1 files changed, 85 insertions, 0 deletions

diff --git a/app/src/main/java/org/pacien/tincapp/commands/Executor.kt b/app/src/main/java/org/pacien/tincapp/commands/Executor.kt
new file mode 100644
index 0000000..29e011f
--- /dev/null
+++ b/app/src/main/java/org/pacien/tincapp/commands/Executor.kt
@@ -0,0 +1,85 @@
+/*
+ * Tinc App, an Android binding and user interface for the tinc mesh VPN daemon
+ * Copyright (C) 2017-2018 Pacien TRAN-GIRARD
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.pacien.tincapp.commands
+
+import android.os.AsyncTask
+import java8.util.concurrent.CompletableFuture
+import java8.util.function.Supplier
+import java.io.BufferedReader
+import java.io.IOException
+import java.io.InputStream
+import java.io.InputStreamReader
+
+/**
+ * @author pacien
+ */
+internal object Executor {
+  private const val FAILED = -1
+  private const val SUCCESS = 0
+
+  class CommandExecutionException(msg: String) : Exception(msg)
+
+  init {
+    System.loadLibrary("exec")
+  }
+
+  /**
+   * @return FAILED (-1) on error, forked child PID otherwise
+   */
+  private external fun forkExec(args: Array<String>): Int
+
+  /**
+   * @return FAILED (-1) on error, the exit status of the process otherwise
+   */
+  private external fun wait(pid: Int): Int
+
+  private fun read(stream: InputStream) = BufferedReader(InputStreamReader(stream)).readLines()
+
+  fun forkExec(cmd: Command): CompletableFuture<Unit> {
+    val pid = forkExec(cmd.asArray()).also {
+      if (it == FAILED) throw CommandExecutionException("Could not fork child process.")
+    }
+
+    return runAsyncTask {
+      val exitCode = wait(pid)
+      when (exitCode) {
+        SUCCESS -> Unit
+        FAILED -> throw CommandExecutionException("Process terminated abnormally.")
+        else -> throw CommandExecutionException("Non-zero exit status code ($exitCode).")
+      }
+    }
+  }
+
+  fun run(cmd: Command): Process = try {
+    ProcessBuilder(cmd.asList()).start()
+  } catch (e: IOException) {
+    throw CommandExecutionException(e.message ?: "Could not start process.")
+  }
+
+  fun call(cmd: Command): CompletableFuture<List<String>> = run(cmd).let { process ->
+    supplyAsyncTask<List<String>> {
+      val exitCode = process.waitFor()
+      if (exitCode == 0) read(process.inputStream)
+      else throw CommandExecutionException(read(process.errorStream).lastOrNull() ?: "Non-zero exit status ($exitCode).")
+    }
+  }
+
+  fun runAsyncTask(r: () -> Unit) = CompletableFuture.supplyAsync(Supplier(r), AsyncTask.THREAD_POOL_EXECUTOR)!!
+  fun <U> supplyAsyncTask(s: () -> U) = CompletableFuture.supplyAsync(Supplier(s), AsyncTask.THREAD_POOL_EXECUTOR)!!
+}