Use a modern chdir(2)-free realpath(3) implementation.
(This is the current OpenBSD implementation.)
Bug: 3055824, 2281992
Change-Id: Iafa8f78e8d6e44c036a547c7210a13d559b7483a
diff --git a/libc/bionic/realpath.c b/libc/bionic/realpath.c
index 274a3a0..4cb847b 100644
--- a/libc/bionic/realpath.c
+++ b/libc/bionic/realpath.c
@@ -1,9 +1,6 @@
+/* $OpenBSD: realpath.c,v 1.13 2005/08/08 08:05:37 espie Exp $ */
/*
- * Copyright (c) 1994
- * The Regents of the University of California. All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * Jan-Simon Pendry.
+ * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
@@ -13,18 +10,14 @@
* 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. All advertising materials mentioning features or use of this software
- * must display the following acknowledgement:
- * This product includes software developed by the University of
- * California, Berkeley and its contributors.
- * 4. 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.
+ * 3. The names of the authors may not 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
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR 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)
@@ -34,133 +27,164 @@
* SUCH DAMAGE.
*/
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94";
-static char rcsid[] =
-"$FreeBSD: /repoman/r/ncvs/src/lib/libc/stdlib/realpath.c,v 1.6.2.1 2003/08/03 23:47:39 nectar Exp $";
-#endif /* LIBC_SCCS and not lint */
-
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
-#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/*
- * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
+ * char *realpath(const char *path, char resolved[PATH_MAX]);
*
* 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(path, resolved)
- const char *path;
- char *resolved;
+realpath(const char *path, char resolved[PATH_MAX])
{
struct stat sb;
- int fd, n, rootd, serrno;
- char *p, *q, wbuf[MAXPATHLEN];
- int symlinks = 0;
+ char *p, *q, *s;
+ size_t left_len, resolved_len;
+ unsigned symlinks;
+ int serrno, slen;
+ char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
- /* Save the starting point. */
- if ((fd = open(".", O_RDONLY)) < 0) {
- (void)strcpy(resolved, ".");
+ serrno = errno;
+ symlinks = 0;
+ if (path[0] == '/') {
+ resolved[0] = '/';
+ resolved[1] = '\0';
+ if (path[1] == '\0')
+ return (resolved);
+ resolved_len = 1;
+ left_len = strlcpy(left, path + 1, sizeof(left));
+ } else {
+ if (getcwd(resolved, PATH_MAX) == NULL) {
+ strlcpy(resolved, ".", PATH_MAX);
+ return (NULL);
+ }
+ resolved_len = strlen(resolved);
+ left_len = strlcpy(left, path, sizeof(left));
+ }
+ if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
+ errno = ENAMETOOLONG;
return (NULL);
}
/*
- * Find the dirname and basename from the path to be resolved.
- * Change directory to the dirname component.
- * lstat the basename part.
- * if it is a symlink, read in the value and loop.
- * if it is a directory, then change to that directory.
- * get the current directory name and append the basename.
+ * Iterate over path components in `left'.
*/
- (void)strncpy(resolved, path, MAXPATHLEN - 1);
- resolved[MAXPATHLEN - 1] = '\0';
-loop:
- q = strrchr(resolved, '/');
- if (q != NULL) {
- p = q + 1;
- if (q == resolved)
- q = "/";
- else {
- do {
- --q;
- } while (q > resolved && *q == '/');
- q[1] = '\0';
- q = resolved;
- }
- if (chdir(q) < 0)
- goto err1;
- } else
- p = resolved;
-
- /* Deal with the last component. */
- if (*p != '\0' && lstat(p, &sb) == 0) {
- if (S_ISLNK(sb.st_mode)) {
- if (++symlinks > MAXSYMLINKS) {
- errno = ELOOP;
- goto err1;
- }
- n = readlink(p, resolved, MAXPATHLEN - 1);
- if (n < 0)
- goto err1;
- resolved[n] = '\0';
- goto loop;
- }
- if (S_ISDIR(sb.st_mode)) {
- if (chdir(p) < 0)
- goto err1;
- p = "";
- }
- }
-
- /*
- * Save the last component name and get the full pathname of
- * the current directory.
- */
- (void)strcpy(wbuf, p);
- if (getcwd(resolved, MAXPATHLEN) == 0)
- goto err1;
-
- /*
- * Join the two strings together, ensuring that the right thing
- * happens if the last component is empty, or the dirname is root.
