Roll skia to r1241.

[chromium-blink-merge.git] / base / process_util.h

// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file/namespace contains utility functions for enumerating, ending and
// computing statistics of processes.

#ifndef BASE_PROCESS_UTIL_H_
#define BASE_PROCESS_UTIL_H_
#pragma once

#include "base/basictypes.h"

#if defined(OS_WIN)
#include <windows.h>
#include <tlhelp32.h>
#elif defined(OS_MACOSX)
// kinfo_proc is defined in <sys/sysctl.h>, but this forward declaration
// is sufficient for the vector<kinfo_proc> below.
struct kinfo_proc;
// malloc_zone_t is defined in <malloc/malloc.h>, but this forward declaration
// is sufficient for GetPurgeableZone() below.
typedef struct _malloc_zone_t malloc_zone_t;
#include <mach/mach.h>
#elif defined(OS_POSIX)
#include <dirent.h>
#include <limits.h>
#include <sys/types.h>
#endif

#include <list>
#include <string>
#include <utility>
#include <vector>

#include "base/base_api.h"
#include "base/file_descriptor_shuffle.h"
#include "base/file_path.h"
#include "base/process.h"

class CommandLine;

namespace base {

#if defined(OS_WIN)
struct ProcessEntry : public PROCESSENTRY32 {
  ProcessId pid() const { return th32ProcessID; }
  ProcessId parent_pid() const { return th32ParentProcessID; }
  const wchar_t* exe_file() const { return szExeFile; }
};

struct IoCounters : public IO_COUNTERS {
};

// Process access masks. These constants provide platform-independent
// definitions for the standard Windows access masks.
// See http://msdn.microsoft.com/en-us/library/ms684880(VS.85).aspx for
// the specific semantics of each mask value.
const uint32 kProcessAccessTerminate              = PROCESS_TERMINATE;
const uint32 kProcessAccessCreateThread           = PROCESS_CREATE_THREAD;
const uint32 kProcessAccessSetSessionId           = PROCESS_SET_SESSIONID;
const uint32 kProcessAccessVMOperation            = PROCESS_VM_OPERATION;
const uint32 kProcessAccessVMRead                 = PROCESS_VM_READ;
const uint32 kProcessAccessVMWrite                = PROCESS_VM_WRITE;
const uint32 kProcessAccessDuplicateHandle        = PROCESS_DUP_HANDLE;
const uint32 kProcessAccessCreateProcess          = PROCESS_CREATE_PROCESS;
const uint32 kProcessAccessSetQuota               = PROCESS_SET_QUOTA;
const uint32 kProcessAccessSetInformation         = PROCESS_SET_INFORMATION;
const uint32 kProcessAccessQueryInformation       = PROCESS_QUERY_INFORMATION;
const uint32 kProcessAccessSuspendResume          = PROCESS_SUSPEND_RESUME;
const uint32 kProcessAccessQueryLimitedInfomation =
    PROCESS_QUERY_LIMITED_INFORMATION;
const uint32 kProcessAccessWaitForTermination     = SYNCHRONIZE;
#elif defined(OS_POSIX)

struct ProcessEntry {
  ProcessEntry();
  ~ProcessEntry();

  ProcessId pid() const { return pid_; }
  ProcessId parent_pid() const { return ppid_; }
  ProcessId gid() const { return gid_; }
  const char* exe_file() const { return exe_file_.c_str(); }
  const std::vector<std::string>& cmd_line_args() const {
    return cmd_line_args_;
  }

  ProcessId pid_;
  ProcessId ppid_;
  ProcessId gid_;
  std::string exe_file_;
  std::vector<std::string> cmd_line_args_;
};

struct IoCounters {
  uint64_t ReadOperationCount;
  uint64_t WriteOperationCount;
  uint64_t OtherOperationCount;
  uint64_t ReadTransferCount;
  uint64_t WriteTransferCount;
  uint64_t OtherTransferCount;
};

