refactor: sandbox stderr goes to host

runtime/src/libc/syscall.c

@@ -131,12 +131,14 @@ err:
 int32_t
 wasm_write(int32_t fd, int32_t buf_offset, int32_t buf_size)
 {
-	struct sandbox *s = current_sandbox_get();
+	struct sandbox *s      = current_sandbox_get();
+	char *          buffer = worker_thread_get_memory_ptr_void(buf_offset, buf_size);
 
-	if (fd == STDOUT_FILENO || fd == STDERR_FILENO) {
-		char *buffer           = worker_thread_get_memory_ptr_void(buf_offset, buf_size);
-		int   buffer_remaining = s->module->max_response_size - s->response.length;
-		int   to_write         = buffer_remaining > buf_size ? buf_size : buffer_remaining;
+	if (fd == STDERR_FILENO) { write(STDERR_FILENO, buffer, buf_size); }
+
+	if (fd == STDOUT_FILENO) {
+		int buffer_remaining = s->module->max_response_size - s->response.length;
+		int to_write         = buffer_remaining > buf_size ? buf_size : buffer_remaining;
 
 		if (to_write == 0) return 0;
 		memcpy(&s->response.base[s->response.length], buffer, to_write);
@@ -265,12 +267,7 @@ wasm_writev(int32_t fd, int32_t iov_offset, int32_t iovcnt)
 		int                len = 0;
 		struct wasm_iovec *iov = worker_thread_get_memory_ptr_void(iov_offset,
 		                                                           iovcnt * sizeof(struct wasm_iovec));
-		for (int i = 0; i < iovcnt; i++) {
-			char *b = worker_thread_get_memory_ptr_void(iov[i].base_offset, iov[i].len);
-			memcpy(&s->response.base[s->response.length], b, iov[i].len);
-			s->response.length += iov[i].len;
-			len += iov[i].len;
-		}
+		for (int i = 0; i < iovcnt; i++) { len += wasm_write(fd, iov[i].base_offset, iov[i].len); }
 
 		return len;
 	}