Improve desktop touch input and process warnings

app/src/main/java/org/randomcoder/udroid/runtime/CapabilityProbe.kt

@@ -4,10 +4,16 @@ import android.content.Context
 import android.hardware.HardwareBuffer
 import android.os.Build
 import android.os.storage.StorageManager
+import android.provider.Settings
 import android.system.Os
 import android.system.OsConstants
 import java.io.File
 
+internal data class ProbeRead(
+    val succeeded: Boolean,
+    val value: String? = null,
+)
+
 object CapabilityProbe {
     fun run(context: Context): List<CapabilityResult> {
         val results = mutableListOf<CapabilityResult>()
@@ -33,6 +39,8 @@ object CapabilityProbe {
                 required = false,
             )
 
+        results += phantomProcessMonitorResult(context)
+
         val dmaHeapDirectory = File("/dev/dma_heap")
         val heaps =
             dmaHeapDirectory.list()
@@ -107,6 +115,37 @@ object CapabilityProbe {
             Os.close(descriptor)
         }.isSuccess
 
+    private fun phantomProcessMonitorResult(context: Context): CapabilityResult {
+        if (Build.VERSION.SDK_INT < 31) {
+            return classifyPhantomProcessMonitor(Build.VERSION.SDK_INT, ProbeRead(false), ProbeRead(false))
+        }
+
+        val global =
+            runCatching {
+                Settings.Global.getString(
+                    context.contentResolver,
+                    PHANTOM_PROCESS_MONITOR_SETTING,
+                )
+            }.fold(
+                onSuccess = { ProbeRead(succeeded = true, value = it?.trim()) },
+                onFailure = { ProbeRead(succeeded = false) },
+            )
+        val property =
+            if (global.succeeded && global.value.isNullOrBlank()) {
+                readSystemProperty(PHANTOM_PROCESS_MONITOR_PROPERTY)
+            } else {
+                ProbeRead(succeeded = false)
+            }
+        return classifyPhantomProcessMonitor(Build.VERSION.SDK_INT, global, property)
+    }
+
+    private fun readSystemProperty(name: String): ProbeRead =
+        runCatching {
+            val process = ProcessBuilder("/system/bin/getprop", name).start()
+            val value = process.inputStream.bufferedReader().use { it.readText().trim() }
+            if (process.waitFor() == 0) ProbeRead(succeeded = true, value = value) else ProbeRead(false)
+        }.getOrElse { ProbeRead(succeeded = false) }
+
     private fun result(
         name: String,
         passed: Boolean,
@@ -123,4 +162,89 @@ object CapabilityProbe {
         val gib = bytes.toDouble() / (1024.0 * 1024.0 * 1024.0)
         return "%.1f GiB".format(gib)
     }
+
+    private const val PHANTOM_PROCESS_MONITOR_SETTING =
+        "settings_enable_monitor_phantom_procs"
+    private const val PHANTOM_PROCESS_MONITOR_PROPERTY =
+        "persist.sys.fflag.override.settings_enable_monitor_phantom_procs"
 }
+
+internal fun classifyPhantomProcessMonitor(
+    sdkInt: Int,
+    global: ProbeRead,
+    property: ProbeRead,
+): CapabilityResult {
+    if (sdkInt < 31) {
+        return CapabilityResult(
+            name = "Child process restrictions",
+            status = CapabilityStatus.PASS,
+            detail = "Not used by this Android version",
+            required = false,
+        )
+    }
+
+    if (!global.succeeded) return unknownPhantomProcessMonitorResult(sdkInt)
+    val selected = if (global.value.isNullOrBlank()) property else global
+    if (!selected.succeeded) return unknownPhantomProcessMonitorResult(sdkInt)
+
+    val value = selected.value.orEmpty()
+    val guidance = phantomProcessMonitorGuidance(sdkInt)
+    if (value.isBlank()) {
+        return CapabilityResult(
+            name = "Child process restrictions",
+            status = CapabilityStatus.WARNING,
+            detail =
+                "No override is set; Android's default is enabled on standard builds and may " +
+                    "stop Linux child processes. $guidance",
+            required = false,
+            showDeveloperOptionsAction = sdkInt >= 34,
+        )
+    }
+
+    return when (value.lowercase()) {
+        "false" ->
+            CapabilityResult(
+                name = "Child process restrictions",
+                status = CapabilityStatus.PASS,
+                detail = "Disabled; Linux child processes are not restricted by this monitor",
+                required = false,
+            )
+        "true" ->
+            CapabilityResult(
+                name = "Child process restrictions",
+                status = CapabilityStatus.WARNING,
+                detail = activePhantomProcessMonitorDetail(sdkInt),
+                required = false,
+                showDeveloperOptionsAction = sdkInt >= 34,
+                linuxProcessRestrictionActive = true,
+            )
+        else -> unknownPhantomProcessMonitorResult(sdkInt)
+    }
+}
+
+private fun unknownPhantomProcessMonitorResult(sdkInt: Int) =
+    CapabilityResult(
+        name = "Child process restrictions",
+        status = CapabilityStatus.WARNING,
+        detail = "State unknown. ${phantomProcessMonitorGuidance(sdkInt)}",
+        required = false,
+        showDeveloperOptionsAction = sdkInt >= 34,
+    )
+
+private fun phantomProcessMonitorGuidance(sdkInt: Int): String =
+    if (sdkInt >= 34) {
+        "Enable Developer options > Disable child process restrictions. uDroid cannot change it."
+    } else {
+        "This Android version has no built-in toggle and uDroid cannot change it. Run: " +
+            "adb shell settings put global settings_enable_monitor_phantom_procs false"
+    }
+
+private fun activePhantomProcessMonitorDetail(sdkInt: Int): String =
+    if (sdkInt >= 34) {
+        "Android can stop desktops and larger Linux apps when they start many background " +
+            "processes. In Developer options, turn on “Disable child process restrictions.”"
+    } else {
+        "Android can stop desktops and larger Linux apps when they start many background " +
+            "processes. This Android version has no settings toggle. Use ADB: adb shell " +
+            "settings put global settings_enable_monitor_phantom_procs false"
+    }

