usr/src/lib/libc/gen/getcwd.c

/*
 * Copyright (c) 1989, 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * %sccs.include.redist.c%
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)getcwd.c	5.11 (Berkeley) %G%";
#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);
		}
		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
	1	/*
	2	* Copyright (c) 1989, 1991 The Regents of the University of California.
	3	* All rights reserved.
	4	*
	5	* %sccs.include.redist.c%
	6	*/
	7
	8	#if defined(LIBC_SCCS) && !defined(lint)
	9	static char sccsid[] = "@(#)getcwd.c 5.11 (Berkeley) %G%";
	10	#endif /* LIBC_SCCS and not lint */
	11
	12	#include <sys/param.h>
	13	#include <sys/stat.h>
	14	#include <errno.h>
	15	#include <dirent.h>
	16	#include <stdio.h>
	17	#include <stdlib.h>
	18	#include <string.h>
	19	#include <unistd.h>
	20
	21	#define ISDOT(dp) \
	22	(dp->d_name[0] == '.' && (dp->d_name[1] == '\0' \|\| \
	23	dp->d_name[1] == '.' && dp->d_name[2] == '\0'))
	24
	25	char *
	26	getcwd(pt, size)
	27	char *pt;
	28	size_t size;
	29	{
	30	register struct dirent *dp;
	31	register DIR *dir;
	32	register dev_t dev;
	33	register ino_t ino;
	34	register int first;
	35	register char bpt, bup;
	36	struct stat s;
	37	dev_t root_dev;
	38	ino_t root_ino;
	39	size_t ptsize, upsize;
	40	int save_errno;
	41	char ept, eup, *up;
	42
	43	/*
	44	* If no buffer specified by the user, allocate one as necessary.
	45	* If a buffer is specified, the size has to be non-zero. The path
	46	* is built from the end of the buffer backwards.
	47	*/
	48	if (pt) {
	49	ptsize = 0;
	50	if (!size) {
	51	errno = EINVAL;
	52	return((char *)NULL);
	53	}
	54	ept = pt + size;
	55	} else {
	56	if (!(pt = (char *)malloc(ptsize = 1024 - 4)))
	57	return((char *)NULL);
	58	ept = pt + ptsize;
	59	}
	60	bpt = ept - 1;
	61	*bpt = '\0';
	62
	63	/*
	64	* Allocate bytes (1024 - malloc space) for the string of "../"'s.
	65	* Should always be enough (it's 340 levels). If it's not, allocate
	66	* as necessary. Special * case the first stat, it's ".", not "..".
	67	*/
	68	if (!(up = (char *)malloc(upsize = 1024 - 4)))
	69	goto err;
	70	eup = up + MAXPATHLEN;
	71	bup = up;
	72	up[0] = '.';
	73	up[1] = '\0';
	74
	75	/* Save root values, so know when to stop. */
	76	if (stat("/", &s))
	77	goto err;
	78	root_dev = s.st_dev;
	79	root_ino = s.st_ino;
	80
	81	errno = 0; /* XXX readdir has no error return. */
	82
	83	for (first = 1;; first = 0) {
	84	/* Stat the current level. */
	85	if (lstat(up, &s))
	86	goto err;
	87
	88	/* Save current node values. */
	89	ino = s.st_ino;
	90	dev = s.st_dev;
	91
	92	/* Check for reaching root. */
	93	if (root_dev == dev && root_ino == ino) {
	94	*--bpt = '/';
	95	/*
	96	* It's unclear that it's a requirement to copy the
	97	* path to the beginning of the buffer, but it's always
	98	* been that way and stuff would probably break.
	99	*/
	100	(void)bcopy(bpt, pt, ept - bpt);
	101	free(up);
	102	return(pt);
	103	}
	104
	105	/*
	106	* Build pointer to the parent directory, allocating memory
	107	* as necessary. Max length is 3 for "../", the largest
	108	* possible component name, plus a trailing NULL.
	109	*/
	110	if (bup + 3 + MAXNAMLEN + 1 >= eup) {
	111	if (!(up = (char )realloc(up, upsize = 2)))
	112	goto err;
	113	eup = up + upsize;
	114	}
	115	*bup++ = '.';
	116	*bup++ = '.';
	117	*bup = '\0';
	118
	119	/* Open and stat parent directory. */
	120	if (!(dir = opendir(up)) \|\| fstat(dirfd(dir), &s))
	121	goto err;
	122
	123	/* Add trailing slash for next directory. */
	124	*bup++ = '/';
	125
	126	/*
	127	* If it's a mount point, have to stat each element because
	128	* the inode number in the directory is for the entry in the
	129	* parent directory, not the inode number of the mounted file.
	130	*/
	131	save_errno = 0;
	132	if (s.st_dev == dev) {
	133	for (;;) {
	134	if (!(dp = readdir(dir)))
	135	goto notfound;
	136	if (dp->d_fileno == ino)
	137	break;
	138	}
	139	} else
	140	for (;;) {
	141	if (!(dp = readdir(dir)))
	142	goto notfound;
	143	if (ISDOT(dp))
	144	continue;
	145	bcopy(dp->d_name, bup, dp->d_namlen + 1);
	146
	147	/* Save the first error for later. */
	148	if (lstat(up, &s)) {
	149	if (!save_errno)
	150	save_errno = errno;
	151	errno = 0;
	152	continue;
	153	}
	154	if (s.st_dev == dev && s.st_ino == ino)
	155	break;
	156	}
	157
	158	/*
	159	* Check for length of the current name, preceding slash,
	160	* leading slash.
	161	*/
	162	if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) {
	163	size_t len, off;
	164
	165	if (!ptsize) {
	166	errno = ERANGE;
	167	goto err;
	168	}
	169	off = bpt - pt;
	170	len = ept - bpt;
	171	if (!(pt = (char )realloc(pt, ptsize = 2)))
	172	goto err;
	173	bpt = pt + off;
	174	ept = pt + ptsize;
	175	(void)bcopy(bpt, ept - len, len);
	176	bpt = ept - len;
	177	}
	178	if (!first)
	179	*--bpt = '/';
	180	bpt -= dp->d_namlen;
	181	bcopy(dp->d_name, bpt, dp->d_namlen);
	182	(void)closedir(dir);
	183
	184	/* Truncate any file name. */
	185	*bup = '\0';
	186	}
	187
	188	notfound:
	189	/*
	190	* If readdir set errno, use it, not any saved error; otherwise,
	191	* didn't find the current directory in its parent directory, set
	192	* errno to ENOENT.
	193	*/
	194	if (!errno)
	195	errno = save_errno ? save_errno : ENOENT;
	196	/* FALLTHROUGH */
	197	err:
	198	if (ptsize)
	199	free(pt);
	200	free(up);
	201	return((char *)NULL);
	202	}