directory in path is
              not in fact a directory.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌────────────────────────┬───────────────┬─────────┐
       │Interface               Attribute     Value   │
       ├────────────────────────┼───────────────┼─────────┤
       │fpathconf(), pathconf() │ Thread safety │ MT-Safe │
       └────────────────────────┴───────────────┴─────────┘

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008.

NOTES         top

       Files with name lengths longer than the value returned for name
       equal to _PC_NAME_MAX may exist in the given directory.

       Some returned values may be huge; they are not suitable for
       allocating memory.

SEE ALSO         top

       getconf(1), open(2), statfs(2), confstr(3), sysconf(3)

COLOPHON         top

       This page is part of release 5.10 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

GNU                            2017-07-13                   FPATHCONF(3)

Pages that refer to this page: confstr(3)getcwd(3)realpath(3)sysconf(3)nfs(5)posixoptions(7)signal-safety(7)standards(7)