path: root/pkg/libevdev/patch/0001-Revert-switch-to-VLAs-for-multitouch-state.patch

From b3fba1efb0475b6e64e4109738bde1e83d87147a Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Tue, 3 Mar 2020 14:17:37 -0800
Subject: [PATCH libevdev] Revert switch to VLAs for multitouch state

Signed-off-by: Michael Forney <mforney@mforney.org>
---
 libevdev/libevdev-int.h | 28 ++++++++++++++
 libevdev/libevdev.c     | 84 ++++++++++++++++++++---------------------
 2 files changed, 68 insertions(+), 44 deletions(-)

diff --git a/libevdev/libevdev-int.h b/libevdev/libevdev-int.h
index 7da5cf0..2743e50 100644
--- a/libevdev/libevdev-int.h
+++ b/libevdev/libevdev-int.h
@@ -24,6 +24,7 @@
 #define LIBEVDEV_INT_H
 
 #include "config.h"
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdbool.h>
@@ -55,6 +56,26 @@ enum SyncState {
 	SYNC_IN_PROGRESS,
 };
 
+struct mt_sync_state {
+	uint32_t code;
+	int32_t val[];
+};
+
+/* Keeps a record of touches during SYN_DROPPED  */
+enum touch_state {
+	TOUCH_OFF,
+	TOUCH_STARTED, /* Started during SYN_DROPPED */
+	TOUCH_STOPPED, /* Stopped during SYN_DROPPED */
+	TOUCH_ONGOING, /* Existed before, still have same tracking ID */
+	TOUCH_CHANGED, /* Existed before but have new tracking ID now, so
+			  stopped + started in that slot */
+};
+
+struct slot_change_state {
+	enum touch_state state;
+	unsigned long axes[NLONGS(ABS_CNT)]; /* bitmask for updated axes */
+};
+
 /**
  * Internal only: log data used to send messages to the respective log
  * handler. We re-use the same struct for a global and inside
@@ -107,6 +128,13 @@ struct libevdev {
 
 	struct timeval last_event_time;
 
+	struct {
+		struct mt_sync_state *mt_state;
+		size_t mt_state_sz;		 /* in bytes */
+		struct slot_change_state *changes;
+		size_t changes_sz;		 /* in bytes */
+	} mt_sync;
+
 	struct logdata log;
 };
 
diff --git a/libevdev/libevdev.c b/libevdev/libevdev.c
index f034637..77cf678 100644
--- a/libevdev/libevdev.c
+++ b/libevdev/libevdev.c
@@ -28,7 +28,6 @@
 #include <limits.h>
 #include <unistd.h>
 #include <stdarg.h>
-#include <stdint.h>
 #include <stdbool.h>
 
 #include "libevdev.h"
@@ -44,23 +43,7 @@ enum event_filter_status {
 	EVENT_FILTER_DISCARD,	/**< Discard current event */
 };
 
-/* Keeps a record of touches during SYN_DROPPED  */
-enum touch_state {
-	TOUCH_OFF,
-	TOUCH_STARTED, /* Started during SYN_DROPPED */
-	TOUCH_STOPPED, /* Stopped during SYN_DROPPED */
-	TOUCH_ONGOING, /* Existed before, still have same tracking ID */
-	TOUCH_CHANGED, /* Existed before but have new tracking ID now, so
-			  stopped + started in that slot */
-};
-
-struct slot_change_state {
-	enum touch_state state;
-	unsigned long axes[NLONGS(ABS_CNT)]; /* bitmask for updated axes */
-};
-
-static int sync_mt_state(struct libevdev *dev,
-			 struct slot_change_state *changes_out);
+static int sync_mt_state(struct libevdev *dev);
 static int
 update_key_state(struct libevdev *dev, const struct input_event *e);
 
@@ -218,6 +201,8 @@ libevdev_reset(struct libevdev *dev)
 	free(dev->phys);
 	free(dev->uniq);
 	free(dev->mt_slot_vals);
+	free(dev->mt_sync.mt_state);
+	free(dev->mt_sync.changes);
 	memset(dev, 0, sizeof(*dev));
 	dev->fd = -1;
 	dev->initialized = false;
@@ -347,7 +332,11 @@ free_slots(struct libevdev *dev)
 {
 	dev->num_slots = -1;
 	free(dev->mt_slot_vals);
+	free(dev->mt_sync.changes);
+	free(dev->mt_sync.mt_state);
 	dev->mt_slot_vals = NULL;
+	dev->mt_sync.changes = NULL;
+	dev->mt_sync.mt_state = NULL;
 }
 
 static int
@@ -357,7 +346,11 @@ init_slots(struct libevdev *dev)
 	int rc = 0;
 
 	free(dev->mt_slot_vals);
+	free(dev->mt_sync.changes);
+	free(dev->mt_sync.mt_state);
 	dev->mt_slot_vals = NULL;
+	dev->mt_sync.changes = NULL;
+	dev->mt_sync.mt_state = NULL;
 
 	/* devices with ABS_RESERVED aren't MT devices,
 	   see the documentation for multitouch-related
@@ -381,6 +374,19 @@ init_slots(struct libevdev *dev)
 	}
 	dev->current_slot = abs_info->value;
 