// Process access masks. They are not used on Posix because access checking
// does not happen during handle creation.
const uint32 kProcessAccessTerminate              = 0;
const uint32 kProcessAccessCreateThread           = 0;
const uint32 kProcessAccessSetSessionId           = 0;
const uint32 kProcessAccessVMOperation            = 0;
const uint32 kProcessAccessVMRead                 = 0;
const uint32 kProcessAccessVMWrite                = 0;
const uint32 kProcessAccessDuplicateHandle        = 0;
const uint32 kProcessAccessCreateProcess          = 0;
const uint32 kProcessAccessSetQuota               = 0;
const uint32 kProcessAccessSetInformation         = 0;
const uint32 kProcessAccessQueryInformation       = 0;
const uint32 kProcessAccessSuspendResume          = 0;
const uint32 kProcessAccessQueryLimitedInfomation = 0;
const uint32 kProcessAccessWaitForTermination     = 0;
#endif  // defined(OS_POSIX)

// Return status values from GetTerminationStatus.  Don't use these as
// exit code arguments to KillProcess*(), use platform/application
// specific values instead.
enum TerminationStatus {
  TERMINATION_STATUS_NORMAL_TERMINATION,   // zero exit status
  TERMINATION_STATUS_ABNORMAL_TERMINATION, // non-zero exit status
  TERMINATION_STATUS_PROCESS_WAS_KILLED,   // e.g. SIGKILL or task manager kill
  TERMINATION_STATUS_PROCESS_CRASHED,      // e.g. Segmentation fault
  TERMINATION_STATUS_STILL_RUNNING,        // child hasn't exited yet
  TERMINATION_STATUS_MAX_ENUM
};

// Returns the id of the current process.
BASE_API ProcessId GetCurrentProcId();

// Returns the ProcessHandle of the current process.
BASE_API ProcessHandle GetCurrentProcessHandle();

// Converts a PID to a process handle. This handle must be closed by
// CloseProcessHandle when you are done with it. Returns true on success.
BASE_API bool OpenProcessHandle(ProcessId pid, ProcessHandle* handle);

// Converts a PID to a process handle. On Windows the handle is opened
// with more access rights and must only be used by trusted code.
// You have to close returned handle using CloseProcessHandle. Returns true
// on success.
// TODO(sanjeevr): Replace all calls to OpenPrivilegedProcessHandle with the
// more specific OpenProcessHandleWithAccess method and delete this.
BASE_API bool OpenPrivilegedProcessHandle(ProcessId pid, ProcessHandle* handle);

// Converts a PID to a process handle using the desired access flags. Use a
// combination of the kProcessAccess* flags defined above for |access_flags|.
BASE_API bool OpenProcessHandleWithAccess(ProcessId pid,
                                          uint32 access_flags,
                                          ProcessHandle* handle);

// Closes the process handle opened by OpenProcessHandle.
BASE_API void CloseProcessHandle(ProcessHandle process);

// Returns the unique ID for the specified process. This is functionally the
// same as Windows' GetProcessId(), but works on versions of Windows before
// Win XP SP1 as well.
BASE_API ProcessId GetProcId(ProcessHandle process);

#if defined(OS_LINUX)
// Returns the path to the executable of the given process.
BASE_API FilePath GetProcessExecutablePath(ProcessHandle process);

// Parse the data found in /proc/<pid>/stat and return the sum of the
// CPU-related ticks.  Returns -1 on parse error.
// Exposed for testing.
BASE_API int ParseProcStatCPU(const std::string& input);

static const char kAdjustOOMScoreSwitch[] = "--adjust-oom-score";

// This adjusts /proc/process/oom_adj so the Linux OOM killer will prefer
// certain process types over others. The range for the adjustment is
// [-17,15], with [0,15] being user accessible.
BASE_API bool AdjustOOMScore(ProcessId process, int score);
#endif

#if defined(OS_POSIX)
// Returns the ID for the parent of the given process.
BASE_API ProcessId GetParentProcessId(ProcessHandle process);

