[LTP] [PATCH v2] mmap01: fix check_file() test for file corruption

[Cyril Hrubis]

Hi!
> mmap01 reported random test failures. Investigation showed
> that check_file() will compare the whole buffer even if less
> bytes were read from the file. Adjust check_file() to:
> 
> - fail the test if the not the correct amount of data has been read.
> - only compare the bytes actually read
> 
> Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
> ---
> Changes in v2:
> 
> - check return value from SAFE_READ
> - only verify bytes actually read
> 
>  testcases/kernel/syscalls/mmap/mmap01.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/testcases/kernel/syscalls/mmap/mmap01.c b/testcases/kernel/syscalls/mmap/mmap01.c
> index c93c37ceda52..b5798c8d2367 100644
> --- a/testcases/kernel/syscalls/mmap/mmap01.c
> +++ b/testcases/kernel/syscalls/mmap/mmap01.c
> @@ -35,15 +35,18 @@ static void check_file(void)
>  {
>  	int i, fildes, buf_len = sizeof(STRING) + 3;
>  	char buf[buf_len];
> +	ssize_t len;
>  
>  	fildes = SAFE_OPEN(TEMPFILE, O_RDONLY);
> -	SAFE_READ(0, fildes, buf, sizeof(buf));
> +	len = SAFE_READ(0, fildes, buf, sizeof(buf));
> +	if (len != strlen(STRING))
> +		tst_res(TFAIL, "Error reading from file\n");
                                                        ^
							no newline here
							please

		And possibly it would make sense to write how many
		characters were read and how many we expected so
		something as:

		tst_res(TFAIL, "Read %zi expected %zu", len, strlen(STRING));

		and we also want to do return; if we fail to read
		strlen(STRING) bytes because checking the buffer content
		does not make sense at that point, since it's possibly
		only partialy intialized

>  
> -	for (i = 0; i < buf_len; i++)
> +	for (i = 0; i < len; i++)
>  		if (buf[i] == 'X' || buf[i] == 'Y' || buf[i] == 'Z')
>  			break;
>  
> -	if (i == buf_len)
> +	if (i == len)
>  		tst_res(TPASS, "Specified pattern not found in file");
>  	else
>  		tst_res(TFAIL, "Specified pattern found in file");
> -- 
> 2.47.1
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz