From b78b0276e04b949a66cffbed9239184d73badf2a Mon Sep 17 00:00:00 2001
From: Joseph Hwang <josephsih@chromium.org>
Date: Tue, 13 Jan 2015 16:49:51 +0800
Subject: [PATCH] Add grab flag

This patch grabs the device when --grab command line option is
present. In this way, no other processes are able to access the
device.

BUG=chromium:443539
TEST=Check that the cursor is frozen when --grab option is specified.
$ evtest --grab
---
 evtest.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/evtest.c b/evtest.c
index 74230ea..6dbe9b5 100644
--- a/evtest.c
+++ b/evtest.c
@@ -55,6 +55,7 @@
 #include <errno.h>
 #include <getopt.h>
 #include <ctype.h>
+#include <signal.h>
 
 #define BITS_PER_LONG (sizeof(long) * 8)
 #define NBITS(x) ((((x)-1)/BITS_PER_LONG)+1)
@@ -93,6 +94,19 @@ static const struct query_mode {
 	{ "EV_SW",  EV_SW, SW_MAX, EVIOCGSW(SW_MAX) },
 };
 
+static int fd;
+static int grab_flag = 0;
+
+/**
+ * An interrupt handler to ungrab the device.
+ */
+static void ungrab(void)
+{
+	if (grab_flag)
+		ioctl(fd, EVIOCGRAB, (void*)0);
+	exit(EXIT_SUCCESS);
+}
+
 /**
  * Look up an entry in the query_modes table by its textual name.
  *
@@ -675,9 +689,12 @@ static int version(void)
 static int usage(void)
 {
 	printf("USAGE:\n");
-	printf(" Grab mode:\n");
+	printf(" Capture mode:\n");
 	printf("   %s /dev/input/eventX\n", program_invocation_short_name);
 	printf("\n");
+	printf(" Capture mode with the device grabbed:\n");
+	printf("   %s --grab /dev/input/eventX\n", program_invocation_short_name);
+	printf("\n");
 	printf(" Query mode: (check exit code)\n");
 	printf("   %s --query /dev/input/eventX <type> <value>\n",
 		program_invocation_short_name);
@@ -814,7 +831,7 @@ static int test_grab(int fd)
 
 	rc = ioctl(fd, EVIOCGRAB, (void*)1);
 
-	if (!rc)
+	if (!rc && !grab_flag)
 		ioctl(fd, EVIOCGRAB, (void*)0);
 
 	return rc;
@@ -829,7 +846,6 @@ static int test_grab(int fd)
  */
 static int do_capture(const char *device)
 {
-	int fd;
 	char *filename;
 
 	if (!device) {
@@ -954,6 +970,7 @@ static int do_query(const char *device, const char *event_type, const char *keyn
 }
 
 static const struct option long_options[] = {
+	{ "grab", no_argument, &grab_flag, 1 },
 	{ "query", no_argument, NULL, MODE_QUERY },
 	{ "version", no_argument, NULL, MODE_VERSION },
 	{ 0, },
@@ -966,12 +983,17 @@ int main (int argc, char **argv)
 	const char *event_type;
 	enum evtest_mode mode = MODE_CAPTURE;
 
+	signal(SIGINT, ungrab);
+	signal(SIGTERM, ungrab);
+
 	while (1) {
 		int option_index = 0;
 		int c = getopt_long(argc, argv, "", long_options, &option_index);
 		if (c == -1)
 			break;
 		switch (c) {
+		case 0:
+			break;
 		case MODE_QUERY:
 			mode = c;
 			break;
-- 
2.2.0.rc0.207.ga3a616c