Add most of ProcessReader and its test.

TEST=util_test ProcessReader.*
R=rsesek@chromium.org

Review URL: https://codereview.chromium.org/491963002

util/mac/process_reader.cc

@@ -0,0 +1,529 @@
+// 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.
+
+#include "util/mac/process_reader.h"
+
+#include <AvailabilityMacros.h>
+#include <mach/mach_vm.h>
+#include <mach-o/loader.h>
+
+#include <algorithm>
+
+#include "base/logging.h"
+#include "base/mac/mach_logging.h"
+#include "base/mac/scoped_mach_port.h"
+#include "base/mac/scoped_mach_vm.h"
+
+namespace {
+
+void MachTimeValueToTimeval(const time_value& mach, timeval* tv) {
+  tv->tv_sec = mach.seconds;
+  tv->tv_usec = mach.microseconds;
+}
+
+kern_return_t MachVMRegionRecurseDeepest(mach_port_t task,
+                                         mach_vm_address_t* address,
+                                         mach_vm_size_t* size,
+                                         natural_t* depth,
+                                         vm_prot_t* protection,
+                                         unsigned int* user_tag) {
+  vm_region_submap_short_info_64 submap_info;
+  mach_msg_type_number_t count = VM_REGION_SUBMAP_SHORT_INFO_COUNT_64;
+  while (true) {
+    kern_return_t kr = mach_vm_region_recurse(
+        task,
+        address,
+        size,
+        depth,
+        reinterpret_cast<vm_region_recurse_info_t>(&submap_info),
+        &count);
+    if (kr != KERN_SUCCESS) {
+      return kr;
+    }
+
+    if (!submap_info.is_submap) {
+      *protection = submap_info.protection;
+      *user_tag = submap_info.user_tag;
+      return KERN_SUCCESS;
+    }
+
+    ++*depth;
+  }
+}
+
+}  // namespace
+
+namespace crashpad {
+
+ProcessReaderThread::ProcessReaderThread()
+    : thread_context(),
+      float_context(),
+      debug_context(),
+      id(0),
+      stack_region_address(0),
+      stack_region_size(0),
+      thread_specific_data_address(0),
+      port(MACH_PORT_NULL),
+      suspend_count(0),
+      priority(0) {
+}
+
+ProcessReaderModule::ProcessReaderModule() : name(), address(0), timestamp(0) {
+}
+
+ProcessReaderModule::~ProcessReaderModule() {
+}
+
+ProcessReader::ProcessReader()
+    : kern_proc_info_(),
+      threads_(),
+      modules_(),
+      task_memory_(),
+      task_(MACH_PORT_NULL),
+      initialized_(),
+      is_64_bit_(false),
+      initialized_threads_(false),
+      initialized_modules_(false) {
+}
+
+ProcessReader::~ProcessReader() {
+  for (const ProcessReaderThread& thread : threads_) {
+    kern_return_t kr = mach_port_deallocate(mach_task_self(), thread.port);
+    MACH_LOG_IF(ERROR, kr != KERN_SUCCESS, kr) << "mach_port_deallocate";
+  }
+}
+
+bool ProcessReader::Initialize(mach_port_t task) {
+  INITIALIZATION_STATE_SET_INITIALIZING(initialized_);
+
+  pid_t pid;
+  kern_return_t kr = pid_for_task(task, &pid);
+  if (kr != KERN_SUCCESS) {
+    MACH_LOG(ERROR, kr) << "pid_for_task";
+    return false;
+  }
+
+  int mib[] = {CTL_KERN, KERN_PROC, KERN_PROC_PID, pid};
+  size_t len = sizeof(kern_proc_info_);
+  if (sysctl(mib, arraysize(mib), &kern_proc_info_, &len, NULL, 0) != 0) {
+    PLOG(ERROR) << "sysctl for pid " << pid;
+    return false;
+  }
+
+  DCHECK_EQ(kern_proc_info_.kp_proc.p_pid, pid);
+
+  is_64_bit_ = kern_proc_info_.kp_proc.p_flag & P_LP64;
+
+  task_memory_.reset(new TaskMemory(task));
+  task_ = task;
+
+  INITIALIZATION_STATE_SET_VALID(initialized_);
+  return true;
+}
+
+void ProcessReader::StartTime(timeval* start_time) const {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+  *start_time = kern_proc_info_.kp_proc.p_starttime;
+}
+
+bool ProcessReader::CPUTimes(timeval* user_time, timeval* system_time) const {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+
+  // Calculate user and system time the same way the kernel does for
+  // getrusage(). See 10.9.2 xnu-2422.90.20/bsd/kern/kern_resource.c calcru().
+  timerclear(user_time);
+  timerclear(system_time);
+
+  // As of the 10.8 SDK, the preferred routine is MACH_TASK_BASIC_INFO.
+  // TASK_BASIC_INFO_64_COUNT is equivalent and works on earlier systems.
