Annotation of src/lib/libc/gen/getcwd.c, Revision 1.15
1.15 ! christos 1: /* $NetBSD: getcwd.c,v 1.14 1998/08/26 00:38:40 perry Exp $ */
1.4 cgd 2:
1.1 cgd 3: /*
1.8 perry 4: * Copyright (c) 1989, 1991, 1993, 1995
1.4 cgd 5: * The Regents of the University of California. All rights reserved.
1.1 cgd 6: *
1.8 perry 7: * This code is derived from software contributed to Berkeley by
8: * Jan-Simon Pendry.
9: *
1.1 cgd 10: * Redistribution and use in source and binary forms, with or without
11: * modification, are permitted provided that the following conditions
12: * are met:
13: * 1. Redistributions of source code must retain the above copyright
14: * notice, this list of conditions and the following disclaimer.
15: * 2. Redistributions in binary form must reproduce the above copyright
16: * notice, this list of conditions and the following disclaimer in the
17: * documentation and/or other materials provided with the distribution.
18: * 3. All advertising materials mentioning features or use of this software
19: * must display the following acknowledgement:
20: * This product includes software developed by the University of
21: * California, Berkeley and its contributors.
22: * 4. Neither the name of the University nor the names of its contributors
23: * may be used to endorse or promote products derived from this software
24: * without specific prior written permission.
25: *
26: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36: * SUCH DAMAGE.
37: */
38:
1.6 christos 39: #include <sys/cdefs.h>
1.1 cgd 40: #if defined(LIBC_SCCS) && !defined(lint)
1.4 cgd 41: #if 0
1.8 perry 42: static char sccsid[] = "@(#)getcwd.c 8.5 (Berkeley) 2/7/95";
1.4 cgd 43: #else
1.15 ! christos 44: __RCSID("$NetBSD: getcwd.c,v 1.14 1998/08/26 00:38:40 perry Exp $");
1.4 cgd 45: #endif
1.1 cgd 46: #endif /* LIBC_SCCS and not lint */
47:
1.7 jtc 48: #include "namespace.h"
1.1 cgd 49: #include <sys/param.h>
50: #include <sys/stat.h>
1.8 perry 51:
52: #include <dirent.h>
1.1 cgd 53: #include <errno.h>
1.8 perry 54: #include <fcntl.h>
1.1 cgd 55: #include <stdio.h>
56: #include <stdlib.h>
57: #include <string.h>
58: #include <unistd.h>
1.7 jtc 59:
60: #ifdef __weak_alias
61: __weak_alias(getcwd,_getcwd);
1.9 perry 62: __weak_alias(realpath,_realpath);
1.7 jtc 63: #endif
1.1 cgd 64:
65: #define ISDOT(dp) \
66: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
1.6 christos 67: (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
1.1 cgd 68:
1.8 perry 69:
1.15 ! christos 70: #if defined(__SVR4) || defined(__svr4__)
! 71: #define d_fileno d_ino
! 72: #endif
! 73:
1.8 perry 74: /*
75: * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
76: *
77: * Find the real name of path, by removing all ".", ".." and symlink
78: * components. Returns (resolved) on success, or (NULL) on failure,
79: * in which case the path which caused trouble is left in (resolved).
80: */
81: char *
82: realpath(path, resolved)
83: const char *path;
84: char *resolved;
85: {
86: struct stat sb;
87: int fd, n, rootd, serrno;
88: char *p, *q, wbuf[MAXPATHLEN];
89:
90: /* Save the starting point. */
91: if ((fd = open(".", O_RDONLY)) < 0) {
92: (void)strcpy(resolved, ".");
93: return (NULL);
94: }
95:
96: /*
97: * Find the dirname and basename from the path to be resolved.
98: * Change directory to the dirname component.
99: * lstat the basename part.
100: * if it is a symlink, read in the value and loop.
101: * if it is a directory, then change to that directory.
102: * get the current directory name and append the basename.
