elf/dl-hwcaps_split.c

   1 /* Hardware capability support for run-time dynamic loader.  String splitting.
   2    Copyright (C) 2020-2021 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 <dl-hwcaps.h>
  20 #include <stdbool.h>
  21 #include <string.h>
  22
  23 _Bool
  24 _dl_hwcaps_split (struct dl_hwcaps_split *s)
  25 {
  26   if (s->segment == NULL)
  27     return false;
  28
  29   /* Skip over the previous segment.   */
  30   s->segment += s->length;
  31
  32   /* Consume delimiters.  This also avoids returning an empty
  33      segment.  */
  34   while (*s->segment == ':')
  35     ++s->segment;
  36   if (*s->segment == '\0')
  37     return false;
  38
  39   /* This could use strchrnul, but we would have to link the function
  40      into ld.so for that.  */
  41   const char *colon = strchr (s->segment, ':');
  42   if (colon == NULL)
  43     s->length = strlen (s->segment);
  44   else
  45     s->length = colon - s->segment;
  46   return true;
  47 }
  48
  49 _Bool
  50 _dl_hwcaps_split_masked (struct dl_hwcaps_split_masked *s)
  51 {
  52   while (true)
  53     {
  54       if (!_dl_hwcaps_split (&s->split))
  55         return false;
  56       bool active = s->bitmask & 1;
  57       s->bitmask >>= 1;
  58       if (active && _dl_hwcaps_contains (s->mask,
  59                                          s->split.segment, s->split.length))
  60         return true;
  61     }
  62 }
  63
  64 _Bool
  65 _dl_hwcaps_contains (const char *hwcaps, const char *name, size_t name_length)
  66 {
  67   if (hwcaps == NULL)
  68     return true;
  69
  70   struct dl_hwcaps_split split;
  71   _dl_hwcaps_split_init (&split, hwcaps);
  72   while (_dl_hwcaps_split (&split))
  73     if (split.length == name_length
  74         && memcmp (split.segment, name, name_length) == 0)
  75       return true;
  76   return false;
  77 }