tests/test-read.c

   1 /* Test the read() function.
   2    Copyright (C) 2011-2024 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 #include <config.h>
  18
  19 #include <unistd.h>
  20
  21 #include "signature.h"
  22 SIGNATURE_CHECK (read, ssize_t, (int, void *, size_t));
  23
  24 #include <errno.h>
  25 #include <fcntl.h>
  26 #include <string.h>
  27
  28 #include "macros.h"
  29
  30 int
  31 main (void)
  32 {
  33   const char *filename = "test-read.tmp";
  34   int fd;
  35
  36   /* Create a file with a simple contents.  */
  37   fd = open (filename, O_CREAT | O_WRONLY, 0600);
  38   ASSERT (fd >= 0);
  39   ASSERT (write (fd, "Hello World", 11) == 11);
  40   ASSERT (close (fd) == 0);
  41
  42   /* Read from the middle of the file.  */
  43   fd = open (filename, O_RDONLY);
  44   ASSERT (fd >= 0);
  45   ASSERT (lseek (fd, 6, SEEK_SET) == 6);
  46   {
  47     char buf[10];
  48     ssize_t ret = read (fd, buf, 10);
  49     ASSERT (ret == 5);
  50     ASSERT (memcmp (buf, "World", 5) == 0);
  51   }
  52   ASSERT (close (fd) == 0);
  53
  54   /* Test behaviour for invalid file descriptors.  */
  55   {
  56     char byte;
  57     errno = 0;
  58     ASSERT (read (-1, &byte, 1) == -1);
  59     ASSERT (errno == EBADF);
  60   }
  61   {
  62     char byte;
  63     close (99);
  64     errno = 0;
  65     ASSERT (read (99, &byte, 1) == -1);
  66     ASSERT (errno == EBADF);
  67   }
  68
  69   /* Clean up.  */
  70   unlink (filename);
  71
  72   return test_exit_status;
  73 }