getcwd.c revision 1.5.4.2
1 /* $NetBSD: getcwd.c,v 1.5.4.2 1996/09/19 20:02:41 jtc Exp $ */ 2 3 /* 4 * Copyright (c) 1989, 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #if defined(LIBC_SCCS) && !defined(lint) 37 #if 0 38 static char sccsid[] = "@(#)getcwd.c 8.1 (Berkeley) 6/4/93"; 39 #else 40 static char rcsid[] = "$NetBSD: getcwd.c,v 1.5.4.2 1996/09/19 20:02:41 jtc Exp $"; 41 #endif 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 #include <sys/param.h> 46 #include <sys/stat.h> 47 48 #include <errno.h> 49 #include <dirent.h> 50 #include <stdio.h> 51 #include <stdlib.h> 52 #include <string.h> 53 #include <unistd.h> 54 55 #ifdef __weak_alias 56 __weak_alias(getcwd,_getcwd); 57 #endif 58 59 #define ISDOT(dp) \ 60 (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \ 61 dp->d_name[1] == '.' && dp->d_name[2] == '\0')) 62 63 char * 64 getcwd(pt, size) 65 char *pt; 66 size_t size; 67 { 68 register struct dirent *dp; 69 register DIR *dir; 70 register dev_t dev; 71 register ino_t ino; 72 register int first; 73 register char *bpt, *bup; 74 struct stat s; 75 dev_t root_dev; 76 ino_t root_ino; 77 size_t ptsize, upsize; 78 int save_errno; 79 char *ept, *eup, *up; 80 81 /* 82 * If no buffer specified by the user, allocate one as necessary. 83 * If a buffer is specified, the size has to be non-zero. The path 84 * is built from the end of the buffer backwards. 85 */ 86 if (pt) { 87 ptsize = 0; 88 if (!size) { 89 errno = EINVAL; 90 return (NULL); 91 } 92 ept = pt + size; 93 } else { 94 if ((pt = malloc(ptsize = 1024 - 4)) == NULL) 95 return (NULL); 96 ept = pt + ptsize; 97 } 98 bpt = ept - 1; 99 *bpt = '\0'; 100 101 /* 102 * Allocate bytes (1024 - malloc space) for the string of "../"'s. 103 * Should always be enough (it's 340 levels). If it's not, allocate 104 * as necessary. Special * case the first stat, it's ".", not "..". 105 */ 106 if ((up = malloc(upsize = 1024 - 4)) == NULL) 107 goto err; 108 eup = up + MAXPATHLEN; 109 bup = up; 110 up[0] = '.'; 111 up[1] = '\0'; 112 113 /* Save root values, so know when to stop. */ 114 if (stat("/", &s)) 115 goto err; 116 root_dev = s.st_dev; 117 root_ino = s.st_ino; 118 119 errno = 0; /* XXX readdir has no error return. */ 120 121 for (first = 1;; first = 0) { 122 /* Stat the current level. */ 123 if (lstat(up, &s)) 124 goto err; 125 126 /* Save current node values. */ 127 ino = s.st_ino; 128 dev = s.st_dev; 129 130 /* Check for reaching root. */ 131 if (root_dev == dev && root_ino == ino) { 132 *--bpt = '/'; 133 /* 134 * It's unclear that it's a requirement to copy the 135 * path to the beginning of the buffer, but it's always 136 * been that way and stuff would probably break. 137 */ 138 bcopy(bpt, pt, ept - bpt); 139 free(up); 140 return (pt); 141 } 142 143 /* 144 * Build pointer to the parent directory, allocating memory 145 * as necessary. Max length is 3 for "../", the largest 146 * possible component name, plus a trailing NULL. 147 */ 148 if (bup + 3 + MAXNAMLEN + 1 >= eup) { 149 if ((up = realloc(up, upsize *= 2)) == NULL) 150 goto err; 151 bup = up; 152 eup = up + upsize; 153 } 154 *bup++ = '.'; 155 *bup++ = '.'; 156 *bup = '\0'; 157 158 /* Open and stat parent directory. */ 159 if (!(dir = opendir(up)) || fstat(dirfd(dir), &s)) 160 goto err; 161 162 /* Add trailing slash for next directory. */ 163 *bup++ = '/'; 164 165 /* 166 * If it's a mount point, have to stat each element because 167 * the inode number in the directory is for the entry in the 168 * parent directory, not the inode number of the mounted file. 169 */ 170 save_errno = 0; 171 if (s.st_dev == dev) { 172 for (;;) { 173 if (!(dp = readdir(dir))) 174 goto notfound; 175 if (dp->d_fileno == ino) 176 break; 177 } 178 } else 179 for (;;) { 180 if (!(dp = readdir(dir))) 181 goto notfound; 182 if (ISDOT(dp)) 183 continue; 184 bcopy(dp->d_name, bup, dp->d_namlen + 1); 185 186 /* Save the first error for later. */ 187 if (lstat(up, &s)) { 188 if (!save_errno) 189 save_errno = errno; 190 errno = 0; 191 continue; 192 } 193 if (s.st_dev == dev && s.st_ino == ino) 194 break; 195 } 196 197 /* 198 * Check for length of the current name, preceding slash, 199 * leading slash. 200 */ 201 if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) { 202 size_t len, off; 203 204 if (!ptsize) { 205 errno = ERANGE; 206 goto err; 207 } 208 off = bpt - pt; 209 len = ept - bpt; 210 if ((pt = realloc(pt, ptsize *= 2)) == NULL) 211 goto err; 212 bpt = pt + off; 213 ept = pt + ptsize; 214 bcopy(bpt, ept - len, len); 215 bpt = ept - len; 216 } 217 if (!first) 218 *--bpt = '/'; 219 bpt -= dp->d_namlen; 220 bcopy(dp->d_name, bpt, dp->d_namlen); 221 (void)closedir(dir); 222 223 /* Truncate any file name. */ 224 *bup = '\0'; 225 } 226 227 notfound: 228 /* 229 * If readdir set errno, use it, not any saved error; otherwise, 230 * didn't find the current directory in its parent directory, set 231 * errno to ENOENT. 232 */ 233 if (!errno) 234 errno = save_errno ? save_errno : ENOENT; 235 /* FALLTHROUGH */ 236 err: 237 if (ptsize) 238 free(pt); 239 free(up); 240 return (NULL); 241 } 242
Indexes created Tue Sep 30 20:09:53 GMT 2025