NAME

fpathconf, pathconf - get configurable pathname variables

SYNOPSIS

#include <unistd.h>

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

DESCRIPTION

The functions fpathconf and pathconf return the current value of a configurable limit or option associated with a file or directory. The path argument points to the pathname of a file or directory; fildes is an open file descriptor; and name is the symbolic constant (defined in <unistd.h>) representing the configurable system limit or option to be returned.

The values returned by pathconf and fpathconf depend on the type of file specified by path or fildes. The following table contains the symbolic constants supported by pathconf and fpathconf along with the POSIX defined return value. The return value is based on the type of file specified by path or fildes.

            ___________________________________
           |____Value_of__________|___See_Note|
           |______________________|___________|
           |______________________|______1____|
           | _PC_MAX_CANNON       |      2    |
           |______________________|___________|
           |______________________|______2____|
           | _PC_NAME_MAX         |     3,4   |
           |______________________|___________|
           |______________________|_____4,5___|
           | _PC_PIPE_BUF         |      6    |
           |______________________|___________|
           |______________________|______7____|
           | _PC_NO_TRUNC         |     3,4   |
           |______________________|___________|
           |______________________|______2____|

Notes:

1 If path or fildes refers to a directory, the value returned applies to the directory itself.

2 The behavior is undefined if path or fildes does not refer to a terminal file.

3 If path or fildes refers to a directory, the value returned applies to the filenames within the directory.

4 The behavior is undefined if path or fildes does not refer to a directory.

5 If path or fildes refers to a directory, the value returned is the maximum length of a relative pathname when the specified directory is the working directory.

6 If path or fildes refers to a pipe or FIFO, the value returned applies to the FIFO itself. If path or fildes refers to a directory, the value returned applies to any FIFOs that exist or can be created within the directory. If path or fildes refer to any other type of file, the behavior is undefined.

7 If path or fildes refers to a directory, the value returned applies to any files, other than directories, that exist or can be created within the directory.

The value of the configurable system limit or option specified by name does not change during the lifetime of the calling process.

fpathconf fails if the following is true:

EBADF  fildes is not a valid file descriptor.

pathconf fails if one or more of the following are true:

EACCES search permission is denied for a  component  of  the
       path prefix.

ELOOP too many symbolic links are encountered while translating path.

EMULTIHOP

components of path require hopping to multiple remote machines and file system type does not allow it.

ENAMETOOLONG

the length of a pathname exceeds {PATH_MAX}, or pathname component is longer than {NAME_MAX} while (_POSIX_NO_TRUNC) is in effect.

ENOENT path is needed for  the  command  specified  and  the
       named  file  does  not  exist or if the path argument
       points to an empty string.

ENOLINKpath points to a remote machine and the link to  that
       machine is no longer active.

ENOTDIRa component of the path prefix is not a directory.

Both fpathconf and pathconf fail if the following is true:

EINVAL if name is an invalid value.

SEE ALSO

sysconf(3C), limits(4)

DIAGNOSTICS

If fpathconf or pathconf are invoked with an invalid symbolic constant or the symbolic constant corresponds to a configurable system limit or option not supported on the system, a value of -1 is returned to the invoking process. If the function fails because the configurable system limit or option corresponding to name is not supported on the system the value of errno is not changed.