Temp files are not removed in dylib engine

[xofyarg]

Describe the bug

dylib creates tempfile to be able to "dlopen" later, but those files are not removed later. This could be an issue for a long running program which constantly (re)loads wasm files, occupying lots of unnecessary disk spaces.

Steps to reproduce

Use dylib engine to load a wasm file, then check /tmp for temp files.

Expected behavior

Temp file is deleted when not being used.

Actual behavior

Temp file persists even program restarts.

Additional context

[Hywan]

Thanks for reporting the issue. I confirm the bug. I've written a fix in #2518.

[vavrusa]

I think this is still a problem, the #2518 fixes the object file cleanup, but

wasmer/lib/engine-dylib/src/artifact.rs

Line 513 in 5dadb3f

pub unsafe fn deserialize(

still leaks the temporary file for the dylib.

[syrusakbary]

Good catch @vavrusa!

[vavrusa]

There's a related issue here (and below)

wasmer/lib/engine-dylib/src/artifact.rs

Line 264 in 5dadb3f

file.write(&obj_bytes).map_err(to_compile_error)?;

(write instead of write_all), and here

wasmer/lib/engine-dylib/src/artifact.rs

Line 278 in 5dadb3f

.keep()

(named temp file leaked again). I think you don't have to leak it in any of these cases, the libloading will dlopen the file for r+x, so you can remove the file (and get rid of the r+w mapping from to the leaked tempfile handle, which is not safe anyway). The file will get removed from fs immediately, and the r+x will disappear after the library is closed with dlclose.