1: /*
2: * Copyright (c) 1989, 1991, 1993
3: * The Regents of the University of California. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: * 3. Neither the name of the University nor the names of its contributors
14: * may be used to endorse or promote products derived from this software
15: * without specific prior written permission.
16: *
17: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27: * SUCH DAMAGE.
28: */
29:
30: #include <config.h>
31:
32: #ifndef HAVE_GETCWD
33:
34: #include <sys/types.h>
35: #include <sys/stat.h>
36:
37: #include <errno.h>
38: #include <stdio.h>
39: #ifdef STDC_HEADERS
40: # include <stdlib.h>
41: # include <stddef.h>
42: #else
43: # ifdef HAVE_STDLIB_H
44: # include <stdlib.h>
45: # endif
46: #endif /* STDC_HEADERS */
47: #ifdef HAVE_STRING_H
48: # include <string.h>
49: #endif /* HAVE_STRING_H */
50: #ifdef HAVE_STRINGS_H
51: # include <strings.h>
52: #endif /* HAVE_STRINGS_H */
53: #if defined(HAVE_MALLOC_H) && !defined(STDC_HEADERS)
54: # include <malloc.h>
55: #endif /* HAVE_MALLOC_H && !STDC_HEADERS */
56: #ifdef HAVE_UNISTD_H
57: # include <unistd.h>
58: #endif /* HAVE_UNISTD_H */
59: #ifdef HAVE_DIRENT_H
60: # include <dirent.h>
61: # define NAMLEN(dirent) strlen((dirent)->d_name)
62: #else
63: # define dirent direct
64: # define NAMLEN(dirent) (dirent)->d_namlen
65: # ifdef HAVE_SYS_NDIR_H
66: # include <sys/ndir.h>
67: # endif
68: # ifdef HAVE_SYS_DIR_H
69: # include <sys/dir.h>
70: # endif
71: # ifdef HAVE_NDIR_H
72: # include <ndir.h>
73: # endif
74: #endif
75:
76: #include "missing.h"
77:
78: #define ISDOT(dp) \
79: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
80: (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
81:
82: char *
83: getcwd(char *pt, size_t size)
84: {
85: struct dirent *dp;
86: DIR *dir = NULL;
87: dev_t dev;
88: ino_t ino;
89: int first;
90: char *bpt, *bup;
91: struct stat s;
92: dev_t root_dev;
93: ino_t root_ino;
94: size_t ptsize, upsize;
95: int save_errno;
96: char *ept, *eup, *up;
97:
98: /*
99: * If no buffer specified by the user, allocate one as necessary.
100: * If a buffer is specified, the size has to be non-zero. The path
101: * is built from the end of the buffer backwards.
102: */
103: if (pt) {
104: ptsize = 0;
105: if (!size) {
106: errno = EINVAL;
107: return NULL;
108: }
109: ept = pt + size;
110: } else {
111: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
112: return NULL;
113: ept = pt + ptsize;
114: }
115: bpt = ept - 1;
116: *bpt = '\0';
117:
118: /*
119: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
120: * Should always be enough (it's 340 levels). If it's not, allocate
121: * as necessary. Special * case the first stat, it's ".", not "..".
122: */
123: if ((up = malloc(upsize = 1024 - 4)) == NULL)
124: goto err;
125: eup = up + PATH_MAX;
126: bup = up;
127: up[0] = '.';
128: up[1] = '\0';
129:
130: /* Save root values, so know when to stop. */
131: if (stat("/", &s))
132: goto err;
133: root_dev = s.st_dev;
134: root_ino = s.st_ino;
135:
136: errno = 0; /* XXX readdir has no error return. */
137:
138: for (first = 1;; first = 0) {
139: /* Stat the current level. */
140: if (lstat(up, &s))
141: goto err;
142:
143: /* Save current node values. */
144: ino = s.st_ino;
145: dev = s.st_dev;
146:
147: /* Check for reaching root. */
148: if (root_dev == dev && root_ino == ino) {
149: *--bpt = '/';
150: /*
151: * It's unclear that it's a requirement to copy the
152: * path to the beginning of the buffer, but it's always
153: * been that way and stuff would probably break.
154: */
155: bcopy(bpt, pt, ept - bpt);
156: free(up);
157: return pt;
158: }
159:
160: /*
161: * Build pointer to the parent directory, allocating memory
162: * as necessary. Max length is 3 for "../", the largest
163: * possible component name, plus a trailing NULL.
164: */
165: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
166: char *nup;
167:
168: if ((nup = realloc(up, upsize *= 2)) == NULL)
169: goto err;
170: up = nup;
171: bup = up;
172: eup = up + upsize;
173: }
174: *bup++ = '.';
175: *bup++ = '.';
176: *bup = '\0';
177:
178: /* Open and stat parent directory. */
179: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
180: goto err;
181:
182: /* Add trailing slash for next directory. */
183: *bup++ = '/';
184:
185: /*
186: * If it's a mount point, have to stat each element because
187: * the inode number in the directory is for the entry in the
188: * parent directory, not the inode number of the mounted file.
189: */
190: save_errno = 0;
191: if (s.st_dev == dev) {
192: for (;;) {
193: if (!(dp = readdir(dir)))
194: goto notfound;
195: if (dp->d_fileno == ino)
196: break;
197: }
198: } else
199: for (;;) {
200: if (!(dp = readdir(dir)))
201: goto notfound;
202: if (ISDOT(dp))
203: continue;
204: bcopy(dp->d_name, bup, NAMLEN(dp) + 1);
205:
206: /* Save the first error for later. */
207: if (lstat(up, &s)) {
208: if (!save_errno)
209: save_errno = errno;
210: errno = 0;
211: continue;
212: }
213: if (s.st_dev == dev && s.st_ino == ino)
214: break;
215: }
216:
217: /*
218: * Check for length of the current name, preceding slash,
219: * leading slash.
220: */
221: if (bpt - pt <= NAMLEN(dp) + (first ? 1 : 2)) {
222: size_t len, off;
223: char *npt;
224:
225: if (!ptsize) {
226: errno = ERANGE;
227: goto err;
228: }
229: off = bpt - pt;
230: len = ept - bpt;
231: if ((npt = realloc(pt, ptsize *= 2)) == NULL)
232: goto err;
233: pt = npt;
234: bpt = pt + off;
235: ept = pt + ptsize;
236: bcopy(bpt, ept - len, len);
237: bpt = ept - len;
238: }
239: if (!first)
240: *--bpt = '/';
241: bpt -= NAMLEN(dp);
242: bcopy(dp->d_name, bpt, NAMLEN(dp));
243: (void)closedir(dir);
244:
245: /* Truncate any file name. */
246: *bup = '\0';
247: }
248:
249: notfound:
250: /*
251: * If readdir set errno, use it, not any saved error; otherwise,
252: * didn't find the current directory in its parent directory, set
253: * errno to ENOENT.
254: */
255: if (!errno)
256: errno = save_errno ? save_errno : ENOENT;
257: /* FALLTHROUGH */
258: err:
259: if (ptsize)
260: free(pt);
261: if (up)
262: free(up);
263: if (dir)
264: (void)closedir(dir);
265: return NULL;
266: }
267: #endif /* HAVE_GETCWD */
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