[LTP] [PATCH v3] syscalls/write06: Add new test

[xuyang2018.jy@fujitsu.com]

Hi Dai
LGTM, merged!

Best Regards
Yang Xu
> Like pwrite04.c, test the write() system call with O_APPEND.
>
> Signed-off-by: Dai Shili<daisl.fnst@fujitsu.com>
> ---
>   runtest/syscalls                           |  1 +
>   testcases/kernel/syscalls/write/.gitignore |  1 +
>   testcases/kernel/syscalls/write/write06.c  | 94 ++++++++++++++++++++++++++++++
>   3 files changed, 96 insertions(+)
>   create mode 100644 testcases/kernel/syscalls/write/write06.c
>
> diff --git a/runtest/syscalls b/runtest/syscalls
> index bcf3d56..32fcda4 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -1699,6 +1699,7 @@ write02 write02
>   write03 write03
>   write04 write04
>   write05 write05
> +write06 write06
>
>   writev01 writev01
>   writev02 writev02
> diff --git a/testcases/kernel/syscalls/write/.gitignore b/testcases/kernel/syscalls/write/.gitignore
> index 7f36194..8529aae 100644
> --- a/testcases/kernel/syscalls/write/.gitignore
> +++ b/testcases/kernel/syscalls/write/.gitignore
> @@ -3,3 +3,4 @@
>   /write03
>   /write04
>   /write05
> +/write06
> diff --git a/testcases/kernel/syscalls/write/write06.c b/testcases/kernel/syscalls/write/write06.c
> new file mode 100644
> index 0000000..c175548
> --- /dev/null
> +++ b/testcases/kernel/syscalls/write/write06.c
> @@ -0,0 +1,94 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2021 FUJITSU LIMITED. All rights reserved.
> + * Author: Dai Shili<daisl.fnst@fujitsu.com>
> + */
> +
> +/*\
> + * [Description]
> + *
> + * Test the write() system call with O_APPEND.
> + *
> + * The full description of O_APPEND is in open(2) man-pages:
> + * The file is opened in append mode.  Before each write(2), the
> + * file offset is positioned at the end of the file, as if with lseek(2).
> + * The modification of the file offset and the write operation are
> + * performed as a single atomic step.
> + *
> + * Writing 2k data to the file, close it and reopen it with O_APPEND.
> + * Verify that the file size is 3k and offset is moved to the end of the file.
> + */
> +
> +#include<stdlib.h>
> +#include<inttypes.h>
> +#include "tst_test.h"
> +#include "tst_safe_prw.h"
> +
> +#define K1              1024
> +#define K2              (K1 * 2)
> +#define K3              (K1 * 3)
> +#define DATA_FILE       "write06_file"
> +
> +static int fd = -1;
> +static char *write_buf[2];
> +
> +static void verify_write(void)
> +{
> +	off_t off;
> +	struct stat statbuf;
> +
> +	fd = SAFE_OPEN(DATA_FILE, O_RDWR | O_CREAT | O_TRUNC, 0666);
> +	SAFE_WRITE(1, fd, write_buf[0], K2);
> +	SAFE_CLOSE(fd);
> +
> +	fd = SAFE_OPEN(DATA_FILE, O_RDWR | O_APPEND);
> +	SAFE_FSTAT(fd,&statbuf);
> +	if (statbuf.st_size != K2)
> +		tst_res(TFAIL, "file size is %ld != K2", statbuf.st_size);
> +
> +	off = SAFE_LSEEK(fd, K1, SEEK_SET);
> +	if (off != K1)
> +		tst_brk(TBROK, "Failed to seek to K1");
> +
> +	SAFE_WRITE(1, fd, write_buf[1], K1);
> +
> +	off = SAFE_LSEEK(fd, 0, SEEK_CUR);
> +	if (off != K3)
> +		tst_res(TFAIL, "Wrong offset after write %zu expected %u", off, K3);
> +	else
> +		tst_res(TPASS, "Offset is correct after write %zu", off);
> +
> +	SAFE_FSTAT(fd,&statbuf);
> +	if (statbuf.st_size != K3)
> +		tst_res(TFAIL, "Wrong file size after append %zu expected %u", statbuf.st_size, K3);
> +	else
> +		tst_res(TPASS, "Correct file size after append %u", K3);
> +
> +	SAFE_CLOSE(fd);
> +}
> +
> +static void setup(void)
> +{
> +	memset(write_buf[0], 0, K2);
> +	memset(write_buf[1], 1, K1);
> +}
> +
> +static void cleanup(void)
> +{
> +	if (fd != -1)
> +		SAFE_CLOSE(fd);
> +
> +	SAFE_UNLINK(DATA_FILE);
> +}
> +
> +static struct tst_test test = {
> +	.needs_tmpdir = 1,
> +	.setup = setup,
> +	.cleanup = cleanup,
> +	.test_all = verify_write,
> +	.bufs = (struct tst_buffers[]) {
> +		{&write_buf[0], .size = K2},
> +		{&write_buf[1], .size = K1},
> +		{}
> +	}
> +};