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. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #if defined(LIBC_SCCS) && !defined(lint) 34 static char *rcsid = "$OpenBSD: realpath.c,v 1.10 2003/08/01 21:04:59 millert Exp $"; 35 #endif /* LIBC_SCCS and not lint */ 36 37 #include <sys/param.h> 38 #include <sys/stat.h> 39 40 #include <errno.h> 41 #include <fcntl.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 46 /* 47 * char *realpath(const char *path, char resolved_path[MAXPATHLEN]); 48 * 49 * Find the real name of path, by removing all ".", ".." and symlink 50 * components. Returns (resolved) on success, or (NULL) on failure, 51 * in which case the path which caused trouble is left in (resolved). 52 */ 53 char * 54 realpath(path, resolved) 55 const char *path; 56 char *resolved; 57 { 58 struct stat sb; 59 int fd, n, needslash, serrno; 60 char *p, *q, wbuf[MAXPATHLEN]; 61 int symlinks = 0; 62 63 /* Save the starting point. */ 64 if ((fd = open(".", O_RDONLY)) < 0) { 65 (void)strlcpy(resolved, ".", MAXPATHLEN); 66 return (NULL); 67 } 68 69 /* Convert "." -> "" to optimize away a needless lstat() and chdir() */ 70 if (path[0] == '.' && path[1] == '\0') 71 path = ""; 72 73 /* 74 * Find the dirname and basename from the path to be resolved. 75 * Change directory to the dirname component. 76 * lstat the basename part. 77 * if it is a symlink, read in the value and loop. 78 * if it is a directory, then change to that directory. 79 * get the current directory name and append the basename. 80 */ 81 strlcpy(resolved, path, MAXPATHLEN); 82 loop: 83 q = strrchr(resolved, '/'); 84 if (q != NULL) { 85 p = q + 1; 86 if (q == resolved) 87 q = "/"; 88 else { 89 do { 90 --q; 91 } while (q > resolved && *q == '/'); 92 q[1] = '\0'; 93 q = resolved; 94 } 95 if (chdir(q) < 0) 96 goto err1; 97 } else 98 p = resolved; 99 100 /* Deal with the last component. */ 101 if (*p != '\0' && lstat(p, &sb) == 0) { 102 if (S_ISLNK(sb.st_mode)) { 103 if (++symlinks > MAXSYMLINKS) { 104 errno = ELOOP; 105 goto err1; 106 } 107 n = readlink(p, resolved, MAXPATHLEN-1); 108 if (n < 0) 109 goto err1; 110 resolved[n] = '\0'; 111 goto loop; 112 } 113 if (S_ISDIR(sb.st_mode)) { 114 if (chdir(p) < 0) 115 goto err1; 116 p = ""; 117 } 118 } 119 120 /* 121 * Save the last component name and get the full pathname of 122 * the current directory. 123 */ 124 (void)strlcpy(wbuf, p, sizeof wbuf); 125 if (getcwd(resolved, MAXPATHLEN) == 0) 126 goto err1; 127 128 /* 129 * Join the two strings together, ensuring that the right thing 130 * happens if the last component is empty, or the dirname is root. 131 */ 132 if (resolved[0] == '/' && resolved[1] == '\0') 133 needslash = 0; 134 else 135 needslash = 1; 136 137 if (*wbuf) { 138 if (strlen(resolved) + strlen(wbuf) + needslash >= MAXPATHLEN) { 139 errno = ENAMETOOLONG; 140 goto err1; 141 } 142 if (needslash) 143 strlcat(resolved, "/", MAXPATHLEN); 144 strlcat(resolved, wbuf, MAXPATHLEN); 145 } 146 147 /* Go back to where we came from. */ 148 if (fchdir(fd) < 0) { 149 serrno = errno; 150 goto err2; 151 } 152 153 /* It's okay if the close fails, what's an fd more or less? */ 154 (void)close(fd); 155 return (resolved); 156 157 err1: serrno = errno; 158 (void)fchdir(fd); 159 err2: (void)close(fd); 160 errno = serrno; 161 return (NULL); 162 } 163