[v6,1/2] splice02: Generate input in C

diff --git a/runtest/smoketest b/runtest/smoketest
index 0c24fc1fa..2224d8f74 100644
--- a/runtest/smoketest
+++ b/runtest/smoketest
@@ -11,5 +11,5 @@  symlink01 symlink01
 stat04 symlink01 -T stat04
 utime01A symlink01 -T utime01
 rename01A symlink01 -T rename01
-splice02 seq 1 20 | splice02
+splice02 splice02 -s 20
 route4-change-dst route-change-dst.sh
diff --git a/runtest/syscalls b/runtest/syscalls
index 2d1e7b648..b89c545f0 100644
--- a/runtest/syscalls
+++ b/runtest/syscalls
@@ -1451,7 +1451,7 @@  socketpair02 socketpair02
 sockioctl01 sockioctl01
 
 splice01 splice01
-splice02 seq 1 20000 | splice02
+splice02 splice02
 splice03 splice03
 splice04 splice04
 splice05 splice05
diff --git a/testcases/kernel/syscalls/splice/splice02.c b/testcases/kernel/syscalls/splice/splice02.c
index b579667b9..f0d414f5f 100644
--- a/testcases/kernel/syscalls/splice/splice02.c
+++ b/testcases/kernel/syscalls/splice/splice02.c
@@ -1,40 +1,164 @@ 
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (c) Jens Axboe <axboe@kernel.dk>, 2009
+ * Copyright (c) 2021 Petr Vorel <pvorel@suse.cz>
+ */
+
+/*\
+ * [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 <fcntl.h>
 
 #include "tst_test.h"
+#include "lapi/mmap.h"
 #include "lapi/splice.h"
 
-#define SPLICE_SIZE (64*1024)
+#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 splice_test(void)
+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");
 
-	fd = SAFE_OPEN("splice02-temp", O_WRONLY | O_CREAT | O_TRUNC, 0644);
+	blocks = LTP_ALIGN(st.st_size, page_size) / page_size;
 
-	TEST(splice(STDIN_FILENO, NULL, fd, NULL, SPLICE_SIZE, 0));
-	if (TST_RET < 0) {
-		tst_res(TFAIL, "splice failed - errno = %d : %s",
-			TST_ERR, strerror(TST_ERR));
-	} else {
-		tst_res(TPASS, "splice() system call Passed");
+	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(1, 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 = splice_test,
+	.test_all = run,
+	.setup = setup,
+	.needs_checkpoints = 1,
 	.needs_tmpdir = 1,
+	.forks_child = 1,
 	.min_kver = "2.6.17",
+	.options = (struct tst_option[]) {
+		{"s:", &sarg, "-s x     Size of output file in bytes (default: 16x max pipe size, i.e. 1M on intel)"},
+		{}
+	},
 };