Annotation of src/lib/libc/gen/getcwd.c, Revision 1.10
1.10 ! perry 1: /* $NetBSD: getcwd.c,v 1.9 1998/02/02 23:33:44 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
1.10 ! perry 44: __RCSID("$NetBSD: getcwd.c,v 1.9 1998/02/02 23:33:44 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:
1.8 perry 65: static char *getcwd_physical __P((char *, size_t));
66:
1.1 cgd 67: #define ISDOT(dp) \
68: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
1.6 christos 69: (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
1.1 cgd 70:
71: char *
72: getcwd(pt, size)
73: char *pt;
74: size_t size;
75: {
1.8 perry 76: char *pwd;
77: size_t pwdlen;
78: dev_t dev;
79: ino_t ino;
80: struct stat s;
81:
82: /* Check $PWD -- if it's right, it's fast. */
83: if ((pwd = getenv("PWD")) != NULL && pwd[0] == '/' && !stat(pwd, &s)) {
84: dev = s.st_dev;
85: ino = s.st_ino;
86: if (!stat(".", &s) && dev == s.st_dev && ino == s.st_ino) {
87: pwdlen = strlen(pwd);
88: if (size != 0) {
89: if (pwdlen + 1 > size) {
90: errno = ERANGE;
91: return (NULL);
92: }
93: } else if ((pt = malloc(pwdlen + 1)) == NULL)
94: return (NULL);
95: memmove(pt, pwd, pwdlen);
96: pt[pwdlen] = '\0';
97: return (pt);
98: }
99: }
100:
101: return (getcwd_physical(pt, size));
102: }
103:
104: /*
105: * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
106: *
107: * Find the real name of path, by removing all ".", ".." and symlink
108: * components. Returns (resolved) on success, or (NULL) on failure,
109: * in which case the path which caused trouble is left in (resolved).
110: */
111: char *
112: realpath(path, resolved)
113: const char *path;
114: char *resolved;
115: {
116: struct stat sb;
117: int fd, n, rootd, serrno;
118: char *p, *q, wbuf[MAXPATHLEN];
119:
120: /* Save the starting point. */
121: if ((fd = open(".", O_RDONLY)) < 0) {
122: (void)strcpy(resolved, ".");
123: return (NULL);
124: }
125:
126: /*
127: * Find the dirname and basename from the path to be resolved.
128: * Change directory to the dirname component.
129: * lstat the basename part.
130: * if it is a symlink, read in the value and loop.
131: * if it is a directory, then change to that directory.
132: * get the current directory name and append the basename.
133: */
134: (void)strncpy(resolved, path, MAXPATHLEN - 1);
135: resolved[MAXPATHLEN - 1] = '\0';
136: loop:
137: q = strrchr(resolved, '/');
138: if (q != NULL) {
139: p = q + 1;
140: if (q == resolved)
141: q = "/";
142: else {
143: do {
144: --q;
145: } while (q > resolved && *q == '/');
146: q[1] = '\0';
147: q = resolved;
148: }
149: if (chdir(q) < 0)
150: goto err1;
151: } else
152: p = resolved;
153:
154: /* Deal with the last component. */
155: if (lstat(p, &sb) == 0) {
156: if (S_ISLNK(sb.st_mode)) {
157: n = readlink(p, resolved, MAXPATHLEN);
158: if (n < 0)
159: goto err1;
160: resolved[n] = '\0';
161: goto loop;
162: }
163: if (S_ISDIR(sb.st_mode)) {
164: if (chdir(p) < 0)
165: goto err1;
166: p = "";
167: }
168: }
169:
170: /*
171: * Save the last component name and get the full pathname of
172: * the current directory.
173: */
1.9 perry 174: (void)strncpy(wbuf, p, (sizeof(wbuf) - 1));
1.8 perry 175:
176: /*
177: * Call the inernal internal version of getcwd which
178: * does a physical search rather than using the $PWD short-cut
179: */
180: if (getcwd_physical(resolved, MAXPATHLEN) == 0)
181: goto err1;
182:
183: /*
184: * Join the two strings together, ensuring that the right thing
185: * happens if the last component is empty, or the dirname is root.
186: */
187: if (resolved[0] == '/' && resolved[1] == '\0')
188: rootd = 1;
189: else
190: rootd = 0;
191:
192: if (*wbuf) {
193: if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
194: errno = ENAMETOOLONG;
195: goto err1;
196: }
197: if (rootd == 0)
1.9 perry 198: (void)strcat(resolved, "/"); /* XXX: strcat is safe */
199: (void)strcat(resolved, wbuf); /* XXX: strcat is safe */
1.8 perry 200: }
201:
202: /* Go back to where we came from. */
203: if (fchdir(fd) < 0) {
204: serrno = errno;
205: goto err2;
206: }
207:
208: /* It's okay if the close fails, what's an fd more or less? */
209: (void)close(fd);
210: return (resolved);
211:
212: err1: serrno = errno;
213: (void)fchdir(fd);
214: err2: (void)close(fd);
215: errno = serrno;
216: return (NULL);
217: }
218:
219: static char *
220: getcwd_physical(pt, size)
221: char *pt;
222: size_t size;
223: {
1.10 ! perry 224: struct dirent *dp;
! 225: DIR *dir;
! 226: dev_t dev;
! 227: ino_t ino;
! 228: int first;
! 229: char *bpt, *bup;
1.1 cgd 230: struct stat s;
231: dev_t root_dev;
232: ino_t root_ino;
233: size_t ptsize, upsize;
234: int save_errno;
235: char *ept, *eup, *up;
236:
237: /*
238: * If no buffer specified by the user, allocate one as necessary.
239: * If a buffer is specified, the size has to be non-zero. The path
240: * is built from the end of the buffer backwards.
241: */
242: if (pt) {
243: ptsize = 0;
244: if (!size) {
245: errno = EINVAL;
1.4 cgd 246: return (NULL);
1.1 cgd 247: }
248: ept = pt + size;
249: } else {
1.4 cgd 250: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
251: return (NULL);
1.1 cgd 252: ept = pt + ptsize;
253: }
254: bpt = ept - 1;
255: *bpt = '\0';
256:
257: /*
258: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
259: * Should always be enough (it's 340 levels). If it's not, allocate
1.8 perry 260: * as necessary. Special case the first stat, it's ".", not "..".
1.1 cgd 261: */
1.4 cgd 262: if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1 cgd 263: goto err;
264: eup = up + MAXPATHLEN;
265: bup = up;
266: up[0] = '.';
267: up[1] = '\0';
268:
269: /* Save root values, so know when to stop. */
270: if (stat("/", &s))
271: goto err;
272: root_dev = s.st_dev;
273: root_ino = s.st_ino;
274:
275: errno = 0; /* XXX readdir has no error return. */
276:
277: for (first = 1;; first = 0) {
278: /* Stat the current level. */
279: if (lstat(up, &s))
280: goto err;
281:
282: /* Save current node values. */
283: ino = s.st_ino;
284: dev = s.st_dev;
285:
286: /* Check for reaching root. */
287: if (root_dev == dev && root_ino == ino) {
288: *--bpt = '/';
289: /*
290: * It's unclear that it's a requirement to copy the
291: * path to the beginning of the buffer, but it's always
292: * been that way and stuff would probably break.
293: */
1.5 jtc 294: bcopy(bpt, pt, ept - bpt);
1.1 cgd 295: free(up);
1.4 cgd 296: return (pt);
1.1 cgd 297: }
298:
299: /*
300: * Build pointer to the parent directory, allocating memory
301: * as necessary. Max length is 3 for "../", the largest
302: * possible component name, plus a trailing NULL.
303: */
304: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
1.4 cgd 305: if ((up = realloc(up, upsize *= 2)) == NULL)
1.1 cgd 306: goto err;
1.4 cgd 307: bup = up;
1.1 cgd 308: eup = up + upsize;
309: }
310: *bup++ = '.';
311: *bup++ = '.';
312: *bup = '\0';
313:
314: /* Open and stat parent directory. */
315: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
316: goto err;
317:
318: /* Add trailing slash for next directory. */
319: *bup++ = '/';
320:
321: /*
322: * If it's a mount point, have to stat each element because
323: * the inode number in the directory is for the entry in the
324: * parent directory, not the inode number of the mounted file.
325: */
326: save_errno = 0;
327: if (s.st_dev == dev) {
328: for (;;) {
329: if (!(dp = readdir(dir)))
330: goto notfound;
331: if (dp->d_fileno == ino)
332: break;
333: }
334: } else
335: for (;;) {
336: if (!(dp = readdir(dir)))
337: goto notfound;
338: if (ISDOT(dp))
339: continue;
340: bcopy(dp->d_name, bup, dp->d_namlen + 1);
341:
342: /* Save the first error for later. */
343: if (lstat(up, &s)) {
344: if (!save_errno)
345: save_errno = errno;
346: errno = 0;
347: continue;
348: }
349: if (s.st_dev == dev && s.st_ino == ino)
350: break;
351: }
352:
353: /*
354: * Check for length of the current name, preceding slash,
355: * leading slash.
356: */
357: if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) {
358: size_t len, off;
359:
360: if (!ptsize) {
361: errno = ERANGE;
362: goto err;
363: }
364: off = bpt - pt;
365: len = ept - bpt;
1.4 cgd 366: if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1 cgd 367: goto err;
368: bpt = pt + off;
369: ept = pt + ptsize;
1.5 jtc 370: bcopy(bpt, ept - len, len);
1.1 cgd 371: bpt = ept - len;
372: }
373: if (!first)
374: *--bpt = '/';
375: bpt -= dp->d_namlen;
376: bcopy(dp->d_name, bpt, dp->d_namlen);
377: (void)closedir(dir);
378:
379: /* Truncate any file name. */
380: *bup = '\0';
381: }
382:
383: notfound:
384: /*
385: * If readdir set errno, use it, not any saved error; otherwise,
386: * didn't find the current directory in its parent directory, set
387: * errno to ENOENT.
388: */
389: if (!errno)
390: errno = save_errno ? save_errno : ENOENT;
391: /* FALLTHROUGH */
392: err:
393: if (ptsize)
394: free(pt);
395: free(up);
1.4 cgd 396: return (NULL);
1.1 cgd 397: }
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