Annotation of src/lib/libc/gen/getcwd.c, Revision 1.14
1.14 ! perry 1: /* $NetBSD: getcwd.c,v 1.13 1998/08/10 02:43:09 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
1.14 ! perry 44: __RCSID("$NetBSD: getcwd.c,v 1.13 1998/08/10 02:43:09 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:
70: /*
71: * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
72: *
73: * Find the real name of path, by removing all ".", ".." and symlink
74: * components. Returns (resolved) on success, or (NULL) on failure,
75: * in which case the path which caused trouble is left in (resolved).
76: */
77: char *
78: realpath(path, resolved)
79: const char *path;
80: char *resolved;
81: {
82: struct stat sb;
83: int fd, n, rootd, serrno;
84: char *p, *q, wbuf[MAXPATHLEN];
85:
86: /* Save the starting point. */
87: if ((fd = open(".", O_RDONLY)) < 0) {
88: (void)strcpy(resolved, ".");
89: return (NULL);
90: }
91:
92: /*
93: * Find the dirname and basename from the path to be resolved.
94: * Change directory to the dirname component.
95: * lstat the basename part.
96: * if it is a symlink, read in the value and loop.
97: * if it is a directory, then change to that directory.
98: * get the current directory name and append the basename.
99: */
100: (void)strncpy(resolved, path, MAXPATHLEN - 1);
101: resolved[MAXPATHLEN - 1] = '\0';
102: loop:
103: q = strrchr(resolved, '/');
104: if (q != NULL) {
105: p = q + 1;
106: if (q == resolved)
107: q = "/";
108: else {
109: do {
110: --q;
111: } while (q > resolved && *q == '/');
112: q[1] = '\0';
113: q = resolved;
114: }
115: if (chdir(q) < 0)
116: goto err1;
117: } else
118: p = resolved;
119:
120: /* Deal with the last component. */
121: if (lstat(p, &sb) == 0) {
122: if (S_ISLNK(sb.st_mode)) {
123: n = readlink(p, resolved, MAXPATHLEN);
124: if (n < 0)
125: goto err1;
126: resolved[n] = '\0';
127: goto loop;
128: }
129: if (S_ISDIR(sb.st_mode)) {
130: if (chdir(p) < 0)
131: goto err1;
132: p = "";
133: }
134: }
135:
136: /*
137: * Save the last component name and get the full pathname of
138: * the current directory.
139: */
1.9 perry 140: (void)strncpy(wbuf, p, (sizeof(wbuf) - 1));
1.8 perry 141:
142: /*
143: * Call the inernal internal version of getcwd which
144: * does a physical search rather than using the $PWD short-cut
145: */
1.12 lukem 146: if (getcwd(resolved, MAXPATHLEN) == 0)
1.8 perry 147: goto err1;
148:
149: /*
150: * Join the two strings together, ensuring that the right thing
151: * happens if the last component is empty, or the dirname is root.
152: */
153: if (resolved[0] == '/' && resolved[1] == '\0')
154: rootd = 1;
155: else
156: rootd = 0;
157:
158: if (*wbuf) {
159: if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
160: errno = ENAMETOOLONG;
161: goto err1;
162: }
163: if (rootd == 0)
1.9 perry 164: (void)strcat(resolved, "/"); /* XXX: strcat is safe */
165: (void)strcat(resolved, wbuf); /* XXX: strcat is safe */
1.8 perry 166: }
167:
168: /* Go back to where we came from. */
169: if (fchdir(fd) < 0) {
170: serrno = errno;
171: goto err2;
172: }
173:
174: /* It's okay if the close fails, what's an fd more or less? */
175: (void)close(fd);
176: return (resolved);
177:
178: err1: serrno = errno;
179: (void)fchdir(fd);
180: err2: (void)close(fd);
181: errno = serrno;
182: return (NULL);
183: }
184:
1.12 lukem 185: char *
186: getcwd(pt, size)
1.8 perry 187: char *pt;
188: size_t size;
189: {
1.10 perry 190: struct dirent *dp;
191: DIR *dir;
192: dev_t dev;
193: ino_t ino;
194: int first;
195: char *bpt, *bup;
1.1 cgd 196: struct stat s;
197: dev_t root_dev;
198: ino_t root_ino;
199: size_t ptsize, upsize;
200: int save_errno;
201: char *ept, *eup, *up;
202:
203: /*
204: * If no buffer specified by the user, allocate one as necessary.
205: * If a buffer is specified, the size has to be non-zero. The path
206: * is built from the end of the buffer backwards.
