/* Test the read() function.

   Copyright (C) 2011-2017 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

#include <unistd.h>

#include "signature.h"

SIGNATURE_CHECK (read, ssize_t, (int, void *, size_t));

#include <errno.h>

#include <fcntl.h>

#include <string.h>

#include "macros.h"

int

main (void)

{

  const char *filename = "test-read.tmp";

  int fd;

  /* Create a file with a simple contents.  */

  fd = open (filename, O_CREAT | O_WRONLY, 0600);

  ASSERT (fd >= 0);

  ASSERT (write (fd, "Hello World", 11) == 11);

  ASSERT (close (fd) == 0);

  /* Read from the middle of the file.  */

  fd = open (filename, O_RDONLY);

  ASSERT (fd >= 0);

  ASSERT (lseek (fd, 6, SEEK_SET) == 6);

  {

    char buf[10];

    ssize_t ret = read (fd, buf, 10);

    ASSERT (ret == 5);

    ASSERT (memcmp (buf, "World", 5) == 0);

  }

  ASSERT (close (fd) == 0);

  /* Test behaviour for invalid file descriptors.  */

  {

    char byte;

    errno = 0;

    ASSERT (read (-1, &byte, 1) == -1);

    ASSERT (errno == EBADF);

  }

  {

    char byte;

    close (99);

    errno = 0;

    ASSERT (read (99, &byte, 1) == -1);

    ASSERT (errno == EBADF);

  }

  /* Clean up.  */

  unlink (filename);

  return 0;

}