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scandir.c revision 1.28 
      1 /*	$NetBSD: scandir.c,v 1.28 2016/12/16 04:45:04 mrg 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
     35 static char sccsid[] = "@(#)scandir.c	8.3 (Berkeley) 1/2/94";
     36 #else
     37 __RCSID("$NetBSD: scandir.c,v 1.28 2016/12/16 04:45:04 mrg 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  */
     62 static size_t
     63 dirsize(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 
     85 #ifndef COMPARARG
     86 #define COMPARARG struct dirent **
     87 #endif
     88 
     89 int
     90 scandir(const char *dirname, struct dirent ***namelist,
     91     int (*selectfn)(const struct dirent *),
     92     int (*dcomp)(const COMPARARG, const COMPARARG))
     93 {
     94 	struct dirent *d, *p, **names, **newnames;
     95 	size_t nitems, arraysz;
     96 	DIR *dirp;
     97 
     98 	_DIAGASSERT(dirname != NULL);
     99 	_DIAGASSERT(namelist != NULL);
    100 
    101 	if ((dirp = opendir(dirname)) == NULL)
    102 		return -1;
    103 
    104 	if ((arraysz = dirsize(dirp->dd_fd, 0)) == 0)
    105 		goto bad;
    106 
    107 	names = malloc(arraysz * sizeof(*names));
    108 	if (names == NULL)
    109 		goto bad;
    110 
    111 	nitems = 0;
    112 	while ((d = readdir(dirp)) != NULL) {
    113 		if (selectfn != NULL && !(*selectfn)(d))
    114 			continue;	/* just selected names */
    115 
    116 		/*
    117 		 * Check to make sure the array has space left and
    118 		 * realloc the maximum size.
    119 		 */
    120 		if (nitems >= arraysz) {
    121 			if ((arraysz = dirsize(dirp->dd_fd, arraysz)) == 0)
    122 				goto bad2;
    123 			newnames = realloc(names, arraysz * sizeof(*names));
    124 			if (newnames == NULL)
    125 				goto bad2;
    126 			names = newnames;
    127 		}
    128 
    129 		/*
    130 		 * Make a minimum size copy of the data
    131 		 */
    132 		p = malloc((size_t)_DIRENT_SIZE(d));
    133 		if (p == NULL)
    134 			goto bad2;
    135 		p->d_fileno = d->d_fileno;
    136 		p->d_reclen = d->d_reclen;
    137 		p->d_type = d->d_type;
    138 		p->d_namlen = d->d_namlen;
    139 		(void)memmove(p->d_name, d->d_name, (size_t)(p->d_namlen + 1));
    140 		names[nitems++] = p;
    141 	}
    142 	(void)closedir(dirp);
    143 	if (nitems && dcomp != NULL)
    144 		qsort(names, nitems, sizeof(*names),
    145 		      (int (*)(const void *, const void *))dcomp);
    146 	*namelist = names;
    147 	_DIAGASSERT(__type_fit(int, nitems));
    148 	return (int)nitems;
    149 
    150 bad2:
    151 	while (nitems-- > 0)
    152 		free(names[nitems]);
    153 	free(names);
    154 bad:
    155 	(void)closedir(dirp);
    156 	return -1;
    157 }
    158