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// Copyright 2013 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// This file contains functions for launching subprocesses.
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#ifndef BASE_PROCESS_LAUNCH_H_
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#define BASE_PROCESS_LAUNCH_H_
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#include "base/base_export.h"
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#include "base/basictypes.h"
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#include "base/environment.h"
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#include "base/process/process_handle.h"
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#include "base/strings/string_piece.h"
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#include "base/posix/file_descriptor_shuffle.h"
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#include "base/win/scoped_handle.h"
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typedef std::vector<HANDLE> HandlesToInheritVector;
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// TODO(viettrungluu): Only define this on POSIX?
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typedef std::vector<std::pair<int, int> > FileHandleMappingVector;
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// Options for launching a subprocess that are passed to LaunchProcess().
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// The default constructor constructs the object with default options.
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struct BASE_EXPORT LaunchOptions {
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// If true, wait for the process to complete.
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// If non-null, inherit exactly the list of handles in this vector (these
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// handles must be inheritable). This is only supported on Vista and higher.
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HandlesToInheritVector* handles_to_inherit;
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// If true, the new process inherits handles from the parent. In production
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// code this flag should be used only when running short-lived, trusted
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// binaries, because open handles from other libraries and subsystems will
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// leak to the child process, causing errors such as open socket hangs.
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// Note: If |handles_to_inherit| is non-null, this flag is ignored and only
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// those handles will be inherited (on Vista and higher).
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// If non-null, runs as if the user represented by the token had launched it.
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// Whether the application is visible on the interactive desktop depends on
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// the token belonging to an interactive logon session.
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// To avoid hard to diagnose problems, when specified this loads the
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// environment variables associated with the user and if this operation fails
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// the entire call fails as well.
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UserTokenHandle as_user;
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// If true, use an empty string for the desktop name.
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bool empty_desktop_name;
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// If non-null, launches the application in that job object. The process will
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// be terminated immediately and LaunchProcess() will fail if assignment to
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// the job object fails.
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// Handles for the redirection of stdin, stdout and stderr. The handles must
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// be inheritable. Caller should either set all three of them or none (i.e.
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// there is no way to redirect stderr without redirecting stdin). The
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// |inherit_handles| flag must be set to true when redirecting stdio stream.
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// If set to true, ensures that the child process is launched with the
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// CREATE_BREAKAWAY_FROM_JOB flag which allows it to breakout of the parent
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bool force_breakaway_from_job_;
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// Set/unset environment variables. Empty (the default) means to inherit
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// the same environment. See AlterEnvironment().
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EnvironmentMap environ;
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// If non-null, remap file descriptors according to the mapping of
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// src fd->dest fd to propagate FDs into the child process.
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// This pointer is owned by the caller and must live through the
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// call to LaunchProcess().
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const FileHandleMappingVector* fds_to_remap;
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// Each element is an RLIMIT_* constant that should be raised to its
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// rlim_max. This pointer is owned by the caller and must live through
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// the call to LaunchProcess().
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const std::vector<int>* maximize_rlimits;
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// If true, start the process in a new process group, instead of
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// inheriting the parent's process group. The pgid of the child process
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// will be the same as its pid.
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bool new_process_group;
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#if defined(OS_LINUX)
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// If non-zero, start the process using clone(), using flags as provided.
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#endif // defined(OS_LINUX)
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#if defined(OS_CHROMEOS)
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// If non-negative, the specified file descriptor will be set as the launched
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// process' controlling terminal.
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int ctrl_terminal_fd;
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#endif // defined(OS_CHROMEOS)
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#endif // !defined(OS_WIN)
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// Launch a process via the command line |cmdline|.
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// See the documentation of LaunchOptions for details on |options|.
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// Returns true upon success.
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// Upon success, if |process_handle| is non-null, it will be filled in with the
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// handle of the launched process. NOTE: In this case, the caller is
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// responsible for closing the handle so that it doesn't leak!
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// Otherwise, the process handle will be implicitly closed.
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// Unix-specific notes:
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// - All file descriptors open in the parent process will be closed in the
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// child process except for any preserved by options::fds_to_remap, and
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// stdin, stdout, and stderr. If not remapped by options::fds_to_remap,
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// stdin is reopened as /dev/null, and the child is allowed to inherit its
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// parent's stdout and stderr.
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// - If the first argument on the command line does not contain a slash,
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// PATH will be searched. (See man execvp.)
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BASE_EXPORT bool LaunchProcess(const CommandLine& cmdline,
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const LaunchOptions& options,
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ProcessHandle* process_handle);
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// Windows-specific LaunchProcess that takes the command line as a
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// string. Useful for situations where you need to control the
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// command line arguments directly, but prefer the CommandLine version
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// if launching Chrome itself.