- */
- if (resolved[0] == '/' && resolved[1] == '\0')
- rootd = 1;
- else
- rootd = 0;
-
- if (*wbuf) {
- if (strlen(resolved) + strlen(wbuf) + (1-rootd) + 1 >
- MAXPATHLEN) {
+ while (left_len != 0) {
+ /*
+ * Extract the next path component and adjust `left'
+ * and its length.
+ */
+ p = strchr(left, '/');
+ s = p ? p : left + left_len;
+ if (s - left >= sizeof(next_token)) {
errno = ENAMETOOLONG;
- goto err1;
+ return (NULL);
}
- if (rootd == 0)
- (void)strcat(resolved, "/");
- (void)strcat(resolved, wbuf);
+ memcpy(next_token, left, s - left);
+ next_token[s - left] = '\0';
+ left_len -= s - left;
+ if (p != NULL)
+ memmove(left, s + 1, left_len + 1);
+ if (resolved[resolved_len - 1] != '/') {
+ if (resolved_len + 1 >= PATH_MAX) {
+ errno = ENAMETOOLONG;
+ return (NULL);
+ }
+ resolved[resolved_len++] = '/';
+ resolved[resolved_len] = '\0';
+ }
+ if (next_token[0] == '\0')
+ continue;
+ else if (strcmp(next_token, ".") == 0)
+ continue;
+ else if (strcmp(next_token, "..") == 0) {
+ /*
+ * Strip the last path component except when we have
+ * single "/"
+ */
+ if (resolved_len > 1) {
+ resolved[resolved_len - 1] = '\0';
+ q = strrchr(resolved, '/') + 1;
+ *q = '\0';
+ resolved_len = q - resolved;
+ }
+ continue;
+ }
+
+ /*
+ * Append the next path component and lstat() it. If
+ * lstat() fails we still can return successfully if
+ * there are no more path components left.
+ */
+ resolved_len = strlcat(resolved, next_token, PATH_MAX);
+ if (resolved_len >= PATH_MAX) {
+ errno = ENAMETOOLONG;
+ return (NULL);
+ }
+ if (lstat(resolved, &sb) != 0) {
+ if (errno == ENOENT && p == NULL) {
+ errno = serrno;
+ return (resolved);
+ }
+ return (NULL);
+ }
+ if (S_ISLNK(sb.st_mode)) {
+ if (symlinks++ > MAXSYMLINKS) {
+ errno = ELOOP;
+ return (NULL);
+ }
+ slen = readlink(resolved, symlink, sizeof(symlink) - 1);
+ if (slen < 0)
+ return (NULL);
+ symlink[slen] = '\0';
+ if (symlink[0] == '/') {
+ resolved[1] = 0;
+ resolved_len = 1;
+ } else if (resolved_len > 1) {
+ /* Strip the last path component. */
+ resolved[resolved_len - 1] = '\0';
+ q = strrchr(resolved, '/') + 1;
+ *q = '\0';
+ resolved_len = q - resolved;
+ }
+
+ /*
+ * If there are any path components left, then
+ * append them to symlink. The result is placed
+ * in `left'.
+ */
+ if (p != NULL) {
+ if (symlink[slen - 1] != '/') {
+ if (slen + 1 >= sizeof(symlink)) {
+ errno = ENAMETOOLONG;
+ return (NULL);
+ }
+ symlink[slen] = '/';
+ symlink[slen + 1] = 0;
+ }
+ left_len = strlcat(symlink, left, sizeof(left));
+ if (left_len >= sizeof(left)) {
+ errno = ENAMETOOLONG;
+ return (NULL);
+ }
+ }
+ left_len = strlcpy(left, symlink, sizeof(left));
+ }
}
- /* Go back to where we came from. */
- if (fchdir(fd) < 0) {
- serrno = errno;
- goto err2;
- }
-
- /* It's okay if the close fails, what's an fd more or less? */
- (void)close(fd);
+ /*
+ * Remove trailing slash except when the resolved pathname
+ * is a single "/".
+ */
+ if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
+ resolved[resolved_len - 1] = '\0';
return (resolved);
-
-err1: serrno = errno;
- (void)fchdir(fd);
-err2: (void)close(fd);
- errno = serrno;
- return (NULL);
}