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scandir.c revision 1.5 
      1 /*
      2  * Copyright (c) 1983, 1993
      3  *	The Regents of the University of California.  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	8.3 (Berkeley) 1/2/94";*/
     36 static char rcsid[] = "$Id: scandir.c,v 1.5 1994/07/27 14:39:50 jtc 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 is the minimum record length which will hold the directory
     54  * entry.  This requires the amount of space in struct dirent without the
     55  * d_name field, plus enough space for the name and a terminating nul byte
     56  * (dp->d_namlen + 1), rounded up to a 4 byte boundary.
     57  */
     58 #undef DIRSIZ
     59 #define DIRSIZ(dp)							\
     60 	((sizeof(struct dirent) - sizeof(dp)->d_name) +			\
     61 	    (((dp)->d_namlen + 1 + 3) &~ 3))
     62 
     63 int
     64 scandir(dirname, namelist, select, dcomp)
     65 	const char *dirname;
     66 	struct dirent ***namelist;
     67 	int (*select) __P((struct dirent *));
     68 	int (*dcomp) __P((const void *, const void *));
     69 {
     70 	register struct dirent *d, *p, **names;
     71 	register size_t nitems;
     72 	struct stat stb;
     73 	long arraysz;
     74 	DIR *dirp;
     75 
     76 	if ((dirp = opendir(dirname)) == NULL)
     77 		return(-1);
     78 	if (fstat(dirp->dd_fd, &stb) < 0)
     79 		return(-1);
     80 
     81 	/*
     82 	 * estimate the array size by taking the size of the directory file
     83 	 * and dividing it by a multiple of the minimum size entry.
     84 	 */
     85 	arraysz = (stb.st_size / 24);
     86 	names = (struct dirent **)malloc(arraysz * sizeof(struct dirent *));
     87 	if (names == NULL)
     88 		return(-1);
     89 
     90 	nitems = 0;
     91 	while ((d = readdir(dirp)) != NULL) {
     92 		if (select != NULL && !(*select)(d))
     93 			continue;	/* just selected names */
     94 		/*
     95 		 * Make a minimum size copy of the data
     96 		 */
     97 		p = (struct dirent *)malloc(DIRSIZ(d));
     98 		if (p == NULL)
     99 			return(-1);
    100 		p->d_ino = d->d_ino;
    101 		p->d_reclen = d->d_reclen;
    102 		p->d_namlen = d->d_namlen;
    103 		bcopy(d->d_name, p->d_name, p->d_namlen + 1);
    104 		/*
    105 		 * Check to make sure the array has space left and
    106 		 * realloc the maximum size.
    107 		 */
    108 		if (++nitems >= arraysz) {
    109 			if (fstat(dirp->dd_fd, &stb) < 0)
    110 				return(-1);	/* just might have grown */
    111 			arraysz = stb.st_size / 12;
    112 			names = (struct dirent **)realloc((char *)names,
    113 				arraysz * sizeof(struct dirent *));
    114 			if (names == NULL)
    115 				return(-1);
    116 		}
    117 		names[nitems-1] = p;
    118 	}
    119 	closedir(dirp);
    120 	if (nitems && dcomp != NULL)
    121 		qsort(names, nitems, sizeof(struct dirent *), dcomp);
    122 	*namelist = names;
    123 	return(nitems);
    124 }
    125 
    126 /*
    127  * Alphabetic order comparison routine for those who want it.
    128  */
    129 int
    130 alphasort(d1, d2)
    131 	const void *d1;
    132 	const void *d2;
    133 {
    134 	return(strcmp((*(struct dirent **)d1)->d_name,
    135 	    (*(struct dirent **)d2)->d_name));
    136 }
    137