[unix-history] / lib / libc / gen / getcwd.c

/*
 * Copyright (c) 1989, 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)getcwd.c	5.11 (Berkeley) 2/24/91";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define	ISDOT(dp) \
	(dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
	    dp->d_name[1] == '.' && dp->d_name[2] == '\0'))

char *
getcwd(pt, size)
	char *pt;
	size_t size;
{
	register struct dirent *dp;
	register DIR *dir;
	register dev_t dev;
	register ino_t ino;
	register int first;
	register char *bpt, *bup;
	struct stat s;
	dev_t root_dev;
	ino_t root_ino;
	size_t ptsize, upsize;
	int save_errno;
	char *ept, *eup, *up;

	/*
	 * If no buffer specified by the user, allocate one as necessary.
	 * If a buffer is specified, the size has to be non-zero.  The path
	 * is built from the end of the buffer backwards.
	 */
	if (pt) {
		ptsize = 0;
		if (!size) {
			errno = EINVAL;
			return((char *)NULL);
		}
		if (size == 1) {
			errno = ERANGE;
			return((char *)NULL);
		}
		ept = pt + size;
	} else {
		if (!(pt = (char *)malloc(ptsize = 1024 - 4)))
			return((char *)NULL);
		ept = pt + ptsize;
	}
	bpt = ept - 1;
	*bpt = '\0';

	/*
	 * Allocate bytes (1024 - malloc space) for the string of "../"'s.
	 * Should always be enough (it's 340 levels).  If it's not, allocate
	 * as necessary.  Special * case the first stat, it's ".", not "..".
	 */
	if (!(up = (char *)malloc(upsize = 1024 - 4)))
		goto err;
	eup = up + MAXPATHLEN;
	bup = up;
	up[0] = '.';
	up[1] = '\0';

	/* Save root values, so know when to stop. */
	if (stat("/", &s))
		goto err;
	root_dev = s.st_dev;
	root_ino = s.st_ino;

	errno = 0;			/* XXX readdir has no error return. */

	for (first = 1;; first = 0) {
		/* Stat the current level. */
		if (lstat(up, &s))
			goto err;

		/* Save current node values. */
		ino = s.st_ino;
		dev = s.st_dev;

		/* Check for reaching root. */
		if (root_dev == dev && root_ino == ino) {
			*--bpt = '/';
			/*
			 * It's unclear that it's a requirement to copy the
			 * path to the beginning of the buffer, but it's always
			 * been that way and stuff would probably break.
			 */
			(void)bcopy(bpt, pt, ept - bpt);
			free(up);
			return(pt);
		}

		/*
		 * Build pointer to the parent directory, allocating memory
		 * as necessary.  Max length is 3 for "../", the largest
		 * possible component name, plus a trailing NULL.
		 */
		if (bup + 3  + MAXNAMLEN + 1 >= eup) {
			if (!(up = (char *)realloc(up, upsize *= 2)))
				goto err;
			eup = up + upsize;
		}
		*bup++ = '.';
		*bup++ = '.';
		*bup = '\0';

		/* Open and stat parent directory. */
		if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
			goto err;

		/* Add trailing slash for next directory. */
		*bup++ = '/';

		/*
		 * If it's a mount point, have to stat each element because
		 * the inode number in the directory is for the entry in the
		 * parent directory, not the inode number of the mounted file.
		 */
		save_errno = 0;
		if (s.st_dev == dev) {
			for (;;) {
				if (!(dp = readdir(dir)))
					goto notfound;
				if (dp->d_fileno == ino)
					break;
			}
		} else
			for (;;) {
				if (!(dp = readdir(dir)))
					goto notfound;
				if (ISDOT(dp))
					continue;
				bcopy(dp->d_name, bup, dp->d_namlen + 1);

				/* Save the first error for later. */
				if (lstat(up, &s)) {
					if (!save_errno)
						save_errno = errno;
					errno = 0;
					continue;
				}
				if (s.st_dev == dev && s.st_ino == ino)
					break;
			}

