[events] Add return value to zjs_pre_emit to allow cancel

Now if you return true from a zjs_pre_emit callback, the event will
go forward, but if you return false it will be cancelled.

Also, fix all call sites.

Signed-off-by: Geoff Gustafson <geoff@linux.intel.com>

5 files changed, 46 insertions, 34 deletions

diff --git a/src/zjs_ble.c b/src/zjs_ble.c
index 644feb7..b138888 100644
--- a/src/zjs_ble.c
+++ b/src/zjs_ble.c
@@ -509,12 +509,13 @@ static void zjs_ble_blvl_ccc_cfg_changed(const struct bt_gatt_attr *attr,
 }
 
 // a zjs_pre_emit callback
-static void string_arg(void *unused, jerry_value_t argv[], u32_t *argc,
+static bool string_arg(void *unused, jerry_value_t argv[], u32_t *argc,
                        const char *buffer, u32_t bytes)
 {
     // requires: buffer contains string with bytes chars including null term
     argv[0] = jerry_create_string((jerry_char_t *)buffer);
     *argc = 1;
+    return true;
 }
 
 // INTERRUPT SAFE FUNCTION: No JerryScript VM, allocs, or release prints!
diff --git a/src/zjs_event.c b/src/zjs_event.c
index a35f99e..fb70bae 100644
--- a/src/zjs_event.c
+++ b/src/zjs_event.c
@@ -319,7 +319,11 @@ static void emit_event_callback(void *handle, const void *args) {
     jerry_value_t *argp = argv;
     u32_t argc = 0;
     if (emit->pre) {
-        emit->pre(user_handle, argv, &argc, emit->data, emit->length);
+        if (!emit->pre(user_handle, argv, &argc, emit->data, emit->length)) {
+            // event cancelled
+            DBG_PRINT("event cancelled\n");
+            return;
+        }
         if (argc > MAX_EVENT_ARGS) {
             ERR_PRINT("Must increase MAX_EVENT_ARGS!");
         }
@@ -340,16 +344,14 @@ static void emit_event_callback(void *handle, const void *args) {
 }
 
 // a zjs_pre_emit callback
-void zjs_copy_arg(void *unused, jerry_value_t argv[], u32_t *argc,
+bool zjs_copy_arg(void *unused, jerry_value_t argv[], u32_t *argc,
                   const char *buffer, u32_t bytes)
 {
     // requires: buffer contains one jerry_value_t
-    if (bytes != sizeof(jerry_value_t)) {
-        // shouldn't get here if used correctly
-        DBG_PRINT("Warning: Expected one jerry value");
-    }
+    ZJS_ASSERT(bytes == sizeof(jerry_value_t), "invalid data received");
     argv[0] = *(jerry_value_t *)buffer;
     *argc = 1;
+    return true;
 }
 
 // a zjs_post_emit callback
diff --git a/src/zjs_event.h b/src/zjs_event.h
index 3738ec6..2b2c401 100644
--- a/src/zjs_event.h
+++ b/src/zjs_event.h
@@ -18,24 +18,28 @@
 /**
  * Callback prototype for before an event is emitted
  *
- * The callback is responsible for setting up the arguments
- *
- * @param handle        Event user handle provided to zjs_make_emitter
- * @param argv          Arg array w/ max of four args to be set up
- * @param argc          Pointer to arg count to be set (default 0)
- * @param buffer        Data provided to zjs_defer_emit_event from which to
- *                        construct arguments
- * @param length        Length of buffer
+ * The callback is responsible for setting up the arguments; if it returns
+ * false, the event will not fire and the post callback will not be called, so
+ * it must clean up after itself.
+ *
+ * @param handle  Event user handle provided to zjs_make_emitter
+ * @param argv    Arg array w/ max of four args to be set up
+ * @param argc    Pointer to arg count to be set (default 0)
+ * @param buffer  Data provided to zjs_defer_emit_event from which to
+ *                  construct arguments
+ * @param length  Length of buffer
+ *
+ * @return        true to confirm event, false to cancel event
  */
-typedef void (*zjs_pre_emit)(void *handle, jerry_value_t argv[], u32_t *argc,
+typedef bool (*zjs_pre_emit)(void *handle, jerry_value_t argv[], u32_t *argc,
                              const char *buffer, u32_t length);
 
 /**
  * Callback prototype for after an event is emitted
  *
- * @param handle        Event user handle provided to zjs_make_emitter
- * @param argv          Arg array w/ max of four args to be cleaned up
- * @param argc          Arg count
+ * @param handle  Event user handle provided to zjs_make_emitter
+ * @param argv    Arg array w/ max of four args to be cleaned up
+ * @param argc    Arg count
  */
 typedef void (*zjs_post_emit)(void *handle, jerry_value_t argv[], u32_t argc);
 
@@ -176,7 +180,7 @@ bool zjs_emit_event_priv(jerry_value_t obj, const char *name,
  *
  * A zjs_pre_emit callback.
  */
-void zjs_copy_arg(void *unused, jerry_value_t argv[], u32_t *argc,
+bool zjs_copy_arg(void *unused, jerry_value_t argv[], u32_t *argc,
                   const char *buffer, u32_t bytes);
 
 /**
diff --git a/src/zjs_net.c b/src/zjs_net.c
index 31e43c8..2dd5753 100644
--- a/src/zjs_net.c
+++ b/src/zjs_net.c
@@ -381,7 +381,7 @@ static error_desc_t create_error_desc(u32_t error_id, jerry_value_t this,
 }
 
