On Mon, Mar 09, 2026 at 11:54:35AM +0000, Pratyush Yadav wrote:
> From: "Pratyush Yadav (Google)" <[email protected]>
>
> Add some helper functions that will be used by memfd tests. This moves
> some of the complexity out of the test itself, which results in better
> test readability and less code duplication.
>
> Signed-off-by: Pratyush Yadav <[email protected]>
> Signed-off-by: Pratyush Yadav (Google) <[email protected]>
> ---
> .../selftests/liveupdate/luo_test_utils.c | 175 +++++++++++++++++-
> .../selftests/liveupdate/luo_test_utils.h | 9 +
> 2 files changed, 183 insertions(+), 1 deletion(-)
Some review comments from an LLM that make sense to me as well :)
> diff --git a/tools/testing/selftests/liveupdate/luo_test_utils.c
> b/tools/testing/selftests/liveupdate/luo_test_utils.c
> --- a/tools/testing/selftests/liveupdate/luo_test_utils.c
> +++ b/tools/testing/selftests/liveupdate/luo_test_utils.c
[ ... ]
> +/* Read exactly specified size from fd. Any less results in error. */
> +int read_size(int fd, char *buffer, size_t size)
> +{
> + size_t remain = size;
> + ssize_t bytes_read;
> +
> + while (remain) {
> + bytes_read = read(fd, buffer, remain);
> + if (bytes_read == 0)
> + return -ENODATA;
> + if (bytes_read < 0)
> + return -errno;
> +
> + remain -= bytes_read;
> + }
Should the buffer pointer be advanced after each read()? As written,
if read() returns a partial result, the next iteration reads into the
same position, overwriting the data just read. Something like
buffer += bytes_read after remain -= bytes_read seems to be missing.
This is exercised by generate_random_data() which reads from
/dev/urandom, where partial reads are possible for large requests.
> +/* Write exactly specified size from fd. Any less results in error. */
> +int write_size(int fd, const char *buffer, size_t size)
> +{
> + size_t remain = size;
> + ssize_t written;
> +
> + while (remain) {
> + written = write(fd, buffer, remain);
> + if (written == 0)
> + return -EIO;
> + if (written < 0)
> + return -errno;
> +
> + remain -= written;
> + }
Same issue here: buffer is not advanced after each write(), so on a
partial write the same initial bytes would be re-sent instead of
continuing from where the previous write left off.
--
Sincerely yours,
Mike.