// Close all file descriptors, except those which are a destination in the
// given multimap. Only call this function in a child process where you know
// that there aren't any other threads.
BASE_API void CloseSuperfluousFds(const InjectiveMultimap& saved_map);
#endif

#if defined(OS_WIN)

enum IntegrityLevel {
  INTEGRITY_UNKNOWN,
  LOW_INTEGRITY,
  MEDIUM_INTEGRITY,
  HIGH_INTEGRITY,
};
// Determine the integrity level of the specified process. Returns false
// if the system does not support integrity levels (pre-Vista) or in the case
// of an underlying system failure.
BASE_API bool GetProcessIntegrityLevel(ProcessHandle process,
                                       IntegrityLevel *level);

// Runs the given application name with the given command line. Normally, the
// first command line argument should be the path to the process, and don't
// forget to quote it.
//
// If wait is true, it will block and wait for the other process to finish,
// otherwise, it will just continue asynchronously.
//
// Example (including literal quotes)
//  cmdline = "c:\windows\explorer.exe" -foo "c:\bar\"
//
// If process_handle is non-NULL, the process handle of the launched app will be
// stored there on a successful launch.
// NOTE: In this case, the caller is responsible for closing the handle so
//       that it doesn't leak!
BASE_API bool LaunchApp(const std::wstring& cmdline,
                        bool wait, bool start_hidden,
                        ProcessHandle* process_handle);

// Same as LaunchApp, except allows the new process to inherit handles of the
// parent process.
BASE_API bool LaunchAppWithHandleInheritance(const std::wstring& cmdline,
                                             bool wait, bool start_hidden,
                                             ProcessHandle* process_handle);

// Runs the given application name with the given command line as if the user
// represented by |token| had launched it. The caveats about |cmdline| and
// |process_handle| explained for LaunchApp above apply as well.
//
// Whether the application is visible on the interactive desktop depends on
// the token belonging to an interactive logon session.
//
// To avoid hard to diagnose problems, this function internally loads the
// environment variables associated with the user and if this operation fails
// the entire call fails as well.
BASE_API bool LaunchAppAsUser(UserTokenHandle token,
                              const std::wstring& cmdline,
                              bool start_hidden,
                              ProcessHandle* process_handle);

// Has the same behavior as LaunchAppAsUser, but offers the boolean option to
// use an empty string for the desktop name and a boolean for allowing the
// child process to inherit handles from its parent.
BASE_API bool LaunchAppAsUser(UserTokenHandle token,
                              const std::wstring& cmdline,
                              bool start_hidden, ProcessHandle* process_handle,
                              bool empty_desktop_name, bool inherit_handles);


#elif defined(OS_POSIX)
// Runs the application specified in argv[0] with the command line argv.
// Before launching all FDs open in the parent process will be marked as
// close-on-exec.  |fds_to_remap| defines a mapping of src fd->dest fd to
// propagate FDs into the child process.
//
// As above, if wait is true, execute synchronously. The pid will be stored
// in process_handle if that pointer is non-null.
//
// Note that the first argument in argv must point to the executable filename.
// If the filename is not fully specified, PATH will be searched.
typedef std::vector<std::pair<int, int> > file_handle_mapping_vector;
BASE_API bool LaunchApp(const std::vector<std::string>& argv,
                        const file_handle_mapping_vector& fds_to_remap,
                        bool wait, ProcessHandle* process_handle);

// Similar to the above, but also (un)set environment variables in child process
// through |environ|.
typedef std::vector<std::pair<std::string, std::string> > environment_vector;
BASE_API bool LaunchApp(const std::vector<std::string>& argv,
                        const environment_vector& environ,
                        const file_handle_mapping_vector& fds_to_remap,
                        bool wait, ProcessHandle* process_handle);

