realpath - resolve pathname
#include <stdlib.h>
char *realpath(const char *restrict file_name,
char *restrict resolved_name);
char *canonicalize_file_name(const char *path);
The realpath() function derives, from the pathname pointed to by
file_name, an absolute pathname that names the same file, whose
resolution does not involve ".", "..", or
symbolic links. The generated pathname is stored as a null-terminated string,
up to a maximum of {PATH_MAX} bytes (defined in
limits.h(3HEAD)), in the buffer pointed to by resolved_name.
The canonicalize_file_name() function is equivalent to
calling realpath(path, NULL). This function is only
provided for compatibility.
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.
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.
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.
See attributes(7) for descriptions of the following attributes:
| ATTRIBUTE
TYPE |
ATTRIBUTE VALUE |
| Interface Stability |
Standard |
| MT-Level |
MT-Safe |