+  task_basic_info_64 task_basic_info;
+  mach_msg_type_number_t task_basic_info_count = TASK_BASIC_INFO_64_COUNT;
+  kern_return_t kr = task_info(task_,
+                               TASK_BASIC_INFO_64,
+                               reinterpret_cast<task_info_t>(&task_basic_info),
+                               &task_basic_info_count);
+  if (kr != KERN_SUCCESS) {
+    MACH_LOG(WARNING, kr) << "task_info TASK_BASIC_INFO_64";
+    return false;
+  }
+
+  task_thread_times_info_data_t task_thread_times;
+  mach_msg_type_number_t task_thread_times_count = TASK_THREAD_TIMES_INFO_COUNT;
+  kr = task_info(task_,
+                 TASK_THREAD_TIMES_INFO,
+                 reinterpret_cast<task_info_t>(&task_thread_times),
+                 &task_thread_times_count);
+  if (kr != KERN_SUCCESS) {
+    MACH_LOG(WARNING, kr) << "task_info TASK_THREAD_TIMES";
+    return false;
+  }
+
+  MachTimeValueToTimeval(task_basic_info.user_time, user_time);
+  MachTimeValueToTimeval(task_basic_info.system_time, system_time);
+
+  timeval thread_user_time;
+  MachTimeValueToTimeval(task_thread_times.user_time, &thread_user_time);
+  timeval thread_system_time;
+  MachTimeValueToTimeval(task_thread_times.system_time, &thread_system_time);
+
+  timeradd(user_time, &thread_user_time, user_time);
+  timeradd(system_time, &thread_system_time, system_time);
+
+  return true;
+}
+
+const std::vector<ProcessReaderThread>& ProcessReader::Threads() {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+
+  if (!initialized_threads_) {
+    InitializeThreads();
+  }
+
+  return threads_;
+}
+
+const std::vector<ProcessReaderModule>& ProcessReader::Modules() {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+
+  if (!initialized_modules_) {
+    InitializeModules();
+  }
+
+  return modules_;
+}
+
+void ProcessReader::InitializeThreads() {
+  DCHECK(!initialized_threads_);
+  DCHECK(threads_.empty());
+
+  initialized_threads_ = true;
+
+  thread_act_array_t threads;
+  mach_msg_type_number_t thread_count = 0;
+  kern_return_t kr = task_threads(task_, &threads, &thread_count);
+  if (kr != KERN_SUCCESS) {
+    MACH_LOG(WARNING, kr) << "task_threads";
+    return;
+  }
+
+  // The send rights in the |threads| array won’t have their send rights managed
+  // by anything until they’re added to |threads_| by the loop below. Any early
+  // return (or exception) that happens between here and the completion of the
+  // loop below will leak thread port send rights.
+
+  base::mac::ScopedMachVM threads_vm(
+      reinterpret_cast<vm_address_t>(threads),
+      mach_vm_round_page(thread_count * sizeof(*threads)));
+
+  for (size_t index = 0; index < thread_count; ++index) {
+    ProcessReaderThread thread;
+    thread.port = threads[index];
+
+#if defined(ARCH_CPU_X86_FAMILY)
+    const thread_state_flavor_t kThreadStateFlavor =
+        Is64Bit() ? x86_THREAD_STATE64 : x86_THREAD_STATE32;
+    mach_msg_type_number_t thread_state_count =
+        Is64Bit() ? x86_THREAD_STATE64_COUNT : x86_THREAD_STATE32_COUNT;
+
+    // TODO(mark): Use the AVX variants instead of the FLOAT variants? They’re
+    // supported on 10.6 and later.
+    const thread_state_flavor_t kFloatStateFlavor =
+        Is64Bit() ? x86_FLOAT_STATE64 : x86_FLOAT_STATE32;
+    mach_msg_type_number_t float_state_count =
+        Is64Bit() ? x86_FLOAT_STATE64_COUNT : x86_FLOAT_STATE32_COUNT;
+
+    const thread_state_flavor_t kDebugStateFlavor =
+        Is64Bit() ? x86_DEBUG_STATE64 : x86_DEBUG_STATE32;
+    mach_msg_type_number_t debug_state_count =
+        Is64Bit() ? x86_DEBUG_STATE64_COUNT : x86_DEBUG_STATE32_COUNT;
+#endif
+
+    kr = thread_get_state(
+        thread.port,
+        kThreadStateFlavor,
+        reinterpret_cast<thread_state_t>(&thread.thread_context),
+        &thread_state_count);
+    if (kr != KERN_SUCCESS) {
+      MACH_LOG(ERROR, kr) << "thread_get_state(" << kThreadStateFlavor << ")";
+      continue;
+    }
+
+    kr = thread_get_state(
+        thread.port,
+        kFloatStateFlavor,
+        reinterpret_cast<thread_state_t>(&thread.float_context),
+        &float_state_count);
+    if (kr != KERN_SUCCESS) {
+      MACH_LOG(ERROR, kr) << "thread_get_state(" << kFloatStateFlavor << ")";
+      continue;
+    }
+
+    kr = thread_get_state(
+        thread.port,
+        kDebugStateFlavor,
+        reinterpret_cast<thread_state_t>(&thread.debug_context),
+        &debug_state_count);
+    if (kr != KERN_SUCCESS) {
+      MACH_LOG(ERROR, kr) << "thread_get_state(" << kDebugStateFlavor << ")";
+      continue;
+    }
+
+    thread_basic_info basic_info;
+    mach_msg_type_number_t count = THREAD_BASIC_INFO_COUNT;
+    kr = thread_info(thread.port,
+                     THREAD_BASIC_INFO,
+                     reinterpret_cast<thread_info_t>(&basic_info),
+                     &count);
+    if (kr != KERN_SUCCESS) {
+      MACH_LOG(WARNING, kr) << "thread_info(THREAD_BASIC_INFO)";
+    } else {
+      thread.suspend_count = basic_info.suspend_count;
+    }
+
+    thread_identifier_info identifier_info;
+    count = THREAD_IDENTIFIER_INFO_COUNT;
+    kr = thread_info(thread.port,
+                     THREAD_IDENTIFIER_INFO,
+                     reinterpret_cast<thread_info_t>(&identifier_info),
+                     &count);
+    if (kr != KERN_SUCCESS) {
+      MACH_LOG(WARNING, kr) << "thread_info(THREAD_IDENTIFIER_INFO)";
+    } else {
+      thread.id = identifier_info.thread_id;
+
+      // thread_identifier_info::thread_handle contains the base of the
+      // thread-specific data area, which on x86 and x86_64 is the thread’s base
+      // address of the %gs segment. 10.9.2 xnu-2422.90.20/osfmk/kern/thread.c
+      // thread_info_internal() gets the value from
+      // machine_thread::cthread_self, which is the same value used to set the
+      // %gs base in xnu-2422.90.20/osfmk/i386/pcb_native.c
+      // act_machine_switch_pcb().
