[LTP] [PATCH] syscalls/read05: Test read with zero count

[Richard Palethorpe]

Hello,

Liao Huangjie <liaohj.jy@fujitsu.com> writes:

> From: Huangjie Liao <liaohj.jy@fujitsu.com>
>
> Signed-off-by: Huangjie Liao <liaohj.jy@fujitsu.com>
> ---
>  runtest/syscalls                          |  1 +
>  testcases/kernel/syscalls/read/.gitignore |  1 +
>  testcases/kernel/syscalls/read/read05.c   | 44 +++++++++++++++++++++++++++++++
>  3 files changed, 46 insertions(+)
>  create mode 100644 testcases/kernel/syscalls/read/read05.c
>
> diff --git a/runtest/syscalls b/runtest/syscalls
> index 3847e8a..0bd47fc 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -1094,6 +1094,7 @@ read01 read01
>  read02 read02
>  read03 read03
>  read04 read04
> +read05 read05
>  
>  readahead01 readahead01
>  readahead02 readahead02
> diff --git a/testcases/kernel/syscalls/read/.gitignore b/testcases/kernel/syscalls/read/.gitignore
> index e89c008..69d97b3 100644
> --- a/testcases/kernel/syscalls/read/.gitignore
> +++ b/testcases/kernel/syscalls/read/.gitignore
> @@ -2,3 +2,4 @@
>  /read02
>  /read03
>  /read04
> +/read05
> diff --git a/testcases/kernel/syscalls/read/read05.c b/testcases/kernel/syscalls/read/read05.c
> new file mode 100644
> index 0000000..83ac763
> --- /dev/null
> +++ b/testcases/kernel/syscalls/read/read05.c
> @@ -0,0 +1,44 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2022 FUJITSU LIMITED. All Rights Reserved.
> + * Author: Huangjie Liao <liaohj.jy@fujitsu.com>
> + */
> +
> +/*\
> + * [Description]
> + *
> + * In the absence of any errors, a read() with a count of 0 returns
>  zero.

This test is quite similar to read04. You could modify that test to read
multiple times from 0 bytes to the total number of bytes available.

> + */
> +
> +#include <errno.h>
> +#include "tst_test.h"
> +
> +#define SIZE 512

This could be set to 2*getpagesize() at runtime. Then you can try
reading every length between 0 and 2*getpagesize().

Errors tend to be made on page boundaries and similar.

> +
> +static int fd;
> +static char buf[SIZE];
> +
> +static void verify_read(void)
> +{
> +	TST_EXP_VAL(read(fd, buf, 0), 0);
> +}
> +
> +static void setup(void)
> +{
> +	memset(buf, '*', SIZE);
> +	fd = SAFE_OPEN("testfile", O_RDWR | O_CREAT, 0700);
> +	SAFE_WRITE(1, fd, buf, SIZE);
> +}
> +
> +static void cleanup(void)
> +{
> +	if (fd > 0)
> +		SAFE_CLOSE(fd);
> +}
> +
> +static struct tst_test test = {
> +	.test_all = verify_read,
> +	.setup = setup,
> +	.cleanup = cleanup,
> +	.needs_tmpdir = 1,

It would increase test coverage greatly to run this on all filesystems
(i.e. set .all_filesystems = 1). For an example see rename10.

> +};
> -- 
> 1.8.3.1


-- 
Thank you,
Richard.