Re: [PULL 03/15] tests/acpi/bios-tables-test: do not write new blobs unless there are changes

[Igor Mammedov <imammedo@redhat.com>]

On Fri, 1 Dec 2023 12:15:16 -0500
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> From: Ani Sinha <anisinha@redhat.com>
> 
> When dumping table blobs using rebuild-expected-aml.sh, table blobs from all
> test variants are dumped regardless of whether there are any actual changes to
> the tables or not. This creates lot of new files for various test variants that
> are not part of the git repository. This is because we do not check in all table
> blobs for all test variants into the repository. Only those blobs for those
> variants that are different from the generic test-variant agnostic blob are
> checked in.
> 
> This change makes the test smarter by checking if at all there are any changes
> in the tables from the checked-in gold master blobs and take actions
> accordingly.
> 
> When there are no changes:
>  - No new table blobs would be written.
>  - Existing table blobs will be refreshed (git diff will show no changes).
> When there are changes:
>  - New table blob files will be dumped.
>  - Existing table blobs will be refreshed (git diff will show that the files
>    changed, asl diff will show the actual changes).

> When new tables are introduced:
>  - Zero byte empty file blobs for new tables as instructed in the header of
>    bios-tables-test.c will be regenerated to actual table blobs.

Ani,

what previously worked is the is there weren't _any_ expected blobs
(exact match/fallback) found a new table would be dumped.
So then later 'git status' would show a list of new files. 
With this commit it's however not dumping new files files,
and explodes at
#5  0x000055555556808e in load_expected_aml (data=0x7fffffffd7b0) at tests/qtest/bios-tables-test.c:414
#6  0x00005555555676b0 in dump_aml_files (data=0x7fffffffd7b0, rebuild=true) at tests/qtest/bios-tables-test.c:256

sure it can be worked around by manually creating empty files
for expected files but if it's a new machine type, one has to create
a bunch of them basically running multiple iterations of rebuild in V=2
mode to see what's missing.
(IMHO cure turned out to be worse than illness)

for reproducing create a test for other than default machine type, ex:

    test_data data = {                                                           
        .machine = "pc-i440fx-2.0",                                              
        .variant = ".pc_legacy",                                                              
    }; 


is it possible to fix it so that one doesn't have to create empty files manually?

> 
> This would make analyzing changes to tables less confusing and there would
> be no need to clean useless untracked files when there are no table changes.
> 
> CC: peter.maydell@linaro.org
> Signed-off-by: Ani Sinha <anisinha@redhat.com>
> Message-Id: <20231107044952.5461-1-anisinha@redhat.com>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  tests/qtest/bios-tables-test.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/tests/qtest/bios-tables-test.c b/tests/qtest/bios-tables-test.c
> index 71af5cf69f..fe6a9a8563 100644
> --- a/tests/qtest/bios-tables-test.c
> +++ b/tests/qtest/bios-tables-test.c
> @@ -112,6 +112,7 @@ static const char *iasl;
>  #endif
>  
>  static int verbosity_level;
> +static GArray *load_expected_aml(test_data *data);
>  
>  static bool compare_signature(const AcpiSdtTable *sdt, const char *signature)
>  {
> @@ -244,21 +245,32 @@ static void test_acpi_fadt_table(test_data *data)
>  
>  static void dump_aml_files(test_data *data, bool rebuild)
>  {
> -    AcpiSdtTable *sdt;
> +    AcpiSdtTable *sdt, *exp_sdt;
>      GError *error = NULL;
>      gchar *aml_file = NULL;
> +    test_data exp_data = {};
>      gint fd;
>      ssize_t ret;
>      int i;
>  
> +    exp_data.tables = load_expected_aml(data);
>      for (i = 0; i < data->tables->len; ++i) {
>          const char *ext = data->variant ? data->variant : "";
>          sdt = &g_array_index(data->tables, AcpiSdtTable, i);
> +        exp_sdt = &g_array_index(exp_data.tables, AcpiSdtTable, i);
>          g_assert(sdt->aml);
> +        g_assert(exp_sdt->aml);
>  
>          if (rebuild) {
>              aml_file = g_strdup_printf("%s/%s/%.4s%s", data_dir, data->machine,
>                                         sdt->aml, ext);
> +            if (!g_file_test(aml_file, G_FILE_TEST_EXISTS) &&
> +                sdt->aml_len == exp_sdt->aml_len &&
> +                !memcmp(sdt->aml, exp_sdt->aml, sdt->aml_len)) {
> +                /* identical tables, no need to write new files */
> +                g_free(aml_file);
> +                continue;
> +            }
>              fd = g_open(aml_file, O_WRONLY|O_TRUNC|O_CREAT,
>                          S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH);
>              if (fd < 0) {