brintos

brintos / llvm-project-archived public Read only

0
0
Text · 23.2 KiB · 618fce3 Raw
593 lines · cpp
1//===-- MachException.cpp ---------------------------------------*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9//  Created by Greg Clayton on 6/18/07.10//11//===----------------------------------------------------------------------===//12 13#include "MachException.h"14#include "DNB.h"15#include "DNBError.h"16#include "DNBLog.h"17#include "MachProcess.h"18#include "SysSignal.h"19#include <cerrno>20#include <inttypes.h>21#include <sys/ptrace.h>22#include <sys/types.h>23 24static void AppendExceptionData(std::vector<mach_exception_data_type_t> &out,25                                mach_exception_data_t data,26                                mach_msg_type_number_t count) {27  mach_exception_data_type_t buf;28  for (mach_msg_type_number_t i = 0; i < count; ++i) {29    // The input Data we receive need not be aligned correctly.30    // Perform an unaligned copy by pretending we're dealing with31    // a char* buffer. This is required to work around UBSAN/ASAN32    // "misaligned address" errors.33    auto *src = reinterpret_cast<char *>(data + i);34    memcpy(&buf, src, sizeof(mach_exception_data_type_t));35    out.push_back(buf);36  }37}38 39// Routine mach_exception_raise40extern "C" kern_return_t41catch_mach_exception_raise(mach_port_t exception_port, mach_port_t thread,42                           mach_port_t task, exception_type_t exception,43                           mach_exception_data_t code,44                           mach_msg_type_number_t codeCnt);45 46extern "C" kern_return_t catch_mach_exception_raise_state(47    mach_port_t exception_port, exception_type_t exception,48    const mach_exception_data_t code, mach_msg_type_number_t codeCnt,49    int *flavor, const thread_state_t old_state,50    mach_msg_type_number_t old_stateCnt, thread_state_t new_state,51    mach_msg_type_number_t *new_stateCnt);52 53// Routine mach_exception_raise_state_identity54extern "C" kern_return_t catch_mach_exception_raise_state_identity(55    mach_port_t exception_port, mach_port_t thread, mach_port_t task,56    exception_type_t exception, mach_exception_data_t code,57    mach_msg_type_number_t codeCnt, int *flavor, thread_state_t old_state,58    mach_msg_type_number_t old_stateCnt, thread_state_t new_state,59    mach_msg_type_number_t *new_stateCnt);60 61extern "C" boolean_t mach_exc_server(mach_msg_header_t *InHeadP,62                                     mach_msg_header_t *OutHeadP);63 64// Note: g_message points to the storage allocated to catch the data from65// catching the current exception raise. It's populated when we catch a raised66// exception which can't immediately be replied to.67//68// If it becomes possible to catch exceptions from multiple threads69// simultaneously, accesses to g_message would need to be mutually exclusive.70static MachException::Data *g_message = NULL;71 72extern "C" kern_return_t catch_mach_exception_raise_state(73    mach_port_t exc_port, exception_type_t exc_type,74    const mach_exception_data_t exc_data, mach_msg_type_number_t exc_data_count,75    int *flavor, const thread_state_t old_state,76    mach_msg_type_number_t old_stateCnt, thread_state_t new_state,77    mach_msg_type_number_t *new_stateCnt) {78  if (DNBLogCheckLogBit(LOG_EXCEPTIONS)) {79    DNBLogThreaded("::%s ( exc_port = 0x%4.4x, exc_type = %d ( %s ), exc_data "80                   "= 0x%llx, exc_data_count = %d)",81                   __FUNCTION__, exc_port, exc_type,82                   MachException::Name(exc_type), (uint64_t)exc_data,83                   exc_data_count);84  }85  return KERN_FAILURE;86}87 88extern "C" kern_return_t catch_mach_exception_raise_state_identity(89    mach_port_t exc_port, mach_port_t thread_port, mach_port_t task_port,90    exception_type_t exc_type, mach_exception_data_t exc_data,91    mach_msg_type_number_t exc_data_count, int *flavor,92    thread_state_t old_state, mach_msg_type_number_t old_stateCnt,93    thread_state_t new_state, mach_msg_type_number_t *new_stateCnt) {94  if (DNBLogCheckLogBit(LOG_EXCEPTIONS)) {95    