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scandir.c revision 1.2 
      1 /*
      2  * Copyright (c) 1983 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[] = "from: @(#)scandir.c	5.10 (Berkeley) 2/23/91";*/
     36 static char rcsid[] = "$Id: scandir.c,v 1.2 1993/07/30 08:23:10 mycroft Exp $";
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 /*
     40  * Scan the directory dirname calling select to make a list of selected
     41  * directory entries then sort using qsort and compare routine dcomp.
     42  * Returns the number of entries and a pointer to a list of pointers to
     43  * struct dirent (through namelist). Returns -1 if there were any errors.
     44  */
     45 
     46 #include <sys/types.h>
     47 #include <sys/stat.h>
     48 #include <dirent.h>
     49 #include <stdlib.h>
     50 #include <string.h>
     51 
     52 /*
     53  * The DIRSIZ macro gives the minimum record length which will hold
     54  * the directory entry.  This requires the amount of space in struct dirent
     55  * without the d_name field, plus enough space for the name with a terminating
     56  * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
     57  */
     58 #undef DIRSIZ
     59 #define DIRSIZ(dp) \
     60     ((sizeof (struct dirent) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3))
     61 
     62 int
     63 scandir(dirname, namelist, select, dcomp)
     64 	const char *dirname;
     65 	struct dirent ***namelist;
     66 	int (*select) __P((struct dirent *));
     67 	int (*dcomp) __P((const void *, const void *));
     68 {
     69 	register struct dirent *d, *p, **names;
     70 	register size_t nitems;
     71 	struct stat stb;
     72 	long arraysz;
     73 	DIR *dirp;
     74 
     75 	if ((dirp = opendir(dirname)) == NULL)
     76 		return(-1);
     77 	if (fstat(dirp->dd_fd, &stb) < 0)
     78 		return(-1);
     79 
     80 	/*
     81 	 * estimate the array size by taking the size of the directory file
     82 	 * and dividing it by a multiple of the minimum size entry.
     83 	 */
     84 	arraysz = (stb.st_size / 24);
     85 	names = (struct dirent **)malloc(arraysz * sizeof(struct dirent *));
     86 	if (names == NULL)
     87 		return(-1);
     88 
     89 	nitems = 0;
     90 	while ((d = readdir(dirp)) != NULL) {
     91 		if (select != NULL && !(*select)(d))
     92 			continue;	/* just selected names */
     93 		/*
     94 		 * Make a minimum size copy of the data
     95 		 */
     96 		p = (struct dirent *)malloc(DIRSIZ(d));
     97 		if (p == NULL)
     98 			return(-1);
     99 		p->d_ino = d->d_ino;
    100 		p->d_reclen = d->d_reclen;
    101 		p->d_namlen = d->d_namlen;
    102 		bcopy(d->d_name, p->d_name, p->d_namlen + 1);
    103 		/*
    104 		 * Check to make sure the array has space left and
    105 		 * realloc the maximum size.
    106 		 */
    107 		if (++nitems >= arraysz) {
    108 			if (fstat(dirp->dd_fd, &stb) < 0)
    109 				return(-1);	/* just might have grown */
    110 			arraysz = stb.st_size / 12;
    111 			names = (struct dirent **)realloc((char *)names,
    112 				arraysz * sizeof(struct dirent *));
    113 			if (names == NULL)
    114 				return(-1);
    115 		}
    116 		names[nitems-1] = p;
    117 	}
    118 	closedir(dirp);
    119 	if (nitems && dcomp != NULL)
    120 		qsort(names, nitems, sizeof(struct dirent *), dcomp);
    121 	*namelist = names;
    122 	return(nitems);
    123 }
    124 
    125 /*
    126  * Alphabetic order comparison routine for those who want it.
    127  */
    128 int
    129 alphasort(d1, d2)
    130 	const void *d1;
    131 	const void *d2;
    132 {
    133 	return(strcmp((*(struct dirent **)d1)->d_name,
    134 	    (*(struct dirent **)d2)->d_name));
    135 }
    136