dirent/scandir-tail.c

   1 /* Logic guts of scandir*.
   2    Copyright (C) 1992-2018 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <dirent.h>
  20 #include <errno.h>
  21 #include <stdlib.h>
  22 #include <string.h>
  23 #include <libc-lock.h>
  24
  25 #ifndef SCANDIR_TAIL
  26 # define SCANDIR_TAIL   __scandir_tail
  27 # define READDIR        __readdir
  28 # define DIRENT_TYPE    struct dirent
  29 #endif
  30
  31 int
  32 SCANDIR_TAIL (DIR *dp,
  33               DIRENT_TYPE ***namelist,
  34               int (*select) (const DIRENT_TYPE *),
  35               int (*cmp) (const DIRENT_TYPE **, const DIRENT_TYPE **))
  36 {
  37   if (dp == NULL)
  38     return -1;
  39
  40   int save = errno;
  41   __set_errno (0);
  42
  43   int result;
  44   struct scandir_cancel_struct c = { .dp = dp };
  45   __libc_cleanup_push (&__scandir_cancel_handler, &c);
  46
  47   DIRENT_TYPE **v = NULL;
  48   size_t vsize = 0;
  49   DIRENT_TYPE *d;
  50   while ((d = READDIR (dp)) != NULL)
  51     {
  52       if (select != NULL)
  53         {
  54           int selected = (*select) (d);
  55
  56           /* The SELECT function might have set errno to non-zero on
  57              success.  It was zero before and it needs to be again to
  58              make the later tests work.  */
  59           __set_errno (0);
  60
  61           if (!selected)
  62             continue;
  63         }
  64
  65       if (__glibc_unlikely (c.cnt == vsize))
  66         {
  67           if (vsize == 0)
  68             vsize = 10;
  69           else
  70             vsize *= 2;
  71           DIRENT_TYPE **new = realloc (v, vsize * sizeof *v);
  72           if (new == NULL)
  73             break;
  74           c.v = v = new;
  75         }
  76
  77       size_t dsize = &d->d_name[_D_ALLOC_NAMLEN (d)] - (char *) d;
  78       DIRENT_TYPE *vnew = malloc (dsize);
  79       if (vnew == NULL)
  80         break;
  81       v[c.cnt++] = (DIRENT_TYPE *) memcpy (vnew, d, dsize);
  82
  83       /* Ignore errors from readdir, malloc or realloc.  These functions
  84          might have set errno to non-zero on success.  It was zero before
  85          and it needs to be again to make the latter tests work.  */
  86       __set_errno (0);
  87     }
  88
  89   if (__glibc_likely (errno == 0))
  90     {
  91       __closedir (dp);
  92
  93       /* Sort the list if we have a comparison function to sort with.  */
  94       if (cmp != NULL)
  95         qsort (v, c.cnt, sizeof *v, (__compar_fn_t) cmp);
  96
  97       *namelist = v;
  98       result = c.cnt;
  99     }
 100   else
 101     {
 102       /* This frees everything and calls closedir.  */
 103       __scandir_cancel_handler (&c);
 104       result = -1;
 105     }
 106
 107   __libc_cleanup_pop (0);
 108
 109   if (result >= 0)
 110     __set_errno (save);
 111   return result;
 112 }