+      //
+      // This address is the internal pthread’s _pthread::tsd[], an array of
+      // void* values that can be indexed by pthread_key_t values.
+      thread.thread_specific_data_address = identifier_info.thread_handle;
+    }
+
+    thread_precedence_policy precedence;
+    count = THREAD_PRECEDENCE_POLICY_COUNT;
+    boolean_t get_default = FALSE;
+    kr = thread_policy_get(thread.port,
+                           THREAD_PRECEDENCE_POLICY,
+                           reinterpret_cast<thread_policy_t>(&precedence),
+                           &count,
+                           &get_default);
+    if (kr != KERN_SUCCESS) {
+      MACH_LOG(INFO, kr) << "thread_policy_get";
+    } else {
+      thread.priority = precedence.importance;
+    }
+
+#if defined(ARCH_CPU_X86_FAMILY)
+    mach_vm_address_t stack_pointer = Is64Bit()
+                                          ? thread.thread_context.t64.__rsp
+                                          : thread.thread_context.t32.__esp;
+#endif
+
+    thread.stack_region_address =
+        CalculateStackRegion(stack_pointer, &thread.stack_region_size);
+
+    threads_.push_back(thread);
+  }
+}
+
+void ProcessReader::InitializeModules() {
+  DCHECK(!initialized_modules_);
+  DCHECK(modules_.empty());
+
+  initialized_modules_ = true;
+
+  // TODO(mark): Complete this implementation. The implementation depends on
+  // process_types, which cannot land yet because it depends on this file,
+  // process_reader. This temporary “cut” was made to avoid a review that’s too
+  // large. Yes, this circular dependency is unfortunate. Suggestions are
+  // welcome.
+}
+
+mach_vm_address_t ProcessReader::CalculateStackRegion(
+    mach_vm_address_t stack_pointer,
+    mach_vm_size_t* stack_region_size) {
+  INITIALIZATION_STATE_DCHECK_VALID(initialized_);
+
+  // For pthreads, it may be possible to compute the stack region based on the
+  // internal _pthread::stackaddr and _pthread::stacksize. The _pthread struct
+  // for a thread can be located at TSD slot 0, or the known offsets of
+  // stackaddr and stacksize from the TSD area could be used.
+  mach_vm_address_t region_base = stack_pointer;
+  mach_vm_size_t region_size;
+  natural_t depth = 0;
+  vm_prot_t protection;
+  unsigned int user_tag;
+  kern_return_t kr = MachVMRegionRecurseDeepest(
+      task_, &region_base, &region_size, &depth, &protection, &user_tag);
+  if (kr != KERN_SUCCESS) {
+    MACH_LOG(INFO, kr) << "mach_vm_region_recurse";
+    *stack_region_size = 0;
+    return 0;
+  }
+
+  if (region_base > stack_pointer) {
+    // There’s nothing mapped at the stack pointer’s address. Something may have
+    // trashed the stack pointer. Note that this shouldn’t happen for a normal
+    // stack guard region violation because the guard region is mapped but has
+    // VM_PROT_NONE protection.
+    *stack_region_size = 0;
+    return 0;
+  }
+
+  mach_vm_address_t start_address = stack_pointer;
+
+  if ((protection & VM_PROT_READ) == 0) {
+    // If the region isn’t readable, the stack pointer probably points to the
+    // guard region. Don’t include it as part of the stack, and don’t include
+    // anything at any lower memory address. The code below may still possibly
+    // find the real stack region at a memory address higher than this region.
+    start_address = region_base + region_size;
+  } else {
+    // If the ABI requires a red zone, adjust the region to include it if
+    // possible.
+    LocateRedZone(&start_address, &region_base, &region_size, user_tag);
+
+    // Regardless of whether the ABI requires a red zone, capture up to
+    // kExtraCaptureSize additional bytes of stack, but only if present in the
+    // region that was already found.
+    const mach_vm_size_t kExtraCaptureSize = 128;
+    start_address = std::max(start_address >= kExtraCaptureSize
+                                 ? start_address - kExtraCaptureSize
+                                 : start_address,
+                             region_base);
+
+    // Align start_address to a 16-byte boundary, which can help readers by
+    // ensuring that data is aligned properly. This could page-align instead,
+    // but that might be wasteful.
+    const mach_vm_size_t kDesiredAlignment = 16;
+    start_address &= ~(kDesiredAlignment - 1);
+    DCHECK_GE(start_address, region_base);
+  }
+
+  region_size -= (start_address - region_base);
+  region_base = start_address;
+
+  mach_vm_size_t total_region_size = region_size;
+
+  // The stack region may have gotten split up into multiple abutting regions.
+  // Try to coalesce them. This frequently happens for the main thread’s stack
+  // when setrlimit(RLIMIT_STACK, …) is called. It may also happen if a region
+  // is split up due to an mprotect() or vm_protect() call.
+  //
+  // Stack regions created by the kernel and the pthreads library will be marked
+  // with the VM_MEMORY_STACK user tag. Scanning for multiple adjacent regions
+  // with the same tag should find an entire stack region. Checking that the
+  // protection on individual regions is not VM_PROT_NONE should guarantee that
+  // this algorithm doesn’t collect map entries belonging to another thread’s
+  // stack: well-behaved stacks (such as those created by the kernel and the
+  // pthreads library) have VM_PROT_NONE guard regions at their low-address
+  // ends.
