Add basic support for wasi in package os

core/os/os_wasi.odin

@@ -0,0 +1,96 @@
+package os
+
+import "core:sys/wasm/wasi"
+
+Handle :: distinct i32
+Errno :: distinct i32
+
+ERROR_NONE :: Errno(wasi.errno_t.SUCCESS)
+
+O_RDONLY   :: 0x00000
+O_WRONLY   :: 0x00001
+O_RDWR     :: 0x00002
+O_CREATE   :: 0x00040
+O_EXCL     :: 0x00080
+O_NOCTTY   :: 0x00100
+O_TRUNC    :: 0x00200
+O_NONBLOCK :: 0x00800
+O_APPEND   :: 0x00400
+O_SYNC     :: 0x01000
+O_ASYNC    :: 0x02000
+O_CLOEXEC  :: 0x80000
+
+stdin:  Handle = 0
+stdout: Handle = 1
+stderr: Handle = 2
+
+
+write :: proc(fd: Handle, data: []byte) -> (int, Errno) {
+	iovs := wasi.ciovec_t(data)
+	n, err := wasi.fd_write(wasi.fd_t(fd), &iovs, 1)
+	return int(n), Errno(err)
+}
+read :: proc(fd: Handle, data: []byte) -> (int, Errno) {
+	iovs := wasi.iovec_t(data)
+	n, err := wasi.fd_read(wasi.fd_t(fd), &iovs, 1)
+	return int(n), Errno(err)
+}
+write_at :: proc(fd: Handle, data: []byte, offset: i64) -> (int, Errno) {
+	iovs := wasi.ciovec_t(data)
+	n, err := wasi.fd_pwrite(wasi.fd_t(fd), &iovs, 1, wasi.filesize_t(offset))
+	return int(n), Errno(err)
+}
+read_at :: proc(fd: Handle, data: []byte, offset: i64) -> (int, Errno) {
+	iovs := wasi.iovec_t(data)
+	n, err := wasi.fd_pread(wasi.fd_t(fd), &iovs, 1, wasi.filesize_t(offset))
+	return int(n), Errno(err)
+}
+open :: proc(path: string, mode: int = O_RDONLY, perm: int = 0) -> (Handle, Errno) {
+	return 0, 0
+}
+close :: proc(fd: Handle) -> Errno {
+	return 0
+}
+seek :: proc(fd: Handle, offset: i64, whence: int) -> (i64, Errno) {
+	n, err := wasi.fd_seek(wasi.fd_t(fd), wasi.filedelta_t(offset), wasi.whence_t(whence))
+	return i64(n), Errno(err)
+}
+current_thread_id :: proc "contextless" () -> int {
+	return 0
+}
+
+
+file_size :: proc(fd: Handle) -> (i64, Errno) {
+	stat, err := wasi.fd_filestat_get(wasi.fd_t(fd))
+	if err != nil {
+		return 0, Errno(err)
+	}
+	return i64(stat.size), 0
+}
+
+
+
+heap_alloc :: proc(size: int) -> rawptr {
+	return nil
+}
+heap_resize :: proc(ptr: rawptr, new_size: int) -> rawptr {
+	if new_size == 0 {
+		heap_free(ptr)
+		return nil
+	}
+	if ptr == nil {
+		return heap_alloc(new_size)
+	}
+
+	return nil
+}
+heap_free :: proc(ptr: rawptr) {
+	if ptr == nil {
+		return
+	}
+}
+
+
+exit :: proc "contextless" (code: int) -> ! {
+	wasi.proc_exit(wasi.exitcode_t(code))
+}