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// The first command line argument should be the path to the process,
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// and don't forget to quote it.
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// Example (including literal quotes)
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// cmdline = "c:\windows\explorer.exe" -foo "c:\bar\"
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BASE_EXPORT bool LaunchProcess(const string16& cmdline,
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const LaunchOptions& options,
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win::ScopedHandle* process_handle);
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// Launches a process with elevated privileges. This does not behave exactly
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// like LaunchProcess as it uses ShellExecuteEx instead of CreateProcess to
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// create the process. This means the process will have elevated privileges
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// and thus some common operations like OpenProcess will fail. The process will
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// be available through the |process_handle| argument. Currently the only
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// supported LaunchOptions are |start_hidden| and |wait|.
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BASE_EXPORT bool LaunchElevatedProcess(const CommandLine& cmdline,
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const LaunchOptions& options,
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ProcessHandle* process_handle);
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#elif defined(OS_POSIX)
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// A POSIX-specific version of LaunchProcess that takes an argv array
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// instead of a CommandLine. Useful for situations where you need to
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// control the command line arguments directly, but prefer the
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// CommandLine version if launching Chrome itself.
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BASE_EXPORT bool LaunchProcess(const std::vector<std::string>& argv,
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const LaunchOptions& options,
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ProcessHandle* process_handle);
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// Close all file descriptors, except those which are a destination in the
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// given multimap. Only call this function in a child process where you know
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// that there aren't any other threads.
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BASE_EXPORT void CloseSuperfluousFds(const InjectiveMultimap& saved_map);
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#endif // defined(OS_POSIX)
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// Set |job_object|'s JOBOBJECT_EXTENDED_LIMIT_INFORMATION
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// BasicLimitInformation.LimitFlags to |limit_flags|.
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BASE_EXPORT bool SetJobObjectLimitFlags(HANDLE job_object, DWORD limit_flags);
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// Output multi-process printf, cout, cerr, etc to the cmd.exe console that ran
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// chrome. This is not thread-safe: only call from main thread.
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BASE_EXPORT void RouteStdioToConsole();
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#endif // defined(OS_WIN)
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// Executes the application specified by |cl| and wait for it to exit. Stores
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// the output (stdout) in |output|. Redirects stderr to /dev/null. Returns true
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// on success (application launched and exited cleanly, with exit code
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// indicating success).
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BASE_EXPORT bool GetAppOutput(const CommandLine& cl, std::string* output);
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// A Windows-specific version of GetAppOutput that takes a command line string
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// instead of a CommandLine object. Useful for situations where you need to
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// control the command line arguments directly.
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BASE_EXPORT bool GetAppOutput(const StringPiece16& cl, std::string* output);
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#if defined(OS_POSIX)
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// A POSIX-specific version of GetAppOutput that takes an argv array
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// instead of a CommandLine. Useful for situations where you need to
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// control the command line arguments directly.
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BASE_EXPORT bool GetAppOutput(const std::vector<std::string>& argv,
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std::string* output);
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// A restricted version of |GetAppOutput()| which (a) clears the environment,
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// and (b) stores at most |max_output| bytes; also, it doesn't search the path
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BASE_EXPORT bool GetAppOutputRestricted(const CommandLine& cl,
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std::string* output, size_t max_output);
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// A version of |GetAppOutput()| which also returns the exit code of the
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// executed command. Returns true if the application runs and exits cleanly. If
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// this is the case the exit code of the application is available in
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BASE_EXPORT bool GetAppOutputWithExitCode(const CommandLine& cl,
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std::string* output, int* exit_code);
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#endif // defined(OS_POSIX)
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// If supported on the platform, and the user has sufficent rights, increase
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// the current process's scheduling priority to a high priority.
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BASE_EXPORT void RaiseProcessToHighPriority();
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#if defined(OS_MACOSX)
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// Restore the default exception handler, setting it to Apple Crash Reporter
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// (ReportCrash). When forking and execing a new process, the child will
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// inherit the parent's exception ports, which may be set to the Breakpad
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// instance running inside the parent. The parent's Breakpad instance should
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// not handle the child's exceptions. Calling RestoreDefaultExceptionHandler
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// in the child after forking will restore the standard exception handler.
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// See http://crbug.com/20371/ for more details.
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void RestoreDefaultExceptionHandler();
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#endif // defined(OS_MACOSX)
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#endif // BASE_PROCESS_LAUNCH_H_