Annotation of src/lib/libc/gen/getcwd.c, Revision 1.5.4.2
1.5.4.2 ! jtc 1: /* $NetBSD: getcwd.c,v 1.5.4.1 1996/09/16 18:40:24 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:
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
1.5.4.2 ! jtc 40: static char rcsid[] = "$NetBSD: getcwd.c,v 1.5.4.1 1996/09/16 18:40:24 jtc Exp $";
1.4 cgd 41: #endif
1.1 cgd 42: #endif /* LIBC_SCCS and not lint */
43:
1.5.4.1 jtc 44: #include "namespace.h"
1.1 cgd 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>
1.5.4.2 ! jtc 54:
! 55: #ifdef __weak_alias
! 56: __weak_alias(getcwd,_getcwd);
! 57: #endif
1.1 cgd 58:
59: #define ISDOT(dp) \
60: (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
61: dp->d_name[1] == '.' && dp->d_name[2] == '\0'))
62:
63: char *
64: getcwd(pt, size)
65: char *pt;
66: size_t size;
67: {
68: register struct dirent *dp;
69: register DIR *dir;
70: register dev_t dev;
71: register ino_t ino;
72: register int first;
73: register char *bpt, *bup;
74: struct stat s;
75: dev_t root_dev;
76: ino_t root_ino;
77: size_t ptsize, upsize;
78: int save_errno;
79: char *ept, *eup, *up;
80:
81: /*
82: * If no buffer specified by the user, allocate one as necessary.
83: * If a buffer is specified, the size has to be non-zero. The path
84: * is built from the end of the buffer backwards.
85: */
86: if (pt) {
87: ptsize = 0;
88: if (!size) {
89: errno = EINVAL;
1.4 cgd 90: return (NULL);
1.1 cgd 91: }
92: ept = pt + size;
93: } else {
1.4 cgd 94: if ((pt = malloc(ptsize = 1024 - 4)) == NULL)
95: return (NULL);
1.1 cgd 96: ept = pt + ptsize;
97: }
98: bpt = ept - 1;
99: *bpt = '\0';
100:
101: /*
102: * Allocate bytes (1024 - malloc space) for the string of "../"'s.
103: * Should always be enough (it's 340 levels). If it's not, allocate
104: * as necessary. Special * case the first stat, it's ".", not "..".
105: */
1.4 cgd 106: if ((up = malloc(upsize = 1024 - 4)) == NULL)
1.1 cgd 107: goto err;
108: eup = up + MAXPATHLEN;
109: bup = up;
110: up[0] = '.';
111: up[1] = '\0';
112:
113: /* Save root values, so know when to stop. */
114: if (stat("/", &s))
115: goto err;
116: root_dev = s.st_dev;
117: root_ino = s.st_ino;
118:
119: errno = 0; /* XXX readdir has no error return. */
120:
121: for (first = 1;; first = 0) {
122: /* Stat the current level. */
123: if (lstat(up, &s))
124: goto err;
125:
126: /* Save current node values. */
127: ino = s.st_ino;
128: dev = s.st_dev;
129:
130: /* Check for reaching root. */
131: if (root_dev == dev && root_ino == ino) {
132: *--bpt = '/';
133: /*
134: * It's unclear that it's a requirement to copy the
135: * path to the beginning of the buffer, but it's always
136: * been that way and stuff would probably break.
137: */
1.5 jtc 138: bcopy(bpt, pt, ept - bpt);
1.1 cgd 139: free(up);
1.4 cgd 140: return (pt);
1.1 cgd 141: }
142:
143: /*
144: * Build pointer to the parent directory, allocating memory
145: * as necessary. Max length is 3 for "../", the largest
146: * possible component name, plus a trailing NULL.
147: */
148: if (bup + 3 + MAXNAMLEN + 1 >= eup) {
1.4 cgd 149: if ((up = realloc(up, upsize *= 2)) == NULL)
1.1 cgd 150: goto err;
1.4 cgd 151: bup = up;
1.1 cgd 152: eup = up + upsize;
153: }
154: *bup++ = '.';
155: *bup++ = '.';
156: *bup = '\0';
157:
158: /* Open and stat parent directory. */
159: if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
160: goto err;
161:
162: /* Add trailing slash for next directory. */
163: *bup++ = '/';
164:
165: /*
166: * If it's a mount point, have to stat each element because
167: * the inode number in the directory is for the entry in the
168: * parent directory, not the inode number of the mounted file.
169: */
170: save_errno = 0;
171: if (s.st_dev == dev) {
172: for (;;) {
173: if (!(dp = readdir(dir)))
174: goto notfound;
175: if (dp->d_fileno == ino)
176: break;
177: }
178: } else
179: for (;;) {
180: if (!(dp = readdir(dir)))
181: goto notfound;
182: if (ISDOT(dp))
183: continue;
184: bcopy(dp->d_name, bup, dp->d_namlen + 1);
185:
186: /* Save the first error for later. */
187: if (lstat(up, &s)) {
188: if (!save_errno)
189: save_errno = errno;
190: errno = 0;
191: continue;
192: }
193: if (s.st_dev == dev && s.st_ino == ino)
194: break;
195: }
196:
197: /*
198: * Check for length of the current name, preceding slash,
199: * leading slash.
200: */
201: if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) {
202: size_t len, off;
203:
204: if (!ptsize) {
205: errno = ERANGE;
206: goto err;
207: }
208: off = bpt - pt;
209: len = ept - bpt;
1.4 cgd 210: if ((pt = realloc(pt, ptsize *= 2)) == NULL)
1.1 cgd 211: goto err;
212: bpt = pt + off;
213: ept = pt + ptsize;
1.5 jtc 214: bcopy(bpt, ept - len, len);
1.1 cgd 215: bpt = ept - len;
216: }
217: if (!first)
218: *--bpt = '/';
219: bpt -= dp->d_namlen;
220: bcopy(dp->d_name, bpt, dp->d_namlen);
221: (void)closedir(dir);
222:
223: /* Truncate any file name. */
224: *bup = '\0';
225: }
226:
227: notfound:
228: /*
229: * If readdir set errno, use it, not any saved error; otherwise,
230: * didn't find the current directory in its parent directory, set
231: * errno to ENOENT.
232: */
233: if (!errno)
234: errno = save_errno ? save_errno : ENOENT;
235: /* FALLTHROUGH */
236: err:
237: if (ptsize)
238: free(pt);
239: free(up);
1.4 cgd 240: return (NULL);
1.1 cgd 241: }
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