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/* Test the read() function.
Copyright (C) 2011-2020 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 <https://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;
}
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