Originální popis anglicky:
realpath - resolve a pathname
Návod, kniha: POSIX Programmer's Manual
#include <stdlib.h>
char *realpath(const char *restrict
file_name,
char *restrict
resolved_name );
The
realpath() function shall derive, 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 shall be stored as a null-terminated string, up to a
maximum of {PATH_MAX} bytes, in the buffer pointed to by
resolved_name.
If
resolved_name is a null pointer, the behavior of
realpath() is
implementation-defined.
Upon successful completion,
realpath() shall return a pointer to the
resolved name. Otherwise,
realpath() shall return a null pointer and
set
errno to indicate the error, and the contents of the buffer pointed
to by
resolved_name are undefined.
The
realpath() function shall fail if:
- EACCES
- Read or search permission was denied for a component of
file_name.
- EINVAL
- The file_name argument is a null pointer.
- EIO
- An error occurred while reading from the file system.
- ELOOP
- A loop exists in symbolic links encountered during
resolution of the path argument.
- ENAMETOOLONG
- The length of the file_name argument exceeds
{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:
- ELOOP
- More than {SYMLOOP_MAX} symbolic links were encountered
during resolution of the path argument.
- ENAMETOOLONG
- Pathname resolution of a symbolic link produced an
intermediate result whose length exceeds {PATH_MAX}.
- ENOMEM
- Insufficient storage space is available.
The following sections are informative.
The following example generates an absolute pathname for the file identified by
the
symlinkpath argument. The generated pathname is stored in the
actualpath array.
#include <stdlib.h>
...
char *symlinkpath = "/tmp/symlink/file";
char actualpath [PATH_MAX+1];
char *ptr;
ptr = realpath(symlinkpath, actualpath);
None.
Since the maximum pathname length is arbitrary unless {PATH_MAX} is defined, an
application generally cannot supply a
resolved_name buffer with size
{{PATH_MAX}+1}.
In the future, passing a null pointer to
realpath() for the
resolved_name argument may be defined to have
realpath()
allocate space for the generated pathname.
getcwd() ,
sysconf() , the Base Definitions volume of
IEEE Std 1003.1-2001,
<stdlib.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