103: */
104: (void)strncpy(resolved, path, MAXPATHLEN - 1);
105: resolved[MAXPATHLEN - 1] = '\0';
106: loop:
107: q = strrchr(resolved, '/');
108: if (q != NULL) {
109: p = q + 1;
110: if (q == resolved)
111: q = "/";
112: else {
113: do {
114: --q;
115: } while (q > resolved && *q == '/');
116: q[1] = '\0';
117: q = resolved;
118: }
119: if (chdir(q) < 0)
120: goto err1;
121: } else
122: p = resolved;
123:
124: /* Deal with the last component. */
125: if (lstat(p, &sb) == 0) {
126: if (S_ISLNK(sb.st_mode)) {
127: n = readlink(p, resolved, MAXPATHLEN);
128: if (n < 0)
129: goto err1;
130: resolved[n] = '\0';
131: goto loop;
132: }
133: if (S_ISDIR(sb.st_mode)) {
134: if (chdir(p) < 0)
135: goto err1;
136: p = "";
137: }
138: }
139:
140: /*
141: * Save the last component name and get the full pathname of
142: * the current directory.
143: */
1.9 perry 144: (void)strncpy(wbuf, p, (sizeof(wbuf) - 1));
1.8 perry 145:
146: /*
147: * Call the inernal internal version of getcwd which
148: * does a physical search rather than using the $PWD short-cut
149: */
1.12 lukem 150: if (getcwd(resolved, MAXPATHLEN) == 0)
1.8 perry 151: goto err1;
152:
153: /*
154: * Join the two strings together, ensuring that the right thing
155: * happens if the last component is empty, or the dirname is root.
156: */
157: if (resolved[0] == '/' && resolved[1] == '\0')
158: rootd = 1;
159: else
160: rootd = 0;
161:
162: if (*wbuf) {
163: if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
164: errno = ENAMETOOLONG;
165: goto err1;
166: }
167: if (rootd == 0)
1.9 perry 168: (void)strcat(resolved, "/"); /* XXX: strcat is safe */
169: (void)strcat(resolved, wbuf); /* XXX: strcat is safe */
1.8 perry 170: }
171:
172: /* Go back to where we came from. */
173: if (fchdir(fd) < 0) {
174: serrno = errno;
175: goto err2;
176: }
177:
178: /* It's okay if the close fails, what's an fd more or less? */
179: (void)close(fd);
180: return (resolved);
181:
182: err1: serrno = errno;
183: (void)fchdir(fd);
184: err2: (void)close(fd);
185: errno = serrno;
186: return (NULL);
187: }
188:
1.12 lukem 189: char *
190: getcwd(pt, size)
1.8 perry 191: char *pt;
192: size_t size;
193: {
1.10 perry 194: struct dirent *dp;
195: DIR *dir;
196: dev_t dev;
197: ino_t ino;
198: int first;
199: char *bpt, *bup;
1.1 cgd 200: struct stat s;
201: dev_t root_dev;
202: ino_t root_ino;
203: size_t ptsize, upsize;
204: int save_errno;
205: char *ept, *eup, *up;
1.15 ! christos 206: size_t dlen;
1.1 cgd 207:
208: /*
209: * If no buffer specified by the user, allocate one as necessary.
210: * If a buffer is specified, the size has to be non-zero. The path
211: * is built from the end of the buffer backwards.
212: */
213: if (pt) {
214: ptsize = 0;
215: if (!size) {
216: errno = EINVAL;
1.4 cgd 217: return (NULL);
1.1 cgd 218: }
219: ept = pt + size;
220: } else {
1.4 cgd 221: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
222: return (NULL);
1.1 cgd 223: ept = pt + ptsize;
224: }
225: bpt = ept - 1;
226: *bpt = '\0';
227:
228: /*
229: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
230: * Should always be enough (it's 340 levels). If it's not, allocate
1.8 perry 231: * as necessary. Special case the first stat, it's ".", not "..".
1.1 cgd 232: */
1.4 cgd 233: if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1 cgd 234: goto err;
235: eup = up + MAXPATHLEN;
236: bup = up;
237: up[0] = '.';
238: up[1] = '\0';
239:
240: /* Save root values, so know when to stop. */
241: if (stat("/", &s))
242: goto err;
243: root_dev = s.st_dev;
244: root_ino = s.st_ino;
245:
246: errno = 0; /* XXX readdir has no error return. */
247:
248: for (first = 1;; first = 0) {
249: /* Stat the current level. */
250: if (lstat(up, &s))
251: goto err;
252:
253: /* Save current node values. */
254: ino = s.st_ino;
255: dev = s.st_dev;
256:
257: /* Check for reaching root. */
258: if (root_dev == dev && root_ino == ino) {
259: *--bpt = '/';
260: /*
261: * It's unclear that it's a requirement to copy the
262: * path to the beginning of the buffer, but it's always
263: * been that way and stuff would probably break.