DNBLogThreaded("::%s ( exc_port = 0x%4.4x, thd_port = 0x%4.4x, tsk_port = "96                   "0x%4.4x, exc_type = %d ( %s ), exc_data[%d] = { 0x%llx, "97                   "0x%llx })",98                   __FUNCTION__, exc_port, thread_port, task_port, exc_type,99                   MachException::Name(exc_type), exc_data_count,100                   (uint64_t)(exc_data_count > 0 ? exc_data[0] : 0xBADDBADD),101                   (uint64_t)(exc_data_count > 1 ? exc_data[1] : 0xBADDBADD));102  }103 104  return KERN_FAILURE;105}106 107extern "C" kern_return_t108catch_mach_exception_raise(mach_port_t exc_port, mach_port_t thread_port,109                           mach_port_t task_port, exception_type_t exc_type,110                           mach_exception_data_t exc_data,111                           mach_msg_type_number_t exc_data_count) {112  if (DNBLogCheckLogBit(LOG_EXCEPTIONS)) {113    std::vector<mach_exception_data_type_t> exc_datas;114    AppendExceptionData(exc_datas, exc_data, exc_data_count);115    DNBLogThreaded("::%s ( exc_port = 0x%4.4x, thd_port = 0x%4.4x, tsk_port = "116                   "0x%4.4x, exc_type = %d ( %s ), exc_data[%d] = { 0x%" PRIx64117                   ", "118                   "0x%" PRIx64 " })",119                   __FUNCTION__, exc_port, thread_port, task_port, exc_type,120                   MachException::Name(exc_type), exc_data_count,121                   (exc_data_count > 0 ? exc_datas[0] : 0xBADDBADD),122                   (exc_data_count > 1 ? exc_datas[1] : 0xBADDBADD));123  }124  g_message->exc_type = 0;125  g_message->exc_data.clear();126 127  if (task_port == g_message->task_port) {128    g_message->task_port = task_port;129    g_message->thread_port = thread_port;130    g_message->exc_type = exc_type;131    AppendExceptionData(g_message->exc_data, exc_data, exc_data_count);132    return KERN_SUCCESS;133  } else if (!MachTask::IsValid(g_message->task_port)) {134    // Our original exception port isn't valid anymore check for a SIGTRAP135    if (exc_type == EXC_SOFTWARE && exc_data_count == 2 &&136        exc_data[0] == EXC_SOFT_SIGNAL && exc_data[1] == SIGTRAP) {137      // We got a SIGTRAP which indicates we might have exec'ed and possibly138      // lost our old task port during the exec, so we just need to switch over139      // to using this new task port140      g_message->task_port = task_port;141      g_message->thread_port = thread_port;142      g_message->exc_type = exc_type;143      AppendExceptionData(g_message->exc_data, exc_data, exc_data_count);144      return KERN_SUCCESS;145    }146  }147  return KERN_FAILURE;148}149 150void MachException::Message::Dump() const {151  DNBLogThreadedIf(LOG_EXCEPTIONS, "  exc_msg { bits = 0x%8.8x size = 0x%8.8x "152                                   "remote-port = 0x%8.8x local-port = 0x%8.8x "153                                   "reserved = 0x%8.8x id = 0x%8.8x } ",154                   exc_msg.hdr.msgh_bits, exc_msg.hdr.msgh_size,155                   exc_msg.hdr.msgh_remote_port, exc_msg.hdr.msgh_local_port,156                   exc_msg.hdr.msgh_reserved, exc_msg.hdr.msgh_id);157 158  DNBLogThreadedIf(LOG_EXCEPTIONS, "reply_msg { bits = 0x%8.8x size = 0x%8.8x "159                                   "remote-port = 0x%8.8x local-port = 0x%8.8x "160                                   "reserved = 0x%8.8x id = 0x%8.8x }",161                   reply_msg.hdr.msgh_bits, reply_msg.hdr.msgh_size,162                   reply_msg.hdr.msgh_remote_port,163                   reply_msg.hdr.msgh_local_port, reply_msg.hdr.msgh_reserved,164                   reply_msg.hdr.msgh_id);165 166  state.Dump();167}168 169bool MachException::Data::GetStopInfo(170    struct DNBThreadStopInfo *stop_info) const {171  // Zero out the structure.172  memset(stop_info, 0, sizeof(struct DNBThreadStopInfo));173 174  if (exc_type == 0) {175    stop_info->reason = eStopTypeInvalid;176    return true;177  }178 179#if defined(__arm64__) || defined(__aarch64__)180  if (exc_type == EXC_BREAKPOINT && exc_data[0] == EXC_ARM_DA_DEBUG &&181      exc_data.size() > 1) {182    stop_info->reason = eStopTypeWatchpoint;183    