Improve WASI implementation

[turbolent]

Implement enough of the WASI spec to get e.g. clang.wasm running

Proc

• wasi_unstable.proc_exit

Environ

• wasi_unstable.environ_sizes_get
• wasi_unstable.environ_get

Args

• wasi_unstable.args_sizes_get
• wasi_unstable.args_get

Clock

• wasi_unstable.clock_time_get

Random

• wasi_unstable.random_get

Poll

• wasi_unstable.poll_oneoff

FD

• wasi_unstable.fd_write
• wasi_unstable.fd_close
• wasi_unstable.fd_seek
• wasi_unstable.fd_fdstat_get
• wasi_unstable.fd_filestat_get
• wasi_unstable.fd_pread
• wasi_unstable.fd_read
• wasi_unstable.fd_readdir
• wasi_unstable.fd_fdstat_set_flags
• wasi_unstable.fd_prestat_get
• wasi_unstable.fd_prestat_dir_name

Path

• wasi_unstable.path_open
• wasi_unstable.path_filestat_get
• wasi_unstable.path_rename
• wasi_unstable.path_unlink_file
• wasi_unstable.path_remove_directory
• wasi_unstable.path_create_directory
• wasi_unstable.path_readlink
• wasi_unstable.path_symlink

[trevor403]

This is great work, let me know if you'd like help with anything... I might have a fd_readdir impl from an old project.

[turbolent]

@trevor403 Great to hear, that would be much welcomed!

[turbolent]

clang.wasm can now compile a hello world C program into a WebAssembly object file. The remaining functions are apparently not needed, but should be still added eventually.