264: */
1.14 perry 265: memmove(pt, bpt, (size_t)(ept - bpt));
1.1 cgd 266: free(up);
1.4 cgd 267: return (pt);
1.1 cgd 268: }
269:
270: /*
271: * Build pointer to the parent directory, allocating memory
272: * as necessary. Max length is 3 for "../", the largest
273: * possible component name, plus a trailing NULL.
274: */
275: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
1.4 cgd 276: if ((up = realloc(up, upsize *= 2)) == NULL)
1.1 cgd 277: goto err;
1.4 cgd 278: bup = up;
1.1 cgd 279: eup = up + upsize;
280: }
281: *bup++ = '.';
282: *bup++ = '.';
283: *bup = '\0';
284:
285: /* Open and stat parent directory. */
286: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
287: goto err;
288:
289: /* Add trailing slash for next directory. */
290: *bup++ = '/';
291:
292: /*
293: * If it's a mount point, have to stat each element because
294: * the inode number in the directory is for the entry in the
295: * parent directory, not the inode number of the mounted file.
296: */
297: save_errno = 0;
298: if (s.st_dev == dev) {
299: for (;;) {
300: if (!(dp = readdir(dir)))
301: goto notfound;
1.15 ! christos 302: if (dp->d_fileno == ino) {
! 303: #if defined(__SVR4) || defined(__svr4__)
! 304: dlen = strlen(dp->d_name);
! 305: #else
! 306: dlen = dp->d_namlen;
! 307: #endif
1.1 cgd 308: break;
1.15 ! christos 309: }
1.1 cgd 310: }
311: } else
312: for (;;) {
313: if (!(dp = readdir(dir)))
314: goto notfound;
315: if (ISDOT(dp))
316: continue;
1.15 ! christos 317: #if defined(__SVR4) || defined(__svr4__)
! 318: dlen = strlen(dp->d_name);
! 319: #else
! 320: dlen = dp->d_namlen;
! 321: #endif
! 322: memmove(bup, dp->d_name, dlen + 1);
1.1 cgd 323:
324: /* Save the first error for later. */
325: if (lstat(up, &s)) {
326: if (!save_errno)
327: save_errno = errno;
328: errno = 0;
329: continue;
330: }
331: if (s.st_dev == dev && s.st_ino == ino)
332: break;
333: }
334:
335: /*
336: * Check for length of the current name, preceding slash,
337: * leading slash.
338: */
1.15 ! christos 339: if (bpt - pt <= dlen + (first ? 1 : 2)) {
1.1 cgd 340: size_t len, off;
341:
342: if (!ptsize) {
343: errno = ERANGE;
344: goto err;
345: }
346: off = bpt - pt;
347: len = ept - bpt;
1.4 cgd 348: if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1 cgd 349: goto err;
350: bpt = pt + off;
351: ept = pt + ptsize;
1.14 perry 352: memmove(ept - len, bpt, len);
1.1 cgd 353: bpt = ept - len;
354: }
355: if (!first)
356: *--bpt = '/';
1.15 ! christos 357: bpt -= dlen;
! 358: memmove(bpt, dp->d_name, dlen);
1.1 cgd 359: (void)closedir(dir);
360:
361: /* Truncate any file name. */
362: *bup = '\0';
363: }
364:
365: notfound:
366: /*
367: * If readdir set errno, use it, not any saved error; otherwise,
368: * didn't find the current directory in its parent directory, set
369: * errno to ENOENT.
370: */
371: if (!errno)
372: errno = save_errno ? save_errno : ENOENT;
373: /* FALLTHROUGH */
374: err:
375: if (ptsize)
376: free(pt);
377: free(up);
1.4 cgd 378: return (NULL);
1.1 cgd 379: }
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