Annotation of src/lib/libc/gen/getcwd.c, Revision 1.8
1.8 ! perry 1: /* $NetBSD: getcwd.c,v 1.7 1997/07/21 14:07:04 jtc 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
1.8 ! perry 44: __RCSID("$NetBSD: getcwd.c,v 1.7 1997/07/21 14:07:04 jtc 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);
62: #endif
1.1 cgd 63:
1.8 ! perry 64: static char *getcwd_physical __P((char *, size_t));
! 65:
1.1 cgd 66: #define ISDOT(dp) \
67: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
1.6 christos 68: (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
1.1 cgd 69:
70: char *
71: getcwd(pt, size)
72: char *pt;
73: size_t size;
74: {
1.8 ! perry 75: char *pwd;
! 76: size_t pwdlen;
! 77: dev_t dev;
! 78: ino_t ino;
! 79: struct stat s;
! 80:
! 81: /* Check $PWD -- if it's right, it's fast. */
! 82: if ((pwd = getenv("PWD")) != NULL && pwd[0] == '/' && !stat(pwd, &s)) {
! 83: dev = s.st_dev;
! 84: ino = s.st_ino;
! 85: if (!stat(".", &s) && dev == s.st_dev && ino == s.st_ino) {
! 86: pwdlen = strlen(pwd);
! 87: if (size != 0) {
! 88: if (pwdlen + 1 > size) {
! 89: errno = ERANGE;
! 90: return (NULL);
! 91: }
! 92: } else if ((pt = malloc(pwdlen + 1)) == NULL)
! 93: return (NULL);
! 94: memmove(pt, pwd, pwdlen);
! 95: pt[pwdlen] = '\0';
! 96: return (pt);
! 97: }
! 98: }
! 99:
! 100: return (getcwd_physical(pt, size));
! 101: }
! 102:
! 103: /*
! 104: * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
! 105: *
! 106: * Find the real name of path, by removing all ".", ".." and symlink
! 107: * components. Returns (resolved) on success, or (NULL) on failure,
! 108: * in which case the path which caused trouble is left in (resolved).
! 109: */
! 110: char *
! 111: realpath(path, resolved)
! 112: const char *path;
! 113: char *resolved;
! 114: {
! 115: struct stat sb;
! 116: int fd, n, rootd, serrno;
! 117: char *p, *q, wbuf[MAXPATHLEN];
! 118:
! 119: /* Save the starting point. */
! 120: if ((fd = open(".", O_RDONLY)) < 0) {
! 121: (void)strcpy(resolved, ".");
! 122: return (NULL);
! 123: }
! 124:
! 125: /*
! 126: * Find the dirname and basename from the path to be resolved.
! 127: * Change directory to the dirname component.
! 128: * lstat the basename part.
! 129: * if it is a symlink, read in the value and loop.
! 130: * if it is a directory, then change to that directory.
! 131: * get the current directory name and append the basename.
! 132: */
! 133: (void)strncpy(resolved, path, MAXPATHLEN - 1);
! 134: resolved[MAXPATHLEN - 1] = '\0';
! 135: loop:
! 136: q = strrchr(resolved, '/');
! 137: if (q != NULL) {
! 138: p = q + 1;
! 139: if (q == resolved)
! 140: q = "/";
! 141: else {
! 142: do {
! 143: --q;
! 144: } while (q > resolved && *q == '/');
! 145: q[1] = '\0';
! 146: q = resolved;
! 147: }
! 148: if (chdir(q) < 0)
! 149: goto err1;
! 150: } else
! 151: p = resolved;
! 152:
! 153: /* Deal with the last component. */
! 154: if (lstat(p, &sb) == 0) {
! 155: if (S_ISLNK(sb.st_mode)) {
! 156: n = readlink(p, resolved, MAXPATHLEN);
! 157: if (n < 0)
! 158: goto err1;
! 159: resolved[n] = '\0';
! 160: goto loop;
! 161: }
! 162: if (S_ISDIR(sb.st_mode)) {
! 163: if (chdir(p) < 0)
! 164: goto err1;
! 165: p = "";
! 166: }
! 167: }
! 168:
! 169: /*
! 170: * Save the last component name and get the full pathname of
! 171: * the current directory.
! 172: */
! 173: (void)strcpy(wbuf, p);
! 174:
! 175: /*
! 176: * Call the inernal internal version of getcwd which
! 177: * does a physical search rather than using the $PWD short-cut
! 178: */
! 179: if (getcwd_physical(resolved, MAXPATHLEN) == 0)
! 180: goto err1;
! 181:
! 182: /*
! 183: * Join the two strings together, ensuring that the right thing
! 184: * happens if the last component is empty, or the dirname is root.
! 185: */
! 186: if (resolved[0] == '/' && resolved[1] == '\0')
! 187: rootd = 1;
! 188: else
! 189: rootd = 0;
! 190:
! 191: if (*wbuf) {
! 192: if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
! 193: errno = ENAMETOOLONG;
! 194: goto err1;
! 195: }
! 196: if (rootd == 0)
! 197: (void)strcat(resolved, "/");
! 198: (void)strcat(resolved, wbuf);
! 199: }
! 200:
! 201: /* Go back to where we came from. */
! 202: if (fchdir(fd) < 0) {
! 203: serrno = errno;
! 204: goto err2;
! 205: }
! 206:
! 207: /* It's okay if the close fails, what's an fd more or less? */
! 208: (void)close(fd);
! 209: return (resolved);
! 210:
! 211: err1: serrno = errno;
! 212: (void)fchdir(fd);
! 213: err2: (void)close(fd);
! 214: errno = serrno;
! 215: return (NULL);
! 216: }
! 217:
! 218: static char *
! 219: getcwd_physical(pt, size)
! 220: char *pt;
! 221: size_t size;
! 222: {
1.1 cgd 223: register struct dirent *dp;
224: register DIR *dir;
225: register dev_t dev;
226: register ino_t ino;
227: register int first;
228: register char *bpt, *bup;
229: struct stat s;
230: dev_t root_dev;
231: ino_t root_ino;
232: size_t ptsize, upsize;
233: int save_errno;
234: char *ept, *eup, *up;
235:
236: /*
237: * If no buffer specified by the user, allocate one as necessary.