stop_info->details.watchpoint.mach_exception_addr = exc_data[1];184    stop_info->details.watchpoint.addr = INVALID_NUB_ADDRESS;185    if (exc_data.size() > 2) {186      stop_info->details.watchpoint.hw_idx = exc_data[2];187    }188    return true;189  }190#endif191 192  // We always stop with a mach exceptions193  stop_info->reason = eStopTypeException;194  // Save the EXC_XXXX exception type195  stop_info->details.exception.type = exc_type;196 197  // Fill in a text description198  const char *exc_name = MachException::Name(exc_type);199  char *desc = stop_info->description;200  const char *end_desc = desc + DNB_THREAD_STOP_INFO_MAX_DESC_LENGTH;201  if (exc_name)202    desc +=203        snprintf(desc, DNB_THREAD_STOP_INFO_MAX_DESC_LENGTH, "%s", exc_name);204  else205    desc +=206        snprintf(desc, DNB_THREAD_STOP_INFO_MAX_DESC_LENGTH, "%i", exc_type);207 208  stop_info->details.exception.data_count = exc_data.size();209 210  int soft_signal = SoftSignal();211  if (soft_signal) {212    if (desc < end_desc) {213      const char *sig_str = SysSignal::Name(soft_signal);214      snprintf(desc, end_desc - desc, " EXC_SOFT_SIGNAL( %i ( %s ))",215               soft_signal, sig_str ? sig_str : "unknown signal");216    }217  } else {218    // No special disassembly for exception data, just219    size_t idx;220    if (desc < end_desc) {221      desc += snprintf(desc, end_desc - desc, " data[%llu] = {",222                       (uint64_t)stop_info->details.exception.data_count);223 224      for (idx = 0;225           desc < end_desc && idx < stop_info->details.exception.data_count;226           ++idx)227        desc += snprintf(228            desc, end_desc - desc, "0x%llx%c", (uint64_t)exc_data[idx],229            ((idx + 1 == stop_info->details.exception.data_count) ? '}' : ','));230    }231  }232 233  // Copy the exception data234  size_t i;235  for (i = 0; i < stop_info->details.exception.data_count; i++)236    stop_info->details.exception.data[i] = exc_data[i];237 238  return true;239}240 241void MachException::Data::DumpStopReason() const {242  int soft_signal = SoftSignal();243  if (soft_signal) {244    const char *signal_str = SysSignal::Name(soft_signal);245    if (signal_str)246      DNBLog("signal(%s)", signal_str);247    else248      DNBLog("signal(%i)", soft_signal);249    return;250  }251  DNBLog("%s", Name(exc_type));252}253 254kern_return_t MachException::Message::Receive(mach_port_t port,255                                              mach_msg_option_t options,256                                              mach_msg_timeout_t timeout,257                                              mach_port_t notify_port) {258  DNBError err;259  const bool log_exceptions = DNBLogCheckLogBit(LOG_EXCEPTIONS);260  mach_msg_timeout_t mach_msg_timeout =261      (options & MACH_RCV_TIMEOUT) ? timeout : 0;262  if (log_exceptions && ((options & MACH_RCV_TIMEOUT) == 0)) {263    // Dump this log message if we have no timeout in case it never returns264    DNBLogThreaded("::mach_msg ( msg->{bits = %#x, size = %u remote_port = "265                   "%#x, local_port = %#x, reserved = 0x%x, id = 0x%x}, option "266                   "= %#x, send_size = 0, rcv_size = %llu, rcv_name = %#x, "267                   "timeout = %u, notify = %#x)",268                   exc_msg.hdr.msgh_bits, exc_msg.hdr.msgh_size,269                   exc_msg.hdr.msgh_remote_port, exc_msg.hdr.msgh_local_port,270                   exc_msg.hdr.msgh_reserved, exc_msg.hdr.msgh_id, options,271                   (uint64_t)sizeof(exc_msg.data), port, mach_msg_timeout,272                   notify_port);273  }274 275  err = ::mach_msg(&exc_msg.hdr,276                   options,              // options277                   0,                    // Send size278                   sizeof(exc_msg.data), // Receive size279                   port,             // exception port to watch for exception on280                   mach_msg_timeout, // timeout in msec (obeyed only if281                                     // MACH_RCV_TIMEOUT is ORed into the282                                     // options