os/os2: wasi target support

core/os/os2/errors_wasi.odin

@@ -0,0 +1,47 @@
+#+private
+package os2
+
+import "base:runtime"
+
+import "core:slice"
+import "core:sys/wasm/wasi"
+
+_Platform_Error :: wasi.errno_t
+
+_error_string :: proc(errno: i32) -> string {
+	e := wasi.errno_t(errno)
+	if e == .NONE {
+		return ""
+	}
+
+	err := runtime.Type_Info_Enum_Value(e)
+
+	ti := &runtime.type_info_base(type_info_of(wasi.errno_t)).variant.(runtime.Type_Info_Enum)
+	if idx, ok := slice.binary_search(ti.values, err); ok {
+		return ti.names[idx]
+	}
+	return "<unknown platform error>"
+}
+
+_get_platform_error :: proc(errno: wasi.errno_t) -> Error {
+	#partial switch errno {
+	case .PERM:
+		return .Permission_Denied
+	case .EXIST:
+		return .Exist
+	case .NOENT:
+		return .Not_Exist
+	case .TIMEDOUT:
+		return .Timeout
+	case .PIPE:
+		return .Broken_Pipe
+	case .BADF:
+		return .Invalid_File
+	case .NOMEM:
+		return .Out_Of_Memory
+	case .NOSYS:
+		return .Unsupported
+	case:
+		return Platform_Error(errno)
+	}
+}