// Similar to the above two methods, but starts the child process in a process
// group of its own, instead of allowing it to inherit the parent's process
// group. The pgid of the child process will be the same as its pid.
bool LaunchAppInNewProcessGroup(const std::vector<std::string>& argv,
                                const environment_vector& environ,
                                const file_handle_mapping_vector& fds_to_remap,
                                bool wait, ProcessHandle* process_handle);

// AlterEnvironment returns a modified environment vector, constructed from the
// given environment and the list of changes given in |changes|. Each key in
// the environment is matched against the first element of the pairs. In the
// event of a match, the value is replaced by the second of the pair, unless
// the second is empty, in which case the key-value is removed.
//
// The returned array is allocated using new[] and must be freed by the caller.
BASE_API char** AlterEnvironment(const environment_vector& changes,
                                 const char* const* const env);
#endif  // defined(OS_POSIX)

// Executes the application specified by cl. This function delegates to one
// of the above two platform-specific functions.
BASE_API bool LaunchApp(const CommandLine& cl, bool wait, bool start_hidden,
                        ProcessHandle* process_handle);

// Executes the application specified by |cl| and wait for it to exit. Stores
// the output (stdout) in |output|. Redirects stderr to /dev/null. Returns true
// on success (application launched and exited cleanly, with exit code
// indicating success).
BASE_API bool GetAppOutput(const CommandLine& cl, std::string* output);

#if defined(OS_POSIX)
// A restricted version of |GetAppOutput()| which (a) clears the environment,
// and (b) stores at most |max_output| bytes; also, it doesn't search the path
// for the command.
BASE_API bool GetAppOutputRestricted(const CommandLine& cl,
                                     std::string* output, size_t max_output);
#endif

// Used to filter processes by process ID.
class ProcessFilter {
 public:
  // Returns true to indicate set-inclusion and false otherwise.  This method
  // should not have side-effects and should be idempotent.
  virtual bool Includes(const ProcessEntry& entry) const = 0;

 protected:
  virtual ~ProcessFilter() {}
};

// Returns the number of processes on the machine that are running from the
// given executable name.  If filter is non-null, then only processes selected
// by the filter will be counted.
BASE_API int GetProcessCount(const FilePath::StringType& executable_name,
                             const ProcessFilter* filter);

// Attempts to kill all the processes on the current machine that were launched
// from the given executable name, ending them with the given exit code.  If
// filter is non-null, then only processes selected by the filter are killed.
// Returns true if all processes were able to be killed off, false if at least
// one couldn't be killed.
BASE_API bool KillProcesses(const FilePath::StringType& executable_name,
                            int exit_code, const ProcessFilter* filter);

// Attempts to kill the process identified by the given process
// entry structure, giving it the specified exit code. If |wait| is true, wait
// for the process to be actually terminated before returning.
// Returns true if this is successful, false otherwise.
BASE_API bool KillProcess(ProcessHandle process, int exit_code, bool wait);

#if defined(OS_POSIX)
// Attempts to kill the process group identified by |process_group_id|. Returns
// true on success.
bool KillProcessGroup(ProcessHandle process_group_id);
#endif

#if defined(OS_WIN)
BASE_API bool KillProcessById(ProcessId process_id, int exit_code, bool wait);
#endif

// Get the termination status of the process by interpreting the
// circumstances of the child process' death. |exit_code| is set to
// the status returned by waitpid() on POSIX, and from
// GetExitCodeProcess() on Windows.  |exit_code| may be NULL if the
// caller is not interested in it.  Note that on Linux, this function
// will only return a useful result the first time it is called after
// the child exits (because it will reap the child and the information
// will no longer be available).
BASE_API TerminationStatus GetTerminationStatus(ProcessHandle handle,
                                                int* exit_code);

// Waits for process to exit. On POSIX systems, if the process hasn't been
// signaled then puts the exit code in |exit_code|; otherwise it's considered
// a failure. On Windows |exit_code| is always filled. Returns true on success,
// and closes |handle| in any case.
BASE_API bool WaitForExitCode(ProcessHandle handle, int* exit_code);