 // a zjs_pre_emit callback
-static void handle_error_arg(void *unused, jerry_value_t argv[], u32_t *argc,
+static bool handle_error_arg(void *unused, jerry_value_t argv[], u32_t *argc,
                              const char *buffer, u32_t bytes)
 {
     // requires: buffer contains a u32_t with an error constant
@@ -399,6 +399,7 @@ static void handle_error_arg(void *unused, jerry_value_t argv[], u32_t *argc,
     jerry_value_clear_error_flag(&error);
     argv[0] = error;
     *argc = 1;
+    return true;
 }
 
 typedef struct {
@@ -1152,7 +1153,7 @@ static ZJS_DECL_FUNC(net_create_server)
 }
 
 // a zjs_pre_emit_callback
-static void connect_callback(void *h, jerry_value_t argv[], u32_t *argc,
+static bool connect_callback(void *h, jerry_value_t argv[], u32_t *argc,
                              const char *buffer, u32_t bytes)
 {
     FTRACE("h = %p, buffer = %p, bytes = %d\n", h, buffer, bytes);
@@ -1160,6 +1161,7 @@ static void connect_callback(void *h, jerry_value_t argv[], u32_t *argc,
     zjs_obj_add_boolean(handle->socket, "connecting", false);
     zjs_add_event_listener(handle->socket, "connect",
                            handle->connect_listener);
+    return true;
 }
 
 static void tcp_connected(struct net_context *context, int status,
diff --git a/src/zjs_web_sockets.c b/src/zjs_web_sockets.c
index 4abed3e..77239c2 100644
--- a/src/zjs_web_sockets.c
+++ b/src/zjs_web_sockets.c
@@ -157,7 +157,7 @@ static error_desc_t create_error_desc(u32_t error_id, jerry_value_t this,
 }
 
 // a zjs_pre_emit callback
-static void handle_error_arg(void *unused, jerry_value_t argv[], u32_t *argc,
+static bool handle_error_arg(void *unused, jerry_value_t argv[], u32_t *argc,
                              const char *buffer, u32_t bytes)
 {
     // requires: buffer contains a u32_t with an error constant
@@ -165,10 +165,7 @@ static void handle_error_arg(void *unused, jerry_value_t argv[], u32_t *argc,
     //             the error flag, and sets this as the first arg; the error
     //             value must be released later (e.g. zjs_release_args)
     FTRACE("buffer = %p, bytes = %d\n", buffer, bytes);
-    if (bytes != sizeof(error_desc_t)) {
-        DBG_PRINT("invalid data in handle_error_arg");
-        return;
-    }
+    ZJS_ASSERT(bytes == sizeof(error_desc_t), "invalid data received");
 
     error_desc_t *desc = (error_desc_t *)buffer;
     const char *message = error_messages[desc->error_id];
@@ -178,6 +175,7 @@ static void handle_error_arg(void *unused, jerry_value_t argv[], u32_t *argc,
     jerry_value_clear_error_flag(&error);
     argv[0] = error;
     *argc = 1;
+    return true;
 }
 
 static void emit_error(jerry_value_t obj, const char *format, ...)
@@ -451,13 +449,14 @@ static void consume_data(ws_connection_t *con, u16_t len)
 }
 
 // a zjs_pre_emit_callback
-static void trigger_data(void *h, jerry_value_t argv[], u32_t *argc,
+static bool trigger_data(void *h, jerry_value_t argv[], u32_t *argc,
                          const char *buffer, u32_t bytes)
 {
     // requires: buffer contains 2-byte length
     FTRACE("h = %p, buffer = %p, bytes = %d\n", h, buffer, bytes);
-    ws_connection_t *con = (ws_connection_t *)h;
+    ZJS_ASSERT(bytes == sizeof(u16_t), "invalid data received");
 
+    ws_connection_t *con = (ws_connection_t *)h;
     u16_t len = *(u16_t *)buffer;
     zjs_buffer_t *buf;
     jerry_value_t buf_obj = zjs_buffer_create(len, &buf);
@@ -466,21 +465,25 @@ static void trigger_data(void *h, jerry_value_t argv[], u32_t *argc,
         consume_data(con, len);
         argv[0] = buf_obj;
         *argc = 1;
+        return true;
     }
+    return false;
 }
 
 // a zjs_pre_emit callback
-static void pre_close_connection(void *handle, jerry_value_t argv[],
+static bool pre_close_connection(void *handle, jerry_value_t argv[],
                                  u32_t *argc, const char *buffer, u32_t length)
 {
     FTRACE("handle = %p, buffer = %p, length = %d\n", handle, buffer, length);
+    ZJS_ASSERT(bytes == sizeof(u16_t), "invalid data received");
 
-    jerry_value_t code = jerry_create_number(*((uint16_t *)buffer));
+    jerry_value_t code = jerry_create_number(*((u16_t *)buffer));
     jerry_value_t reason = jerry_create_string("socket closed");
 
     argv[0] = code;
     argv[1] = reason;
     *argc = 2;
+    return true;
 }
 
 // a zjs_post_emit callback
@@ -563,7 +566,7 @@ static void process_packet(ws_connection_t *con, u8_t *data, u32_t len)
         break;
     case WS_PACKET_CLOSE:
         zjs_defer_emit_event(con->conn, "close", packet->payload,
-                             sizeof(uint16_t), pre_close_connection,
+                             sizeof(packet->payload), pre_close_connection,
                              close_connection);
         break;
     default:
@@ -832,8 +835,8 @@ static void tcp_received(struct net_context *context,
         net_pkt_unref(pkt);
         if (con && con->state == CONNECTED) {
             // close the socket
-            uint16_t stat = (uint16_t)status;
-            zjs_defer_emit_event(con->conn, "close", &stat, sizeof(uint16_t),
+            u16_t stat = (u16_t)status;
+            zjs_defer_emit_event(con->conn, "close", &stat, sizeof(stat),
                                  pre_close_connection, close_connection);
             return;
         } else {