/* $Id: realpath.c,v 1.2 2010/04/21 17:47:49 sjg Exp $ */
/* from: $NetBSD: getcwd.c,v 1.45 2007/10/26 19:48:14 christos Exp $ */
/*
* Copyright (c) 1989, 1991, 1993, 1995
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Jan-Simon Pendry.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#ifndef HAVE_REALPATH
#include <sys/cdefs.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#ifdef HAVE_STDLIB_H
# include <stdlib.h>
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#endif
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
/*
* char *realpath(const char *path, char resolved[MAXPATHLEN]);
*
* Find the real name of path, by removing all ".", ".." and symlink
* components. Returns (resolved) on success, or (NULL) on failure,
* in which case the path which caused trouble is left in (resolved).
*/
char *
realpath(const char *path, char *resolved)
{
struct stat sb;
int idx = 0, n, nlnk = 0;
const char *q;
char *p, wbuf[2][MAXPATHLEN];
size_t len;
if (!path || !resolved || path == resolved)
return (NULL);
/*
* Build real path one by one with paying an attention to .,
* .. and symbolic link.
*/
/*
* `p' is where we'll put a new component with prepending
* a delimiter.
*/
p = resolved;
if (*path == 0) {
*p = 0;
errno = ENOENT;
return (NULL);
}
/* If relative path, start from current working directory. */
if (*path != '/') {
/* check for resolved pointer to appease coverity */
if (resolved && getcwd(resolved, MAXPATHLEN) == NULL) {
p[0] = '.';
p[1] = 0;
return (NULL);
}
len = strlen(resolved);
if (len > 1)
p += len;
}
loop:
/* Skip any slash. */
while (*path == '/')
path++;
if (*path == 0) {
if (p == resolved)
*p++ = '/';
*p = 0;
return (resolved);
}
/* Find the end of this component. */
q = path;
do
q++;
while (*q != '/' && *q != 0);
/* Test . or .. */
if (path[0] == '.') {
if (q - path == 1) {
path = q;
goto loop;
}
if (path[1] == '.' && q - path == 2) {
/* Trim the last component. */
if (p != resolved)
while (*--p != '/')
;
path = q;
goto loop;
}
}
/* Append this component. */
if (p - resolved + 1 + q - path + 1 > MAXPATHLEN) {
errno = ENAMETOOLONG;
if (p == resolved)
*p++ = '/';
*p = 0;
return (NULL);
}
p[0] = '/';
memcpy(&p[1], path,
/* LINTED We know q > path. */
q - path);
p[1 + q - path] = 0;
/*
* If this component is a symlink, toss it and prepend link
* target to unresolved path.
*/
if (lstat(resolved, &sb) == -1) {
return (NULL);
}
if (S_ISLNK(sb.st_mode)) {
if (nlnk++ >= MAXSYMLINKS) {
errno = ELOOP;
return (NULL);
}
n = readlink(resolved, wbuf[idx], sizeof(wbuf[0]) - 1);
if (n < 0)
return (NULL);
if (n == 0) {
errno = ENOENT;
return (NULL);
}
/* Append unresolved path to link target and switch to it. */
if (n + (len = strlen(q)) + 1 > sizeof(wbuf[0])) {
errno = ENAMETOOLONG;
return (NULL);
}
memcpy(&wbuf[idx][n], q, len + 1);
path = wbuf[idx];
idx ^= 1;
/* If absolute symlink, start from root. */
if (*path == '/')
p = resolved;
goto loop;
}
if (*q == '/' && !S_ISDIR(sb.st_mode)) {
errno = ENOTDIR;
return (NULL);
}
/* Advance both resolved and unresolved path. */
p += 1 + q - path;
path = q;
goto loop;
}
#endif
