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/*
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* Copyright (c) 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Jan-Simon Pendry.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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static char *rcsid = "$OpenBSD: realpath.c,v 1.7.2.1 2003/08/03 02:29:29 brad Exp $";
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#endif /* LIBC_SCCS and not lint */
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#include <sys/param.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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/*
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* char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
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*
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* Find the real name of path, by removing all ".", ".." and symlink
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* components. Returns (resolved) on success, or (NULL) on failure,
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* in which case the path which caused trouble is left in (resolved).
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*/
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char *
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realpath(path, resolved)
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const char *path;
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char *resolved;
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{
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struct stat sb;
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int fd, n, needslash, serrno;
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char *p, *q, wbuf[MAXPATHLEN];
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int symlinks = 0;
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/* Save the starting point. */
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if ((fd = open(".", O_RDONLY)) < 0) {
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(void)strlcpy(resolved, ".", MAXPATHLEN);
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return (NULL);
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}
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/* Convert "." -> "" to optimize away a needless lstat() and chdir() */
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if (path[0] == '.' && path[1] == '\0')
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path = "";
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/*
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* Find the dirname and basename from the path to be resolved.
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* Change directory to the dirname component.
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* lstat the basename part.
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* if it is a symlink, read in the value and loop.
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* if it is a directory, then change to that directory.
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* get the current directory name and append the basename.
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*/
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strlcpy(resolved, path, MAXPATHLEN);
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loop:
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q = strrchr(resolved, '/');
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if (q != NULL) {
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p = q + 1;
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if (q == resolved)
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q = "/";
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else {
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do {
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--q;
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} while (q > resolved && *q == '/');
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q[1] = '\0';
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q = resolved;
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}
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if (chdir(q) < 0)
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goto err1;
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} else
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p = resolved;
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/* Deal with the last component. */
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if (*p != '\0' && lstat(p, &sb) == 0) {
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if (S_ISLNK(sb.st_mode)) {
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if (++symlinks > MAXSYMLINKS) {
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errno = ELOOP;
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goto err1;
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}
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n = readlink(p, resolved, MAXPATHLEN-1);
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if (n < 0)
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goto err1;
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resolved[n] = '\0';
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goto loop;
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}
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if (S_ISDIR(sb.st_mode)) {
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if (chdir(p) < 0)
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goto err1;
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p = "";
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}
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}
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/*
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* Save the last component name and get the full pathname of
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* the current directory.
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*/
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(void)strlcpy(wbuf, p, sizeof wbuf);
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if (getcwd(resolved, MAXPATHLEN) == 0)
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goto err1;
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/*
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* Join the two strings together, ensuring that the right thing
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* happens if the last component is empty, or the dirname is root.
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*/
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if (resolved[0] == '/' && resolved[1] == '\0')
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needslash = 0;
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else
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needslash = 1;
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if (*wbuf) {
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if (strlen(resolved) + strlen(wbuf) + needslash >= MAXPATHLEN) {
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errno = ENAMETOOLONG;
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goto err1;
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}
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if (needslash)
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(void)strlcat(resolved, "/", MAXPATHLEN);
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(void)strlcat(resolved, wbuf, MAXPATHLEN);
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}
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/* Go back to where we came from. */
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if (fchdir(fd) < 0) {
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serrno = errno;
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goto err2;
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}
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/* It's okay if the close fails, what's an fd more or less? */
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(void)close(fd);
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return (resolved);
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err1: serrno = errno;
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(void)fchdir(fd);
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err2: (void)close(fd);
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errno = serrno;
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return (NULL);
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}
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