The fpathconf() and pathconf() functions provide a method for the application to determine the current value of a configurable limit or option ( variable ) that is associated with a file or directory.

For pathconf(), the path argument points to the pathname of a file or directory.

For fpathconf(), the fildes argument is an open file descriptor.

The name argument represents the variable to be queried relative to that file or directory. The variables in the following table come from <limits.h> or <unistd.h> and the symbolic constants, defined in <unistd.h>, are the corresponding values used for name:

Notes:

1. If path or fildes refers to a directory, the value returned applies to the directory itself.
2. If path or fildes does not refer to a terminal file, it is unspecified whether an implementation supports an association of the variable name with the specified file.
3. If path or fildes refers to a directory, the value returned applies to filenames within the directory.
4. If path or fildes does not refer to a directory, it is unspecified whether an implementation supports an association of the variable name with the specified file.
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 refers to a FIFO, or fildes refers to a pipe or FIFO, the value returned applies to the referenced object. If path or fildes refers to a directory, the value returned applies to any FIFO that exists or can be created within the directory. If path or fildes refers to any other type of file, it is unspecified whether an implementation supports an association of the variable name with the specified file.
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.
8. If path or fildes refers to a directory, it is unspecified whether an implementation supports an association of the variable name with the specified file.

If name is an invalid value, both pathconf() and fpathconf() return -1 and errno is set to indicate the error.

If the variable corresponding to name has no limit for the path or file descriptor, both pathconf() and fpathconf() return -1 without changing errno. If the implementation needs to use path to determine the value of name and the implementation does not support the association of name with the file specified by path, or if the process did not have appropriate privileges to query the file specified by path, or path does not exist, pathconf() returns -1 and errno is set to indicate the error.

If the implementation needs to use fildes to determine the value of name and the implementation does not support the association of name with the file specified by fildes, or if fildes is an invalid file descriptor, fpathconf() will return -1 and errno is set to indicate the error.

Otherwise pathconf() or fpathconf() returns the current variable value for the file or directory without changing errno. The value returned will not be more restrictive than the corresponding value available to the application when it was compiled with the implementation's <limits.h> or <unistd.h>.

The pathconf() function will fail if:

EINVAL

The value of name is not valid.

ELOOP

Too many symbolic links were encountered in resolving path.

The pathconf() function may fail if:

EACCES

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

EINVAL

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

ENAMETOOLONG

The length of the path argument exceeds PATH_MAX or a pathname component is longer than NAME_MAX.

ENAMETOOLONG

Pathname resolution of a symbolic link produced an intermediate result whose length exceeds PATH_MAX.

ENOENT

A component of path does not name an existing file or path is an empty string.

ENOTDIR

A component of the path prefix is not a directory.

The fpathconf() function will fail if:

EINVAL

The value of name is not valid.

The fpathconf() function may fail if:

EBADF

The fildes argument is not a valid file descriptor.

EINVAL

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

See attributes(5) for descriptions of the following attributes:

sysconf(3C), limits(4), attributes(5), standards(5)