// Waits for process to exit. If it did exit within |timeout_milliseconds|,
// then puts the exit code in |exit_code|, and returns true.
// In POSIX systems, if the process has been signaled then |exit_code| is set
// to -1. Returns false on failure (the caller is then responsible for closing
// |handle|).
// The caller is always responsible for closing the |handle|.
BASE_API bool WaitForExitCodeWithTimeout(ProcessHandle handle, int* exit_code,
                                         int64 timeout_milliseconds);

// Wait for all the processes based on the named executable to exit.  If filter
// is non-null, then only processes selected by the filter are waited on.
// Returns after all processes have exited or wait_milliseconds have expired.
// Returns true if all the processes exited, false otherwise.
BASE_API bool WaitForProcessesToExit(
    const FilePath::StringType& executable_name,
    int64 wait_milliseconds,
    const ProcessFilter* filter);

// Wait for a single process to exit. Return true if it exited cleanly within
// the given time limit. On Linux |handle| must be a child process, however
// on Mac and Windows it can be any process.
BASE_API bool WaitForSingleProcess(ProcessHandle handle,
                                   int64 wait_milliseconds);

// Waits a certain amount of time (can be 0) for all the processes with a given
// executable name to exit, then kills off any of them that are still around.
// If filter is non-null, then only processes selected by the filter are waited
// on.  Killed processes are ended with the given exit code.  Returns false if
// any processes needed to be killed, true if they all exited cleanly within
// the wait_milliseconds delay.
BASE_API bool CleanupProcesses(const FilePath::StringType& executable_name,
                               int64 wait_milliseconds,
                               int exit_code,
                               const ProcessFilter* filter);

// This class provides a way to iterate through a list of processes on the
// current machine with a specified filter.
// To use, create an instance and then call NextProcessEntry() until it returns
// false.
class BASE_API ProcessIterator {
 public:
  typedef std::list<ProcessEntry> ProcessEntries;

  explicit ProcessIterator(const ProcessFilter* filter);
  virtual ~ProcessIterator();

  // If there's another process that matches the given executable name,
  // returns a const pointer to the corresponding PROCESSENTRY32.
  // If there are no more matching processes, returns NULL.
  // The returned pointer will remain valid until NextProcessEntry()
  // is called again or this NamedProcessIterator goes out of scope.
  const ProcessEntry* NextProcessEntry();

  // Takes a snapshot of all the ProcessEntry found.
  ProcessEntries Snapshot();

 protected:
  virtual bool IncludeEntry();
  const ProcessEntry& entry() { return entry_; }

 private:
  // Determines whether there's another process (regardless of executable)
  // left in the list of all processes.  Returns true and sets entry_ to
  // that process's info if there is one, false otherwise.
  bool CheckForNextProcess();

  // Initializes a PROCESSENTRY32 data structure so that it's ready for
  // use with Process32First/Process32Next.
  void InitProcessEntry(ProcessEntry* entry);

#if defined(OS_WIN)
  HANDLE snapshot_;
  bool started_iteration_;
#elif defined(OS_MACOSX)
  std::vector<kinfo_proc> kinfo_procs_;
  size_t index_of_kinfo_proc_;
#elif defined(OS_POSIX)
  DIR *procfs_dir_;
#endif
  ProcessEntry entry_;
  const ProcessFilter* filter_;

  DISALLOW_COPY_AND_ASSIGN(ProcessIterator);
};

// This class provides a way to iterate through the list of processes
// on the current machine that were started from the given executable
// name.  To use, create an instance and then call NextProcessEntry()
// until it returns false.
class BASE_API NamedProcessIterator : public ProcessIterator {
 public:
  NamedProcessIterator(const FilePath::StringType& executable_name,
                       const ProcessFilter* filter);
  virtual ~NamedProcessIterator();

 protected:
  virtual bool IncludeEntry();

 private:
  FilePath::StringType executable_name_;

  DISALLOW_COPY_AND_ASSIGN(NamedProcessIterator);
};

