xref: /aosp_15_r20/external/ltp/testcases/kernel/syscalls/splice/splice02.c (revision 49cdfc7efb34551c7342be41a7384b9c40d7cab7)

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (c) Jens Axboe <[email protected]>, 2009
 * Copyright (c) 2021 Petr Vorel <[email protected]>
 */

/*\
 * [Description]
 * Original reproducer for kernel fix
 * bf40d3435caf NFS: add support for splice writes
 * from v2.6.31-rc1.
 *
 * http://lkml.org/lkml/2009/4/2/55
 *
 * [ALGORITHM]
 * - create pipe
 * - fork(), child replace stdin with pipe
 * - parent write to pipe
 * - child slice from pipe
 * - check resulted file size and content
 */

#define _GNU_SOURCE

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>

#include "tst_test.h"
#include "lapi/mmap.h"
#include "lapi/splice.h"

#define BUFSIZE 512
#define SPLICE_SIZE 1024

#define TEST_FILENAME "splice02-temp"

static char *sarg;
static int file_size;
static int pipe_fd[2];

static void setup(void)
{
	if (tst_parse_int(sarg, &file_size, 1, INT_MAX))
		tst_brk(TBROK, "invalid number of writes '%s', use <1,%d>", sarg, INT_MAX);
}

static inline int get_letter(int n)
{
	return n % ('z' - 'a' + 1) + 'a';
}

static void do_child(void)
{
	int fd;
	size_t page_size, to_check, block, blocks, i, fail = 0;
	struct stat st;
	char *map;

	SAFE_CLOSE(pipe_fd[1]);
	SAFE_DUP2(pipe_fd[0], STDIN_FILENO);

	fd = SAFE_OPEN(TEST_FILENAME, O_WRONLY | O_CREAT | O_TRUNC, 0644);

	do {
		TEST(splice(STDIN_FILENO, NULL, fd, NULL, SPLICE_SIZE, 0));
		if (TST_RET < 0) {
			tst_res(TFAIL | TTERRNO, "splice failed");
			goto cleanup;
		}
	} while (TST_RET > 0);

	stat(TEST_FILENAME, &st);
	if (st.st_size != file_size) {
		tst_res(TFAIL, "file size is different from expected: %ld (%d)",
				st.st_size, file_size);
		goto cleanup;
	}

	SAFE_CLOSE(fd);
	fd = SAFE_OPEN(TEST_FILENAME, O_RDONLY);

	page_size = sysconf(_SC_PAGESIZE);

	tst_res(TINFO, "checking file content");

	blocks = LTP_ALIGN(st.st_size, page_size) / page_size;

	for (block = 0; block < blocks; block++) {
		map = SAFE_MMAP(NULL, page_size, PROT_READ, MAP_PRIVATE,
				fd,block * page_size);

		to_check = (block+1) * page_size < (unsigned long)st.st_size ?
			page_size : st.st_size % page_size;

		for (i = 0; i < to_check; i++) {
			if (map[i] != get_letter(block * page_size + i))
				fail++;
		}

		SAFE_MUNMAP(map, page_size);
	}

	if (fail) {
		tst_res(TFAIL, "%ld unexpected bytes found", fail);
		goto cleanup;
	}

	tst_res(TPASS, "splice() system call passed");

cleanup:
	SAFE_CLOSE(fd);
	exit(0);
}

static void run(void)
{
	size_t i, size, written, max_pipe_size, to_write;
	char buf[BUFSIZE];

	SAFE_PIPE(pipe_fd);

	if (!file_size) {
		max_pipe_size = SAFE_FCNTL(pipe_fd[1], F_GETPIPE_SZ);
		file_size = max_pipe_size << 4;
	}

	to_write = file_size;

	if (!SAFE_FORK())
		do_child();

	tst_res(TINFO, "writting %d bytes", file_size);

	while (to_write > 0) {
		size = to_write > BUFSIZE ? BUFSIZE : to_write;

		for (i = 0; i < size; i++)
			buf[i] = get_letter(file_size - to_write + i);

		written = SAFE_WRITE(SAFE_WRITE_ALL, pipe_fd[1], &buf, size);
		to_write -= written;
	}

	SAFE_CLOSE(pipe_fd[0]);
	SAFE_CLOSE(pipe_fd[1]);

	tst_reap_children();
}

static struct tst_test test = {
	.test_all = run,
	.setup = setup,
	.needs_tmpdir = 1,
	.forks_child = 1,
	.options = (struct tst_option[]) {
		{"s:", &sarg, "Size of output file in bytes (default: 16x max pipe size, i.e. 1M on intel)"},
		{}
	},
};