tests/test-pread.c

   1 /* Test the pread function.
   2    Copyright (C) 2009-2024 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Jim Meyering.  */
  18
  19 #include <config.h>
  20
  21 #include <unistd.h>
  22
  23 #include "signature.h"
  24 SIGNATURE_CHECK (pread, ssize_t, (int, void *, size_t, off_t));
  25
  26 #include <sys/types.h>
  27 #include <fcntl.h>
  28 #include <errno.h>
  29
  30 #include "macros.h"
  31
  32 #define N (sizeof buf - 1)
  33
  34 int
  35 main (void)
  36 {
  37   char const *file = "in";
  38   int fd;
  39   char buf[] = "0123456789";
  40   off_t pos;
  41
  42   ASSERT (file);
  43
  44   fd = open (file, O_CREAT | O_WRONLY, 0600);
  45   ASSERT (0 <= fd);
  46   ASSERT (write (fd, buf, N) == N);
  47   ASSERT (close (fd) == 0);
  48
  49   fd = open (file, O_RDONLY);
  50   ASSERT (0 <= fd);
  51
  52   for (pos = 0; pos < 3; pos++)
  53     {
  54       size_t i;
  55       off_t init_pos = lseek (fd, pos, SEEK_SET);
  56       ASSERT (init_pos == pos);
  57
  58       for (i = 0; i < N; i++)
  59         {
  60           char byte_buf;
  61           ASSERT (pread (fd, &byte_buf, 1, i) == 1);
  62           ASSERT (byte_buf == buf[i]);
  63           ASSERT (lseek (fd, 0, SEEK_CUR) == init_pos);
  64         }
  65     }
  66
  67   {
  68     /* Invalid offset must evoke failure with EINVAL.  */
  69     char byte;
  70     ASSERT (pread (fd, &byte, 1, (off_t) -1) == -1);
  71     ASSERT (errno == EINVAL
  72             || errno == EFBIG /* seen on OpenBSD 4.9 */
  73            );
  74   }
  75
  76   ASSERT (close (fd) == 0);
  77
  78   {
  79     char byte;
  80     /* Trying to operate on a pipe must evoke failure with ESPIPE.
  81        This assumes that stdin is a pipe, and hence not seekable.  */
  82     ASSERT (pread (STDIN_FILENO, &byte, 1, 1) == -1);
  83     ASSERT (errno == ESPIPE);
  84   }
  85
  86   /* Test behaviour for invalid file descriptors.  */
  87   {
  88     char byte;
  89     errno = 0;
  90     ASSERT (pread (-1, &byte, 1, 0) == -1);
  91     ASSERT (errno == EBADF);
  92   }
  93   {
  94     char byte;
  95     close (99);
  96     errno = 0;
  97     ASSERT (pread (99, &byte, 1, 0) == -1);
  98     ASSERT (errno == EBADF);
  99   }
 100
 101   return test_exit_status;
 102 }