tests/test-memchr.c

   1 /*
   2  * Copyright (C) 2008-2024 Free Software Foundation, Inc.
   3  * Written by Eric Blake and Bruno Haible
   4  *
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation, either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program 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
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 #include <string.h>
  21
  22 #include "signature.h"
  23 SIGNATURE_CHECK (memchr, void *, (void const *, int, size_t));
  24
  25 #include <stdlib.h>
  26
  27 #include "zerosize-ptr.h"
  28 #include "macros.h"
  29
  30 /* Test the library, not the compiler+library.  */
  31 static void *
  32 lib_memchr (void const *s, int c, size_t n)
  33 {
  34   return memchr (s, c, n);
  35 }
  36 static void *(*volatile volatile_memchr) (void const *, int, size_t)
  37   = lib_memchr;
  38 #undef memchr
  39 #define memchr volatile_memchr
  40
  41 int
  42 main (void)
  43 {
  44   size_t n = 0x100000;
  45   char *input = malloc (n);
  46   ASSERT (input);
  47
  48   input[0] = 'a';
  49   input[1] = 'b';
  50   memset (input + 2, 'c', 1024);
  51   memset (input + 1026, 'd', n - 1028);
  52   input[n - 2] = 'e';
  53   input[n - 1] = 'a';
  54
  55   /* Basic behavior tests.  */
  56   ASSERT (memchr (input, 'a', n) == input);
  57
  58   ASSERT (memchr (input, 'a', 0) == NULL);
  59
  60   {
  61     void *page_boundary = zerosize_ptr ();
  62     if (page_boundary)
  63       ASSERT (memchr (page_boundary, 'a', 0) == NULL);
  64   }
  65
  66   ASSERT (memchr (input, 'b', n) == input + 1);
  67   ASSERT (memchr (input, 'c', n) == input + 2);
  68   ASSERT (memchr (input, 'd', n) == input + 1026);
  69
  70   ASSERT (memchr (input + 1, 'a', n - 1) == input + n - 1);
  71   ASSERT (memchr (input + 1, 'e', n - 1) == input + n - 2);
  72   ASSERT (memchr (input + 1, 0x789abc00 | 'e', n - 1) == input + n - 2);
  73
  74   ASSERT (memchr (input, 'f', n) == NULL);
  75   ASSERT (memchr (input, '\0', n) == NULL);
  76
  77   /* Check that a very long haystack is handled quickly if the byte is
  78      found near the beginning.  */
  79   {
  80     size_t repeat = 10000;
  81     for (; repeat > 0; repeat--)
  82       {
  83         ASSERT (memchr (input, 'c', n) == input + 2);
  84       }
  85   }
  86
  87   /* Alignment tests.  */
  88   {
  89     int i, j;
  90     for (i = 0; i < 32; i++)
  91       {
  92         for (j = 0; j < 256; j++)
  93           input[i + j] = j;
  94         for (j = 0; j < 256; j++)
  95           {
  96             ASSERT (memchr (input + i, j, 256) == input + i + j);
  97           }
  98       }
  99   }
 100
 101   /* Check that memchr() does not read past the first occurrence of the
 102      byte being searched.  See the Austin Group's clarification
 103      <https://www.opengroup.org/austin/docs/austin_454.txt>.
 104      Test both '\0' and something else, since some implementations
 105      special-case searching for NUL.
 106   */
 107   {
 108     char *page_boundary = (char *) zerosize_ptr ();
 109     /* Too small, and we miss cache line boundary tests; too large,
 110        and the test takes cubically longer to complete.  */
 111     int limit = 257;
 112
 113     if (page_boundary != NULL)
 114       {
 115         for (n = 1; n <= limit; n++)
 116           {
 117             char *mem = page_boundary - n;
 118             memset (mem, 'X', n);
 119             ASSERT (memchr (mem, 'U', n) == NULL);
 120             ASSERT (memchr (mem, 0, n) == NULL);
 121
 122             {
 123               size_t i;
 124               size_t k;
 125
 126               for (i = 0; i < n; i++)
 127                 {
 128                   mem[i] = 'U';
 129                   for (k = i + 1; k < n + limit; k++)
 130                     ASSERT (memchr (mem, 'U', k) == mem + i);
 131                   mem[i] = 0;
 132                   for (k = i + 1; k < n + limit; k++)
 133                     ASSERT (memchr (mem, 0, k) == mem + i);
 134                   mem[i] = 'X';
 135                 }
 136             }
 137           }
 138       }
 139   }
 140
 141   free (input);
 142
 143   /* Test zero-length operations on NULL pointers, allowed by
 144      <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3322.pdf>.  */
 145   ASSERT (memchr (NULL, '?', 0) == NULL);
 146
 147   return test_exit_status;
 148 }