+  //
+  // Other stack regions may not be so well-behaved and thus if user_tag is not
+  // VM_MEMORY_STACK, the single region that was found is used as-is without
+  // trying to merge it with other adjacent regions.
+  if (user_tag == VM_MEMORY_STACK) {
+    mach_vm_address_t try_address = region_base;
+    mach_vm_address_t original_try_address;
+
+    while (try_address += region_size,
+           original_try_address = try_address,
+           (kr = MachVMRegionRecurseDeepest(task_,
+                                            &try_address,
+                                            &region_size,
+                                            &depth,
+                                            &protection,
+                                            &user_tag) == KERN_SUCCESS) &&
+               try_address == original_try_address &&
+               (protection & VM_PROT_READ) != 0 &&
+               user_tag == VM_MEMORY_STACK) {
+      total_region_size += region_size;
+    }
+
+    if (kr != KERN_SUCCESS && kr != KERN_INVALID_ADDRESS) {
+      // Tolerate KERN_INVALID_ADDRESS because it will be returned when there
+      // are no more regions in the map at or above the specified |try_address|.
+      MACH_LOG(INFO, kr) << "mach_vm_region_recurse";
+    }
+  }
+
+  *stack_region_size = total_region_size;
+  return region_base;
+}
+
+void ProcessReader::LocateRedZone(mach_vm_address_t* const start_address,
+                                  mach_vm_address_t* const region_base,
+                                  mach_vm_address_t* const region_size,
+                                  const unsigned int user_tag) {
+#if defined(ARCH_CPU_X86_FAMILY)
+  if (Is64Bit()) {
+    // x86_64 has a red zone. See AMD64 ABI 0.99.6,
+    // http://www.x86-64.org/documentation/abi.pdf, section 3.2.2, “The Stack
+    // Frame”.
+    const mach_vm_size_t kRedZoneSize = 128;
+    mach_vm_address_t red_zone_base =
+        *start_address >= kRedZoneSize ? *start_address - kRedZoneSize : 0;
+    bool red_zone_ok = false;
+    if (red_zone_base >= *region_base) {
+      // The red zone is within the region already discovered.
+      red_zone_ok = true;
+    } else if (red_zone_base < *region_base && user_tag == VM_MEMORY_STACK) {
+      // Probe to see if there’s a region immediately below the one already
+      // discovered.
+      mach_vm_address_t red_zone_region_base = red_zone_base;
+      mach_vm_size_t red_zone_region_size;
+      natural_t red_zone_depth = 0;
+      vm_prot_t red_zone_protection;
+      unsigned int red_zone_user_tag;
+      kern_return_t kr = MachVMRegionRecurseDeepest(task_,
+                                                    &red_zone_region_base,
+                                                    &red_zone_region_size,
+                                                    &red_zone_depth,
+                                                    &red_zone_protection,
+                                                    &red_zone_user_tag);
+      if (kr != KERN_SUCCESS) {
+        MACH_LOG(INFO, kr) << "mach_vm_region_recurse";
+        *start_address = *region_base;
+      } else if (red_zone_region_base + red_zone_region_size == *region_base &&
+                 (red_zone_protection & VM_PROT_READ) != 0 &&
+                 red_zone_user_tag == user_tag) {
+        // The region containing the red zone is immediately below the region
+        // already found, it’s readable (not the guard region), and it has the
+        // same user tag as the region already found, so merge them.
+        red_zone_ok = true;
+        *region_base -= red_zone_region_size;
+        *region_size += red_zone_region_size;
+      }
+    }
+
+    if (red_zone_ok) {
+      // Begin capturing from the base of the red zone (but not the entire
+      // region that encompasses the red zone).
+      *start_address = red_zone_base;
+    } else {
+      // The red zone would go lower into another region in memory, but no
+      // region was found. Memory can only be captured to an address as low as
+      // the base address of the region already found.
+      *start_address = *region_base;
+    }
+  }
+#endif
+}
+
+}  // namespace crashpad

util/mac/process_reader.h

@@ -0,0 +1,209 @@
+// 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_

util/mac/process_reader_test.cc

@@ -0,0 +1,572 @@
+// 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.
