realpath

, canonicalize_file_name

- resolve pathname

Synopsis

#include <stdlib.h>

char *realpath(const char *restrict file_name,
     char *restrict resolved_name);

char *canonicalize_file_name (const char *path); 

Description

The realpath() function derives, from the pathname pointed to by file_name, an absolute pathname that resolves to the same directory entry, whose resolution does not involve “.”, “..”, or symbolic links. If resolved_name is not null, the generated pathname is stored as a null-terminated string, up to a maximum of {PATH_MAX} (defined in limits.h(3HEAD)) bytes in the buffer pointed to by resolved_name. If resolved_name is null, the generated pathname is stored as a null-terminated string in a buffer that is allocated as if malloc(3C) were called.

The call canonicalize_file_name(path) is equivalent to the call realpath(path, NULL).

Return Values

On successful completion, realpath() returns a pointer to the resolved name. Otherwise, realpath() returns a null pointer and sets errno to indicate the error, and the contents of the buffer pointed to by resolved_name are left in an indeterminate state.

Errors

The realpath() function will fail if:

EACCES

Read or search permission was denied for a component of file_name.

EINVAL

Either the file_name or resolved_name argument is a null pointer.

EIO

An error occurred while reading from the file system.

ELOOP

Too many symbolic links were encountered in resolving file_name.

ELOOP

A loop exists in symbolic links encountered during resolution of the file_name argument.

ENAMETOOLONG

The file_name argument is longer than {PATH_MAX} or a pathname component is longer than {NAME_MAX}.

ENOENT

A component of file_name does not name an existing file or file_name points to an empty string.

ENOTDIR

A component of the path prefix is not a directory.

The realpath() function may fail if:

ENAMETOOLONG

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

ENOMEM

Insufficient storage space is available.

Usage

The realpath() function operates on null-terminated strings.

Execute permission is required for all the directories in the given and the resolved path.

The realpath() function might fail to return to the current directory if an error occurs.

Attributes

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

See Also

getcwd(3C), limits.h(3HEAD), malloc(3C), sysconf(3C), attributes(5), standards(5)