ibratbag-hidraw: add optional filter to hidraw read

Currently, these functions will read and timeout after 1s if
no packets were received. The issue with this is that a lot of times we
may catch unrelated packets, such as mouse or keyboard changes.
To solve this, this patch adds a new optional filter argument, when a filter
is passed the functions now will keep reading packets until a valid packet is found.
The filter argument is user written function that returns true or false.

Co-authored-by: Filipe Laíns <lains@riseup.net>
Signed-off-by: Rafael Silva <perigoso@riseup.net>

src/driver-openinput.c

@@ -159,6 +159,22 @@ openinput_get_report_size(unsigned int report)
 	}
 }
 
+static bool
+openinput_report_filter(uint8_t *buf, size_t len)
+{
+	if (len < 1)
+		return false;
+
+	switch(buf[0]) {
+	case OI_REPORT_SHORT:
+		return len == OI_REPORT_SHORT_SIZE;
+	case OI_REPORT_LONG:
+		return len == OI_REPORT_LONG_SIZE;
+	default:
+		return false;
+	}
+}
+
 static int
 openinput_send_report(struct ratbag_device *device, struct oi_report_t *report)
 {
@@ -175,7 +191,7 @@ openinput_send_report(struct ratbag_device *device, struct oi_report_t *report)
 		return ret;
 	}
 
-	ret = ratbag_hidraw_read_input_report(device, buffer, OI_REPORT_MAX_SIZE);
+	ret = ratbag_hidraw_read_input_report(device, buffer, OI_REPORT_MAX_SIZE, openinput_report_filter);
 	if (ret < 0) {
 		log_error(device->ratbag, "openinput: failed to read data from device (%s)\n",
 			  strerror(-ret));

src/driver-steelseries.c

@@ -234,7 +234,7 @@ steelseries_get_firmware_version(struct ratbag_device *device)
 	if (ret < 0)
 		return ret;
 
-	ret = ratbag_hidraw_read_input_report_index(device, buf, sizeof(buf), STEELSERIES_INPUT_HIDRAW);
+	ret = ratbag_hidraw_read_input_report_index(device, buf, sizeof(buf), STEELSERIES_INPUT_HIDRAW, NULL);
 	if (ret < 0)
 		return ret;
 
@@ -278,7 +278,7 @@ steelseries_read_settings(struct ratbag_device *device)
 	if (ret < 0)
 		return ret;
 
-	ret = ratbag_hidraw_read_input_report_index(device, buf, STEELSERIES_REPORT_SIZE, STEELSERIES_INPUT_HIDRAW);
+	ret = ratbag_hidraw_read_input_report_index(device, buf, STEELSERIES_REPORT_SIZE, STEELSERIES_INPUT_HIDRAW, NULL);
 	if (ret < 0)
 		return ret;
 

src/libratbag-hidraw.c

@@ -1642,16 +1642,19 @@ ratbag_hidraw_output_report(struct ratbag_device *device, uint8_t *buf, size_t l
 }
 
 int
-ratbag_hidraw_read_input_report(struct ratbag_device *device, uint8_t *buf, size_t len)
+ratbag_hidraw_read_input_report(struct ratbag_device *device, uint8_t *buf, size_t len,
+				 ratbagd_hidraw_filter_t filter)
 {
-	return ratbag_hidraw_read_input_report_index(device, buf, len, 0);
+	return ratbag_hidraw_read_input_report_index(device, buf, len, 0, filter);
 }
 
 int
-ratbag_hidraw_read_input_report_index(struct ratbag_device *device, uint8_t *buf, size_t len, int hidrawno)
+ratbag_hidraw_read_input_report_index(struct ratbag_device *device, uint8_t *buf, size_t len, int hidrawno,
+				 ratbagd_hidraw_filter_t filter)
 {
-	int rc;
+	int rc, nfds;
 	struct pollfd fds;
+	int ts, ts_end;
 
 	assert(hidrawno >= 0 && hidrawno < MAX_HIDRAW);
 
@@ -1661,17 +1664,32 @@ ratbag_hidraw_read_input_report_index(struct ratbag_device *device, uint8_t *buf
 	fds.fd = device->hidraw[hidrawno].fd;
 	fds.events = POLLIN;
 
-	rc = poll(&fds, 1, 1000);
-	if (rc == -1)
-		return -errno;
+	/* convert to ms */
+	ts = now(CLOCK_MONOTONIC_RAW) / 1000 / 1000;
+	ts_end = ts + 1000; /* end in now + 1000ms */
 
-	if (rc == 0)
-		return -ETIMEDOUT;
+	while (ts < ts_end) {
+		nfds = poll(&fds, 1, ts_end - ts); /* poll for the remainder of timeout */
 
-	rc = read(device->hidraw[hidrawno].fd, buf, len);
+		if (nfds < 0)
+			return -errno;
 
-	if (rc > 0)
-		log_buf_raw(device->ratbag, "input report:  ", buf, rc);
+		if (nfds > 0) {
+			rc = read(device->hidraw[hidrawno].fd, buf, len);
 
-	return rc >= 0 ? rc : -errno;
+			if (rc < 0)
+  				return -errno;
+
+			if (rc > 0) {
+				if(!filter || (filter && filter(buf, rc))) {
+					log_buf_raw(device->ratbag, "input report:  ", buf, rc);
+					return rc;
+				}
+			}
+		}
+
+		ts = now(CLOCK_MONOTONIC_RAW) / 1000 / 1000;
+	}
+
+	return -ETIMEDOUT;
 }

src/libratbag-hidraw.h

@@ -47,6 +47,8 @@ struct ratbag_hidraw {
 	char *sysname;
 };
 
+typedef bool (*ratbagd_hidraw_filter_t)(uint8_t *buf, size_t len);
+
 /**
  * Open the hidraw device associated with the device.
  *
@@ -162,27 +164,32 @@ int ratbag_hidraw_output_report(struct ratbag_device *device, uint8_t *buf, size
 
 /**
  * Read an input report from the device
+ * Optional filter function can be provided, when the filter returns false the packet is ignored
  *
  * @param device the ratbag device
  * @param[out] buf resulting raw data
  * @param len length of buf
+ * @param filter filter function
  *
  * @return count of data transfered, or a negative errno on error
  */
-int ratbag_hidraw_read_input_report(struct ratbag_device *device, uint8_t *buf, size_t len);
+int ratbag_hidraw_read_input_report(struct ratbag_device *device, uint8_t *buf, size_t len,
+				 ratbagd_hidraw_filter_t filter);
 
 /**
  * Read an input report from the device from a specific hidraw index
+ * Optional filter function can be provided, when the filter returns false the packet is ignored
  *
  * @param device the ratbag device
  * @param[out] buf resulting raw data
  * @param len length of buf
- * @param interal index of hidraw array
+ * @param hidrawno index of hidraw array
+ * @param filter filter function
  *
  * @return count of data transfered, or a negative errno on error
  */
-int ratbag_hidraw_read_input_report_index(struct ratbag_device *device, uint8_t *buf, size_t len, int hidrawno);
-
+int ratbag_hidraw_read_input_report_index(struct ratbag_device *device, uint8_t *buf, size_t len, int hidrawno,
+				 ratbagd_hidraw_filter_t filter);
 
 /**
  * Tells if a given device has the specified report ID.