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1.6 ! christos 1: /* $NetBSD: getcwd.c,v 1.5 1995/06/16 07:05:30 jtc 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:
1.6 ! christos 36: #include <sys/cdefs.h>
1.1 cgd 37: #if defined(LIBC_SCCS) && !defined(lint)
1.4 cgd 38: #if 0
39: static char sccsid[] = "@(#)getcwd.c 8.1 (Berkeley) 6/4/93";
40: #else
1.6 ! christos 41: __RCSID("$NetBSD$");
1.4 cgd 42: #endif
1.1 cgd 43: #endif /* LIBC_SCCS and not lint */
44:
45: #include <sys/param.h>
46: #include <sys/stat.h>
1.4 cgd 47:
1.1 cgd 48: #include <errno.h>
49: #include <dirent.h>
50: #include <stdio.h>
51: #include <stdlib.h>
52: #include <string.h>
53: #include <unistd.h>
54:
55: #define ISDOT(dp) \
56: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
1.6 ! christos 57: (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
1.1 cgd 58:
59: char *
60: getcwd(pt, size)
61: char *pt;
62: size_t size;
63: {
64: register struct dirent *dp;
65: register DIR *dir;
66: register dev_t dev;
67: register ino_t ino;
68: register int first;
69: register char *bpt, *bup;
70: struct stat s;
71: dev_t root_dev;
72: ino_t root_ino;
73: size_t ptsize, upsize;
74: int save_errno;
75: char *ept, *eup, *up;
76:
77: /*
78: * If no buffer specified by the user, allocate one as necessary.
79: * If a buffer is specified, the size has to be non-zero. The path
80: * is built from the end of the buffer backwards.
81: */
82: if (pt) {
83: ptsize = 0;
84: if (!size) {
85: errno = EINVAL;
1.4 cgd 86: return (NULL);
1.1 cgd 87: }
88: ept = pt + size;
89: } else {
1.4 cgd 90: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
91: return (NULL);
1.1 cgd 92: ept = pt + ptsize;
93: }
94: bpt = ept - 1;
95: *bpt = '\0';
96:
97: /*
98: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
99: * Should always be enough (it's 340 levels). If it's not, allocate
100: * as necessary. Special * case the first stat, it's ".", not "..".
101: */
1.4 cgd 102: if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1 cgd 103: goto err;
104: eup = up + MAXPATHLEN;
105: bup = up;
106: up[0] = '.';
107: up[1] = '\0';
108:
109: /* Save root values, so know when to stop. */
110: if (stat("/", &s))
111: goto err;
112: root_dev = s.st_dev;
113: root_ino = s.st_ino;
114:
115: errno = 0; /* XXX readdir has no error return. */
116:
117: for (first = 1;; first = 0) {
118: /* Stat the current level. */
119: if (lstat(up, &s))
120: goto err;
121:
122: /* Save current node values. */
123: ino = s.st_ino;
124: dev = s.st_dev;
125:
126: /* Check for reaching root. */
127: if (root_dev == dev && root_ino == ino) {
128: *--bpt = '/';
129: /*
130: * It's unclear that it's a requirement to copy the
131: * path to the beginning of the buffer, but it's always
132: * been that way and stuff would probably break.
133: */
1.5 jtc 134: bcopy(bpt, pt, ept - bpt);
1.1 cgd 135: free(up);
1.4 cgd 136: return (pt);
1.1 cgd 137: }
138:
139: /*
140: * Build pointer to the parent directory, allocating memory
141: * as necessary. Max length is 3 for "../", the largest
142: * possible component name, plus a trailing NULL.
143: */
144: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
1.4 cgd 145: if ((up = realloc(up, upsize *= 2)) == NULL)
1.1 cgd 146: goto err;
1.4 cgd 147: bup = up;
1.1 cgd 148: eup = up + upsize;
149: }
150: *bup++ = '.';
151: *bup++ = '.';
152: *bup = '\0';
153:
154: /* Open and stat parent directory. */
155: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
156: goto err;
157:
158: /* Add trailing slash for next directory. */
159: *bup++ = '/';
160:
161: /*
162: * If it's a mount point, have to stat each element because
163: * the inode number in the directory is for the entry in the
164: * parent directory, not the inode number of the mounted file.
165: */
166: save_errno = 0;
167: if (s.st_dev == dev) {
168: for (;;) {
169: if (!(dp = readdir(dir)))
170: goto notfound;
171: if (dp->d_fileno == ino)
172: break;
173: }
174: } else
175: for (;;) {
176: if (!(dp = readdir(dir)))
177: goto notfound;
178: if (ISDOT(dp))
179: continue;
180: bcopy(dp->d_name, bup, dp->d_namlen + 1);
181:
182: /* Save the first error for later. */
183: if (lstat(up, &s)) {
184: if (!save_errno)
185: save_errno = errno;
186: errno = 0;
187: continue;
188: }
189: if (s.st_dev == dev && s.st_ino == ino)
190: break;
191: }
192:
193: /*
194: * Check for length of the current name, preceding slash,
195: * leading slash.
196: */
197: if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) {
198: size_t len, off;
199:
200: if (!ptsize) {
201: errno = ERANGE;
202: goto err;
203: }
204: off = bpt - pt;
205: len = ept - bpt;
1.4 cgd 206: if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1 cgd 207: goto err;
208: bpt = pt + off;
209: ept = pt + ptsize;
1.5 jtc 210: bcopy(bpt, ept - len, len);
1.1 cgd 211: bpt = ept - len;
212: }
213: if (!first)
214: *--bpt = '/';
215: bpt -= dp->d_namlen;
216: bcopy(dp->d_name, bpt, dp->d_namlen);
217: (void)closedir(dir);
218:
219: /* Truncate any file name. */
220: *bup = '\0';
221: }
222:
223: notfound:
224: /*
225: * If readdir set errno, use it, not any saved error; otherwise,
226: * didn't find the current directory in its parent directory, set
227: * errno to ENOENT.
228: */
229: if (!errno)
230: errno = save_errno ? save_errno : ENOENT;
231: /* FALLTHROUGH */
232: err:
233: if (ptsize)
234: free(pt);
235: free(up);
1.4 cgd 236: return (NULL);
1.1 cgd 237: }