207: */
208: if (pt) {
209: ptsize = 0;
210: if (!size) {
211: errno = EINVAL;
1.4 cgd 212: return (NULL);
1.1 cgd 213: }
214: ept = pt + size;
215: } else {
1.4 cgd 216: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
217: return (NULL);
1.1 cgd 218: ept = pt + ptsize;
219: }
220: bpt = ept - 1;
221: *bpt = '\0';
222:
223: /*
224: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
225: * Should always be enough (it's 340 levels). If it's not, allocate
1.8 perry 226: * as necessary. Special case the first stat, it's ".", not "..".
1.1 cgd 227: */
1.4 cgd 228: if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1 cgd 229: goto err;
230: eup = up + MAXPATHLEN;
231: bup = up;
232: up[0] = '.';
233: up[1] = '\0';
234:
235: /* Save root values, so know when to stop. */
236: if (stat("/", &s))
237: goto err;
238: root_dev = s.st_dev;
239: root_ino = s.st_ino;
240:
241: errno = 0; /* XXX readdir has no error return. */
242:
243: for (first = 1;; first = 0) {
244: /* Stat the current level. */
245: if (lstat(up, &s))
246: goto err;
247:
248: /* Save current node values. */
249: ino = s.st_ino;
250: dev = s.st_dev;
251:
252: /* Check for reaching root. */
253: if (root_dev == dev && root_ino == ino) {
254: *--bpt = '/';
255: /*
256: * It's unclear that it's a requirement to copy the
257: * path to the beginning of the buffer, but it's always
258: * been that way and stuff would probably break.
259: */
1.14 ! perry 260: memmove(pt, bpt, (size_t)(ept - bpt));
1.1 cgd 261: free(up);
1.4 cgd 262: return (pt);
1.1 cgd 263: }
264:
265: /*
266: * Build pointer to the parent directory, allocating memory
267: * as necessary. Max length is 3 for "../", the largest
268: * possible component name, plus a trailing NULL.
269: */
270: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
1.4 cgd 271: if ((up = realloc(up, upsize *= 2)) == NULL)
1.1 cgd 272: goto err;
1.4 cgd 273: bup = up;
1.1 cgd 274: eup = up + upsize;
275: }
276: *bup++ = '.';
277: *bup++ = '.';
278: *bup = '\0';
279:
280: /* Open and stat parent directory. */
281: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
282: goto err;
283:
284: /* Add trailing slash for next directory. */
285: *bup++ = '/';
286:
287: /*
288: * If it's a mount point, have to stat each element because
289: * the inode number in the directory is for the entry in the
290: * parent directory, not the inode number of the mounted file.
291: */
292: save_errno = 0;
293: if (s.st_dev == dev) {
294: for (;;) {
295: if (!(dp = readdir(dir)))
296: goto notfound;
297: if (dp->d_fileno == ino)
298: break;
299: }
300: } else
301: for (;;) {
302: if (!(dp = readdir(dir)))
303: goto notfound;
304: if (ISDOT(dp))
305: continue;
1.14 ! perry 306: memmove(bup, dp->d_name,
1.11 perry 307: (size_t)(dp->d_namlen + 1));
1.1 cgd 308:
309: /* Save the first error for later. */
310: if (lstat(up, &s)) {
311: if (!save_errno)
312: save_errno = errno;
313: errno = 0;
314: continue;
315: }
316: if (s.st_dev == dev && s.st_ino == ino)
317: break;
318: }
319:
320: /*
321: * Check for length of the current name, preceding slash,
322: * leading slash.
323: */
324: if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) {
325: size_t len, off;
326:
327: if (!ptsize) {
328: errno = ERANGE;
329: goto err;
330: }
331: off = bpt - pt;
332: len = ept - bpt;
1.4 cgd 333: if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1 cgd 334: goto err;
335: bpt = pt + off;
336: ept = pt + ptsize;
1.14 ! perry 337: memmove(ept - len, bpt, len);
1.1 cgd 338: bpt = ept - len;
339: }
340: if (!first)
341: *--bpt = '/';
342: bpt -= dp->d_namlen;
1.14 ! perry 343: memmove(bpt, dp->d_name, (size_t)dp->d_namlen);
1.1 cgd 344: (void)closedir(dir);
345:
346: /* Truncate any file name. */
347: *bup = '\0';
348: }
349:
350: notfound:
351: /*
352: * If readdir set errno, use it, not any saved error; otherwise,
353: * didn't find the current directory in its parent directory, set
354: * errno to ENOENT.
355: */
356: if (!errno)
357: errno = save_errno ? save_errno : ENOENT;
358: /* FALLTHROUGH */
359: err:
360: if (ptsize)
361: free(pt);
362: free(up);
1.4 cgd 363: return (NULL);
1.1 cgd 364: }
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