nptl/tst-memstream.c

   1 /* Test for open_memstream locking.
   2    Copyright (C) 2017-2020 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 /* This test checks if concurrent writes to a FILE created with
  20    open_memstream are correctly interleaved without loss or corruption
  21    of data.  Large number of concurrent fputc operations are used
  22    and in the end the bytes written to the memstream buffer are
  23    counted to see if they all got recorded.
  24
  25    This is a regression test to see if the single threaded stdio
  26    optimization broke multi-threaded open_memstream usage.  */
  27
  28 #include <pthread.h>
  29 #include <stdio.h>
  30 #include <support/check.h>
  31 #include <support/xthread.h>
  32
  33 enum
  34 {
  35   thread_count = 2,
  36   byte_count = 1000000,
  37 };
  38
  39 struct closure
  40 {
  41   FILE *fp;
  42   char b;
  43 };
  44
  45 static void *
  46 thread_func (void *closure)
  47 {
  48   struct closure *args = closure;
  49
  50   for (int i = 0; i < byte_count; ++i)
  51     fputc (args->b, args->fp);
  52
  53   return NULL;
  54 }
  55
  56 int
  57 do_test (void)
  58 {
  59   char *buffer = NULL;
  60   size_t buffer_length = 0;
  61   FILE *fp = open_memstream (&buffer, &buffer_length);
  62   if (fp == NULL)
  63     FAIL_RET ("open_memstream: %m");
  64
  65   pthread_t threads[thread_count];
  66   struct closure args[thread_count];
  67
  68   for (int i = 0; i < thread_count; ++i)
  69     {
  70       args[i].fp = fp;
  71       args[i].b = 'A' + i;
  72       threads[i] = xpthread_create (NULL, thread_func, args + i);
  73     }
  74
  75   for (int i = 0; i < thread_count; ++i)
  76     xpthread_join (threads[i]);
  77
  78   fclose (fp);
  79
  80   if (buffer_length != thread_count * byte_count)
  81     FAIL_RET ("unexpected number of written bytes: %zu (should be %d)",
  82               buffer_length, thread_count * byte_count);
  83
  84   /* Verify that each thread written its unique character byte_count times.  */
  85   size_t counts[thread_count] = { 0, };
  86   for (size_t i = 0; i < buffer_length; ++i)
  87     {
  88       if (buffer[i] < 'A' || buffer[i] >= 'A' + thread_count)
  89         FAIL_RET ("written byte at %zu out of range: %d", i, buffer[i] & 0xFF);
  90       ++counts[buffer[i] - 'A'];
  91     }
  92   for (int i = 0; i < thread_count; ++i)
  93     if (counts[i] != byte_count)
  94       FAIL_RET ("incorrect write count for thread %d: %zu (should be %d)", i,
  95                 counts[i], byte_count);
  96
  97   return 0;
  98 }
  99
 100 #define TIMEOUT 100
 101 #include <support/test-driver.c>