Dump Auto-revoke logs

- Introduce dumping from PermissionControllerServiceImpl
- Introduce a way to log and also store the logs for dumping later

Test: adb shell dumpsys permissionmgr
Bug: 155680199
Change-Id: I60128c9d027395888e22dc999051911a1fe6a034

1 files changed, 102 insertions, 0 deletions

diff --git a/PermissionController/src/com/android/permissioncontroller/DumpableLog.kt b/PermissionController/src/com/android/permissioncontroller/DumpableLog.kt
new file mode 100644
index 000000000..0b482fcd3
--- /dev/null
+++ b/PermissionController/src/com/android/permissioncontroller/DumpableLog.kt
@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.permissioncontroller
+
+import android.util.Log
+import com.android.permissioncontroller.Constants.LOGS_TO_DUMP_FILE
+import java.io.File
+import java.io.PrintWriter
+
+/**
+ * Like {@link Log} but stores the logs in a file which can later be dumped via {@link #dump}
+ */
+object DumpableLog {
+    private const val MAX_FILE_SIZE = 32 * 1024
+
+    private val lock = Any()
+    private val file = File(PermissionControllerApplication.get().filesDir, LOGS_TO_DUMP_FILE)
+
+    init {
+        file.createNewFile()
+    }
+
+    /**
+     * Equivalent to {@link Log.v}
+     */
+    fun v(tag: String, message: String, exception: Exception? = null) {
+        Log.v(tag, message, exception)
+        addLogToDump("v", tag, message, exception)
+    }
+
+    /**
+     * Equivalent to {@link Log.d}
+     */
+    fun d(tag: String, message: String, exception: Exception? = null) {
+        Log.d(tag, message, exception)
+        addLogToDump("d", tag, message, exception)
+    }
+
+    /**
+     * Equivalent to {@link Log.i}
+     */
+    fun i(tag: String, message: String, exception: Exception? = null) {
+        Log.i(tag, message, exception)
+        addLogToDump("i", tag, message, exception)
+    }
+
+    /**
+     * Equivalent to {@link Log.w}
+     */
+    fun w(tag: String, message: String, exception: Exception? = null) {
+        Log.w(tag, message, exception)
+        addLogToDump("w", tag, message, exception)
+    }
+
+    /**
+     * Equivalent to {@link Log.e}
+     */
+    fun e(tag: String, message: String, exception: Exception? = null) {
+        Log.e(tag, message, exception)
+        addLogToDump("e", tag, message, exception)
+    }
+
+    private fun addLogToDump(level: String, tag: String, message: String, exception: Exception?) {
+        synchronized(lock) {
+            // TODO: Needs to be replaced by proper log rotation
+            if (file.length() > MAX_FILE_SIZE) {
+                val dump = file.readLines()
+
+                file.writeText("truncated at ${System.currentTimeMillis()}\n")
+                dump.subList(dump.size / 2, dump.size).forEach { file.appendText(it + "\n") }
+            }
+
+            file.appendText("${System.currentTimeMillis()} $tag:$level $message " +
+                    "${exception?.let { it.message + Log.getStackTraceString(it) } ?: ""}\n")
+        }
+    }
+
+    /**
+     * Write the previously logged entries to the print writer.
+     *
+     * @param pw the writer to dump to
+     */
+    fun dump(pw: PrintWriter) {
+        synchronized(lock) {
+            file.forEachLine { pw.println(it) }
+        }
+    }
+}
\ No newline at end of file