Do not use hard-coded apex name

libinput checks input_device.config_file.apex sysprop when loading input
config.

This removes hard-coded apex name (com.android.input.config).

Bug: 315080500
Test: adb shell dumpsys input
  # set "touch.orientationAware = 0" in Touchscreen_0.idc
  # build/install the input config apex
  # Observe the Input configuration
  # "Touch Input Mapper" shows "OrientationAware: false"
Change-Id: I4e0415f26397f4ec4d77ee1d1909da47a04b986a

Author: Jooyung Han

libs/input/InputDevice.cpp

@@ -20,12 +20,14 @@
 #include <unistd.h>
 #include <ctype.h>
 
+#include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <ftl/enum.h>
 #include <gui/constants.h>
 #include <input/InputDevice.h>
 #include <input/InputEventLabels.h>
 
+using android::base::GetProperty;
 using android::base::StringPrintf;
 
 namespace android {
@@ -96,21 +98,22 @@ std::string getInputDeviceConfigurationFilePathByName(
 
     // Treblized input device config files will be located /product/usr, /system_ext/usr,
     // /odm/usr or /vendor/usr.
-    // These files may also be in the com.android.input.config APEX.
-    const char* rootsForPartition[]{
-            "/product",
-            "/system_ext",
-            "/odm",
-            "/vendor",
-            "/apex/com.android.input.config/etc",
-            getenv("ANDROID_ROOT"),
+    std::vector<std::string> pathPrefixes{
+            "/product/usr/",
+            "/system_ext/usr/",
+            "/odm/usr/",
+            "/vendor/usr/",
     };
-    for (size_t i = 0; i < size(rootsForPartition); i++) {
-        if (rootsForPartition[i] == nullptr) {
-            continue;
-        }
-        path = rootsForPartition[i];
-        path += "/usr/";
+    // These files may also be in the APEX pointed by input_device.config_file.apex sysprop.
+    if (auto apex = GetProperty("input_device.config_file.apex", ""); !apex.empty()) {
+        pathPrefixes.push_back("/apex/" + apex + "/etc/usr/");
+    }
+    // ANDROID_ROOT may not be set on host
+    if (auto android_root = getenv("ANDROID_ROOT"); android_root != nullptr) {
+        pathPrefixes.push_back(std::string(android_root) + "/usr/");
+    }
+    for (const auto& prefix : pathPrefixes) {
+        path = prefix;
         appendInputDeviceConfigurationFileRelativePath(path, name, type);
 #if DEBUG_PROBE
         ALOGD("Probing for system provided input device configuration file: path='%s'",