From 18139e39c7e81ac8845462d05c42d883bd31923d Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Mon, 15 Aug 2022 22:05:34 +0100
Subject: [PATCH] add command-line arg for input device to read from

also an error message if /dev/uinput can't be opened
---
 adb-forward-touch.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/adb-forward-touch.c b/adb-forward-touch.c
index 5273f16..0c735e7 100644
--- a/adb-forward-touch.c
+++ b/adb-forward-touch.c
@@ -2,12 +2,10 @@
 #include <stdio.h>
 #include <fcntl.h>
 #include <string.h>
+#include <stdlib.h>
 #include <unistd.h>
 #include <stdbool.h>
 
-
-
-
 void set_axis(int fd, unsigned short code, int max)
 {
   struct uinput_abs_setup abs_setup;
@@ -18,14 +16,30 @@ void set_axis(int fd, unsigned short code, int max)
   ioctl(fd, UI_ABS_SETUP, &abs_setup);
 }
 
-int main(void)
+static char adb_prefix[] = "adb exec-out getevent ";
+
+int main(int argc, char *argv[])
 {
    struct uinput_setup usetup;
    int i = 50;
 
-   FILE *from_android = popen("adb exec-out getevent /dev/input/event2", "r");
+   if(argc < 2) {
+       system("adb shell getevent -p");
+       fprintf(stderr, "\nUsage: %s /dev/input/eventX\n\n  where /dev/input/eventX matches the touchscreen device of your phone\n" , argv[0]);
+       exit(1);
+   }
+   char * adb_command = malloc(strlen(argv[1]) + strlen(adb_prefix));
+   strcpy(adb_command, adb_prefix);
+   strcat(adb_command, argv[1]);
+
+   FILE *from_android = popen(adb_command, "r");
 
    int fd = open("/dev/uinput", O_WRONLY | O_NONBLOCK);
+   if(fd < 0) {
+       perror("Can't open /dev/uinput");
+       exit(1);
+   }
+
 
    ioctl(fd, UI_SET_EVBIT, EV_KEY);
    ioctl(fd, UI_SET_KEYBIT, BTN_TOUCH);