+
+#include "util/mac/process_reader.h"
+
+#include <dispatch/dispatch.h>
+#include <mach/mach.h>
+#include <string.h>
+
+#include <map>
+#include <string>
+
+#include "base/logging.h"
+#include "base/mac/scoped_mach_port.h"
+#include "base/posix/eintr_wrapper.h"
+#include "build/build_config.h"
+#include "gtest/gtest.h"
+#include "util/file/fd_io.h"
+#include "util/stdlib/pointer_container.h"
+#include "util/test/mac/mach_errors.h"
+#include "util/test/mac/mach_multiprocess.h"
+#include "util/test/errors.h"
+
+namespace {
+
+using namespace crashpad;
+using namespace crashpad::test;
+
+TEST(ProcessReader, SelfBasic) {
+  ProcessReader process_reader;
+  ASSERT_TRUE(process_reader.Initialize(mach_task_self()));
+
+#if !defined(ARCH_CPU_64_BITS)
+  EXPECT_FALSE(process_reader.Is64Bit());
+#else
+  EXPECT_TRUE(process_reader.Is64Bit());
+#endif
+
+  EXPECT_EQ(getpid(), process_reader.ProcessID());
+  EXPECT_EQ(getppid(), process_reader.ParentProcessID());
+
+  const char kTestMemory[] = "Some test memory";
+  char buffer[arraysize(kTestMemory)];
+  ASSERT_TRUE(process_reader.Memory()->Read(
+      reinterpret_cast<mach_vm_address_t>(kTestMemory),
+      sizeof(kTestMemory),
+      &buffer));
+  EXPECT_STREQ(kTestMemory, buffer);
+}
+
+const char kTestMemory[] = "Read me from another process";
+
+class ProcessReaderChild final : public MachMultiprocess {
+ public:
+  ProcessReaderChild() : MachMultiprocess() {}
+
+  ~ProcessReaderChild() {}
+
+ protected:
+  void Parent() override {
+    ProcessReader process_reader;
+    ASSERT_TRUE(process_reader.Initialize(ChildTask()));
+
+#if !defined(ARCH_CPU_64_BITS)
+    EXPECT_FALSE(process_reader.Is64Bit());
+#else
+    EXPECT_TRUE(process_reader.Is64Bit());
+#endif
+
+    EXPECT_EQ(getpid(), process_reader.ParentProcessID());
+    EXPECT_EQ(ChildPID(), process_reader.ProcessID());
+
+    int read_fd = ReadPipeFD();
+
+    mach_vm_address_t address;
+    int rv = ReadFD(read_fd, &address, sizeof(address));
+    ASSERT_EQ(static_cast<ssize_t>(sizeof(address)), rv)
+        << ErrnoMessage("read");
+
+    std::string read_string;
+    ASSERT_TRUE(process_reader.Memory()->ReadCString(address, &read_string));
+    EXPECT_EQ(kTestMemory, read_string);
+
+    // Tell the child that it’s OK to exit. The child needed to be kept alive
+    // until the parent finished working with it.
+    int write_fd = WritePipeFD();
+    char c = '\0';
+    rv = WriteFD(write_fd, &c, 1);
+    ASSERT_EQ(1, rv) << ErrnoMessage("write");
+  }
+
+  void Child() override {
+    int write_fd = WritePipeFD();
+
+    mach_vm_address_t address =
+        reinterpret_cast<mach_vm_address_t>(kTestMemory);
+    int rv = WriteFD(write_fd, &address, sizeof(address));
+    ASSERT_EQ(static_cast<ssize_t>(sizeof(address)), rv)
+        << ErrnoMessage("write");
+
+    // Wait for the parent to say that it’s OK to exit.
+    int read_fd = ReadPipeFD();
+    char c;
+    rv = ReadFD(read_fd, &c, 1);
+    ASSERT_EQ(1, rv) << ErrnoMessage("read");
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ProcessReaderChild);
+};
+
+TEST(ProcessReader, ChildBasic) {
+  ProcessReaderChild process_reader_child;
+  process_reader_child.Run();
+}
+
+// Returns a thread ID given a pthread_t. This wraps pthread_threadid_np() but
+// that function has a cumbersome interface because it returns a success value.
+// This function CHECKs success and returns the thread ID directly.
+uint64_t PthreadToThreadID(pthread_t pthread) {
+  uint64_t thread_id;
+  int rv = pthread_threadid_np(pthread, &thread_id);
+  CHECK_EQ(rv, 0);
+  return thread_id;
+}
+
+TEST(ProcessReader, SelfOneThread) {
+  ProcessReader process_reader;
+  ASSERT_TRUE(process_reader.Initialize(mach_task_self()));
+
+  const std::vector<ProcessReaderThread>& threads = process_reader.Threads();
+
+  // If other tests ran in this process previously, threads may have been
+  // created and may still be running. This check must look for at least one
+  // thread, not exactly one thread.
+  ASSERT_GE(threads.size(), 1u);
+
+  EXPECT_EQ(PthreadToThreadID(pthread_self()), threads[0].id);
+
+  base::mac::ScopedMachSendRight thread_self(mach_thread_self());
+  EXPECT_EQ(thread_self, threads[0].port);
+
+  EXPECT_EQ(0, threads[0].suspend_count);
+}
+
+class TestThreadPool {
+ public:
+  struct ThreadExpectation {
+    mach_vm_address_t stack_address;
+    int suspend_count;
+  };
+
+  TestThreadPool() : thread_infos_() {
+  }
+
+  // Resumes suspended threads, signals each thread’s exit semaphore asking it
+  // to exit, and joins each thread, blocking until they have all exited.
+  ~TestThreadPool() {
+    for (ThreadInfo* thread_info : thread_infos_) {
+      mach_port_t thread_port = pthread_mach_thread_np(thread_info->pthread);
+      while (thread_info->suspend_count > 0) {
+        kern_return_t kr = thread_resume(thread_port);
+        EXPECT_EQ(KERN_SUCCESS, kr) << MachErrorMessage(kr, "thread_resume");
+        --thread_info->suspend_count;
+      }
+    }
+
+    for (const ThreadInfo* thread_info : thread_infos_) {
+      dispatch_semaphore_signal(thread_info->exit_semaphore);
+    }
+
+    for (const ThreadInfo* thread_info : thread_infos_) {
+      int rv = pthread_join(thread_info->pthread, NULL);
+      CHECK_EQ(0, rv);
+    }
+  }
+
+  // Starts |thread_count| threads and waits on each thread’s ready semaphore,
+  // so that when this function returns, all threads have been started and have
+  // all run to the point that they’ve signalled that they are ready.
+  void StartThreads(size_t thread_count) {
+    ASSERT_TRUE(thread_infos_.empty());
+
+    for (size_t thread_index = 0; thread_index < thread_count; ++thread_index) {
+      ThreadInfo* thread_info = new ThreadInfo();
+      thread_infos_.push_back(thread_info);
+
+      int rv = pthread_create(&thread_info->pthread,
+                              NULL,
+                              ThreadMain,
+                              thread_info);
+      ASSERT_EQ(0, rv);
+    }
+
+    for (const ThreadInfo* thread_info : thread_infos_) {
+      long rv = dispatch_semaphore_wait(thread_info->ready_semaphore,
+                                        DISPATCH_TIME_FOREVER);
+      ASSERT_EQ(0, rv);
+    }
+
+    // If present, suspend the thread at indices 1 through 3 the same number of
+    // times as their index. This tests reporting of suspend counts.