app/src/main/java/org/randomcoder/udroid/runtime/RuntimeModels.kt

@@ -23,6 +23,7 @@ data class RuntimeSnapshot(
 enum class CapabilityStatus {
     PASS,
     FAIL,
+    WARNING,
     INFO,
 }
 
@@ -31,4 +32,6 @@ data class CapabilityResult(
     val status: CapabilityStatus,
     val detail: String,
     val required: Boolean,
+    val showDeveloperOptionsAction: Boolean = false,
+    val linuxProcessRestrictionActive: Boolean = false,
 )

app/src/main/java/org/randomcoder/udroid/ui/AppShell.kt

@@ -2,9 +2,13 @@ package org.randomcoder.udroid.ui
 
 import android.content.ClipData
 import android.content.ClipboardManager
+import android.content.Intent
 import android.os.Build
+import android.provider.Settings
 import android.widget.Toast
 import androidx.activity.compose.BackHandler
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.animation.AnimatedContent
 import androidx.compose.animation.fadeIn
 import androidx.compose.animation.fadeOut
@@ -834,6 +838,10 @@ private fun ManagementPane(
                                 scanMessage = desktopScanMessage,
                                 audioConfiguration = audioConfiguration,
                                 audioConfigurationMessage = audioConfigurationMessage,
+                                childProcessRestriction =
+                                    capabilities.firstOrNull {
+                                        it.linuxProcessRestrictionActive
+                                    },
                                 resetAvailable =
                                     selectedRootfs.name in resettableRootfsNames ||
                                         selectedDistro != null,
@@ -863,6 +871,7 @@ private fun ManagementPane(
                                 onGraphicsProfileChanged = onGraphicsProfileChanged,
                                 onAudioOutputChanged = onAudioOutputChanged,
                                 onMicrophoneChanged = onMicrophoneChanged,
+                                onRefreshCapabilities = onRefresh,
                                 onStartDesktop = onStartDesktop,
                                 onStopTerminal = onStop,
                                 onStopDesktop = onStopDesktop,
@@ -1241,6 +1250,7 @@ private fun DevicePage(
     capabilities: List<CapabilityResult>,
     onRefresh: () -> Unit,
 ) {
+    val openDeveloperOptions = rememberDeveloperOptionsAction(onRefresh)
     LazyColumn(
         modifier =
             Modifier
@@ -1265,14 +1275,20 @@ private fun DevicePage(
             )
         }
         items(capabilities) { capability ->
-            CapabilityRow(capability)
+            CapabilityRow(
+                capability = capability,
+                onOpenDeveloperOptions = openDeveloperOptions,
+            )
         }
         item { Spacer(Modifier.height(16.dp)) }
     }
 }
 
 @Composable
-private fun CapabilityRow(capability: CapabilityResult) {
+private fun CapabilityRow(
+    capability: CapabilityResult,
+    onOpenDeveloperOptions: () -> Unit,
+) {
     val (icon, tint, label) =
         when (capability.status) {
             CapabilityStatus.PASS ->
@@ -1283,6 +1299,8 @@ private fun CapabilityRow(capability: CapabilityResult) {
                     if (capability.required) MaterialTheme.colorScheme.error else UdroidWarning,
                     if (capability.required) "Required" else "Unavailable",
                 )
+            CapabilityStatus.WARNING ->
+                Triple(Icons.Rounded.ErrorOutline, UdroidWarning, "Review")
             CapabilityStatus.INFO ->
                 Triple(Icons.Rounded.Info, MaterialTheme.colorScheme.tertiary, "Detected")
         }
@@ -1300,7 +1318,16 @@ private fun CapabilityRow(capability: CapabilityResult) {
             Text(capability.name, style = MaterialTheme.typography.titleMedium)
         },
         supportingContent = {
-            Text(capability.detail, style = MaterialTheme.typography.bodySmall)
+            Column {
+                Text(capability.detail, style = MaterialTheme.typography.bodySmall)
+                if (capability.showDeveloperOptionsAction) {
+                    TextButton(
+                        onClick = onOpenDeveloperOptions,
+                    ) {
+                        Text("Open Developer options")
+                    }
+                }
+            }
         },
         trailingContent = {
             Text(
@@ -1312,6 +1339,26 @@ private fun CapabilityRow(capability: CapabilityResult) {
     )
 }
 
+@Composable
+internal fun rememberDeveloperOptionsAction(onReturn: () -> Unit): () -> Unit {
+    val context = LocalContext.current
+    val launcher =
+        rememberLauncherForActivityResult(ActivityResultContracts.StartActivityForResult()) {
+            onReturn()
+        }
+    return {
+        runCatching {
+            launcher.launch(Intent(Settings.ACTION_APPLICATION_DEVELOPMENT_SETTINGS))
+        }.onFailure {
+            Toast.makeText(
+                context,
+                "Developer options are unavailable on this device",
+                Toast.LENGTH_LONG,
+            ).show()
+        }
+    }
+}
+
 @Composable
 private fun AboutPage(
     journalLines: List<String>,