debuggerd: advance our amazing bet.

Remove debuggerd in favor of a helper process that gets execed by
crashing processes.

Bug: http://b/30705528
Test: debuggerd_test
Change-Id: I9906c69473989cbf7fe5ea6cccf9a9c563d75906

1 files changed, 724 insertions, 0 deletions

diff --git a/debuggerd/libdebuggerd/tombstone.cpp b/debuggerd/libdebuggerd/tombstone.cpp
new file mode 100644
index 000000000..01e9cf69b
--- /dev/null
+++ b/debuggerd/libdebuggerd/tombstone.cpp
@@ -0,0 +1,724 @@
+/*
+ * Copyright (C) 2012-2014 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#define LOG_TAG "DEBUG"
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <signal.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ptrace.h>
+#include <sys/stat.h>
+#include <time.h>
+
+#include <memory>
+#include <string>
+
+#include <android/log.h>
+#include <android-base/stringprintf.h>
+#include <backtrace/Backtrace.h>
+#include <backtrace/BacktraceMap.h>
+#include <cutils/properties.h>
+#include <log/log.h>
+#include <log/logprint.h>
+#include <private/android_filesystem_config.h>
+
+#include "debuggerd/handler.h"
+
+#include "backtrace.h"
+#include "elf_utils.h"
+#include "machine.h"
+#include "open_files_list.h"
+#include "tombstone.h"
+
+#define STACK_WORDS 16
+
+#define MAX_TOMBSTONES  10
+#define TOMBSTONE_DIR   "/data/tombstones"
+#define TOMBSTONE_TEMPLATE (TOMBSTONE_DIR"/tombstone_%02d")
+
+static bool signal_has_si_addr(int si_signo, int si_code) {
+  // Manually sent signals won't have si_addr.
+  if (si_code == SI_USER || si_code == SI_QUEUE || si_code == SI_TKILL) {
+    return false;
+  }
+
+  switch (si_signo) {
+    case SIGBUS:
+    case SIGFPE:
+    case SIGILL:
+    case SIGSEGV:
+    case SIGTRAP:
+      return true;
+    default:
+      return false;
+  }
+}
+
+static const char* get_signame(int sig) {
+  switch(sig) {
+    case SIGABRT: return "SIGABRT";
+    case SIGBUS: return "SIGBUS";
+    case SIGFPE: return "SIGFPE";
+    case SIGILL: return "SIGILL";
+    case SIGSEGV: return "SIGSEGV";
+#if defined(SIGSTKFLT)
+    case SIGSTKFLT: return "SIGSTKFLT";
+#endif
+    case SIGSTOP: return "SIGSTOP";
+    case SIGSYS: return "SIGSYS";
+    case SIGTRAP: return "SIGTRAP";
+    case DEBUGGER_SIGNAL: return "<debuggerd signal>";
+    default: return "?";
+  }
+}
+
+static const char* get_sigcode(int signo, int code) {
+  // Try the signal-specific codes...
+  switch (signo) {
+    case SIGILL:
+      switch (code) {
+        case ILL_ILLOPC: return "ILL_ILLOPC";
+        case ILL_ILLOPN: return "ILL_ILLOPN";
+        case ILL_ILLADR: return "ILL_ILLADR";
+        case ILL_ILLTRP: return "ILL_ILLTRP";
+        case ILL_PRVOPC: return "ILL_PRVOPC";
+        case ILL_PRVREG: return "ILL_PRVREG";
+        case ILL_COPROC: return "ILL_COPROC";
+        case ILL_BADSTK: return "ILL_BADSTK";
+      }
+      static_assert(NSIGILL == ILL_BADSTK, "missing ILL_* si_code");
+      break;
+    case SIGBUS:
+      switch (code) {
+        case BUS_ADRALN: return "BUS_ADRALN";
+        case BUS_ADRERR: return "BUS_ADRERR";
+        case BUS_OBJERR: return "BUS_OBJERR";
