Annotation of src/lib/libc/gen/getcwd.c, Revision 1.1.1.2
1.1 cgd 1: /*
1.1.1.2 ! cgd 2: * Copyright (c) 1989, 1991, 1993
! 3: * The Regents of the University of California. All rights reserved.
1.1 cgd 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)
1.1.1.2 ! cgd 35: static char sccsid[] = "@(#)getcwd.c 8.1 (Berkeley) 6/4/93";
1.1 cgd 36: #endif /* LIBC_SCCS and not lint */
37:
38: #include <sys/param.h>
39: #include <sys/stat.h>
1.1.1.2 ! cgd 40:
1.1 cgd 41: #include <errno.h>
42: #include <dirent.h>
43: #include <stdio.h>
44: #include <stdlib.h>
45: #include <string.h>
46: #include <unistd.h>
47:
48: #define ISDOT(dp) \
49: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
50: dp->d_name[1] == '.' && dp->d_name[2] == '\0'))
51:
52: char *
53: getcwd(pt, size)
54: char *pt;
55: size_t size;
56: {
57: register struct dirent *dp;
58: register DIR *dir;
59: register dev_t dev;
60: register ino_t ino;
61: register int first;
62: register char *bpt, *bup;
63: struct stat s;
64: dev_t root_dev;
65: ino_t root_ino;
66: size_t ptsize, upsize;
67: int save_errno;
68: char *ept, *eup, *up;
69:
70: /*
71: * If no buffer specified by the user, allocate one as necessary.
72: * If a buffer is specified, the size has to be non-zero. The path
73: * is built from the end of the buffer backwards.
74: */
75: if (pt) {
76: ptsize = 0;
77: if (!size) {
78: errno = EINVAL;
1.1.1.2 ! cgd 79: return (NULL);
1.1 cgd 80: }
81: ept = pt + size;
82: } else {
1.1.1.2 ! cgd 83: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
! 84: return (NULL);
1.1 cgd 85: ept = pt + ptsize;
86: }
87: bpt = ept - 1;
88: *bpt = '\0';
89:
90: /*
91: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
92: * Should always be enough (it's 340 levels). If it's not, allocate
93: * as necessary. Special * case the first stat, it's ".", not "..".
94: */
1.1.1.2 ! cgd 95: if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1 cgd 96: goto err;
97: eup = up + MAXPATHLEN;
98: bup = up;
99: up[0] = '.';
100: up[1] = '\0';
101:
102: /* Save root values, so know when to stop. */
103: if (stat("/", &s))
104: goto err;
105: root_dev = s.st_dev;
106: root_ino = s.st_ino;
107:
108: errno = 0; /* XXX readdir has no error return. */
109:
110: for (first = 1;; first = 0) {
111: /* Stat the current level. */
112: if (lstat(up, &s))
113: goto err;
114:
115: /* Save current node values. */
116: ino = s.st_ino;
117: dev = s.st_dev;
118:
119: /* Check for reaching root. */
120: if (root_dev == dev && root_ino == ino) {
121: *--bpt = '/';
122: /*
123: * It's unclear that it's a requirement to copy the
124: * path to the beginning of the buffer, but it's always
125: * been that way and stuff would probably break.
126: */
127: (void)bcopy(bpt, pt, ept - bpt);
128: free(up);
1.1.1.2 ! cgd 129: return (pt);
1.1 cgd 130: }
131:
132: /*
133: * Build pointer to the parent directory, allocating memory
134: * as necessary. Max length is 3 for "../", the largest
135: * possible component name, plus a trailing NULL.
136: */
137: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
1.1.1.2 ! cgd 138: if ((up = realloc(up, upsize *= 2)) == NULL)
1.1 cgd 139: goto err;
1.1.1.2 ! cgd 140: bup = up;
1.1 cgd 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;
1.1.1.2 ! cgd 199: if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1 cgd 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);
1.1.1.2 ! cgd 229: return (NULL);
1.1 cgd 230: }
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