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1.1 misho 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: #include <sys/param.h>
33: #include <sys/stat.h>
34:
35: #include <errno.h>
36: #include <stdio.h>
37: #ifdef STDC_HEADERS
38: # include <stdlib.h>
39: # include <stddef.h>
40: #else
41: # ifdef HAVE_STDLIB_H
42: # include <stdlib.h>
43: # endif
44: #endif /* STDC_HEADERS */
45: #ifdef HAVE_STRING_H
46: # include <string.h>
47: #endif /* HAVE_STRING_H */
48: #ifdef HAVE_STRINGS_H
49: # include <strings.h>
50: #endif /* HAVE_STRINGS_H */
51: #if defined(HAVE_MALLOC_H) && !defined(STDC_HEADERS)
52: # include <malloc.h>
53: #endif /* HAVE_MALLOC_H && !STDC_HEADERS */
54: #ifdef HAVE_UNISTD_H
55: # include <unistd.h>
56: #endif /* HAVE_UNISTD_H */
57: #ifdef HAVE_DIRENT_H
58: # include <dirent.h>
59: # define NAMLEN(dirent) strlen((dirent)->d_name)
60: #else
61: # define dirent direct
62: # define NAMLEN(dirent) (dirent)->d_namlen
63: # ifdef HAVE_SYS_NDIR_H
64: # include <sys/ndir.h>
65: # endif
66: # ifdef HAVE_SYS_DIR_H
67: # include <sys/dir.h>
68: # endif
69: # ifdef HAVE_NDIR_H
70: # include <ndir.h>
71: # endif
72: #endif
73:
74: #include "missing.h"
75:
76: #define ISDOT(dp) \
77: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
78: (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
79:
80: char *
81: getcwd(char *pt, size_t size)
82: {
83: struct dirent *dp;
84: DIR *dir = NULL;
85: dev_t dev;
86: ino_t ino;
87: int first;
88: char *bpt, *bup;
89: struct stat s;
90: dev_t root_dev;
91: ino_t root_ino;
92: size_t ptsize, upsize;
93: int save_errno;
94: char *ept, *eup, *up;
95:
96: /*
97: * If no buffer specified by the user, allocate one as necessary.
98: * If a buffer is specified, the size has to be non-zero. The path
99: * is built from the end of the buffer backwards.
100: */
101: if (pt) {
102: ptsize = 0;
103: if (!size) {
104: errno = EINVAL;
105: return NULL;
106: }
107: ept = pt + size;
108: } else {
109: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
110: return NULL;
111: ept = pt + ptsize;
112: }
113: bpt = ept - 1;
114: *bpt = '\0';
115:
116: /*
117: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
118: * Should always be enough (it's 340 levels). If it's not, allocate
119: * as necessary. Special * case the first stat, it's ".", not "..".
120: */
121: if ((up = malloc(upsize = 1024 - 4)) == NULL)
122: goto err;
123: eup = up + PATH_MAX;
124: bup = up;
125: up[0] = '.';
126: up[1] = '\0';
127:
128: /* Save root values, so know when to stop. */
129: if (stat("/", &s))
130: goto err;
131: root_dev = s.st_dev;
132: root_ino = s.st_ino;
133:
134: errno = 0; /* XXX readdir has no error return. */
135:
136: for (first = 1;; first = 0) {
137: /* Stat the current level. */
138: if (lstat(up, &s))
139: goto err;
140:
141: /* Save current node values. */
142: ino = s.st_ino;
143: dev = s.st_dev;
144:
145: /* Check for reaching root. */
146: if (root_dev == dev && root_ino == ino) {
147: *--bpt = '/';
148: /*
149: * It's unclear that it's a requirement to copy the
150: * path to the beginning of the buffer, but it's always
151: * been that way and stuff would probably break.
152: */
153: bcopy(bpt, pt, ept - bpt);
154: free(up);
155: return pt;
156: }
157:
158: /*
159: * Build pointer to the parent directory, allocating memory
160: * as necessary. Max length is 3 for "../", the largest
161: * possible component name, plus a trailing NULL.
162: */
163: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
164: char *nup;
165:
166: if ((nup = realloc(up, upsize *= 2)) == NULL)
167: goto err;
168: up = nup;
169: bup = up;
170: eup = up + upsize;
171: }
172: *bup++ = '.';
173: *bup++ = '.';
174: *bup = '\0';
175:
176: /* Open and stat parent directory. */
177: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
178: goto err;
179:
180: /* Add trailing slash for next directory. */
181: *bup++ = '/';
182:
183: /*
184: * If it's a mount point, have to stat each element because
185: * the inode number in the directory is for the entry in the
186: * parent directory, not the inode number of the mounted file.
187: */
188: save_errno = 0;
189: if (s.st_dev == dev) {
190: for (;;) {
191: if (!(dp = readdir(dir)))
192: goto notfound;
193: if (dp->d_fileno == ino)
194: break;
195: }
196: } else
197: for (;;) {
198: if (!(dp = readdir(dir)))
199: goto notfound;
200: if (ISDOT(dp))
201: continue;
202: bcopy(dp->d_name, bup, NAMLEN(dp) + 1);
203:
204: /* Save the first error for later. */
205: if (lstat(up, &s)) {
206: if (!save_errno)
207: save_errno = errno;
208: errno = 0;
209: continue;
210: }
211: if (s.st_dev == dev && s.st_ino == ino)
212: break;
213: }
214:
215: /*
216: * Check for length of the current name, preceding slash,
217: * leading slash.
218: */
219: if (bpt - pt <= NAMLEN(dp) + (first ? 1 : 2)) {
220: size_t len, off;
221: char *npt;
222:
223: if (!ptsize) {
224: errno = ERANGE;
225: goto err;
226: }
227: off = bpt - pt;
228: len = ept - bpt;
229: if ((npt = realloc(pt, ptsize *= 2)) == NULL)
230: goto err;
231: pt = npt;
232: bpt = pt + off;
233: ept = pt + ptsize;
234: bcopy(bpt, ept - len, len);
235: bpt = ept - len;
236: }
237: if (!first)
238: *--bpt = '/';
239: bpt -= NAMLEN(dp);
240: bcopy(dp->d_name, bpt, NAMLEN(dp));
241: (void)closedir(dir);
242:
243: /* Truncate any file name. */
244: *bup = '\0';
245: }
246:
247: notfound:
248: /*
249: * If readdir set errno, use it, not any saved error; otherwise,
250: * didn't find the current directory in its parent directory, set
251: * errno to ENOENT.
252: */
253: if (!errno)
254: errno = save_errno ? save_errno : ENOENT;
255: /* FALLTHROUGH */
256: err:
257: if (ptsize)
258: free(pt);
259: if (up)
260: free(up);
261: if (dir)
262: (void)closedir(dir);
263: return NULL;
264: }