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1.1 cgd 1: /*
2: * Copyright (c) 1989, 1991 The Regents of the University of California.
3: * 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. All advertising materials mentioning features or use of this software
14: * must display the following acknowledgement:
15: * This product includes software developed by the University of
16: * California, Berkeley and its contributors.
17: * 4. Neither the name of the University nor the names of its contributors
18: * may be used to endorse or promote products derived from this software
19: * without specific prior written permission.
20: *
21: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31: * SUCH DAMAGE.
32: */
33:
34: #if defined(LIBC_SCCS) && !defined(lint)
1.3 jtc 35: /*static char *sccsid = "from: @(#)getcwd.c 5.11 (Berkeley) 2/24/91";*/
1.3.4.1 ! jtc 36: static char *rcsid = "$Id: getcwd.c,v 1.3 1993/08/26 00:44:36 jtc Exp $";
1.1 cgd 37: #endif /* LIBC_SCCS and not lint */
38:
1.3.4.1 ! jtc 39: #include "namespace.h"
1.1 cgd 40: #include <sys/param.h>
41: #include <sys/stat.h>
42: #include <errno.h>
43: #include <dirent.h>
44: #include <stdio.h>
45: #include <stdlib.h>
46: #include <string.h>
47: #include <unistd.h>
48:
49: #define ISDOT(dp) \
50: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
51: dp->d_name[1] == '.' && dp->d_name[2] == '\0'))
52:
53: char *
54: getcwd(pt, size)
55: char *pt;
56: size_t size;
57: {
58: register struct dirent *dp;
59: register DIR *dir;
60: register dev_t dev;
61: register ino_t ino;
62: register int first;
63: register char *bpt, *bup;
64: struct stat s;
65: dev_t root_dev;
66: ino_t root_ino;
67: size_t ptsize, upsize;
68: int save_errno;
69: char *ept, *eup, *up;
70:
71: /*
72: * If no buffer specified by the user, allocate one as necessary.
73: * If a buffer is specified, the size has to be non-zero. The path
74: * is built from the end of the buffer backwards.
75: */
76: if (pt) {
77: ptsize = 0;
78: if (!size) {
79: errno = EINVAL;
80: return((char *)NULL);
81: }
82: ept = pt + size;
83: } else {
84: if (!(pt = (char *)malloc(ptsize = 1024 - 4)))
85: return((char *)NULL);
86: ept = pt + ptsize;
87: }
88: bpt = ept - 1;
89: *bpt = '\0';
90:
91: /*
92: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
93: * Should always be enough (it's 340 levels). If it's not, allocate
94: * as necessary. Special * case the first stat, it's ".", not "..".
95: */
96: if (!(up = (char *)malloc(upsize = 1024 - 4)))
97: goto err;
98: eup = up + MAXPATHLEN;
99: bup = up;
100: up[0] = '.';
101: up[1] = '\0';
102:
103: /* Save root values, so know when to stop. */
104: if (stat("/", &s))
105: goto err;
106: root_dev = s.st_dev;
107: root_ino = s.st_ino;
108:
109: errno = 0; /* XXX readdir has no error return. */
110:
111: for (first = 1;; first = 0) {
112: /* Stat the current level. */
113: if (lstat(up, &s))
114: goto err;
115:
116: /* Save current node values. */
117: ino = s.st_ino;
118: dev = s.st_dev;
119:
120: /* Check for reaching root. */
121: if (root_dev == dev && root_ino == ino) {
122: *--bpt = '/';
123: /*
124: * It's unclear that it's a requirement to copy the
125: * path to the beginning of the buffer, but it's always
126: * been that way and stuff would probably break.
127: */
128: (void)bcopy(bpt, pt, ept - bpt);
129: free(up);
130: return(pt);
131: }
132:
133: /*
134: * Build pointer to the parent directory, allocating memory
135: * as necessary. Max length is 3 for "../", the largest
136: * possible component name, plus a trailing NULL.
137: */
138: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
139: if (!(up = (char *)realloc(up, upsize *= 2)))
140: goto err;
141: eup = up + upsize;
142: }
143: *bup++ = '.';
144: *bup++ = '.';
145: *bup = '\0';
146:
147: /* Open and stat parent directory. */
148: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
149: goto err;
150:
151: /* Add trailing slash for next directory. */
152: *bup++ = '/';
153:
154: /*
155: * If it's a mount point, have to stat each element because
156: * the inode number in the directory is for the entry in the
157: * parent directory, not the inode number of the mounted file.
158: */
159: save_errno = 0;
160: if (s.st_dev == dev) {
161: for (;;) {
162: if (!(dp = readdir(dir)))
163: goto notfound;
164: if (dp->d_fileno == ino)
165: break;
166: }
167: } else
168: for (;;) {
169: if (!(dp = readdir(dir)))
170: goto notfound;
171: if (ISDOT(dp))
172: continue;
173: bcopy(dp->d_name, bup, dp->d_namlen + 1);
174:
175: /* Save the first error for later. */
176: if (lstat(up, &s)) {
177: if (!save_errno)
178: save_errno = errno;
179: errno = 0;
180: continue;
181: }
182: if (s.st_dev == dev && s.st_ino == ino)
183: break;
184: }
185:
186: /*
187: * Check for length of the current name, preceding slash,
188: * leading slash.
189: */
190: if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) {
191: size_t len, off;
192:
193: if (!ptsize) {
194: errno = ERANGE;
195: goto err;
196: }
197: off = bpt - pt;
198: len = ept - bpt;
199: if (!(pt = (char *)realloc(pt, ptsize *= 2)))
200: goto err;
201: bpt = pt + off;
202: ept = pt + ptsize;
203: (void)bcopy(bpt, ept - len, len);
204: bpt = ept - len;
205: }
206: if (!first)
207: *--bpt = '/';
208: bpt -= dp->d_namlen;
209: bcopy(dp->d_name, bpt, dp->d_namlen);
210: (void)closedir(dir);
211:
212: /* Truncate any file name. */
213: *bup = '\0';
214: }
215:
216: notfound:
217: /*
218: * If readdir set errno, use it, not any saved error; otherwise,
219: * didn't find the current directory in its parent directory, set
220: * errno to ENOENT.
221: */
222: if (!errno)
223: errno = save_errno ? save_errno : ENOENT;
224: /* FALLTHROUGH */
225: err:
226: if (ptsize)
227: free(pt);
228: free(up);
229: return((char *)NULL);
230: }