		/*
		 * Check for length of the current name, preceding slash,
		 * leading slash.
		 */
		if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
			size_t len, off;

			if (!ptsize) {
				errno = ERANGE;
				goto err;
			}
			off = bpt - pt;
			len = ept - bpt;
			if (!(pt = (char *)realloc(pt, ptsize *= 2)))
				goto err;
			bpt = pt + off;
			ept = pt + ptsize;
			(void)bcopy(bpt, ept - len, len);
			bpt = ept - len;
		}
		if (!first)
			*--bpt = '/';
		bpt -= dp->d_namlen;
		bcopy(dp->d_name, bpt, dp->d_namlen);
		(void)closedir(dir);

		/* Truncate any file name. */
		*bup = '\0';
	}

notfound:
	/*
	 * If readdir set errno, use it, not any saved error; otherwise,
	 * didn't find the current directory in its parent directory, set
	 * errno to ENOENT.
	 */
	if (!errno)
		errno = save_errno ? save_errno : ENOENT;
	/* FALLTHROUGH */
err:
	if (ptsize)
		free(pt);
	free(up);
	return((char *)NULL);
}
Commit	Line	Data
15637ed4 RG	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)
	35	static char sccsid[] = "@(#)getcwd.c 5.11 (Berkeley) 2/24/91";
	36	#endif /* LIBC_SCCS and not lint */
	37
	38	#include <sys/param.h>
	39	#include <sys/stat.h>
	40	#include <errno.h>
	41	#include <dirent.h>
	42	#include <stdio.h>
	43	#include <stdlib.h>
	44	#include <string.h>
	45	#include <unistd.h>
	46
	47	#define ISDOT(dp) \
	48	(dp->d_name[0] == '.' && (dp->d_name[1] == '\0' \|\| \
	49	dp->d_name[1] == '.' && dp->d_name[2] == '\0'))
	50
	51	char *
	52	getcwd(pt, size)
	53	char *pt;
	54	size_t size;
	55	{
	56	register struct dirent *dp;
	57	register DIR *dir;
	58	register dev_t dev;
	59	register ino_t ino;
	60	register int first;
	61	register char bpt, bup;
	62	struct stat s;
	63	dev_t root_dev;
	64	ino_t root_ino;
65	size_t ptsize, upsize;
66	int save_errno;
67	char ept, eup, *up;
68
69	/*
70	* If no buffer specified by the user, allocate one as necessary.
71	* If a buffer is specified, the size has to be non-zero. The path
72	* is built from the end of the buffer backwards.
73	*/
74	if (pt) {
75	ptsize = 0;
76	if (!size) {
77	errno = EINVAL;
78	return((char *)NULL);
79	}
2058d509 DG	80	if (size == 1) {
	81	errno = ERANGE;
	82	return((char *)NULL);
	83	}
15637ed4 RG	84	ept = pt + size;
	85	} else {
	86	if (!(pt = (char *)malloc(ptsize = 1024 - 4)))
	87	return((char *)NULL);
	88	ept = pt + ptsize;
	89	}
	90	bpt = ept - 1;
	91	*bpt = '\0';
	92
	93	/*
	94	* Allocate bytes (1024 - malloc space) for the string of "../"'s.
	95	* Should always be enough (it's 340 levels). If it's not, allocate
	96	* as necessary. Special * case the first stat, it's ".", not "..".
	97	*/
	98	if (!(up = (char *)malloc(upsize = 1024 - 4)))
	99	goto err;
	100	eup = up + MAXPATHLEN;
	101	bup = up;
	102	up[0] = '.';
	103	up[1] = '\0';
	104
	105	/* Save root values, so know when to stop. */
	106	if (stat("/", &s))
	107	goto err;
	108	root_dev = s.st_dev;
	109	root_ino = s.st_ino;
	110
	111	errno = 0; /* XXX readdir has no error return. */
