`strstr` function does not perform well

[HNYuuu]

Describe the bug In Wasm-samples/c_samples.nosync/source/test_c_library.c, we add a strstr function to illustrate the ability of our engine.

However, after several tests, we find that: once the needle is longer than 4 bytes, the strstr would invoke twoway_strstr, and the return value of strstr is always 0.

We find the source code of twoway_strstr, and put it in Wasm-samples/c_samples.nosync/source/twoway_strstr.c, whose result is equivalent to the real execution.

Thus, we guess the reason behind that is:

• something error happened on the way from strstr to twoway_strstr
• the twoway_strstr embedded in strstr is not equivalent to ours

To Reproduce Directly execute these two samples to see the different:

The twoway_strstr we found:

python3 eunomia_entry -f /Users/ningyuhe/Downloads/test.wasm -s --onlyfunc __original_main --concrete_globals

The problematic strstr:

python3 eunomia_entry -f ./Wasm-samples/c_samples.nosync/wasi/test_c_library.wasm -s --onlyfunc __original_main --concrete_globals

Expected behavior The haystack is TutorialPoint and the needle is Point. Thus, the output should be Point.

[HNYuuu]

I doubted that it may be the compiler's problem. However, the wasmtime can output the correct string.

Thus, we can conclude it is due to some inherent problems in our framework.

[HNYuuu]

Weird output, but I have no time to step in this issue. Leave for other developers.