1 /* 2 * Copyright (c) 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * Jan-Simon Pendry. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if defined(LIBC_SCCS) && !defined(lint) 38 static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94"; 39 #endif /* LIBC_SCCS and not lint */ 40 #include <sys/cdefs.h> 41 __FBSDID("$FreeBSD$"); 42 43 #include "namespace.h" 44 #include <sys/param.h> 45 #include <sys/stat.h> 46 47 #include <errno.h> 48 #include <fcntl.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include <unistd.h> 52 #include "un-namespace.h" 53 54 /* 55 * char *realpath(const char *path, char resolved_path[PATH_MAX]); 56 * 57 * Find the real name of path, by removing all ".", ".." and symlink 58 * components. Returns (resolved) on success, or (NULL) on failure, 59 * in which case the path which caused trouble is left in (resolved). 60 */ 61 char * 62 realpath(path, resolved) 63 const char *path; 64 char *resolved; 65 { 66 struct stat sb; 67 int fd, n, rootd, serrno; 68 char *p, *q, wbuf[PATH_MAX]; 69 int symlinks = 0; 70 71 /* Save the starting point. */ 72 if ((fd = _open(".", O_RDONLY)) < 0) { 73 (void)strcpy(resolved, "."); 74 return (NULL); 75 } 76 77 /* 78 * Find the dirname and basename from the path to be resolved. 79 * Change directory to the dirname component. 80 * lstat the basename part. 81 * if it is a symlink, read in the value and loop. 82 * if it is a directory, then change to that directory. 83 * get the current directory name and append the basename. 84 */ 85 (void)strlcpy(resolved, path, PATH_MAX); 86 loop: 87 q = strrchr(resolved, '/'); 88 if (q != NULL) { 89 p = q + 1; 90 if (q == resolved) 91 q = "/"; 92 else { 93 do { 94 --q; 95 } while (q > resolved && *q == '/'); 96 q[1] = '\0'; 97 q = resolved; 98 } 99 if (chdir(q) < 0) 100 goto err1; 101 } else 102 p = resolved; 103 104 /* Deal with the last component. */ 105 if (*p != '\0' && lstat(p, &sb) == 0) { 106 if (S_ISLNK(sb.st_mode)) { 107 if (++symlinks > MAXSYMLINKS) { 108 errno = ELOOP; 109 goto err1; 110 } 111 n = readlink(p, resolved, PATH_MAX - 1); 112 if (n < 0) 113 goto err1; 114 resolved[n] = '\0'; 115 goto loop; 116 } 117 if (S_ISDIR(sb.st_mode)) { 118 if (chdir(p) < 0) 119 goto err1; 120 p = ""; 121 } 122 } 123 124 /* 125 * Save the last component name and get the full pathname of 126 * the current directory. 127 */ 128 (void)strcpy(wbuf, p); 129 if (getcwd(resolved, PATH_MAX) == 0) 130 goto err1; 131 132 /* 133 * Join the two strings together, ensuring that the right thing 134 * happens if the last component is empty, or the dirname is root. 135 */ 136 if (resolved[0] == '/' && resolved[1] == '\0') 137 rootd = 1; 138 else 139 rootd = 0; 140 141 if (*wbuf) { 142 if (strlen(resolved) + strlen(wbuf) + rootd + 1 > PATH_MAX) { 143 errno = ENAMETOOLONG; 144 goto err1; 145 } 146 if (rootd == 0) 147 (void)strcat(resolved, "/"); 148 (void)strcat(resolved, wbuf); 149 } 150 151 /* Go back to where we came from. */ 152 if (fchdir(fd) < 0) { 153 serrno = errno; 154 goto err2; 155 } 156 157 /* It's okay if the close fails, what's an fd more or less? */ 158 (void)_close(fd); 159 return (resolved); 160 161 err1: serrno = errno; 162 (void)fchdir(fd); 163 err2: (void)_close(fd); 164 errno = serrno; 165 return (NULL); 166 } 167