xref: /aosp_15_r20/external/ltp/testcases/kernel/syscalls/pread/pread01.c (revision 49cdfc7efb34551c7342be41a7384b9c40d7cab7)

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (c) Linux Test Project, 2021
 * Copyright (c) International Business Machines  Corp., 2001
 * 07/2001 Ported by Wayne Boyer
 */

/*\
 * [Description]
 *
 * Verify the functionality of pread() by writing known data using pwrite()
 * to the file at various specified offsets and later read from the file from
 * various specified offsets, comparing the data read against the data written.
 */

#include <stdlib.h>
#include <inttypes.h>
#include "tst_test.h"
#include "tst_safe_prw.h"

#define TEMPFILE        "pread_file"
#define K1              1024
#define K2              (K1 * 2)
#define K3              (K1 * 3)
#define K4              (K1 * 4)
#define NBUFS           4

static int fildes;
static char *write_buf[NBUFS];
static char *read_buf[NBUFS];

static void l_seek(int fdesc, off_t offset, int whence, off_t checkoff)
{
	off_t offloc;

	offloc = SAFE_LSEEK(fdesc, offset, whence);
	if (offloc != checkoff) {
		tst_res(TFAIL, "return = %" PRId64 ", expected %" PRId64,
			(int64_t) offloc, (int64_t) checkoff);
	}
}

static void compare_bufers(void)
{
	int count;
	int err_flg = 0;

	for (count = 0; count < NBUFS; count++) {
		if (memcmp(write_buf[count], read_buf[count], K1) != 0) {
			tst_res(TFAIL, "read/write buffer[%d] data mismatch", count);
			err_flg++;
		}
	}

	if (!err_flg)
		tst_res(TPASS, "Functionality of pread() is correct");
}

static void verify_pread(void)
{
	SAFE_PREAD(1, fildes, read_buf[2], K1, K2);
	l_seek(fildes, 0, SEEK_CUR, K4);
	l_seek(fildes, 0, SEEK_SET, 0);

	SAFE_PREAD(1, fildes, read_buf[3], K1, K3);
	l_seek(fildes, 0, SEEK_CUR, 0);

	SAFE_READ(1, fildes, read_buf[0], K1);
	l_seek(fildes, 0, SEEK_CUR, K1);

	SAFE_PREAD(1, fildes, read_buf[1], K1, K1);
	l_seek(fildes, 0, SEEK_CUR, K1);

	compare_bufers();

	l_seek(fildes, K4, SEEK_SET, K4);
}

static void setup(void)
{
	int count;

	for (count = 0; count < NBUFS; count++) {
		write_buf[count] = SAFE_MALLOC(K1);
		read_buf[count] = SAFE_MALLOC(K1);
		memset(write_buf[count], count, K1);
	}

	fildes = SAFE_OPEN(TEMPFILE, O_RDWR | O_CREAT, 0666);

	SAFE_PWRITE(1, fildes, write_buf[0], K1, 0);
	SAFE_PWRITE(1, fildes, write_buf[2], K1, K2);
	SAFE_PWRITE(1, fildes, write_buf[3], K1, K3);
	SAFE_PWRITE(1, fildes, write_buf[1], K1, K1);
	SAFE_LSEEK(fildes, K4, SEEK_SET);
}

static void cleanup(void)
{
	int count;

	for (count = 0; count < NBUFS; count++) {
		free(write_buf[count]);
		free(read_buf[count]);
	}

	if (fildes > 0)
		SAFE_CLOSE(fildes);
}

static struct tst_test test = {
	.needs_tmpdir = 1,
	.setup = setup,
	.cleanup = cleanup,
	.test_all = verify_pread,
};