dirent/scandir-tail-common.c

   1 /* Common implementation for scandir{at}.
   2    Copyright (C) 2018-2024 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    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <string.h>
  20 #include <errno.h>
  21
  22 int
  23 SCANDIR_TAIL (DIR *dp,
  24               DIRENT_TYPE ***namelist,
  25               int (*select) (const DIRENT_TYPE *),
  26               int (*cmp) (const DIRENT_TYPE **, const DIRENT_TYPE **))
  27 {
  28   if (dp == NULL)
  29     return -1;
  30
  31   int save = errno;
  32   __set_errno (0);
  33
  34   int result;
  35   struct scandir_cancel_struct c = { .dp = dp };
  36   __libc_cleanup_push (&__scandir_cancel_handler, &c);
  37
  38   DIRENT_TYPE **v = NULL;
  39   size_t vsize = 0;
  40   DIRENT_TYPE *d;
  41   while ((d = READDIR (dp)) != NULL)
  42     {
  43       if (select != NULL)
  44         {
  45           int selected = (*select) (d);
  46
  47           /* The SELECT function might have set errno to non-zero on
  48              success.  It was zero before and it needs to be again to
  49              make the later tests work.  */
  50           __set_errno (0);
  51
  52           if (!selected)
  53             continue;
  54         }
  55
  56       if (__glibc_unlikely (c.cnt == vsize))
  57         {
  58           if (vsize == 0)
  59             vsize = 10;
  60           else
  61             vsize *= 2;
  62           DIRENT_TYPE **new = realloc (v, vsize * sizeof *v);
  63           if (new == NULL)
  64             break;
  65           c.v = v = new;
  66         }
  67
  68       size_t dsize = &d->d_name[_D_ALLOC_NAMLEN (d)] - (char *) d;
  69       DIRENT_TYPE *vnew = malloc (dsize);
  70       if (vnew == NULL)
  71         break;
  72       v[c.cnt++] = (DIRENT_TYPE *) memcpy (vnew, d, dsize);
  73
  74       /* Ignore errors from readdir, malloc or realloc.  These functions
  75          might have set errno to non-zero on success.  It was zero before
  76          and it needs to be again to make the latter tests work.  */
  77       __set_errno (0);
  78     }
  79
  80   if (__glibc_likely (errno == 0))
  81     {
  82       __closedir (dp);
  83
  84       /* Sort the list if we have a comparison function to sort with.  */
  85       if (cmp != NULL)
  86         qsort (v, c.cnt, sizeof *v, (__compar_fn_t) cmp);
  87
  88       *namelist = v;
  89       result = c.cnt;
  90     }
  91   else
  92     {
  93       /* This frees everything and calls closedir.  */
  94       __scandir_cancel_handler (&c);
  95       result = -1;
  96     }
  97
  98   __libc_cleanup_pop (0);
  99
 100   if (result >= 0)
 101     __set_errno (save);
 102   return result;
 103 }