PGlite bindings for other runtimes?

[samkhawase]

I'm trying to run and access PGLite through a golang program via wasmer-go. However it fails with the error regardgin env not instantiated. I assume that there is no support for other runtimes (#40)

Is there a way I could contribute to adding support for more runtimes?

$ wazero run postgres.wasm                                                                                                                                                                                         
error instantiating wasm binary: module[env] not instantiated

$ wasmtime postgres.wasm                                                                                                                                                                                           
Error: failed to run main module `postgres.wasm`

Caused by:
    0: failed to instantiate "postgres.wasm"
    1: unknown import: `env::invoke_ii` has not been defined

[e253]

A .wasm file will declare a bunch of functions it needs to execute properly. WASI and WASIX are standard sets of such functions. A pure WASI/WASIX web assembly program can be run in a WASI/WASIX runtime like wasmer without changes. At the moment, PGlite ships a wasm binary with a JS file that provides many custom Emscripten non-standard functions that wasmer doesn't have.

// postgres.js (generated)
var wasmImports = {
//...
      emscripten_date_now: _emscripten_date_now,
      emscripten_dispatch_result: emscripten_dispatch_result,
      emscripten_get_heap_max: _emscripten_get_heap_max,
      emscripten_get_now: _emscripten_get_now,
      emscripten_get_now_res: _emscripten_get_now_res,
      emscripten_memcpy_js: _emscripten_memcpy_js,
      emscripten_resize_heap: _emscripten_resize_heap,
      environ_get: _environ_get,
      environ_sizes_get: _environ_sizes_get,
      exit: _exit,
      fd_close: _fd_close,
      fd_fdstat_get: _fd_fdstat_get,
      fd_pread: _fd_pread,
      fd_pwrite: _fd_pwrite,
      fd_read: _fd_read,
      fd_seek: _fd_seek,
      fd_sync: _fd_sync,
      fd_write: _fd_write,
// ...
}

A WASIX (note the x, not WASI) build of pglite shouldn't be too tough because it has a very broad API. You link the wasix libc and that libc will compile imports in the .wasm binary that wasmer understands. You could even compile totally vanilla postgres to wasm32-wasix-none. I'd love to use a wasix pg instead of bloated, ram hungry docker pg! https://wasix.org/docs/language-guide/c/usage.

WASI should be possible through Emscripten by using the -sWASM_STANDALONE=1 linker flag. It can work, but will take some finagling to pass tests.