1  #include <errno.h>
       2  #include <stdio.h>
       3  #include <stdlib.h>
       4  #include <unistd.h>
       5  
       6  #include <support/xstdio.h>
       7  
       8  static char *fname;
       9  
      10  
      11  static void do_prepare (void);
      12  #define PREPARE(argc, argv) do_prepare ()
      13  static int do_test (void);
      14  #define TEST_FUNCTION do_test ()
      15  #include <test-skeleton.c>
      16  
      17  
      18  static void
      19  do_prepare (void)
      20  {
      21    static const char pattern[] = "12345678901234567890";
      22    int fd = create_temp_file ("bug-fseek.", &fname);
      23    if (fd == -1)
      24      {
      25        printf ("cannot create temporary file: %m\n");
      26        exit (1);
      27      }
      28  
      29    if (write (fd, pattern, sizeof (pattern)) != sizeof (pattern))
      30      {
      31        perror ("short write");
      32        abort ();
      33      }
      34    close (fd);
      35  }
      36  
      37  
      38  
      39  static int
      40  do_test (void)
      41  {
      42    FILE *f;
      43    int result = 0;
      44    char buf[10];
      45  
      46  
      47    if ((f = fopen (fname, "r")) == (FILE *) NULL)
      48      {
      49        perror ("fopen(\"r\")");
      50      }
      51  
      52    xfread (buf, 3, 1, f);
      53    errno = 0;
      54    if (fseek (f, -10, SEEK_CUR) == 0)
      55      {
      56        printf ("fseek() for r to before start of file worked!\n");
      57        result = 1;
      58      }
      59    else if (errno != EINVAL)
      60      {
      61        printf ("\
      62  fseek() for r to before start of file did not set errno to EINVAL.  \
      63  Got %d instead\n",
      64  	 errno);
      65        result = 1;
      66      }
      67  
      68    fclose (f);
      69  
      70  
      71    if ((f = fopen (fname, "r+")) == (FILE *) NULL)
      72      {
      73        perror ("fopen(\"r+\")");
      74      }
      75  
      76    xfread (buf, 3, 1, f);
      77    errno = 0;
      78    if (fseek (f, -10, SEEK_CUR) == 0)
      79      {
      80        printf ("fseek() for r+ to before start of file worked!\n");
      81        result = 1;
      82      }
      83    else if (errno != EINVAL)
      84      {
      85        printf ("\
      86  fseek() for r+ to before start of file did not set errno to EINVAL.  \
      87  Got %d instead\n",
      88  	 errno);
      89        result = 1;
      90      }
      91  
      92    fclose (f);
      93  
      94  
      95    if ((f = fopen (fname, "r+")) == (FILE *) NULL)
      96      {
      97        perror ("fopen(\"r+\")");
      98      }
      99  
     100    xfread (buf, 3, 1, f);
     101    if (ftell (f) != 3)
     102      {
     103        puts ("ftell failed");
     104        return 1;
     105      }
     106    errno = 0;
     107    if (fseek (f, -10, SEEK_CUR) == 0)
     108      {
     109        printf ("fseek() for r+ to before start of file worked!\n");
     110        result = 1;
     111      }
     112    else if (errno != EINVAL)
     113      {
     114        printf ("\
     115  fseek() for r+ to before start of file did not set errno to EINVAL.  \
     116  Got %d instead\n",
     117  	 errno);
     118        result = 1;
     119      }
     120  
     121    fclose (f);
     122  
     123    return result;
     124  }