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      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 "base/test/multiprocess_test.h"
      6 
      7 #include <unistd.h>
      8 
      9 #include "base/containers/hash_tables.h"
     10 #include "base/logging.h"
     11 #include "testing/multiprocess_func_list.h"
     12 
     13 namespace base {
     14 
     15 // A very basic implementation for Android. On Android tests can run in an APK
     16 // and we don't have an executable to exec*. This implementation does the bare
     17 // minimum to execute the method specified by procname (in the child process).
     18 //  - All options except |fds_to_remap| are ignored.
     19 //  - |debug_on_start| is ignored.
     20 ProcessHandle MultiProcessTest::SpawnChildWithOptions(
     21     const std::string& procname,
     22     const LaunchOptions& options,
     23     bool debug_on_start) {
     24   // TODO(vtl): The FD-remapping done below is wrong in the presence of cycles
     25   // (e.g., fd1 -> fd2, fd2 -> fd1). crbug.com/326576
     26   FileHandleMappingVector empty;
     27   const FileHandleMappingVector* fds_to_remap =
     28       options.fds_to_remap ? options.fds_to_remap : &empty;
     29 
     30   pid_t pid = fork();
     31 
     32   if (pid < 0) {
     33     PLOG(ERROR) << "fork";
     34     return kNullProcessHandle;
     35   }
     36   if (pid > 0) {
     37     // Parent process.
     38     return pid;
     39   }
     40   // Child process.
     41   std::hash_set<int> fds_to_keep_open;
     42   for (FileHandleMappingVector::const_iterator it = fds_to_remap->begin();
     43        it != fds_to_remap->end(); ++it) {
     44     fds_to_keep_open.insert(it->first);
     45   }
     46   // Keep stdin, stdout and stderr open since this is not meant to spawn a
     47   // daemon.
     48   const int kFdForAndroidLogging = 3;  // FD used by __android_log_write().
     49   for (int fd = kFdForAndroidLogging + 1; fd < getdtablesize(); ++fd) {
     50     if (fds_to_keep_open.find(fd) == fds_to_keep_open.end()) {
     51       close(fd);
     52     }
     53   }
     54   for (FileHandleMappingVector::const_iterator it = fds_to_remap->begin();
     55        it != fds_to_remap->end(); ++it) {
     56     int old_fd = it->first;
     57     int new_fd = it->second;
     58     if (dup2(old_fd, new_fd) < 0) {
     59       PLOG(FATAL) << "dup2";
     60     }
     61     close(old_fd);
     62   }
     63   _exit(multi_process_function_list::InvokeChildProcessTest(procname));
     64   return 0;
     65 }
     66 
     67 }  // namespace base
     68