Re: [igt-dev] [PATCH v3 7/8] tests/fbdev: Add tests for accessing framebuffer near EOF

[Petri Latvala <petri.latvala@intel.com>]

On Tue, Nov 10, 2020 at 08:51:01AM +0100, Thomas Zimmermann wrote:
> Fbdev has some specific behavior when reading/writing near the EOF, which
> the eof test checks. If at least one bytes has been written, the number
> of bytes has to be returned, otherwise an error code (if any) has to be
> returned, or otherwise 0 has to returned. Not all drivers get this right.
> 
> v3:
> 	* put igt_describe() before igt_subtest() (Petri)
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  tests/fbdev.c | 47 ++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 46 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/fbdev.c b/tests/fbdev.c
> index 522da8e2..8fd920be 100644
> --- a/tests/fbdev.c
> +++ b/tests/fbdev.c
> @@ -78,7 +78,8 @@ static void framebuffer_tests(int fd)
>  			   PROT_WRITE, MAP_SHARED, fd, 0);
>  		igt_assert(map != MAP_FAILED);
>  
> -		buf = malloc(fix_info.smem_len);
> +		/* allocate two additional bytes for eof test */
> +		buf = malloc(fix_info.smem_len + 2);
>  		igt_assert(buf);
>  
>  		ret = sysconf(_SC_PAGESIZE);
> @@ -184,6 +185,50 @@ static void framebuffer_tests(int fd)
>  		igt_require_f(pos, "found 0x55 at pos %zu, none expected\n", pos - map);
>  	}
>  
> +	igt_describe("Check framebuffer access near EOF");
> +	igt_subtest("eof") {
> +		unsigned long lastindex = fix_info.smem_len - 1;
> +		unsigned char *maplast = &((unsigned char *)map)[lastindex];
> +		unsigned char *buflast = &((unsigned char *)buf)[lastindex];
> +		ssize_t ret;
> +
> +		*buflast = 0x55;
> +
> +		/* write across EOF; set remaining bytes */
> +		ret = pwrite(fd, buflast, 2, lastindex);
> +		igt_require_f(ret == 1, "write crossed EOF, ret=%zd\n", ret);
> +		igt_require_f(*maplast == *buflast, "write buffer differs from mapped framebuffer at final byte, "
> +		                                    "maplast=%u buflast=%u\n", *maplast, *buflast);
> +
> +		/* write at EOF; get ENOSPC */
> +		ret = pwrite(fd, &buflast[1], 1, lastindex + 1);
> +		igt_require_f((ret == -1) && (errno == ENOSPC), "write at EOF, ret=%zd\n", ret);
> +
> +		*maplast = 0;
> +
> +		/* write final byte */
> +		ret = pwrite(fd, buflast, 1, lastindex);
> +		igt_require_f(ret == 1, "write before EOF, ret=%zd\n", ret);
> +		igt_require_f(*maplast == *buflast, "write buffer differs from mapped framebuffer at final byte, "
> +		                                    "maplast=%u buflast=%u\n", *maplast, *buflast);
> +
> +		/* write after EOF; get EFBIG */
> +		ret = pwrite(fd, &buflast[2], 1, lastindex + 2);
> +		igt_require_f((ret == -1) && (errno == EFBIG), "write after EOF, ret=%zd\n", ret);
> +
> +		*maplast = 0;
> +
> +		/* read across the EOF; get remaining bytes */
> +		ret = pread(fd, buflast, 2, lastindex);
> +		igt_require_f(ret == 1, "read before EOF, ret=%zd\n", ret);
> +		igt_require_f(*maplast == *buflast, "read buffer differs from mapped framebuffer at final byte, "
> +		                                    "maplast=%u buflast=%u\n", *maplast, *buflast);
> +
> +		/* read after EOF; get 0 */
> +		ret = pread(fd, &buflast[1], 1, lastindex + 1);
> +		igt_require_f(ret == 0, "read at EOF, ret=%zd\n", ret);

igt_asserts instead of igt_requires.


-- 
Petri Latvala



> +	}
> +
>  	igt_fixture {
>  		free(buf);
>  		memset(map, 0, fix_info.smem_len); // don't leave garbage on the screen
> -- 
> 2.29.2
> 
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