238: * If a buffer is specified, the size has to be non-zero. The path
239: * is built from the end of the buffer backwards.
240: */
241: if (pt) {
242: ptsize = 0;
243: if (!size) {
244: errno = EINVAL;
1.4 cgd 245: return (NULL);
1.1 cgd 246: }
247: ept = pt + size;
248: } else {
1.4 cgd 249: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
250: return (NULL);
1.1 cgd 251: ept = pt + ptsize;
252: }
253: bpt = ept - 1;
254: *bpt = '\0';
255:
256: /*
257: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
258: * Should always be enough (it's 340 levels). If it's not, allocate
1.8 ! perry 259: * as necessary. Special case the first stat, it's ".", not "..".
1.1 cgd 260: */
1.4 cgd 261: if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1 cgd 262: goto err;
263: eup = up + MAXPATHLEN;
264: bup = up;
265: up[0] = '.';
266: up[1] = '\0';
267:
268: /* Save root values, so know when to stop. */
269: if (stat("/", &s))
270: goto err;
271: root_dev = s.st_dev;
272: root_ino = s.st_ino;
273:
274: errno = 0; /* XXX readdir has no error return. */
275:
276: for (first = 1;; first = 0) {
277: /* Stat the current level. */
278: if (lstat(up, &s))
279: goto err;
280:
281: /* Save current node values. */
282: ino = s.st_ino;
283: dev = s.st_dev;
284:
285: /* Check for reaching root. */
286: if (root_dev == dev && root_ino == ino) {
287: *--bpt = '/';
288: /*
289: * It's unclear that it's a requirement to copy the
290: * path to the beginning of the buffer, but it's always
291: * been that way and stuff would probably break.
292: */
1.5 jtc 293: bcopy(bpt, pt, ept - bpt);
1.1 cgd 294: free(up);
1.4 cgd 295: return (pt);
1.1 cgd 296: }
297:
298: /*
299: * Build pointer to the parent directory, allocating memory
300: * as necessary. Max length is 3 for "../", the largest
301: * possible component name, plus a trailing NULL.
302: */
303: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
1.4 cgd 304: if ((up = realloc(up, upsize *= 2)) == NULL)
1.1 cgd 305: goto err;
1.4 cgd 306: bup = up;
1.1 cgd 307: eup = up + upsize;
308: }
309: *bup++ = '.';
310: *bup++ = '.';
311: *bup = '\0';
312:
313: /* Open and stat parent directory. */
314: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
315: goto err;
316:
317: /* Add trailing slash for next directory. */
318: *bup++ = '/';
319:
320: /*
321: * If it's a mount point, have to stat each element because
322: * the inode number in the directory is for the entry in the
323: * parent directory, not the inode number of the mounted file.
324: */
325: save_errno = 0;
326: if (s.st_dev == dev) {
327: for (;;) {
328: if (!(dp = readdir(dir)))
329: goto notfound;
330: if (dp->d_fileno == ino)
331: break;
332: }
333: } else
334: for (;;) {
335: if (!(dp = readdir(dir)))
336: goto notfound;
337: if (ISDOT(dp))
338: continue;
339: bcopy(dp->d_name, bup, dp->d_namlen + 1);
340:
341: /* Save the first error for later. */
342: if (lstat(up, &s)) {
343: if (!save_errno)
344: save_errno = errno;
345: errno = 0;
346: continue;
347: }
348: if (s.st_dev == dev && s.st_ino == ino)
349: break;
350: }
351:
352: /*
353: * Check for length of the current name, preceding slash,
354: * leading slash.
355: */
356: if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) {
357: size_t len, off;
358:
359: if (!ptsize) {
360: errno = ERANGE;
361: goto err;
362: }
363: off = bpt - pt;
364: len = ept - bpt;
1.4 cgd 365: if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1 cgd 366: goto err;
367: bpt = pt + off;
368: ept = pt + ptsize;
1.5 jtc 369: bcopy(bpt, ept - len, len);
1.1 cgd 370: bpt = ept - len;
371: }
372: if (!first)
373: *--bpt = '/';
374: bpt -= dp->d_namlen;
375: bcopy(dp->d_name, bpt, dp->d_namlen);
376: (void)closedir(dir);
377:
378: /* Truncate any file name. */
379: *bup = '\0';
380: }
381:
382: notfound:
383: /*
384: * If readdir set errno, use it, not any saved error; otherwise,
385: * didn't find the current directory in its parent directory, set
386: * errno to ENOENT.
387: */
388: if (!errno)
389: errno = save_errno ? save_errno : ENOENT;
390: /* FALLTHROUGH */
391: err:
392: if (ptsize)
393: free(pt);
394: free(up);
1.4 cgd 395: return (NULL);
1.1 cgd 396: }
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