// Working Set (resident) memory usage broken down by
//
// On Windows:
// priv (private): These pages (kbytes) cannot be shared with any other process.
// shareable:      These pages (kbytes) can be shared with other processes under
//                 the right circumstances.
// shared :        These pages (kbytes) are currently shared with at least one
//                 other process.
//
// On Linux:
// priv:           Pages mapped only by this process
// shared:         PSS or 0 if the kernel doesn't support this
// shareable:      0
//
// On OS X: TODO(thakis): Revise.
// priv:           Memory.
// shared:         0
// shareable:      0
struct WorkingSetKBytes {
  WorkingSetKBytes() : priv(0), shareable(0), shared(0) {}
  size_t priv;
  size_t shareable;
  size_t shared;
};

// Committed (resident + paged) memory usage broken down by
// private: These pages cannot be shared with any other process.
// mapped:  These pages are mapped into the view of a section (backed by
//          pagefile.sys)
// image:   These pages are mapped into the view of an image section (backed by
//          file system)
struct CommittedKBytes {
  CommittedKBytes() : priv(0), mapped(0), image(0) {}
  size_t priv;
  size_t mapped;
  size_t image;
};

// Free memory (Megabytes marked as free) in the 2G process address space.
// total : total amount in megabytes marked as free. Maximum value is 2048.
// largest : size of the largest contiguous amount of memory found. It is
//   always smaller or equal to FreeMBytes::total.
// largest_ptr: starting address of the largest memory block.
struct FreeMBytes {
  size_t total;
  size_t largest;
  void* largest_ptr;
};

// Convert a POSIX timeval to microseconds.
BASE_API int64 TimeValToMicroseconds(const struct timeval& tv);

// Provides performance metrics for a specified process (CPU usage, memory and
// IO counters). To use it, invoke CreateProcessMetrics() to get an instance
// for a specific process, then access the information with the different get
// methods.
class BASE_API ProcessMetrics {
 public:
  ~ProcessMetrics();

  // Creates a ProcessMetrics for the specified process.
  // The caller owns the returned object.
#if !defined(OS_MACOSX)
  static ProcessMetrics* CreateProcessMetrics(ProcessHandle process);
#else
  class PortProvider {
   public:
    // Should return the mach task for |process| if possible, or else
    // |MACH_PORT_NULL|. Only processes that this returns tasks for will have
    // metrics on OS X (except for the current process, which always gets
    // metrics).
    virtual mach_port_t TaskForPid(ProcessHandle process) const = 0;
  };

  // The port provider needs to outlive the ProcessMetrics object returned by
  // this function. If NULL is passed as provider, the returned object
  // only returns valid metrics if |process| is the current process.
  static ProcessMetrics* CreateProcessMetrics(ProcessHandle process,
                                              PortProvider* port_provider);
#endif  // !defined(OS_MACOSX)

  // Returns the current space allocated for the pagefile, in bytes (these pages
  // may or may not be in memory).  On Linux, this returns the total virtual
  // memory size.
  size_t GetPagefileUsage() const;
  // Returns the peak space allocated for the pagefile, in bytes.
  size_t GetPeakPagefileUsage() const;
  // Returns the current working set size, in bytes.  On Linux, this returns
  // the resident set size.
  size_t GetWorkingSetSize() const;
  // Returns the peak working set size, in bytes.
  size_t GetPeakWorkingSetSize() const;
  // Returns private and sharedusage, in bytes. Private bytes is the amount of
  // memory currently allocated to a process that cannot be shared. Returns
  // false on platform specific error conditions.  Note: |private_bytes|
  // returns 0 on unsupported OSes: prior to XP SP2.
  bool GetMemoryBytes(size_t* private_bytes,
                      size_t* shared_bytes);
  // Fills a CommittedKBytes with both resident and paged
  // memory usage as per definition of CommittedBytes.
  void GetCommittedKBytes(CommittedKBytes* usage) const;
  // Fills a WorkingSetKBytes containing resident private and shared memory
  // usage in bytes, as per definition of WorkingSetBytes.
  bool GetWorkingSetKBytes(WorkingSetKBytes* ws_usage) const;

