1 /* 2 * Copyright (c) 1989, 1991 The Regents of the University of California. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #if defined(LIBC_SCCS) && !defined(lint) 35 static char sccsid[] = "@(#)getcwd.c 5.11 (Berkeley) 2/24/91"; 36 #endif /* LIBC_SCCS and not lint */ 37 38 #include <sys/param.h> 39 #include <sys/stat.h> 40 #include <errno.h> 41 #include <dirent.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <unistd.h> 46 47 #define ISDOT(dp) \ 48 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 49 dp->d_name[1] == '.' && dp->d_name[2] == '\0')) 50 51 char * 52 getcwd(pt, size) 53 char *pt; 54 size_t size; 55 { 56 register struct dirent *dp; 57 register DIR *dir; 58 register dev_t dev; 59 register ino_t ino; 60 register int first; 61 register char *bpt, *bup; 62 struct stat s; 63 dev_t root_dev; 64 ino_t root_ino; 65 size_t ptsize, upsize; 66 int save_errno; 67 char *ept, *eup, *up; 68 69 /* 70 * If no buffer specified by the user, allocate one as necessary. 71 * If a buffer is specified, the size has to be non-zero. The path 72 * is built from the end of the buffer backwards. 73 */ 74 if (pt) { 75 ptsize = 0; 76 if (!size) { 77 errno = EINVAL; 78 return((char *)NULL); 79 } 80 ept = pt + size; 81 } else { 82 if (!(pt = (char *)malloc(ptsize = 1024 - 4))) 83 return((char *)NULL); 84 ept = pt + ptsize; 85 } 86 bpt = ept - 1; 87 *bpt = '\0'; 88 89 /* 90 * Allocate bytes (1024 - malloc space) for the string of "../"'s. 91 * Should always be enough (it's 340 levels). If it's not, allocate 92 * as necessary. Special * case the first stat, it's ".", not "..". 93 */ 94 if (!(up = (char *)malloc(upsize = 1024 - 4))) 95 goto err; 96 eup = up + MAXPATHLEN; 97 bup = up; 98 up[0] = '.'; 99 up[1] = '\0'; 100 101 /* Save root values, so know when to stop. */ 102 if (stat("/", &s)) 103 goto err; 104 root_dev = s.st_dev; 105 root_ino = s.st_ino; 106 107 errno = 0; /* XXX readdir has no error return. */ 108 109 for (first = 1;; first = 0) { 110 /* Stat the current level. */ 111 if (lstat(up, &s)) 112 goto err; 113 114 /* Save current node values. */ 115 ino = s.st_ino; 116 dev = s.st_dev; 117 118 /* Check for reaching root. */ 119 if (root_dev == dev && root_ino == ino) { 120 *--bpt = '/'; 121 /* 122 * It's unclear that it's a requirement to copy the 123 * path to the beginning of the buffer, but it's always 124 * been that way and stuff would probably break. 125 */ 126 (void)bcopy(bpt, pt, ept - bpt); 127 free(up); 128 return(pt); 129 } 130 131 /* 132 * Build pointer to the parent directory, allocating memory 133 * as necessary. Max length is 3 for "../", the largest 134 * possible component name, plus a trailing NULL. 135 */ 136 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 137 if (!(up = (char *)realloc(up, upsize *= 2))) 138 goto err; 139 eup = up + upsize; 140 } 141 *bup++ = '.'; 142 *bup++ = '.'; 143 *bup = '\0'; 144 145 /* Open and stat parent directory. */ 146 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 147 goto err; 148 149 /* Add trailing slash for next directory. */ 150 *bup++ = '/'; 151 152 /* 153 * If it's a mount point, have to stat each element because 154 * the inode number in the directory is for the entry in the 155 * parent directory, not the inode number of the mounted file. 156 */ 157 save_errno = 0; 158 if (s.st_dev == dev) { 159 for (;;) { 160 if (!(dp = readdir(dir))) 161 goto notfound; 162 if (dp->d_fileno == ino) 163 break; 164 } 165 } else 166 for (;;) { 167 if (!(dp = readdir(dir))) 168 goto notfound; 169 if (ISDOT(dp)) 170 continue; 171 bcopy(dp->d_name, bup, dp->d_namlen + 1); 172 173 /* Save the first error for later. */ 174 if (lstat(up, &s)) { 175 if (!save_errno) 176 save_errno = errno; 177 errno = 0; 178 continue; 179 } 180 if (s.st_dev == dev && s.st_ino == ino) 181 break; 182 } 183 184 /* 185 * Check for length of the current name, preceding slash, 186 * leading slash. 187 */ 188 if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) { 189 size_t len, off; 190 191 if (!ptsize) { 192 errno = ERANGE; 193 goto err; 194 } 195 off = bpt - pt; 196 len = ept - bpt; 197 if (!(pt = (char *)realloc(pt, ptsize *= 2))) 198 goto err; 199 bpt = pt + off; 200 ept = pt + ptsize; 201 (void)bcopy(bpt, ept - len, len); 202 bpt = ept - len; 203 } 204 if (!first) 205 *--bpt = '/'; 206 bpt -= dp->d_namlen; 207 bcopy(dp->d_name, bpt, dp->d_namlen); 208 (void)closedir(dir); 209 210 /* Truncate any file name. */ 211 *bup = '\0'; 212 } 213 214 notfound: 215 /* 216 * If readdir set errno, use it, not any saved error; otherwise, 217 * didn't find the current directory in its parent directory, set 218 * errno to ENOENT. 219 */ 220 if (!errno) 221 errno = save_errno ? save_errno : ENOENT; 222 /* FALLTHROUGH */ 223 err: 224 if (ptsize) 225 free(pt); 226 free(up); 227 return((char *)NULL); 228 } 229