+    for (size_t thread_index = 1;
+         thread_index < thread_infos_.size() && thread_index < 4;
+         ++thread_index) {
+      mach_port_t thread_port =
+          pthread_mach_thread_np(thread_infos_[thread_index]->pthread);
+      for (size_t suspend_count = 0;
+           suspend_count < thread_index;
+           ++suspend_count) {
+        kern_return_t kr = thread_suspend(thread_port);
+        EXPECT_EQ(KERN_SUCCESS, kr) << MachErrorMessage(kr, "thread_suspend");
+        if (kr == KERN_SUCCESS) {
+          ++thread_infos_[thread_index]->suspend_count;
+        }
+      }
+    }
+  }
+
+  uint64_t GetThreadInfo(size_t thread_index,
+                         ThreadExpectation* expectation) {
+    CHECK_LT(thread_index, thread_infos_.size());
+
+    const ThreadInfo* thread_info = thread_infos_[thread_index];
+    expectation->stack_address = thread_info->stack_address;
+    expectation->suspend_count = thread_info->suspend_count;
+
+    return PthreadToThreadID(thread_info->pthread);
+  }
+
+ private:
+  struct ThreadInfo {
+    ThreadInfo()
+        : pthread(NULL),
+          stack_address(0),
+          ready_semaphore(dispatch_semaphore_create(0)),
+          exit_semaphore(dispatch_semaphore_create(0)),
+          suspend_count(0) {
+    }
+
+    ~ThreadInfo() {
+      dispatch_release(exit_semaphore);
+      dispatch_release(ready_semaphore);
+    }
+
+    // The thread’s ID, set at the time the thread is created.
+    pthread_t pthread;
+
+    // An address somewhere within the thread’s stack. The thread sets this in
+    // its ThreadMain().
+    mach_vm_address_t stack_address;
+
+    // The worker thread signals ready_semaphore to indicate that it’s done
+    // setting up its ThreadInfo structure. The main thread waits on this
+    // semaphore before using any data that the worker thread is responsible for
+    // setting.
+    dispatch_semaphore_t ready_semaphore;
+
+    // The worker thread waits on exit_semaphore to determine when it’s safe to
+    // exit. The main thread signals exit_semaphore when it no longer needs the
+    // worker thread.
+    dispatch_semaphore_t exit_semaphore;
+
+    // The thread’s suspend count.
+    int suspend_count;
+  };
+
+  static void* ThreadMain(void* argument) {
+    ThreadInfo* thread_info = static_cast<ThreadInfo*>(argument);
+
+    thread_info->stack_address =
+        reinterpret_cast<mach_vm_address_t>(&thread_info);
+
+    dispatch_semaphore_signal(thread_info->ready_semaphore);
+    dispatch_semaphore_wait(thread_info->exit_semaphore, DISPATCH_TIME_FOREVER);
+
+    // Check this here after everything’s known to be synchronized, otherwise
+    // there’s a race between the parent thread storing this thread’s pthread_t
+    // in thread_info_pthread and this thread starting and attempting to access
+    // it.
+    CHECK_EQ(pthread_self(), thread_info->pthread);
+
+    return NULL;
+  }
+
+  // This is a PointerVector because the address of a ThreadInfo object is
+  // passed to each thread’s ThreadMain(), so they cannot move around in memory.
+  PointerVector<ThreadInfo> thread_infos_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestThreadPool);
+};
+
+typedef std::map<uint64_t, TestThreadPool::ThreadExpectation> ThreadMap;
+
+// Verifies that all of the threads in |threads|, obtained from ProcessReader,
+// agree with the expectation in |thread_map|. If |tolerate_extra_threads| is
+// true, |threads| is allowed to contain threads that are not listed in
+// |thread_map|. This is useful when testing situations where code outside of
+// the test’s control (such as system libraries) may start threads, or may have
+// started threads prior to a test’s execution.
+void ExpectSeveralThreads(ThreadMap* thread_map,
+                          const std::vector<ProcessReaderThread>& threads,
+                          const bool tolerate_extra_threads) {
+  if (tolerate_extra_threads) {
+    ASSERT_GE(threads.size(), thread_map->size());
+  } else {
+    ASSERT_EQ(thread_map->size(), threads.size());
+  }
+
+  for (size_t thread_index = 0; thread_index < threads.size(); ++thread_index) {
+    const ProcessReaderThread& thread = threads[thread_index];
+    mach_vm_address_t thread_stack_region_end =
+        thread.stack_region_address + thread.stack_region_size;
+
+    const auto& iterator = thread_map->find(thread.id);
+    if (!tolerate_extra_threads) {
+      // Make sure that the thread is in the expectation map.
+      ASSERT_NE(thread_map->end(), iterator);
+    }
+
+    if (iterator != thread_map->end()) {
+      EXPECT_GE(iterator->second.stack_address, thread.stack_region_address);
+      EXPECT_LT(iterator->second.stack_address, thread_stack_region_end);
+
+      EXPECT_EQ(iterator->second.suspend_count, thread.suspend_count);
+
+      // Remove the thread from the expectation map since it’s already been
+      // found. This makes it easy to check for duplicate thread IDs, and makes
+      // it easy to check that all expected threads were found.
