1  /* Derived from the test case in
       2     https://sourceware.org/bugzilla/show_bug.cgi?id=1078.  */
       3  #include <stdio.h>
       4  #include <stdlib.h>
       5  #include <unistd.h>
       6  
       7  #define OUT_SIZE 10000
       8  
       9  
      10  static int fd;
      11  
      12  static void prepare (void);
      13  #define PREPARE(argc, argv) prepare ()
      14  
      15  static int do_test (void);
      16  #define TEST_FUNCTION do_test ()
      17  
      18  #include "../test-skeleton.c"
      19  
      20  
      21  static void
      22  prepare (void)
      23  {
      24    fd = create_temp_file ("tst-fwrite.", NULL);
      25    if (fd == -1)
      26      {
      27        puts ("cannot create temporary file");
      28        exit (1);
      29      }
      30  }
      31  
      32  
      33  static int
      34  do_test (void)
      35  {
      36    FILE* f = fdopen (fd, "w+");
      37    if (f == NULL) {
      38      puts ("cannot create stream");
      39      return 1;
      40    }
      41    puts ("Opened temp file");
      42  
      43    if (fwrite ("a", 1, 1, f) != 1)
      44      {
      45        puts ("1st fwrite failed");
      46        return 1;
      47      }
      48    puts ("Wrote a byte");
      49    fflush (f);
      50  
      51    char buffer[10000];
      52    size_t i = fread (buffer, 1, sizeof (buffer), f);
      53    printf ("Read %zu bytes\n", i);
      54  
      55    for (i = 0; i < OUT_SIZE; i++)
      56      {
      57        if (fwrite ("n", 1, 1, f) != 1)
      58  	{
      59  	  printf ("fwrite in loop round %zu failed\n", i);
      60  	  return 1;
      61  	}
      62  
      63        if ((i + 1) % 1000 == 0)
      64  	printf ("wrote %zu bytes ...\n", i + 1);
      65      }
      66  
      67    printf ("Wrote %i bytes [done]\n", OUT_SIZE);
      68  
      69    return 0;
      70  }