tools/android/common/daemon.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "tools/android/common/daemon.h"
   6
   7 #include <errno.h>
   8 #include <signal.h>
   9 #include <stdio.h>
  10 #include <sys/types.h>
  11 #include <unistd.h>
  12
  13 #include "base/command_line.h"
  14 #include "base/logging.h"
  15
  16 namespace {
  17
  18 const char kNoSpawnDaemon[] = "D";
  19
  20 int g_exit_status = 0;
  21
  22 void Exit(int unused) {
  23   _exit(g_exit_status);
  24 }
  25
  26 void CloseFileDescriptor(int fd) {
  27   int old_errno = errno;
  28   close(fd);
  29   errno = old_errno;
  30 }
  31
  32 }  // namespace
  33
  34 namespace tools {
  35
  36 bool HasHelpSwitch(const CommandLine& command_line) {
  37   return command_line.HasSwitch("h") || command_line.HasSwitch("help");
  38 }
  39
  40 bool HasNoSpawnDaemonSwitch(const CommandLine& command_line) {
  41   return command_line.HasSwitch(kNoSpawnDaemon);
  42 }
  43
  44 void ShowHelp(const char* program,
  45               const char* extra_title,
  46               const char* extra_descriptions) {
  47   printf("Usage: %s [-%s] %s\n"
  48          " -%s  stops from spawning a daemon process\n%s",
  49          program, kNoSpawnDaemon, extra_title, kNoSpawnDaemon,
  50          extra_descriptions);
  51 }
  52
  53 void SpawnDaemon(int exit_status) {
  54   g_exit_status = exit_status;
  55   signal(SIGUSR1, Exit);
  56
  57   if (fork()) {
  58     // In parent process.
  59     sleep(10);  // Wait for the child process to finish setsid().
  60     NOTREACHED();
  61   }
  62
  63   // In child process.
  64   setsid();  // Detach the child process from its parent.
  65   kill(getppid(), SIGUSR1);  // Inform the parent process to exit.
  66
  67   // Close the standard input and outputs, otherwise the process may block
  68   // adbd when the shell exits.
  69   // Comment out these lines if you want to see outputs for debugging.
  70   CloseFileDescriptor(0);
  71   CloseFileDescriptor(1);
  72   CloseFileDescriptor(2);
  73 }
  74
  75 }  // namespace tools