parameter)283                   notify_port);284 285  // Dump any errors we get286  if (log_exceptions) {287    err.LogThreaded("::mach_msg ( msg->{bits = %#x, size = %u remote_port = "288                    "%#x, local_port = %#x, reserved = 0x%x, id = 0x%x}, "289                    "option = %#x, send_size = %u, rcv_size = %u, rcv_name = "290                    "%#x, timeout = %u, notify = %#x)",291                    exc_msg.hdr.msgh_bits, exc_msg.hdr.msgh_size,292                    exc_msg.hdr.msgh_remote_port, exc_msg.hdr.msgh_local_port,293                    exc_msg.hdr.msgh_reserved, exc_msg.hdr.msgh_id, options, 0,294                    sizeof(exc_msg.data), port, mach_msg_timeout, notify_port);295  }296  return err.Status();297}298 299bool MachException::Message::CatchExceptionRaise(task_t task) {300  bool success = false;301  state.task_port = task;302  g_message = &state;303  // The exc_server function is the MIG generated server handling function304  // to handle messages from the kernel relating to the occurrence of an305  // exception in a thread. Such messages are delivered to the exception port306  // set via thread_set_exception_ports or task_set_exception_ports. When an307  // exception occurs in a thread, the thread sends an exception message to308  // its exception port, blocking in the kernel waiting for the receipt of a309  // reply. The exc_server function performs all necessary argument handling310  // for this kernel message and calls catch_exception_raise,311  // catch_exception_raise_state or catch_exception_raise_state_identity,312  // which should handle the exception. If the called routine returns313  // KERN_SUCCESS, a reply message will be sent, allowing the thread to314  // continue from the point of the exception; otherwise, no reply message315  // is sent and the called routine must have dealt with the exception316  // thread directly.317  if (mach_exc_server(&exc_msg.hdr, &reply_msg.hdr)) {318    success = true;319  } else if (DNBLogCheckLogBit(LOG_EXCEPTIONS)) {320    DNBLogThreaded("mach_exc_server returned zero...");321  }322  g_message = NULL;323  return success;324}325 326kern_return_t MachException::Message::Reply(MachProcess *process, int signal) {327  // Reply to the exception...328  DNBError err;329 330  // If we had a soft signal, we need to update the thread first so it can331  // continue without signaling332  int soft_signal = state.SoftSignal();333  if (soft_signal) {334    int state_pid = -1;335    if (process->Task().TaskPort() == state.task_port) {336      // This is our task, so we can update the signal to send to it337      state_pid = process->ProcessID();338      soft_signal = signal;339    } else {340      err = ::pid_for_task(state.task_port, &state_pid);341    }342 343    assert(state_pid != -1);344    if (state_pid != -1) {345      errno = 0;346      if (::ptrace(PT_THUPDATE, state_pid,347                   (caddr_t)((uintptr_t)state.thread_port), soft_signal) != 0)348        err.SetError(errno, DNBError::POSIX);349      else350        err.Clear();351 352      if (DNBLogCheckLogBit(LOG_EXCEPTIONS) || err.Fail())353        err.LogThreaded("::ptrace (request = PT_THUPDATE, pid = 0x%4.4x, tid = "354                        "0x%4.4x, signal = %i)",355                        state_pid, state.thread_port, soft_signal);356    }357  }358 359  DNBLogThreadedIf(360      LOG_EXCEPTIONS, "::mach_msg ( msg->{bits = %#x, size = %u, remote_port = "361                      "%#x, local_port = %#x, reserved = 0x%x, id = 0x%x}, "362                      "option = %#x, send_size = %u, rcv_size = %u, rcv_name = "363                      "%#x, timeout = %u, notify = %#x)",364      reply_msg.hdr.msgh_bits, reply_msg.hdr.msgh_size,365      reply_msg.hdr.msgh_remote_port, reply_msg.hdr.msgh_local_port,366      reply_msg.hdr.msgh_reserved, reply_msg.hdr.msgh_id,367      MACH_SEND_MSG | MACH_SEND_INTERRUPT, reply_msg.hdr.msgh_size, 0,368      MACH_PORT_NULL, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);369 370  err = ::mach_msg(&reply_msg.hdr, MACH_SEND_MSG | MACH_SEND_INTERRUPT,371                   