lib/libc/gen/scandir.c

   1 /*      $NetBSD: scandir.c,v 1.27 2012/03/13 21:13:36 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
  35 static char sccsid[] = "@(#)scandir.c   8.3 (Berkeley) 1/2/94";
  36 #else
  37 __RCSID("$NetBSD: scandir.c,v 1.27 2012/03/13 21:13:36 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  */
  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 int
  86 scandir(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         _DIAGASSERT(__type_fit(int, nitems));
 143         return (int)nitems;
 144
 145 bad2:
 146         while (nitems-- > 0)
 147                 free(names[nitems]);
 148         free(names);
 149 bad:
 150         (void)closedir(dirp);
 151         return -1;
 152 }