	112
	113	for (first = 1;; first = 0) {
	114	/* Stat the current level. */
	115	if (lstat(up, &s))
	116	goto err;
	117
	118	/* Save current node values. */
	119	ino = s.st_ino;
	120	dev = s.st_dev;
	121
	122	/* Check for reaching root. */
	123	if (root_dev == dev && root_ino == ino) {
	124	*--bpt = '/';
	125	/*
	126	* It's unclear that it's a requirement to copy the
	127	* path to the beginning of the buffer, but it's always
	128	* been that way and stuff would probably break.
	129	*/
	130	(void)bcopy(bpt, pt, ept - bpt);
	131	free(up);
	132	return(pt);
	133	}
	134
	135	/*
	136	* Build pointer to the parent directory, allocating memory
	137	* as necessary. Max length is 3 for "../", the largest
	138	* possible component name, plus a trailing NULL.
	139	*/
	140	if (bup + 3 + MAXNAMLEN + 1 >= eup) {
	141	if (!(up = (char )realloc(up, upsize = 2)))
	142	goto err;
	143	eup = up + upsize;
	144	}
	145	*bup++ = '.';
	146	*bup++ = '.';
	147	*bup = '\0';
148
149	/* Open and stat parent directory. */
150	if (!(dir = opendir(up)) \|\| fstat(dirfd(dir), &s))
151	goto err;
152
153	/* Add trailing slash for next directory. */
154	*bup++ = '/';
155
156	/*
157	* If it's a mount point, have to stat each element because
158	* the inode number in the directory is for the entry in the
159	* parent directory, not the inode number of the mounted file.
160	*/
161	save_errno = 0;
162	if (s.st_dev == dev) {
163	for (;;) {
164	if (!(dp = readdir(dir)))
165	goto notfound;
166	if (dp->d_fileno == ino)
167	break;
168	}
169	} else
170	for (;;) {
171	if (!(dp = readdir(dir)))
172	goto notfound;
173	if (ISDOT(dp))
174	continue;
175	bcopy(dp->d_name, bup, dp->d_namlen + 1);
176
177	/* Save the first error for later. */
178	if (lstat(up, &s)) {
179	if (!save_errno)
180	save_errno = errno;
181	errno = 0;
182	continue;
183	}
184	if (s.st_dev == dev && s.st_ino == ino)
185	break;
186	}
187
188	/*
189	* Check for length of the current name, preceding slash,
190	* leading slash.
191	*/
2058d509	192	if (bpt - pt < dp->d_namlen + (first ? 1 : 2)) {
15637ed4 RG	193	size_t len, off;
	194
	195	if (!ptsize) {
	196	errno = ERANGE;
	197	goto err;
	198	}
	199	off = bpt - pt;
	200	len = ept - bpt;
	201	if (!(pt = (char )realloc(pt, ptsize = 2)))
	202	goto err;
	203	bpt = pt + off;
	204	ept = pt + ptsize;
	205	(void)bcopy(bpt, ept - len, len);
	206	bpt = ept - len;
	207	}
	208	if (!first)
	209	*--bpt = '/';
	210	bpt -= dp->d_namlen;
	211	bcopy(dp->d_name, bpt, dp->d_namlen);
	212	(void)closedir(dir);
	213
	214	/* Truncate any file name. */
	215	*bup = '\0';
	216	}
	217
	218	notfound:
	219	/*
	220	* If readdir set errno, use it, not any saved error; otherwise,
	221	* didn't find the current directory in its parent directory, set
	222	* errno to ENOENT.
	223	*/
	224	if (!errno)
	225	errno = save_errno ? save_errno : ENOENT;
	226	/* FALLTHROUGH */
	227	err:
	228	if (ptsize)
	229	free(pt);
	230	free(up);
	231	return((char *)NULL);
	232	}