reply_msg.hdr.msgh_size, 0, MACH_PORT_NULL,372                   MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);373 374  if (err.Fail()) {375    if (err.Status() == MACH_SEND_INTERRUPTED) {376      if (DNBLogCheckLogBit(LOG_EXCEPTIONS))377        err.LogThreaded("::mach_msg() - send interrupted");378      // TODO: keep retrying to reply???379    } else {380      if (state.task_port == process->Task().TaskPort()) {381        DNBLogThreaded("error: mach_msg() returned an error when replying to a "382                       "mach exception: error = %u",383                       err.Status());384      } else {385        if (DNBLogCheckLogBit(LOG_EXCEPTIONS))386          err.LogThreaded("::mach_msg() - failed (child of task)");387      }388    }389  }390 391  return err.Status();392}393 394void MachException::Data::Dump() const {395  const char *exc_type_name = MachException::Name(exc_type);396  DNBLogThreadedIf(397      LOG_EXCEPTIONS, "    state { task_port = 0x%4.4x, thread_port =  "398                      "0x%4.4x, exc_type = %i (%s) ...",399      task_port, thread_port, exc_type, exc_type_name ? exc_type_name : "???");400 401  const size_t exc_data_count = exc_data.size();402  // Dump any special exception data contents403  int soft_signal = SoftSignal();404  if (soft_signal != 0) {405    const char *sig_str = SysSignal::Name(soft_signal);406    DNBLogThreadedIf(LOG_EXCEPTIONS,407                     "            exc_data: EXC_SOFT_SIGNAL (%i (%s))",408                     soft_signal, sig_str ? sig_str : "unknown signal");409  } else {410    // No special disassembly for this data, just dump the data411    size_t idx;412    for (idx = 0; idx < exc_data_count; ++idx) {413      DNBLogThreadedIf(LOG_EXCEPTIONS, "            exc_data[%llu]: 0x%llx",414                       (uint64_t)idx, (uint64_t)exc_data[idx]);415    }416  }417}418 419// The EXC_MASK_ALL value hard-coded here so that lldb can be built420// on a new OS with an older deployment target .  The new OS may have421// an addition to its EXC_MASK_ALL that the old OS will not recognize -422// <mach/exception_types.h> doesn't vary the value based on the deployment423// target.  So we need a known set of masks that can be assumed to be424// valid when running on an older OS.  We'll fall back to trying425// PREV_EXC_MASK_ALL if the EXC_MASK_ALL value lldb was compiled with is426// not recognized.427 428#define PREV_EXC_MASK_ALL (EXC_MASK_BAD_ACCESS |                \429                         EXC_MASK_BAD_INSTRUCTION |             \430                         EXC_MASK_ARITHMETIC |                  \431                         EXC_MASK_EMULATION |                   \432                         EXC_MASK_SOFTWARE |                    \433                         EXC_MASK_BREAKPOINT |                  \434                         EXC_MASK_SYSCALL |                     \435                         EXC_MASK_MACH_SYSCALL |                \436                         EXC_MASK_RPC_ALERT |                   \437                         EXC_MASK_RESOURCE |                    \438                         EXC_MASK_GUARD |                       \439                         EXC_MASK_MACHINE)440 441#define LLDB_EXC_MASK EXC_MASK_ALL442 443kern_return_t MachException::PortInfo::Save(task_t task) {444  DNBLogThreadedIf(LOG_EXCEPTIONS | LOG_VERBOSE,445                   "MachException::PortInfo::Save ( task = 0x%4.4x )", task);446  // Be careful to be able to have debugserver built on a newer OS than what447  // it is currently running on by being able to start with all exceptions448  // and back off to just what is supported on the current system449  DNBError err;450 451  mask = LLDB_EXC_MASK;452 453  count = (sizeof(ports) / sizeof(ports[0]));454  err = ::task_get_exception_ports(task, mask, masks, &count, ports, behaviors,455                                   flavors);456  if (DNBLogCheckLogBit(LOG_EXCEPTIONS) || err.Fail())457    err.LogThreaded("::task_get_exception_ports ( task = 0x%4.4x, mask = 0x%x, "458                    "maskCnt => %u, ports, behaviors, flavors )",459                    task, mask, count);460 