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1.5 ! jtc 1: /* $NetBSD: getcwd.c,v 1.4 1995/02/27 04:12:20 cgd Exp $ */
1.4 cgd 2:
1.1 cgd 3: /*
1.4 cgd 4: * Copyright (c) 1989, 1991, 1993
5: * The Regents of the University of California. All rights reserved.
1.1 cgd 6: *
7: * Redistribution and use in source and binary forms, with or without
8: * modification, are permitted provided that the following conditions
9: * are met:
10: * 1. Redistributions of source code must retain the above copyright
11: * notice, this list of conditions and the following disclaimer.
12: * 2. Redistributions in binary form must reproduce the above copyright
13: * notice, this list of conditions and the following disclaimer in the
14: * documentation and/or other materials provided with the distribution.
15: * 3. All advertising materials mentioning features or use of this software
16: * must display the following acknowledgement:
17: * This product includes software developed by the University of
18: * California, Berkeley and its contributors.
19: * 4. Neither the name of the University nor the names of its contributors
20: * may be used to endorse or promote products derived from this software
21: * without specific prior written permission.
22: *
23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: * SUCH DAMAGE.
34: */
35:
36: #if defined(LIBC_SCCS) && !defined(lint)
1.4 cgd 37: #if 0
38: static char sccsid[] = "@(#)getcwd.c 8.1 (Berkeley) 6/4/93";
39: #else
1.5 ! jtc 40: static char rcsid[] = "$NetBSD: getcwd.c,v 1.4 1995/02/27 04:12:20 cgd Exp $";
1.4 cgd 41: #endif
1.1 cgd 42: #endif /* LIBC_SCCS and not lint */
43:
44: #include <sys/param.h>
45: #include <sys/stat.h>
1.4 cgd 46:
1.1 cgd 47: #include <errno.h>
48: #include <dirent.h>
49: #include <stdio.h>
50: #include <stdlib.h>
51: #include <string.h>
52: #include <unistd.h>
53:
54: #define ISDOT(dp) \
55: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
56: dp->d_name[1] == '.' && dp->d_name[2] == '\0'))
57:
58: char *
59: getcwd(pt, size)
60: char *pt;
61: size_t size;
62: {
63: register struct dirent *dp;
64: register DIR *dir;
65: register dev_t dev;
66: register ino_t ino;
67: register int first;
68: register char *bpt, *bup;
69: struct stat s;
70: dev_t root_dev;
71: ino_t root_ino;
72: size_t ptsize, upsize;
73: int save_errno;
74: char *ept, *eup, *up;
75:
76: /*
77: * If no buffer specified by the user, allocate one as necessary.
78: * If a buffer is specified, the size has to be non-zero. The path
79: * is built from the end of the buffer backwards.
80: */
81: if (pt) {
82: ptsize = 0;
83: if (!size) {
84: errno = EINVAL;
1.4 cgd 85: return (NULL);
1.1 cgd 86: }
87: ept = pt + size;
88: } else {
1.4 cgd 89: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
90: return (NULL);
1.1 cgd 91: ept = pt + ptsize;
92: }
93: bpt = ept - 1;
94: *bpt = '\0';
95:
96: /*
97: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
98: * Should always be enough (it's 340 levels). If it's not, allocate
99: * as necessary. Special * case the first stat, it's ".", not "..".
100: */
1.4 cgd 101: if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1 cgd 102: goto err;
103: eup = up + MAXPATHLEN;
104: bup = up;
105: up[0] = '.';
106: up[1] = '\0';
107:
108: /* Save root values, so know when to stop. */
109: if (stat("/", &s))
110: goto err;
111: root_dev = s.st_dev;
112: root_ino = s.st_ino;
113:
114: errno = 0; /* XXX readdir has no error return. */
115:
116: for (first = 1;; first = 0) {
117: /* Stat the current level. */
118: if (lstat(up, &s))
119: goto err;
120:
121: /* Save current node values. */
122: ino = s.st_ino;
123: dev = s.st_dev;
124:
125: /* Check for reaching root. */
126: if (root_dev == dev && root_ino == ino) {
127: *--bpt = '/';
128: /*
129: * It's unclear that it's a requirement to copy the
130: * path to the beginning of the buffer, but it's always
131: * been that way and stuff would probably break.
132: */
1.5 ! jtc 133: bcopy(bpt, pt, ept - bpt);
1.1 cgd 134: free(up);
1.4 cgd 135: return (pt);
1.1 cgd 136: }
137:
138: /*
139: * Build pointer to the parent directory, allocating memory
140: * as necessary. Max length is 3 for "../", the largest
141: * possible component name, plus a trailing NULL.
142: */
143: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
1.4 cgd 144: if ((up = realloc(up, upsize *= 2)) == NULL)
1.1 cgd 145: goto err;
1.4 cgd 146: bup = up;
1.1 cgd 147: eup = up + upsize;
148: }
149: *bup++ = '.';
150: *bup++ = '.';
151: *bup = '\0';
152:
153: /* Open and stat parent directory. */
154: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
155: goto err;
156:
157: /* Add trailing slash for next directory. */
158: *bup++ = '/';
159:
160: /*
161: * If it's a mount point, have to stat each element because
162: * the inode number in the directory is for the entry in the
163: * parent directory, not the inode number of the mounted file.
164: */
165: save_errno = 0;
166: if (s.st_dev == dev) {
167: for (;;) {
168: if (!(dp = readdir(dir)))
169: goto notfound;
170: if (dp->d_fileno == ino)
171: break;
172: }
173: } else
174: for (;;) {
175: if (!(dp = readdir(dir)))
176: goto notfound;
177: if (ISDOT(dp))
178: continue;
179: bcopy(dp->d_name, bup, dp->d_namlen + 1);
180:
181: /* Save the first error for later. */
182: if (lstat(up, &s)) {
183: if (!save_errno)
184: save_errno = errno;
185: errno = 0;
186: continue;
187: }
188: if (s.st_dev == dev && s.st_ino == ino)
189: break;
190: }
191:
192: /*
193: * Check for length of the current name, preceding slash,
194: * leading slash.
195: */
196: if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) {
197: size_t len, off;
198:
199: if (!ptsize) {
200: errno = ERANGE;
201: goto err;
202: }
203: off = bpt - pt;
204: len = ept - bpt;
1.4 cgd 205: if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1 cgd 206: goto err;
207: bpt = pt + off;
208: ept = pt + ptsize;
1.5 ! jtc 209: bcopy(bpt, ept - len, len);
1.1 cgd 210: bpt = ept - len;
211: }
212: if (!first)
213: *--bpt = '/';
214: bpt -= dp->d_namlen;
215: bcopy(dp->d_name, bpt, dp->d_namlen);
216: (void)closedir(dir);
217:
218: /* Truncate any file name. */
219: *bup = '\0';
220: }
221:
222: notfound:
223: /*
224: * If readdir set errno, use it, not any saved error; otherwise,
225: * didn't find the current directory in its parent directory, set
226: * errno to ENOENT.
227: */
228: if (!errno)
229: errno = save_errno ? save_errno : ENOENT;
230: /* FALLTHROUGH */
231: err:
232: if (ptsize)
233: free(pt);
234: free(up);
1.4 cgd 235: return (NULL);
1.1 cgd 236: }