realpath(3) [osx man page]

REALPATH(3)						   BSD Library Functions Manual 					       REALPATH(3)

NAME

     realpath -- returns the canonicalized absolute pathname

SYNOPSIS

     #include <stdlib.h>

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

DESCRIPTION

     The realpath() function resolves all symbolic links, extra ``/'' characters, and references to /./ and /../ in file_name.	If the
     resolved_name argument is non-NULL, the resulting absolute pathname is copied there (it must refer to a buffer capable of storing at least
     PATH_MAX characters).

     As a permitted extension to the standard, if resolved_name is NULL, memory is allocated for the resulting absolute pathname, and is returned
     by realpath().  This memory should be freed by a call to free(3) when no longer needed.

     The realpath() function will resolve both absolute and relative paths and return the absolute pathname corresponding to file_name.  All com-
     ponents of file_name must exist when realpath() is called.

RETURN VALUES

     On success, the realpath() function returns the address of the resulting absolute pathname, which is resolved_name if it was non-NULL, or the
     address of newly allocated memory.  If an error occurs, realpath() returns NULL.  If resolved_name was non-NULL, it will contains the path-
     name which caused the problem.

VARIANTS

     Defining _DARWIN_C_SOURCE or _DARWIN_BETTER_REALPATH before including stdio.h will cause the provided implementation of realpath() to use
     F_GETPATH from fcntl(2) to discover the path.

ERRORS

     The function realpath() may fail and set the external variable errno for any of the errors specified for the library functions alloca(3),
     getattrlist(2), getcwd(3), lstat(2), readlink(2), stat(2), and strdup(3).

LEGACY SYNOPSIS

     #include <sys/param.h>
     #include <stdlib.h>

     The include file <sys/param.h> is necessary.

LEGACY DESCRIPTION

     In legacy mode, the last component of file_name does not need to exist when realpath() is called.

SEE ALSO

     free(3), getcwd(3), compat(5)

HISTORY

     The realpath() function first appeared in 4.4BSD.

BSD
								   April 5, 2008							       BSD

REALPATH(3)						     Linux Programmer's Manual						       REALPATH(3)

NAME

       realpath - return the canonicalized absolute pathname

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 indi-
       cate 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  ver-
       sion.

       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)

								    1999-08-24							       REALPATH(3)