+	dev->mt_sync.mt_state_sz = sizeof(*dev->mt_sync.mt_state) +
+				   dev->num_slots * sizeof(int32_t);
+	dev->mt_sync.mt_state = calloc(1, dev->mt_sync.mt_state_sz);
+
+	dev->mt_sync.changes_sz = dev->num_slots *
+				  sizeof(dev->mt_sync.changes[0]);
+	dev->mt_sync.changes = malloc(dev->mt_sync.changes_sz);
+
+	if (!dev->mt_sync.changes || !dev->mt_sync.mt_state) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
 	reset_tracking_ids(dev);
 out:
 	return rc;
@@ -536,10 +542,8 @@ libevdev_set_fd(struct libevdev* dev, int fd)
 	if (rc != 0)
 		goto out;
 
-	if (dev->num_slots != -1) {
-		struct slot_change_state unused[dev->num_slots];
-		sync_mt_state(dev, unused);
-	}
+	if (dev->num_slots != -1)
+		sync_mt_state(dev);
 
 	rc = init_event_queue(dev);
 	if (rc < 0) {
@@ -674,32 +678,27 @@ out:
 }
 
 static int
-sync_mt_state(struct libevdev *dev,
-	      struct slot_change_state changes_out[dev->num_slots])
+sync_mt_state(struct libevdev *dev)
 {
-#define MAX_SLOTS 256
 	int rc = 0;
-	struct slot_change_state changes[MAX_SLOTS] = {0};
+	struct mt_sync_state *mt_state = dev->mt_sync.mt_state;
+	struct slot_change_state *changes = dev->mt_sync.changes;
 
-	for (int axis = ABS_MT_MIN; axis <= ABS_MT_MAX; axis++) {
-		/* EVIOCGMTSLOTS required format */
-		struct mt_sync_state {
-			uint32_t code;
-			int32_t val[MAX_SLOTS];
-		} mt_state;
+	memset(dev->mt_sync.changes, 0, dev->mt_sync.changes_sz);
 
+	for (int axis = ABS_MT_MIN; axis <= ABS_MT_MAX; axis++) {
 		if (axis == ABS_MT_SLOT ||
 		    !libevdev_has_event_code(dev, EV_ABS, axis))
 			continue;
 
-		mt_state.code = axis;
-		rc = ioctl(dev->fd, EVIOCGMTSLOTS(sizeof(mt_state)), &mt_state);
+		mt_state->code = axis;
+		rc = ioctl(dev->fd, EVIOCGMTSLOTS(dev->mt_sync.mt_state_sz), mt_state);
 		if (rc < 0)
 			goto out;
 
-		for (int slot = 0; slot < min(MAX_SLOTS, dev->num_slots); slot++) {
+		for (int slot = 0; slot < dev->num_slots; slot++) {
 			int val_before = *slot_value(dev, slot, axis),
-			    val_after = mt_state.val[slot];
+			    val_after = mt_state->val[slot];
 
 			if (axis == ABS_MT_TRACKING_ID) {
 				if (val_before == -1 && val_after != -1) {
@@ -728,14 +727,12 @@ sync_mt_state(struct libevdev *dev,
 		}
 	}
 
-	memcpy(changes_out, changes, sizeof(*changes) * dev->num_slots);
 out:
 	return rc;
 }
 
 static void
 terminate_slots(struct libevdev *dev,
-		const struct slot_change_state changes[dev->num_slots],
 		int *last_reported_slot)
 {
 	const unsigned int map[] = {BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
@@ -743,6 +740,7 @@ terminate_slots(struct libevdev *dev,
 				    BTN_TOOL_QUINTTAP};
 	bool touches_stopped = false;
 	int ntouches_before = 0, ntouches_after = 0;
+	struct slot_change_state *changes = dev->mt_sync.changes;
 
 	/* For BTN_TOOL_* emulation, we need to know how many touches we had
 	 * before and how many we have left once we terminate all the ones
@@ -806,10 +804,10 @@ terminate_slots(struct libevdev *dev,
 
 static int
 push_mt_sync_events(struct libevdev *dev,
-		    const struct slot_change_state changes[dev->num_slots],
 		    int last_reported_slot)
 {
 	struct input_absinfo abs_info;
+	struct slot_change_state *changes = dev->mt_sync.changes;
 	int rc;
 
 	for (int slot = 0; slot < dev->num_slots;  slot++) {
@@ -916,8 +914,6 @@ sync_state(struct libevdev *dev)
 	int rc = 0;
 	bool want_mt_sync = false;
 	int last_reported_slot = 0;
-	struct slot_change_state changes[dev->num_slots > 0 ? dev->num_slots : 1];
-		memset(changes, 0, sizeof(changes));
 
 	 /* see section "Discarding events before synchronizing" in
 	  * libevdev/libevdev.h */
@@ -935,9 +931,9 @@ sync_state(struct libevdev *dev)
 	if (dev->num_slots > -1 &&
 	    libevdev_has_event_code(dev, EV_ABS, ABS_MT_SLOT)) {
 		want_mt_sync = true;
-		rc = sync_mt_state(dev, changes);
+		rc = sync_mt_state(dev);
 		if (rc == 0)
-			terminate_slots(dev, changes, &last_reported_slot);
+			terminate_slots(dev, &last_reported_slot);
 		else
 			want_mt_sync = false;
 	}
@@ -951,7 +947,7 @@ sync_state(struct libevdev *dev)
 	if (rc == 0 && libevdev_has_event_type(dev, EV_ABS))
 		rc = sync_abs_state(dev);
 	if (rc == 0 && want_mt_sync)
-		push_mt_sync_events(dev, changes, last_reported_slot);
+		push_mt_sync_events(dev, last_reported_slot);
 
 	dev->queue_nsync = queue_num_elements(dev);
 
-- 
2.25.1