tests: internal: log_event_encoder: Add test code

[nokute78]

This is a refactor PR for #7584

This patch is to add test code for log_event_encoder.

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[nokute78]

Windows CI on x86_64 failed...

[nokute78]

I tested following minimum test code.
It will work on windows x64 using /Od that means no compilation optimization.
On the other hand, it will not work on windows x64 using /O2.

#include <stdio.h>
#include <stdarg.h>
#include <string.h>

void Test(int loop_cnt, ...)
{
    va_list arg;
    int type1;
    int type2;
    char* str;
    size_t len1;
    size_t len2;
    int i;
    va_start(arg, loop_cnt);

    for (i = 0; i < loop_cnt; i++) {
        printf("i=%d\n", i);

        type1 = va_arg(arg, int);
        if (type1 != 1) {
            printf("%d:type is not 1\n", i);
        }

        len1 = va_arg(arg, size_t);
        if (len1 > 20) {
            printf("%d: len error. len=%zu\n", i, len1);
        }

        type2 = va_arg(arg, int);
        if (type2 != 2) {
            printf("%d:type is not 2\n", i);
        }

        str = va_arg(arg, char*);
        len2 = va_arg(arg, size_t);
        if (len2 != strlen(str)) {
            printf("%d: len error2. len=%zu\n", i, len2);
        }

        if (len1 != len2) {
            printf("%d: len error3. len1=%zu len2=%zu\n", i, len1, len2);
        }
    }
    va_end(arg);
}

int main(void) {
    int cnt = 2;

    Test(cnt,
        (int)1, (size_t)strlen("key1"), (int)2, (char*)"key1", (size_t)strlen("key1"),
        (int)1, (size_t)strlen("value2"), (int)2, (char*)"value2", (size_t)strlen("value2"));
    return 0;
}

[nokute78]

I checked assembly code and it passed strlen("value2") using mov dword ptr [rsp+50h],6.
dword means 4bytes. I think it should be qword since size_t is unsigned __int64 on Windows x86_64.
https://learn.microsoft.com/en-us/cpp/c-runtime-library/standard-types?view=msvc-170

[nokute78]

@edsiper @leonardo-albertovich Wow CI on Windows x64 passed!

I defined uint32_t type as an alternate size_t on Windows x64 for workaround.
Since fluent-bit that is compiled using /O2 passes dword as size_t and it causes a bug.

I also tried to define uint64_t , but it didn't work correctly.

[nokute78]

ping

[leonardo-albertovich]

Hi @nokute78, I have this on my queue, I'll independently verify the claims in your PR using your test case in master because I'm not quite convinced about it.

I'll get back to you as soon as I'm able to.

[nokute78]

@leonardo-albertovich Thank you.

The point is following code will cause runtime error using MSVC + /O2 option.
#7736 (comment)
It is the reason failing CI on Windows x64.

The code is to imitate a following macro FLB_LOG_EVENT_CSTRING_VALUE.

    ret = flb_log_event_encoder_append_body_values(
                &encoder,
                FLB_LOG_EVENT_CSTRING_VALUE("key1"),
                FLB_LOG_EVENT_CSTRING_VALUE("value2"),

MSVC outputs an assembly mov dword ptr [rsp+50h],6 for strlen("value2").
dword is 4bytes , but size_t should be 8bytes on Windows x64.

[leonardo-albertovich]

I have opened PR #7971 to fix this issue, once it's merged you can rebase and revert the rest of the changes so this PR only adds the test case.

I have verified the PR with your test case and it works as expected.

The issue is not that msvc defines size_t as a DWORD, that goes against the standard, the issue is that it's not respecting the cast and promotion rules which probably stems from the level of indirection and variadic function.

[leonardo-albertovich]

You can revert the rest of the modifications and rebase from master now leaving only the new test case.

[nokute78]

I created a new PR #7992