Read all events and verify dev node after adding watcher fd (#85)

* Currently, the dev node is checked before adding the watcher FD. If
the dev node is created between this check and the addition of the
watcher FD, it will be missed by the poll. Therefore, check the dev
node’s existence after adding the watcher FD. Additionally, read all
events once the poll completes to ensure no events are missed.

* define the local pointer variable properly.

---------

Signed-off-by: Abhishek <quic_abhishes@quicinc.com>

src/adsp_default_listener.c

@@ -141,13 +141,18 @@ static int fastrpc_wait_for_secure_device(int domain)
 		VERIFY_EPRINTF("Error: inotify_add_watch failed, invalid fd errno = %s\n", strerror(errno));
 		return AEE_EINVALIDFD;
 	}
+
+	if (fastrpc_dev_exists(dev_name))
+		goto bail;
+
 	memset(pfd, 0 , sizeof(pfd));
 	pfd[0].fd = inotify_fd;
 	pfd[0].events = POLLIN;
 
 	while (1) {
 		int ret = 0;
 		char buffer[EVENT_BUF_LEN];
+		struct inotify_event *event;
 
 		ret = poll(pfd, 1, POLL_TIMEOUT);
 		if(ret < 0){
@@ -160,21 +165,27 @@ static int fastrpc_wait_for_secure_device(int domain)
 			err = AEE_EPOLL;
 			break;
 		}
+		/* read on inotify fd never reads partial events. */
 		ssize_t len = read(inotify_fd, buffer, sizeof(buffer));
 		if (len < 0) {
 			VERIFY_EPRINTF("Error: %s: read failed, errno = %s\n", __func__, strerror(errno));
 			err = AEE_EEVENTREAD;
 			break;
 		}
-		// Check if the event corresponds to the creation of the device node.
-		struct inotify_event* event = (struct inotify_event*)buffer;
-		if (event->wd == watch_fd && (event->mask & IN_CREATE) &&
-			(std_strcmp(dev_name, event->name) == 0)) {
-			// Device node created, process proceed to open and use it.
-			VERIFY_IPRINTF("Device node created!\n");
-			break; // Exit the loop after device creation is detected.
+		 /* Loop over all events in the buffer. */
+		for (char *ptr = buffer; ptr < buffer + len;
+					ptr += sizeof(struct inotify_event) + event->len) {
+			event = (struct inotify_event *) ptr;
+			/* Check if the event corresponds to the creation of the device node. */
+			if (event->wd == watch_fd && (event->mask & IN_CREATE) &&
+				(std_strcmp(dev_name, event->name) == 0)) {
+				/* Device node created, process proceed to open and use it. */
+				VERIFY_IPRINTF("Device node %s created!\n", event->name);
+				goto bail; /* Exit the loop after device creation is detected. */
+			}
 		}
 	}
+bail:
 	inotify_rm_watch(inotify_fd, watch_fd);
 	close(inotify_fd);