  // Computes the current process available memory for allocation.
  // It does a linear scan of the address space querying each memory region
  // for its free (unallocated) status. It is useful for estimating the memory
  // load and fragmentation.
  bool CalculateFreeMemory(FreeMBytes* free) const;

  // Returns the CPU usage in percent since the last time this method was
  // called. The first time this method is called it returns 0 and will return
  // the actual CPU info on subsequent calls.
  // On Windows, the CPU usage value is for all CPUs. So if you have 2 CPUs and
  // your process is using all the cycles of 1 CPU and not the other CPU, this
  // method returns 50.
  double GetCPUUsage();

  // Retrieves accounting information for all I/O operations performed by the
  // process.
  // If IO information is retrieved successfully, the function returns true
  // and fills in the IO_COUNTERS passed in. The function returns false
  // otherwise.
  bool GetIOCounters(IoCounters* io_counters) const;

 private:
#if !defined(OS_MACOSX)
  explicit ProcessMetrics(ProcessHandle process);
#else
  ProcessMetrics(ProcessHandle process, PortProvider* port_provider);
#endif  // !defined(OS_MACOSX)

  ProcessHandle process_;

  int processor_count_;

  // Used to store the previous times and CPU usage counts so we can
  // compute the CPU usage between calls.
  int64 last_time_;
  int64 last_system_time_;

#if defined(OS_MACOSX)
  // Queries the port provider if it's set.
  mach_port_t TaskForPid(ProcessHandle process) const;

  PortProvider* port_provider_;
#elif defined(OS_POSIX)
  // Jiffie count at the last_time_ we updated.
  int last_cpu_;
#endif  // defined(OS_MACOSX)

  DISALLOW_COPY_AND_ASSIGN(ProcessMetrics);
};

// Returns the memory commited by the system in KBytes.
// Returns 0 if it can't compute the commit charge.
BASE_API size_t GetSystemCommitCharge();

// Enables low fragmentation heap (LFH) for every heaps of this process. This
// won't have any effect on heaps created after this function call. It will not
// modify data allocated in the heaps before calling this function. So it is
// better to call this function early in initialization and again before
// entering the main loop.
// Note: Returns true on Windows 2000 without doing anything.
BASE_API bool EnableLowFragmentationHeap();

// Enables 'terminate on heap corruption' flag. Helps protect against heap
// overflow. Has no effect if the OS doesn't provide the necessary facility.
BASE_API void EnableTerminationOnHeapCorruption();

#if !defined(OS_WIN)
// Turns on process termination if memory runs out. This is handled on Windows
// inside RegisterInvalidParamHandler().
BASE_API void EnableTerminationOnOutOfMemory();
#if defined(OS_MACOSX)
// Exposed for testing.
malloc_zone_t* GetPurgeableZone();
#endif
#endif

// Enables stack dump to console output on exception and signals.
// When enabled, the process will quit immediately. This is meant to be used in
// unit_tests only!
BASE_API bool EnableInProcessStackDumping();

// If supported on the platform, and the user has sufficent rights, increase
// the current process's scheduling priority to a high priority.
BASE_API void RaiseProcessToHighPriority();

#if defined(OS_MACOSX)
// Restore the default exception handler, setting it to Apple Crash Reporter
// (ReportCrash).  When forking and execing a new process, the child will
// inherit the parent's exception ports, which may be set to the Breakpad
// instance running inside the parent.  The parent's Breakpad instance should
// not handle the child's exceptions.  Calling RestoreDefaultExceptionHandler
// in the child after forking will restore the standard exception handler.
// See http://crbug.com/20371/ for more details.
void RestoreDefaultExceptionHandler();
#endif  // defined(OS_MACOSX)

}  // namespace base

#endif  // BASE_PROCESS_UTIL_H_