+      thread_map->erase(iterator);
+    }
+
+    // Make sure that this thread’s ID, stack region, and port don’t conflict
+    // with any other thread’s. Each thread should have a unique value for its
+    // ID and port, and each should have its own stack that doesn’t touch any
+    // other thread’s stack.
+    for (size_t other_thread_index = 0;
+         other_thread_index < threads.size();
+         ++other_thread_index) {
+      if (thread_index == other_thread_index) {
+        continue;
+      }
+
+      const ProcessReaderThread& other_thread = threads[other_thread_index];
+
+      EXPECT_NE(thread.id, other_thread.id);
+      EXPECT_NE(thread.port, other_thread.port);
+
+      mach_vm_address_t other_thread_stack_region_end =
+          other_thread.stack_region_address + other_thread.stack_region_size;
+      EXPECT_FALSE(
+          thread.stack_region_address >= other_thread.stack_region_address &&
+          thread.stack_region_address < other_thread_stack_region_end);
+      EXPECT_FALSE(
+          thread_stack_region_end > other_thread.stack_region_address &
+          thread_stack_region_end <= other_thread_stack_region_end);
+    }
+  }
+
+  // Make sure that each expected thread was found.
+  EXPECT_TRUE(thread_map->empty());
+}
+
+TEST(ProcessReader, SelfSeveralThreads) {
+  // Set up the ProcessReader here, before any other threads are running. This
+  // tests that the threads it returns are lazily initialized as a snapshot of
+  // the threads at the time of the first call to Threads(), and not at the
+  // time the ProcessReader was created or initialized.
+  ProcessReader process_reader;
+  ASSERT_TRUE(process_reader.Initialize(mach_task_self()));
+
+  TestThreadPool thread_pool;
+  const size_t kChildThreads = 16;
+  thread_pool.StartThreads(kChildThreads);
+  if (Test::HasFatalFailure()) {
+    return;
+  }
+
+  // Build a map of all expected threads, keyed by each thread’s ID. The values
+  // are addresses that should lie somewhere within each thread’s stack.
+  ThreadMap thread_map;
+  const uint64_t self_thread_id = PthreadToThreadID(pthread_self());
+  TestThreadPool::ThreadExpectation expectation;
+  expectation.stack_address = reinterpret_cast<mach_vm_address_t>(&thread_map);
+  expectation.suspend_count = 0;
+  thread_map[self_thread_id] = expectation;
+  for (size_t thread_index = 0; thread_index < kChildThreads; ++thread_index) {
+    uint64_t thread_id = thread_pool.GetThreadInfo(thread_index, &expectation);
+
+    // There can’t be any duplicate thread IDs.
+    EXPECT_EQ(0u, thread_map.count(thread_id));
+
+    thread_map[thread_id] = expectation;
+  }
+
+  const std::vector<ProcessReaderThread>& threads = process_reader.Threads();
+
+  // Other tests that have run previously may have resulted in the creation of
+  // threads that still exist, so pass true for |tolerate_extra_threads|.
+  ExpectSeveralThreads(&thread_map, threads, true);
+
+  // When testing in-process, verify that when this thread shows up in the
+  // vector, it has the expected thread port, and that this thread port only
+  // shows up once.
+  base::mac::ScopedMachSendRight thread_self(mach_thread_self());
+  bool found_thread_self = false;
+  for (const ProcessReaderThread& thread : threads) {
+    if (thread.port == thread_self) {
+      EXPECT_FALSE(found_thread_self);
+      found_thread_self = true;
+      EXPECT_EQ(self_thread_id, thread.id);
+    }
+  }
+  EXPECT_TRUE(found_thread_self);
+}
+
+class ProcessReaderThreadedChild final : public MachMultiprocess {
+ public:
+  explicit ProcessReaderThreadedChild(size_t thread_count)
+      : MachMultiprocess(),
+        thread_count_(thread_count) {
+  }
+
+  ~ProcessReaderThreadedChild() {}
+
+ protected:
+  void Parent() override {
+    ProcessReader process_reader;
+    ASSERT_TRUE(process_reader.Initialize(ChildTask()));
+
+    int read_fd = ReadPipeFD();
+
+    // Build a map of all expected threads, keyed by each thread’s ID, and with
+    // addresses that should lie somewhere within each thread’s stack as values.
+    // These IDs and addresses all come from the child process via the pipe.
+    ThreadMap thread_map;
+    for (size_t thread_index = 0;
+         thread_index < thread_count_ + 1;
+         ++thread_index) {
+      uint64_t thread_id;
+      int rv = ReadFD(read_fd, &thread_id, sizeof(thread_id));
+      ASSERT_EQ(static_cast<ssize_t>(sizeof(thread_id)), rv)
+          << ErrnoMessage("read");
+
+      TestThreadPool::ThreadExpectation expectation;
+      rv = ReadFD(read_fd,
+                  &expectation.stack_address,
+                  sizeof(expectation.stack_address));
+      ASSERT_EQ(static_cast<ssize_t>(sizeof(expectation.stack_address)), rv)
+          << ErrnoMessage("read");
+
+      rv = ReadFD(read_fd,
+                  &expectation.suspend_count,
+                  sizeof(expectation.suspend_count));
+      ASSERT_EQ(static_cast<ssize_t>(sizeof(expectation.suspend_count)), rv)
+          << ErrnoMessage("read");
+
+      // There can’t be any duplicate thread IDs.
+      EXPECT_EQ(0u, thread_map.count(thread_id));
+
+      thread_map[thread_id] = expectation;
+    }
+
+    const std::vector<ProcessReaderThread>& threads = process_reader.Threads();
+
+    // The child shouldn’t have any threads other than its main thread and the
+    // ones it created in its pool, so pass false for |tolerate_extra_threads|.
