1 files changed, 134 insertions, 103 deletions

diff --git a/src/lib/libc/stdlib/realpath.c b/src/lib/libc/stdlib/realpath.c
index e349b7e068..4cb847b313 100644
--- a/src/lib/libc/stdlib/realpath.c
+++ b/src/lib/libc/stdlib/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)
@@ -34,126 +27,164 @@
  * SUCH DAMAGE.
  */
 
-#if defined(LIBC_SCCS) && !defined(lint)
-/*static char sccsid[] = "from: @(#)realpath.c  8.1 (Berkeley) 2/16/94";*/
-static char *rcsid = "$Id: realpath.c,v 1.1.1.1 1995/10/18 08:42:19 deraadt 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];
+        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;
+        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;
+                        return (NULL);
                 }
-                if (chdir(q) < 0)
-                        goto err1;
-        } else
-                p = resolved;
-
-        /* Deal with the last component. */
-        if (lstat(p, &sb) == 0) {
-                if (S_ISLNK(sb.st_mode)) {
-                        n = readlink(p, resolved, MAXPATHLEN);
-                        if (n < 0)
-                                goto err1;
-                        resolved[n] = '\0';
-                        goto loop;
+                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 (S_ISDIR(sb.st_mode)) {
-                        if (chdir(p) < 0)
-                                goto err1;
-                        p = "";
+                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;
                 }
-        }
-
-        /*
-         * 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) + rootd + 1 > MAXPATHLEN) {
+                /*
+                 * 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;
-                        goto err1;
+                        return (NULL);
                 }
-                if (rootd == 0)
-                        (void)strcat(resolved, "/");
-                (void)strcat(resolved, wbuf);
-        }
+                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;
+                        }
 
-        /* Go back to where we came from. */
-        if (fchdir(fd) < 0) {
-                serrno = errno;
-                goto err2;
+                        /*
+                         * 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));
+                }
         }
 
-        /* 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);
 }