android: Added the ability to share text as a .txt file

android/src/main/AndroidManifest.xml

@@ -131,6 +131,16 @@
                 android:value="true" />
         </service>
 
+        <provider
+            android:name="androidx.core.content.FileProvider"
+            android:authorities="com.tailscale.ipn.fileprovider"
+            android:exported="false"
+            android:grantUriPermissions="true">
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/file_paths" />
+        </provider>
+
         <meta-data
             android:name="android.content.APP_RESTRICTIONS"
             android:resource="@xml/app_restrictions" />

android/src/main/java/com/tailscale/ipn/App.kt

@@ -45,6 +45,7 @@ import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import kotlinx.serialization.encodeToString
 import kotlinx.serialization.json.Json
 import libtailscale.Libtailscale
@@ -52,6 +53,8 @@ import java.io.IOException
 import java.net.NetworkInterface
 import java.security.GeneralSecurityException
 import java.util.Locale
+import kotlin.time.Duration.Companion.hours
+
 class App : UninitializedApp(), libtailscale.AppContext, ViewModelStoreOwner {
   val applicationScope = CoroutineScope(SupervisorJob() + Dispatchers.Default)
   companion object {
@@ -178,6 +181,9 @@ class App : UninitializedApp(), libtailscale.AppContext, ViewModelStoreOwner {
     applicationScope.launch {
       val hideDisconnectAction = MDMSettings.forceEnabled.flow.first()
     }
+    applicationScope.launch {
+        cleanupOldCacheFiles()
+    }
     TSLog.init(this)
     FeatureFlags.initialize(mapOf("enable_new_search" to true))
   }
@@ -335,6 +341,18 @@ class App : UninitializedApp(), libtailscale.AppContext, ViewModelStoreOwner {
   fun notifyPolicyChanged() {
     app.notifyPolicyChanged()
   }
+
+  suspend fun cleanupOldCacheFiles() {
+    val maxAgeMs = 1.hours.inWholeMilliseconds
+    val cutoffTime = System.currentTimeMillis() - maxAgeMs
+    withContext(Dispatchers.IO) {
+      cacheDir.listFiles()?.forEach { file ->
+        if (file.name.startsWith("shared_text_") && file.lastModified() < cutoffTime) {
+          file.delete()
+        }
+      }
+    }
+  }
 }
 /**
  * UninitializedApp contains all of the methods of App that can be used without having to initialize

android/src/main/java/com/tailscale/ipn/ShareActivity.kt

@@ -3,6 +3,7 @@
 
 package com.tailscale.ipn
 
+import android.content.Context
 import android.content.Intent
 import android.net.Uri
 import android.os.Build
@@ -14,6 +15,7 @@ import androidx.activity.compose.setContent
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.ui.Modifier
+import androidx.core.content.FileProvider
 import androidx.lifecycle.lifecycleScope
 import com.tailscale.ipn.ui.model.Ipn
 import com.tailscale.ipn.ui.theme.AppTheme
@@ -27,6 +29,7 @@ import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
+import java.io.File
 
 // ShareActivity is the entry point for Taildrop share intents
 class ShareActivity : ComponentActivity() {
@@ -57,11 +60,13 @@ class ShareActivity : ComponentActivity() {
   override fun onNewIntent(intent: Intent) {
     super.onNewIntent(intent)
     setIntent(intent)
+    lifecycleScope.launch {
       loadFiles()
     }
+  }
 
   // Loads the files from the intent.
-  fun loadFiles() {
+  suspend fun loadFiles() {
     if (intent == null) {
       TSLog.e(TAG, "Share failure - No intent found")
       return
@@ -76,6 +81,13 @@ class ShareActivity : ComponentActivity() {
               // If EXTRA_STREAM is present, get the single URI for that stream
               listOfNotNull(intent.versionSafeGetStreamUri())
             }
+            else if (intent.extras?.containsKey(Intent.EXTRA_TEXT) == true) {
+              // If EXTRA_TEXT is present, create a temporary file with the text content.
+              // This could be any shared text, like a URL or plain text from the clipboard.
+              val text = intent.getStringExtra(Intent.EXTRA_TEXT) ?: ""
+              val uri = createTemporaryFile(text)
+              listOf(uri)
+            }
             else {
               TSLog.e(TAG, "No extras found in intent - nothing to share")
               emptyList()
@@ -141,3 +153,35 @@ private fun Intent.versionSafeGetStreamUris(): List<Uri> =
   }
     ?.filterNotNull()
     ?: emptyList()
+
+/**
+ * Creates a temporary txt file in the app's cache directory with the given content.
+ * Then grants temporary read permission to the file using FileProvider and returns its URI.
+ */
+private suspend fun Context.createTemporaryFile(
+  content: String,
+  dir: File = cacheDir,
+  fileName: String = "shared_text_${System.currentTimeMillis()}.txt",
+): Uri {
+  // Create temporary file in cache directory
+  val tempFile = File(dir, fileName)
+  withContext(Dispatchers.IO) {
+    tempFile.writeText(content)
+  }
+
+  // Get content URI using FileProvider
+  val uri = FileProvider.getUriForFile(
+    this,
+    "${applicationContext.packageName}.fileprovider",
+    tempFile
+  )
+
+  // Grant temporary read permission
+  grantUriPermission(
+    packageName,
+    uri,
+    Intent.FLAG_GRANT_READ_URI_PERMISSION
+  )
+
+  return uri
+}

android/src/main/res/xml/file_paths.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<paths xmlns:android="http://schemas.android.com/apk/res/android">
+    <cache-path name="shared" path="/" />
+</paths>