tools/gn/exec_process.cc

   1 // Copyright 2014 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 "base/command_line.h"
   6 #include "base/files/file_util.h"
   7 #include "base/logging.h"
   8 #include "base/process/kill.h"
   9 #include "base/process/launch.h"
  10
  11 #if defined(OS_WIN)
  12 #include <windows.h>
  13
  14 #include "base/win/scoped_handle.h"
  15 #include "base/win/scoped_process_information.h"
  16 #endif
  17
  18 #if defined(OS_POSIX)
  19 #include <fcntl.h>
  20 #include <unistd.h>
  21
  22 #include "base/posix/eintr_wrapper.h"
  23 #include "base/posix/file_descriptor_shuffle.h"
  24 #endif
  25
  26 namespace internal {
  27
  28 #if defined(OS_WIN)
  29 bool ExecProcess(const base::CommandLine& cmdline,
  30                  const base::FilePath& startup_dir,
  31                  std::string* std_out,
  32                  std::string* std_err,
  33                  int* exit_code) {
  34   SECURITY_ATTRIBUTES sa_attr;
  35   // Set the bInheritHandle flag so pipe handles are inherited.
  36   sa_attr.nLength = sizeof(SECURITY_ATTRIBUTES);
  37   sa_attr.bInheritHandle = TRUE;
  38   sa_attr.lpSecurityDescriptor = nullptr;
  39
  40   // Create the pipe for the child process's STDOUT.
  41   HANDLE out_read = nullptr;
  42   HANDLE out_write = nullptr;
  43   if (!CreatePipe(&out_read, &out_write, &sa_attr, 0)) {
  44     NOTREACHED() << "Failed to create pipe";
  45     return false;
  46   }
  47   base::win::ScopedHandle scoped_out_read(out_read);
  48   base::win::ScopedHandle scoped_out_write(out_write);
  49
  50   // Create the pipe for the child process's STDERR.
  51   HANDLE err_read = nullptr;
  52   HANDLE err_write = nullptr;
  53   if (!CreatePipe(&err_read, &err_write, &sa_attr, 0)) {
  54     NOTREACHED() << "Failed to create pipe";
  55     return false;
  56   }
  57   base::win::ScopedHandle scoped_err_read(err_read);
  58   base::win::ScopedHandle scoped_err_write(err_write);
  59
  60   // Ensure the read handle to the pipe for STDOUT/STDERR is not inherited.
  61   if (!SetHandleInformation(out_read, HANDLE_FLAG_INHERIT, 0)) {
  62     NOTREACHED() << "Failed to disabled pipe inheritance";
  63     return false;
  64   }
  65   if (!SetHandleInformation(err_read, HANDLE_FLAG_INHERIT, 0)) {
  66     NOTREACHED() << "Failed to disabled pipe inheritance";
  67     return false;
  68   }
  69
  70   base::FilePath::StringType cmdline_str(cmdline.GetCommandLineString());
  71
  72   STARTUPINFO start_info = {};
  73
  74   start_info.cb = sizeof(STARTUPINFO);
  75   start_info.hStdOutput = out_write;
  76   // Keep the normal stdin.
  77   start_info.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
  78   // FIXME(brettw) set stderr here when we actually read it below.
  79   //start_info.hStdError = err_write;
  80   start_info.hStdError = GetStdHandle(STD_ERROR_HANDLE);
  81   start_info.dwFlags |= STARTF_USESTDHANDLES;
  82
  83   // Create the child process.
  84   PROCESS_INFORMATION temp_process_info = {};
  85   if (!CreateProcess(nullptr,
  86                      &cmdline_str[0],
  87                      nullptr, nullptr,
  88                      TRUE,  // Handles are inherited.
  89                      0, nullptr,
  90                      startup_dir.value().c_str(),
  91                      &start_info, &temp_process_info)) {
  92     return false;
  93   }
  94   base::win::ScopedProcessInformation proc_info(temp_process_info);
  95
  96   // Close our writing end of pipes now. Otherwise later read would not be able
  97   // to detect end of child's output.
  98   scoped_out_write.Close();
  99   scoped_err_write.Close();
 100
 101   // Read output from the child process's pipe for STDOUT
 102   const int kBufferSize = 1024;
 103   char buffer[kBufferSize];
 104
 105   // FIXME(brettw) read from stderr here! This is complicated because we want
 106   // to read both of them at the same time, probably need overlapped I/O.
 107   // Also uncomment start_info code above.
 108   for (;;) {
 109     DWORD bytes_read = 0;
 110     BOOL success =
 111         ReadFile(out_read, buffer, kBufferSize, &bytes_read, nullptr);
 112     if (!success || bytes_read == 0)
 113       break;
 114     std_out->append(buffer, bytes_read);
 115   }
 116
 117   // Let's wait for the process to finish.