+    ExpectSeveralThreads(&thread_map, threads, false);
+
+    // Tell the child that it’s OK to exit. The child needed to be kept alive
+    // until the parent finished working with it.
+    int write_fd = WritePipeFD();
+    char c = '\0';
+    int rv = WriteFD(write_fd, &c, 1);
+    ASSERT_EQ(1, rv) << ErrnoMessage("write");
+  }
+
+  void Child() override {
+    TestThreadPool thread_pool;
+    thread_pool.StartThreads(thread_count_);
+    if (testing::Test::HasFatalFailure()) {
+      return;
+    }
+
+    int write_fd = WritePipeFD();
+
+    // This thread isn’t part of the thread pool, but the parent will be able
+    // to inspect it. Write an entry for it.
+    uint64_t thread_id = PthreadToThreadID(pthread_self());
+
+    int rv = WriteFD(write_fd, &thread_id, sizeof(thread_id));
+    ASSERT_EQ(static_cast<ssize_t>(sizeof(thread_id)), rv)
+        << ErrnoMessage("write");
+
+    TestThreadPool::ThreadExpectation expectation;
+    expectation.stack_address = reinterpret_cast<mach_vm_address_t>(&thread_id);
+    expectation.suspend_count = 0;
+
+    rv = WriteFD(write_fd,
+                 &expectation.stack_address,
+                 sizeof(expectation.stack_address));
+    ASSERT_EQ(static_cast<ssize_t>(sizeof(expectation.stack_address)), rv)
+        << ErrnoMessage("write");
+
+    rv = WriteFD(write_fd,
+                 &expectation.suspend_count,
+                 sizeof(expectation.suspend_count));
+    ASSERT_EQ(static_cast<ssize_t>(sizeof(expectation.suspend_count)), rv)
+        << ErrnoMessage("write");
+
+    // Write an entry for everything in the thread pool.
+    for (size_t thread_index = 0;
+         thread_index < thread_count_;
+         ++thread_index) {
+      uint64_t thread_id =
+          thread_pool.GetThreadInfo(thread_index, &expectation);
+
+      rv = WriteFD(write_fd, &thread_id, sizeof(thread_id));
+      ASSERT_EQ(static_cast<ssize_t>(sizeof(thread_id)), rv)
+          << ErrnoMessage("write");
+
+      rv = WriteFD(write_fd,
+                   &expectation.stack_address,
+                   sizeof(expectation.stack_address));
+      ASSERT_EQ(static_cast<ssize_t>(sizeof(expectation.stack_address)), rv)
+          << ErrnoMessage("write");
+
+      rv = WriteFD(write_fd,
+                   &expectation.suspend_count,
+                   sizeof(expectation.suspend_count));
+      ASSERT_EQ(static_cast<ssize_t>(sizeof(expectation.suspend_count)), rv)
+          << ErrnoMessage("write");
+    }
+
+    // Wait for the parent to say that it’s OK to exit.
+    int read_fd = ReadPipeFD();
+    char c;
+    rv = ReadFD(read_fd, &c, 1);
+    ASSERT_EQ(1, rv) << ErrnoMessage("read");
+  }
+
+ private:
+  size_t thread_count_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProcessReaderThreadedChild);
+};
+
+TEST(ProcessReader, ChildOneThread) {
+  // The main thread plus zero child threads equals one thread.
+  const size_t kChildThreads = 0;
+  ProcessReaderThreadedChild process_reader_threaded_child(kChildThreads);
+  process_reader_threaded_child.Run();
+}
+
+TEST(ProcessReader, ChildSeveralThreads) {
+  const size_t kChildThreads = 64;
+  ProcessReaderThreadedChild process_reader_threaded_child(kChildThreads);
+  process_reader_threaded_child.Run();
+}
+
+}  // namespace

util/stdlib/pointer_container.h

@@ -0,0 +1,43 @@
+// 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_STDLIB_POINTER_CONTAINER_H_
+#define CRASHPAD_UTIL_STDLIB_POINTER_CONTAINER_H_
+
+#include <vector>
+
+#include "base/stl_util.h"
+
+namespace crashpad {
+
+// PointerContainer allows an STL container such as std::vector<> to “own”
+// pointer elements stored in it. When the container is destroyed, “delete” will
+// be called on its pointer elements.
+template <typename ContainerType>
+class PointerContainer : public ContainerType {
+ public:
+  PointerContainer() : ContainerType(), pointer_deleter_(this) {}
+
+  ~PointerContainer() {}
+
+ private:
+  STLElementDeleter<ContainerType> pointer_deleter_;
+};
+
+template <typename T>
+class PointerVector : public PointerContainer<std::vector<T*> > {};
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_UTIL_STDLIB_POINTER_CONTAINER_H_

util/util.gyp

@@ -38,6 +38,8 @@
         'mac/mac_util.h',
         'mac/service_management.cc',
         'mac/service_management.h',
+        'mac/process_reader.cc',
+        'mac/process_reader.h',
         'mach/bootstrap.cc',
         'mach/bootstrap.h',
         'mach/task_memory.cc',
@@ -54,6 +56,7 @@
         'posix/process_util_mac.cc',
         'stdlib/cxx.h',
         'stdlib/objc.h',
+        'stdlib/pointer_container.h',
         'stdlib/strlcpy.cc',
         'stdlib/strlcpy.h',
       ],
@@ -102,6 +105,7 @@
         'file/string_file_writer_test.cc',
         'mac/launchd_test.mm',
         'mac/mac_util_test.mm',
+        'mac/process_reader_test.cc',
         'mac/service_management_test.mm',
         'mach/bootstrap_test.cc',
         'mach/task_memory_test.cc',