1/*	$NetBSD: scandir.c,v 1.25 2005/09/13 01:44:09 christos Exp $	*/
2
3/*
4 * Copyright (c) 1983, 1993
5 *	The Regents of the University of California.  All rights reserved.
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. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#if defined(LIBC_SCCS) && !defined(lint)
34#if 0
35static char sccsid[] = "@(#)scandir.c	8.3 (Berkeley) 1/2/94";
36#else
37__RCSID("$NetBSD: scandir.c,v 1.25 2005/09/13 01:44:09 christos Exp $");
38#endif
39#endif /* LIBC_SCCS and not lint */
40
41/*
42 * Scan the directory dirname calling selectfn to make a list of selected
43 * directory entries then sort using qsort and compare routine dcomp.
44 * Returns the number of entries and a pointer to a list of pointers to
45 * struct dirent (through namelist). Returns -1 if there were any errors.
46 */
47
48#include "namespace.h"
49#include <sys/types.h>
50#include <sys/stat.h>
51
52#include <assert.h>
53#include <errno.h>
54#include <dirent.h>
55#include <stdlib.h>
56#include <string.h>
57
58/*
59 * Compute an estimate of the number of entries in a directory based on
60 * the file size. Returns the estimated number of entries or 0 on failure.
61 */
62static size_t
63dirsize(int fd, size_t olen)
64{
65	struct stat stb;
66	size_t nlen;
67
68	if (fstat(fd, &stb) == -1)
69		return 0;
70	/*
71	 * Estimate the array size by taking the size of the directory file
72	 * and dividing it by a multiple of the minimum size entry.
73	 */
74	nlen = (size_t)(stb.st_size / _DIRENT_MINSIZE((struct dirent *)0));
75	/*
76	 * If the size turns up 0, switch to an alternate strategy and use the
77	 * file size as the number of entries like ZFS returns. If that turns
78	 * out to be 0 too return a minimum of 10 entries, plus the old length.
79	 */
80	if (nlen == 0)
81		nlen = (size_t)(stb.st_size ? stb.st_size : 10);
82	return olen + nlen;
83}
84
85int
86scandir(const char *dirname, struct dirent ***namelist,
87    int (*selectfn)(const struct dirent *),
88    int (*dcomp)(const void *, const void *))
89{
90	struct dirent *d, *p, **names, **newnames;
91	size_t nitems, arraysz;
92	DIR *dirp;
93
94	_DIAGASSERT(dirname != NULL);
95	_DIAGASSERT(namelist != NULL);
96
97	if ((dirp = opendir(dirname)) == NULL)
98		return -1;
99
100	if ((arraysz = dirsize(dirp->dd_fd, 0)) == 0)
101		goto bad;
102
103	names = malloc(arraysz * sizeof(*names));
104	if (names == NULL)
105		goto bad;
106
107	nitems = 0;
108	while ((d = readdir(dirp)) != NULL) {
109		if (selectfn != NULL && !(*selectfn)(d))
110			continue;	/* just selected names */
111
112		/*
113		 * Check to make sure the array has space left and
114		 * realloc the maximum size.
115		 */
116		if (nitems >= arraysz) {
117			if ((arraysz = dirsize(dirp->dd_fd, arraysz)) == 0)
118				goto bad2;
119			newnames = realloc(names, arraysz * sizeof(*names));
120			if (newnames == NULL)
121				goto bad2;
122			names = newnames;
123		}
124
125		/*
126		 * Make a minimum size copy of the data
127		 */
128		p = malloc((size_t)_DIRENT_SIZE(d));
129		if (p == NULL)
130			goto bad2;
131		p->d_fileno = d->d_fileno;
132		p->d_reclen = d->d_reclen;
133		p->d_type = d->d_type;
134		p->d_namlen = d->d_namlen;
135		(void)memmove(p->d_name, d->d_name, (size_t)(p->d_namlen + 1));
136		names[nitems++] = p;
137	}
138	(void)closedir(dirp);
139	if (nitems && dcomp != NULL)
140		qsort(names, nitems, sizeof(*names), dcomp);
141	*namelist = names;
142	return nitems;
143
144bad2:
145	while (nitems-- > 0)
146		free(names[nitems]);
147	free(names);
148bad:
149	(void)closedir(dirp);
150	return -1;
151}
152