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 * $FreeBSD$ 37 */ 38 39 #if defined(LIBC_SCCS) && !defined(lint) 40 static char sccsid[] = "@(#)realpath.c 8.1 (Berkeley) 2/16/94"; 41 #endif /* LIBC_SCCS and not lint */ 42 43 #include <sys/param.h> 44 #include <sys/stat.h> 45 46 #include <errno.h> 47 #include <fcntl.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include <unistd.h> 51 52 /* 53 * char *realpath(const char *path, char resolved_path[MAXPATHLEN]); 54 * 55 * Find the real name of path, by removing all ".", ".." and symlink 56 * components. Returns (resolved) on success, or (NULL) on failure, 57 * in which case the path which caused trouble is left in (resolved). 58 */ 59 char * 60 realpath(path, resolved) 61 const char *path; 62 char *resolved; 63 { 64 struct stat sb; 65 int fd, n, rootd, serrno; 66 char *p, *q, wbuf[MAXPATHLEN]; 67 int symlinks = 0; 68 69 /* Save the starting point. */ 70 if ((fd = _open(".", O_RDONLY)) < 0) { 71 (void)strcpy(resolved, "."); 72 return (NULL); 73 } 74 75 /* 76 * Find the dirname and basename from the path to be resolved. 77 * Change directory to the dirname component. 78 * lstat the basename part. 79 * if it is a symlink, read in the value and loop. 80 * if it is a directory, then change to that directory. 81 * get the current directory name and append the basename. 82 */ 83 (void)strncpy(resolved, path, MAXPATHLEN - 1); 84 resolved[MAXPATHLEN - 1] = '\0'; 85 loop: 86 q = strrchr(resolved, '/'); 87 if (q != NULL) { 88 p = q + 1; 89 if (q == resolved) 90 q = "/"; 91 else { 92 do { 93 --q; 94 } while (q > resolved && *q == '/'); 95 q[1] = '\0'; 96 q = resolved; 97 } 98 if (chdir(q) < 0) 99 goto err1; 100 } else 101 p = resolved; 102 103 /* Deal with the last component. */ 104 if (*p != '\0' && lstat(p, &sb) == 0) { 105 if (S_ISLNK(sb.st_mode)) { 106 if (++symlinks > MAXSYMLINKS) { 107 errno = ELOOP; 108 goto err1; 109 } 110 n = readlink(p, resolved, MAXPATHLEN - 1); 111 if (n < 0) 112 goto err1; 113 resolved[n] = '\0'; 114 goto loop; 115 } 116 if (S_ISDIR(sb.st_mode)) { 117 if (chdir(p) < 0) 118 goto err1; 119 p = ""; 120 } 121 } 122 123 /* 124 * Save the last component name and get the full pathname of 125 * the current directory. 126 */ 127 (void)strcpy(wbuf, p); 128 if (getcwd(resolved, MAXPATHLEN) == 0) 129 goto err1; 130 131 /* 132 * Join the two strings together, ensuring that the right thing 133 * happens if the last component is empty, or the dirname is root. 134 */ 135 if (resolved[0] == '/' && resolved[1] == '\0') 136 rootd = 1; 137 else 138 rootd = 0; 139 140 if (*wbuf) { 141 if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) { 142 errno = ENAMETOOLONG; 143 goto err1; 144 } 145 if (rootd == 0) 146 (void)strcat(resolved, "/"); 147 (void)strcat(resolved, wbuf); 148 } 149 150 /* Go back to where we came from. */ 151 if (fchdir(fd) < 0) { 152 serrno = errno; 153 goto err2; 154 } 155 156 /* It's okay if the close fails, what's an fd more or less? */ 157 (void)_close(fd); 158 return (resolved); 159 160 err1: serrno = errno; 161 (void)fchdir(fd); 162 err2: (void)_close(fd); 163 errno = serrno; 164 return (NULL); 165 } 166