 118   WaitForSingleObject(proc_info.process_handle(), INFINITE);
 119
 120   DWORD dw_exit_code;
 121   GetExitCodeProcess(proc_info.process_handle(), &dw_exit_code);
 122   *exit_code = static_cast<int>(dw_exit_code);
 123
 124   return true;
 125 }
 126 #else
 127 // Reads from the provided file descriptor and appends to output. Returns false
 128 // if the fd is closed or there is an unexpected error (not
 129 // EINTR/EAGAIN/EWOULDBLOCK).
 130 bool ReadFromPipe(int fd, std::string* output) {
 131   char buffer[256];
 132   int bytes_read = HANDLE_EINTR(read(fd, buffer, sizeof(buffer)));
 133   if (bytes_read == -1) {
 134     return errno == EAGAIN || errno == EWOULDBLOCK;
 135   } else if (bytes_read <= 0) {
 136     return false;
 137   }
 138   output->append(buffer, bytes_read);
 139   return true;
 140 }
 141
 142 bool ExecProcess(const base::CommandLine& cmdline,
 143                  const base::FilePath& startup_dir,
 144                  std::string* std_out,
 145                  std::string* std_err,
 146                  int* exit_code) {
 147   *exit_code = EXIT_FAILURE;
 148
 149   std::vector<std::string> argv = cmdline.argv();
 150
 151   int out_fd[2], err_fd[2];
 152   pid_t pid;
 153   base::InjectiveMultimap fd_shuffle1, fd_shuffle2;
 154   scoped_ptr<char*[]> argv_cstr(new char*[argv.size() + 1]);
 155
 156   fd_shuffle1.reserve(3);
 157   fd_shuffle2.reserve(3);
 158
 159   if (pipe(out_fd) < 0)
 160     return false;
 161   base::ScopedFD out_read(out_fd[0]), out_write(out_fd[1]);
 162
 163   if (pipe(err_fd) < 0)
 164     return false;
 165   base::ScopedFD err_read(err_fd[0]), err_write(err_fd[1]);
 166
 167   if (out_read.get() >= FD_SETSIZE || err_read.get() >= FD_SETSIZE)
 168     return false;
 169
 170   switch (pid = fork()) {
 171     case -1:  // error
 172       return false;
 173     case 0:  // child
 174       {
 175         // DANGER: no calls to malloc are allowed from now on:
 176         // http://crbug.com/36678
 177
 178         // Obscure fork() rule: in the child, if you don't end up doing exec*(),
 179         // you call _exit() instead of exit(). This is because _exit() does not
 180         // call any previously-registered (in the parent) exit handlers, which
 181         // might do things like block waiting for threads that don't even exist
 182         // in the child.
 183         int dev_null = open("/dev/null", O_WRONLY);
 184         if (dev_null < 0)
 185           _exit(127);
 186
 187         fd_shuffle1.push_back(
 188             base::InjectionArc(out_write.get(), STDOUT_FILENO, true));
 189         fd_shuffle1.push_back(
 190             base::InjectionArc(err_write.get(), STDERR_FILENO, true));
 191         fd_shuffle1.push_back(
 192             base::InjectionArc(dev_null, STDIN_FILENO, true));
 193         // Adding another element here? Remeber to increase the argument to
 194         // reserve(), above.
 195
 196         for (size_t i = 0; i < fd_shuffle1.size(); ++i)
 197           fd_shuffle2.push_back(fd_shuffle1[i]);
 198
 199         if (!ShuffleFileDescriptors(&fd_shuffle1))
 200           _exit(127);
 201
 202         base::SetCurrentDirectory(startup_dir);
 203
 204         // TODO(brettw) the base version GetAppOutput does a
 205         // CloseSuperfluousFds call here. Do we need this?
 206
 207         for (size_t i = 0; i < argv.size(); i++)
 208           argv_cstr[i] = const_cast<char*>(argv[i].c_str());
 209         argv_cstr[argv.size()] = nullptr;
 210         execvp(argv_cstr[0], argv_cstr.get());
 211         _exit(127);
 212       }
 213     default:  // parent
 214       {
 215         // Close our writing end of pipe now. Otherwise later read would not
 216         // be able to detect end of child's output (in theory we could still
 217         // write to the pipe).
 218         out_write.reset();
 219         err_write.reset();
 220
 221         bool out_open = true, err_open = true;
 222         while (out_open || err_open) {
 223           fd_set read_fds;
 224           FD_ZERO(&read_fds);
 225           FD_SET(out_read.get(), &read_fds);
 226           FD_SET(err_read.get(), &read_fds);
 227           int res =
 228               HANDLE_EINTR(select(std::max(out_read.get(), err_read.get()) + 1,
 229                                   &read_fds, nullptr, nullptr, nullptr));
 230           if (res <= 0)
 231             break;
 232           if (FD_ISSET(out_read.get(), &read_fds))
 233             out_open = ReadFromPipe(out_read.get(), std_out);
 234           if (FD_ISSET(err_read.get(), &read_fds))
 235             err_open = ReadFromPipe(err_read.get(), std_err);
 236         }
 237
 238         return base::WaitForExitCode(pid, exit_code);
 239       }
 240   }
 241
 242   return false;
 243 }
 244 #endif
 245
 246 }  // namespace internal
 247