REALPATH (3)

SYNOPSIS

#include <limits.h>
#include <stdlib.h>
  char *realpath(const char * path , char * resolved_path );  

DESCRIPTION

realpath expands all symbolic links and resolves references to '/./' , '/../' and extra '/' characters in the null terminated string named by path and stores the canonicalized absolute pathname in the buffer of size PATH_MAX named by resolved_path . The resulting path will have no symbolic link, '/./' or '/../' components.

RETURN VALUE

If there is no error, it returns a pointer to the resolved_path .

Otherwise it returns a NULL pointer, and the contents of the array resolved_path are undefined. The global variable errno is set to indicate the error.

ERRORS

EACCES

Read or search permission was denied for a component of the path prefix.

EINVAL

Either path or resolved_path is NULL. (In libc5 this would just cause a segfault.)

EIO

An I/O error occurred while reading from the file system.

ELOOP

Too many symbolic links were encountered in translating the pathname.

ENAMETOOLONG

A component of a path name exceeded NAME_MAX characters, or an entire path name exceeded PATH_MAX characters.

ENOENT

The named file does not exist.

ENOTDIR

A component of the path prefix is not a directory.

BUGS

The libc4 and libc5 implementation contains a buffer overflow (fixed in libc-5.4.13). Thus, suid programs like mount need a private version.

The length of the output buffer should have been an additional parameter, especially since pathconf (3) warns that the result of pathconf() may be huge and unsuitable for mallocing memory.

HISTORY

The realpath function first appeared in BSD 4.4, contributed by Jan-Simon Pendry. In Linux this function appears in libc 4.5.21.

CONFORMING TO

In BSD 4.4 and Solaris the limit on the pathname length is MAXPATHLEN (found in <sys/param.h>). The SUSv2 prescribes PATH_MAX and NAME_MAX, as found in <limits.h> or provided by the pathconf() function. A typical source fragment would be

#ifdef PATH_MAX
  path_max = PATH_MAX;
#else
  path_max = pathconf (path, _PC_PATH_MAX);
  if (path_max <= 0)
    path_max = 4096;
#endif

The BSD 4.4, Linux and SUSv2 versions always return an absolute path name. Solaris may return a relative path name when the path argument is relative. The prototype of realpath is given in <unistd.h> in libc4 and libc5, but in <stdlib.h> everywhere else.

SEE ALSO

- readlink (2) - - getcwd (3) - pathconf(3) - sysconf (3) - ' " ' " Copyright(c) 1997 Sun Microsystems Inc ' " ' " See the file "license terms" for information on usage and redistribution ' " of this file and for a DISCLAIMER OF ALL WARRANTIES ' " ' " RCS: @(#) $Id: RecEvalObj 3 v 1 2 1998/09/14 18:39:49 stanton Exp $ ' " ' " The definitions below are for supplemental macros used in Tcl/Tk ' " manual entries ' " ' " AP type name in/out ?indent? ' " Start paragraph describing an argument to a library procedure ' " type is type of argument(int etc ) in/out is either "in" "out" ' " or "in/out" to describe whether procedure reads or modifies arg ' " and indent is equivalent to second arg of IP(shouldn't ever be ' " needed; use AS below instead) ' " ' " AS ?type? ?name? ' " Give maximum sizes of arguments for setting tab stops Type and ' " name are examples of largest possible arguments that will be passed ' " to AP later If args are omitted default tab stops are used ' " ' " BS ' " Start box enclosure From here until next BE everything will be ' " enclosed in one large box ' " ' " BE ' " End of box enclosure ' " ' " CS ' " Begin code excerpt ' " ' " CE ' " End code excerpt ' " ' " VS ?version? ?br? ' " Begin vertical sidebar for use in marking newly-changed parts ' " of man pages The first argument is ignored and used for recording ' " the version when the VS was added so that the sidebars can be ' " found and removed when they reach a certain age If another argument ' " is present then a line break is forced before starting the sidebar ' " ' " VE ' " End of vertical sidebar ' " ' " DS ' " Begin an indented unfilled display ' " ' " DE ' " End of indented unfilled display ' " ' " SO ' " Start of list of standard options for a Tk widget The ' " options follow on successive lines in four columns separated ' " by tabs ' " ' " SE ' " End of list of standard options for a Tk widget ' " ' " OP cmdName dbName dbClass ' " Start of description of a specific option cmdName gives the ' " option's name as specified in the class command dbName gives ' " the option's name in the option database and dbClass gives ' " the option's class in the option database ' " ' " UL arg1 arg2 ' " Print arg1 underlined then print arg2 normally ' " ' " RCS: @(#) $Id: man macros v 1 2 1998/09/14 18:39:54 stanton Exp $ ' " ' " # Set up traps and other miscellaneous stuff for Tcl/Tk man pages t wh -1 3i ^B ^l n( l b ' " # Start an argument description AP !" $4"" TP $4 { !" $2"" TP n()Cu 15