crashpad/util/mac/process_reader.h

// Copyright 2014 The Crashpad Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef CRASHPAD_UTIL_MAC_PROCESS_READER_H_
#define CRASHPAD_UTIL_MAC_PROCESS_READER_H_

#include <mach/mach.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <sys/types.h>
#include <time.h>

#include <string>
#include <vector>

#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "build/build_config.h"
#include "util/mach/task_memory.h"
#include "util/misc/initialization_state_dcheck.h"

namespace crashpad {

//! \brief Contains information about a thread that belongs to a task (process).
struct ProcessReaderThread {
#if defined(ARCH_CPU_X86_FAMILY)
  union ThreadContext {
    x86_thread_state64_t t64;
    x86_thread_state32_t t32;
  };
  union FloatContext {
    x86_float_state64_t f64;
    x86_float_state32_t f32;
  };
  union DebugContext {
    x86_debug_state64_t d64;
    x86_debug_state32_t d32;
  };
#endif

  ProcessReaderThread();
  ~ProcessReaderThread() {}

  ThreadContext thread_context;
  FloatContext float_context;
  DebugContext debug_context;
  uint64_t id;
  mach_vm_address_t stack_region_address;
  mach_vm_size_t stack_region_size;
  mach_vm_address_t thread_specific_data_address;
  mach_port_t port;
  int suspend_count;
  int priority;
};

//! \brief Contains information about a module loaded into a process.
struct ProcessReaderModule {
  ProcessReaderModule();
  ~ProcessReaderModule();

  std::string name;
  mach_vm_address_t address;
  time_t timestamp;
};

//! \brief Accesses information about another process, identified by a Mach
//!     task.
class ProcessReader {
 public:
  ProcessReader();
  ~ProcessReader();

  //! \brief Initializes this object. This method must be called before any
  //!     other.
  //!
  //! \param[in] task A send right to the target task’s task port. This object
  //!     does not take ownership of the send right.
  //!
  //! \return `true` on success, indicating that this object will respond
  //!     validly to further method calls. `false` on failure. On failure, no
  //!     further method calls should be made.
  bool Initialize(mach_port_t task);

  //! \return `true` if the target task is a 64-bit process.
  bool Is64Bit() const { return is_64_bit_; }

  //! \return The target task’s process ID.
  pid_t ProcessID() const { return kern_proc_info_.kp_proc.p_pid; }

  //! \return The target task’s parent process ID.
  pid_t ParentProcessID() const { return kern_proc_info_.kp_eproc.e_ppid; }

  //! \param[out] start_time The time that the process started.
  void StartTime(timeval* start_time) const;

  //! \param[out] user_time The amount of time the process has executed code in
  //!     user mode.
  //! \param[out] system_time The amount of time the process has executed code
  //!     in system mode.
  //!
  //! \return `true` on success, `false` on failure, with a warning logged. On
  //!     failure, \a user_time and \a system_time will be set to represent no
  //!     time spent executing code in user or system mode.
  bool CPUTimes(timeval* user_time, timeval* system_time) const;

  //! \return Accesses the memory of the target task.
  TaskMemory* Memory() { return task_memory_.get(); }

  //! \return The threads that are in the task (process).
  const std::vector<ProcessReaderThread>& Threads();

  //! \return The modules loaded in the process.
  const std::vector<ProcessReaderModule>& Modules();

 private:
  //! Performs lazy initialization of the \a threads_ vector on behalf of
  //! Threads().
  void InitializeThreads();

  //! Performs lazy initialization of the \a modules_ vector on behalf of
  //! Modules().
  void InitializeModules();

  //! \brief Calculates the base address and size of the region used as a
  //!     thread’s stack.
  //!
  //! The region returned by this method may be formed by merging multiple
  //! adjacent regions in a process’ memory map if appropriate. The base address
  //! of the returned region may be lower than the \a stack_pointer passed in
  //! when the ABI mandates a red zone below the stack pointer.
  //!
  //! \param[in] stack_pointer The stack pointer, referring to the top (lowest
  //!     address) of a thread’s stack.
  //! \param[out] stack_region_size The size of the memory region used as the
  //!     thread’s stack.
  //!
  //! \return The base address (lowest address) of the memory region used as the
  //!     thread’s stack.
  mach_vm_address_t CalculateStackRegion(mach_vm_address_t stack_pointer,
                                         mach_vm_size_t* stack_region_size);

  //! \brief Adjusts the region for the red zone, if the ABI requires one.
  //!
  //! This method performs red zone calculation for CalculateStackRegion(). Its
  //! parameters are local variables used within that method, and may be
  //! modified as needed.
  //!
  //! Where a red zone is required, the region of memory captured for a thread’s
  //! stack will be extended to include the red zone below the stack pointer,
  //! provided that such memory is mapped, readable, and has the correct user
  //! tag value. If these conditions cannot be met fully, as much of the red
  //! zone will be captured as is possible while meeting these conditions.
  //!
  //! \param[inout] start_address The base address of the region to begin
  //!     capturing stack memory from. On entry, \a start_address is the stack
  //!     pointer. On return, \a start_address may be decreased to encompass a
  //!     red zone.
  //! \param[inout] region_base The base address of the region that contains
  //!     stack memory. This is distinct from \a start_address in that \a
  //!     region_base will be page-aligned. On entry, \a region_base is the
  //!     base address of a region that contains \a start_address. On return,
  //!     if \a start_address is decremented and is outside of the region
  //!     originally described by \a region_base, \a region_base will also be
  //!     decremented appropriately.
  //! \param[inout] region_size The size of the region that contains stack
  //!     memory. This region begins at \a region_base. On return, if \a
  //!     region_base is decremented, \a region_size will be incremented
  //!     appropriately.
  //! \param[in] user_tag The Mach VM system’s user tag for the region described
  //!     by the initial values of \a region_base and \a region_size. The red
  //!     zone will only be allowed to extend out of the region described by
  //!     these initial values if the user tag is appropriate for stack memory
  //!     and the expanded region has the same user tag value.
  void LocateRedZone(mach_vm_address_t* start_address,
                     mach_vm_address_t* region_base,
                     mach_vm_address_t* region_size,
                     unsigned int user_tag);

  kinfo_proc kern_proc_info_;
  std::vector<ProcessReaderThread> threads_;  // owns send rights
  std::vector<ProcessReaderModule> modules_;
  scoped_ptr<TaskMemory> task_memory_;
  mach_port_t task_;  // weak
  InitializationStateDcheck initialized_;

  // This shadows a bit in kern_proc_info_, but it’s accessed so frequently that
  // it’s given a first-class field to save a few bit operations on each access.
  bool is_64_bit_;

  bool initialized_threads_;
  bool initialized_modules_;

  DISALLOW_COPY_AND_ASSIGN(ProcessReader);
};

}  // namespace crashpad

#endif  // CRASHPAD_UTIL_MAC_PROCESS_READER_H_