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/* Test the pread function.
Copyright (C) 2009-2023 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/>. */
/* Written by Jim Meyering. */
#include <config.h>
#include <unistd.h>
#include "signature.h"
SIGNATURE_CHECK (pread, ssize_t, (int, void *, size_t, off_t));
#include <sys/types.h>
#include <fcntl.h>
#include <errno.h>
#include "macros.h"
#define N (sizeof buf - 1)
int
main (void)
{
char const *file = "in";
int fd;
char buf[] = "0123456789";
off_t pos;
ASSERT (file);
fd = open (file, O_CREAT | O_WRONLY, 0600);
ASSERT (0 <= fd);
ASSERT (write (fd, buf, N) == N);
ASSERT (close (fd) == 0);
fd = open (file, O_RDONLY);
ASSERT (0 <= fd);
for (pos = 0; pos < 3; pos++)
{
size_t i;
off_t init_pos = lseek (fd, pos, SEEK_SET);
ASSERT (init_pos == pos);
for (i = 0; i < N; i++)
{
char byte_buf;
ASSERT (pread (fd, &byte_buf, 1, i) == 1);
ASSERT (byte_buf == buf[i]);
ASSERT (lseek (fd, 0, SEEK_CUR) == init_pos);
}
}
{
/* Invalid offset must evoke failure with EINVAL. */
char byte;
ASSERT (pread (fd, &byte, 1, (off_t) -1) == -1);
ASSERT (errno == EINVAL
|| errno == EFBIG /* seen on OpenBSD 4.9 */
);
}
ASSERT (close (fd) == 0);
{
char byte;
/* Trying to operate on a pipe must evoke failure with ESPIPE.
This assumes that stdin is a pipe, and hence not seekable. */
ASSERT (pread (STDIN_FILENO, &byte, 1, 1) == -1);
ASSERT (errno == ESPIPE);
}
/* Test behaviour for invalid file descriptors. */
{
char byte;
errno = 0;
ASSERT (pread (-1, &byte, 1, 0) == -1);
ASSERT (errno == EBADF);
}
{
char byte;
close (99);
errno = 0;
ASSERT (pread (99, &byte, 1, 0) == -1);
ASSERT (errno == EBADF);
}
return 0;
}
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