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scandir.c revision 1.22 
      1 /*	$NetBSD: scandir.c,v 1.22 2003/08/07 16:42:56 agc 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 1.22 2003/08/07 16:42:56 agc Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 /*
     42  * Scan the directory dirname calling select 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 #ifdef __weak_alias
     59 __weak_alias(scandir,_scandir)
     60 __weak_alias(alphasort,_alphasort)
     61 #endif
     62 
     63 /*
     64  * The DIRSIZ macro is the minimum record length which will hold the directory
     65  * entry.  This requires the amount of space in struct dirent without the
     66  * d_name field, plus enough space for the name and a terminating nul byte
     67  * (dp->d_namlen + 1), rounded up to a 4 byte boundary.
     68  */
     69 #undef DIRSIZ
     70 #define DIRSIZ(dp)							\
     71 	((sizeof(struct dirent) - sizeof(dp)->d_name) +			\
     72 	    (((dp)->d_namlen + 1 + 3) &~ 3))
     73 
     74 int
     75 scandir(dirname, namelist, select, dcomp)
     76 	const char *dirname;
     77 	struct dirent ***namelist;
     78 	int (*select) __P((const struct dirent *));
     79 	int (*dcomp) __P((const void *, const void *));
     80 {
     81 	struct dirent *d, *p, **names, **newnames;
     82 	size_t nitems, arraysz;
     83 	struct stat stb;
     84 	DIR *dirp;
     85 
     86 	_DIAGASSERT(dirname != NULL);
     87 	_DIAGASSERT(namelist != NULL);
     88 
     89 	if ((dirp = opendir(dirname)) == NULL)
     90 		return (-1);
     91 	if (fstat(dirp->dd_fd, &stb) < 0)
     92 		goto bad;
     93 
     94 	/*
     95 	 * estimate the array size by taking the size of the directory file
     96 	 * and dividing it by a multiple of the minimum size entry.
     97 	 */
     98 	arraysz = (size_t)(stb.st_size / 24);
     99 	names = malloc(arraysz * sizeof(struct dirent *));
    100 	if (names == NULL)
    101 		goto bad;
    102 
    103 	nitems = 0;
    104 	while ((d = readdir(dirp)) != NULL) {
    105 		if (select != NULL && !(*select)(d))
    106 			continue;	/* just selected names */
    107 
    108 		/*
    109 		 * Check to make sure the array has space left and
    110 		 * realloc the maximum size.
    111 		 */
    112 		if (nitems >= arraysz) {
    113 			if (fstat(dirp->dd_fd, &stb) < 0)
    114 				goto bad2;	/* just might have grown */
    115 			arraysz = (size_t)(stb.st_size / 12);
    116 			newnames = realloc(names,
    117 			    arraysz * sizeof(struct dirent *));
    118 			if (newnames == NULL)
    119 				goto bad2;
    120 			names = newnames;
    121 		}
    122 
    123 		/*
    124 		 * Make a minimum size copy of the data
    125 		 */
    126 		p = (struct dirent *)malloc(DIRSIZ(d));
    127 		if (p == NULL)
    128 			goto bad2;
    129 		p->d_fileno = d->d_fileno;
    130 		p->d_reclen = d->d_reclen;
    131 		p->d_type = d->d_type;
    132 		p->d_namlen = d->d_namlen;
    133 		memmove(p->d_name, d->d_name, (size_t)(p->d_namlen + 1));
    134 		names[nitems++] = p;
    135 	}
    136 	closedir(dirp);
    137 	if (nitems && dcomp != NULL)
    138 		qsort(names, nitems, sizeof(struct dirent *), dcomp);
    139 	*namelist = names;
    140 	return (nitems);
    141 
    142 bad2:
    143 	while (nitems-- > 0)
    144 		free(names[nitems]);
    145 	free(names);
    146 bad:
    147 	closedir(dirp);
    148 	return (-1);
    149 }
    150 
    151 /*
    152  * Alphabetic order comparison routine for those who want it.
    153  */
    154 int
    155 alphasort(d1, d2)
    156 	const void *d1;
    157 	const void *d2;
    158 {
    159 
    160 	_DIAGASSERT(d1 != NULL);
    161 	_DIAGASSERT(d2 != NULL);
    162 
    163 	return (strcmp((*(const struct dirent *const *)d1)->d_name,
    164 	    (*(const struct dirent *const *)d2)->d_name));
    165 }
    166