fix user code read NULL content bug

runtime/include/sandbox_types.h

@@ -68,6 +68,8 @@ struct sandbox {
 	                                 deadline (cycles) */
 	uint64_t total_time;          /* Total time from Request to Response */
 
+	int cursor;
+
 	/* System Interface State */
 	int32_t         return_value;
 	wasi_context_t *wasi_context;

runtime/src/libc/wasi_impl_serverless.c

@@ -660,7 +660,7 @@ wasi_snapshot_preview1_backing_fd_read(wasi_context_t *context, __wasi_fd_t fd,
 	if (fd == STDIN_FILENO) {
 		struct sandbox      *current_sandbox = current_sandbox_get();
 		struct http_request *current_request = &current_sandbox->http->http_request;
-		int                  old_read        = current_request->cursor;
+		int                  old_read        = current_sandbox->cursor;
 		int                  bytes_to_read   = current_request->body_length - old_read;
 
 		assert(current_request->body_length >= 0);
@@ -669,13 +669,13 @@ wasi_snapshot_preview1_backing_fd_read(wasi_context_t *context, __wasi_fd_t fd,
 			if (bytes_to_read == 0) goto done;
 
 			int amount_to_copy = iovs[i].buf_len > bytes_to_read ? bytes_to_read : iovs[i].buf_len;
-			memcpy(iovs[i].buf, current_request->body + current_request->cursor, amount_to_copy);
-			current_request->cursor += amount_to_copy;
-			bytes_to_read = current_request->body_length - current_request->cursor;
+			memcpy(iovs[i].buf, current_request->body + current_sandbox->cursor, amount_to_copy);
+			current_sandbox->cursor += amount_to_copy;
+			bytes_to_read = current_request->body_length - current_sandbox->cursor;
 		}
 
 	done:
-		*nwritten_retptr = current_request->cursor - old_read;
+		*nwritten_retptr = current_sandbox->cursor - old_read;
 		return __WASI_ERRNO_SUCCESS;
 	}
 

runtime/src/sandbox.c

@@ -29,6 +29,7 @@ int
 init_response_body(struct sandbox *sandbox)
 {
         if (sandbox->response_body.data == NULL) {
+		sandbox->response_body.size = 0;
                 int rc = auto_buf_init(&sandbox->response_body);
                 if (rc < 0) {
                         printf("failed to init http body autobuf, exit\n");