461  if (err.Status() == KERN_INVALID_ARGUMENT && mask != PREV_EXC_MASK_ALL) {462    mask = PREV_EXC_MASK_ALL;463    count = (sizeof(ports) / sizeof(ports[0]));464    err = ::task_get_exception_ports(task, mask, masks, &count, ports,465                                     behaviors, flavors);466    if (DNBLogCheckLogBit(LOG_EXCEPTIONS) || err.Fail())467      err.LogThreaded("::task_get_exception_ports ( task = 0x%4.4x, mask = "468                      "0x%x, maskCnt => %u, ports, behaviors, flavors )",469                      task, mask, count);470  }471  if (err.Fail()) {472    mask = 0;473    count = 0;474  }475  return err.Status();476}477 478kern_return_t MachException::PortInfo::Restore(task_t task) {479  DNBLogThreadedIf(LOG_EXCEPTIONS | LOG_VERBOSE,480                   "MachException::PortInfo::Restore( task = 0x%4.4x )", task);481  uint32_t i = 0;482  DNBError err;483  if (count > 0) {484    for (i = 0; i < count; i++) {485      err = ::task_set_exception_ports(task, masks[i], ports[i], behaviors[i],486                                       flavors[i]);487      if (DNBLogCheckLogBit(LOG_EXCEPTIONS) || err.Fail()) {488        err.LogThreaded("::task_set_exception_ports ( task = 0x%4.4x, "489                        "exception_mask = 0x%8.8x, new_port = 0x%4.4x, "490                        "behavior = 0x%8.8x, new_flavor = 0x%8.8x )",491                        task, masks[i], ports[i], behaviors[i], flavors[i]);492        // Bail if we encounter any errors493      }494 495      if (err.Fail())496        break;497    }498  }499  count = 0;500  return err.Status();501}502 503const char *MachException::Name(exception_type_t exc_type) {504  switch (exc_type) {505  case EXC_BAD_ACCESS:506    return "EXC_BAD_ACCESS";507  case EXC_BAD_INSTRUCTION:508    return "EXC_BAD_INSTRUCTION";509  case EXC_ARITHMETIC:510    return "EXC_ARITHMETIC";511  case EXC_EMULATION:512    return "EXC_EMULATION";513  case EXC_SOFTWARE:514    return "EXC_SOFTWARE";515  case EXC_BREAKPOINT:516    return "EXC_BREAKPOINT";517  case EXC_SYSCALL:518    return "EXC_SYSCALL";519  case EXC_MACH_SYSCALL:520    return "EXC_MACH_SYSCALL";521  case EXC_RPC_ALERT:522    return "EXC_RPC_ALERT";523#ifdef EXC_CRASH524  case EXC_CRASH:525    return "EXC_CRASH";526#endif527  case EXC_RESOURCE:528    return "EXC_RESOURCE";529#ifdef EXC_GUARD530  case EXC_GUARD:531    return "EXC_GUARD";532#endif533#ifdef EXC_CORPSE_NOTIFY534  case EXC_CORPSE_NOTIFY:535    return "EXC_CORPSE_NOTIFY";536#endif537#ifdef EXC_CORPSE_VARIANT_BIT538  case EXC_CORPSE_VARIANT_BIT:539    return "EXC_CORPSE_VARIANT_BIT";540#endif541  default:542    break;543  }544  return NULL;545}546 547// Returns the exception mask for a given exception name.  548// 0 is not a legit mask, so we return that in the case of an error.549exception_mask_t MachException::ExceptionMask(const char *name) {550  static const char *exception_prefix = "EXC_";551  static const int prefix_len = strlen(exception_prefix);552 553  // All mach exceptions start with this prefix:554  if (strstr(name, exception_prefix) != name)555    return 0;556 557  name += prefix_len;558  std::string name_str = name;559  if (name_str == "BAD_ACCESS")560    return EXC_MASK_BAD_ACCESS;561  if (name_str == "BAD_INSTRUCTION")562    return EXC_MASK_BAD_INSTRUCTION;563  if (name_str == "ARITHMETIC")564    return EXC_MASK_ARITHMETIC;565  if (name_str == "EMULATION")566    return EXC_MASK_EMULATION;567  if (name_str == "SOFTWARE")568    return EXC_MASK_SOFTWARE;569  if (name_str == "BREAKPOINT")570    return EXC_MASK_BREAKPOINT;571  if (name_str == "SYSCALL")572    return EXC_MASK_SYSCALL;573  if (name_str == "MACH_SYSCALL")574    return EXC_MASK_MACH_SYSCALL;575  if (name_str == "RPC_ALERT")576    return EXC_MASK_RPC_ALERT;577#ifdef EXC_CRASH578  if (name_str == "CRASH")579    return EXC_MASK_CRASH;580#endif581  if (name_str == "RESOURCE")582    return EXC_MASK_RESOURCE;583#ifdef EXC_GUARD584  if (name_str == "GUARD")585    return EXC_MASK_GUARD;586#endif587#ifdef EXC_CORPSE_NOTIFY588  if (name_str == "CORPSE_NOTIFY")589    return EXC_MASK_CORPSE_NOTIFY;590#endif591  return 0;592}593