+        case BUS_MCEERR_AR: return "BUS_MCEERR_AR";
+        case BUS_MCEERR_AO: return "BUS_MCEERR_AO";
+      }
+      static_assert(NSIGBUS == BUS_MCEERR_AO, "missing BUS_* si_code");
+      break;
+    case SIGFPE:
+      switch (code) {
+        case FPE_INTDIV: return "FPE_INTDIV";
+        case FPE_INTOVF: return "FPE_INTOVF";
+        case FPE_FLTDIV: return "FPE_FLTDIV";
+        case FPE_FLTOVF: return "FPE_FLTOVF";
+        case FPE_FLTUND: return "FPE_FLTUND";
+        case FPE_FLTRES: return "FPE_FLTRES";
+        case FPE_FLTINV: return "FPE_FLTINV";
+        case FPE_FLTSUB: return "FPE_FLTSUB";
+      }
+      static_assert(NSIGFPE == FPE_FLTSUB, "missing FPE_* si_code");
+      break;
+    case SIGSEGV:
+      switch (code) {
+        case SEGV_MAPERR: return "SEGV_MAPERR";
+        case SEGV_ACCERR: return "SEGV_ACCERR";
+#if defined(SEGV_BNDERR)
+        case SEGV_BNDERR: return "SEGV_BNDERR";
+#endif
+#if defined(SEGV_PKUERR)
+        case SEGV_PKUERR: return "SEGV_PKUERR";
+#endif
+      }
+#if defined(SEGV_PKUERR)
+      static_assert(NSIGSEGV == SEGV_PKUERR, "missing SEGV_* si_code");
+#elif defined(SEGV_BNDERR)
+      static_assert(NSIGSEGV == SEGV_BNDERR, "missing SEGV_* si_code");
+#else
+      static_assert(NSIGSEGV == SEGV_ACCERR, "missing SEGV_* si_code");
+#endif
+      break;
+#if defined(SYS_SECCOMP) // Our glibc is too old, and we build this for the host too.
+    case SIGSYS:
+      switch (code) {
+        case SYS_SECCOMP: return "SYS_SECCOMP";
+      }
+      static_assert(NSIGSYS == SYS_SECCOMP, "missing SYS_* si_code");
+      break;
+#endif
+    case SIGTRAP:
+      switch (code) {
+        case TRAP_BRKPT: return "TRAP_BRKPT";
+        case TRAP_TRACE: return "TRAP_TRACE";
+        case TRAP_BRANCH: return "TRAP_BRANCH";
+        case TRAP_HWBKPT: return "TRAP_HWBKPT";
+      }
+      static_assert(NSIGTRAP == TRAP_HWBKPT, "missing TRAP_* si_code");
+      break;
+  }
+  // Then the other codes...
+  switch (code) {
+    case SI_USER: return "SI_USER";
+    case SI_KERNEL: return "SI_KERNEL";
+    case SI_QUEUE: return "SI_QUEUE";
+    case SI_TIMER: return "SI_TIMER";
+    case SI_MESGQ: return "SI_MESGQ";
+    case SI_ASYNCIO: return "SI_ASYNCIO";
+    case SI_SIGIO: return "SI_SIGIO";
+    case SI_TKILL: return "SI_TKILL";
+    case SI_DETHREAD: return "SI_DETHREAD";
+  }
+  // Then give up...
+  return "?";
+}
+
+static void dump_header_info(log_t* log) {
+  char fingerprint[PROPERTY_VALUE_MAX];
+  char revision[PROPERTY_VALUE_MAX];
+
+  property_get("ro.build.fingerprint", fingerprint, "unknown");
+  property_get("ro.revision", revision, "unknown");
+
+  _LOG(log, logtype::HEADER, "Build fingerprint: '%s'\n", fingerprint);
+  _LOG(log, logtype::HEADER, "Revision: '%s'\n", revision);
+  _LOG(log, logtype::HEADER, "ABI: '%s'\n", ABI_STRING);
+}
+
+static void dump_signal_info(log_t* log, pid_t tid) {
+  siginfo_t si;
+  memset(&si, 0, sizeof(si));
+  if (ptrace(PTRACE_GETSIGINFO, tid, 0, &si) == -1) {
+    ALOGE("cannot get siginfo: %s\n", strerror(errno));
+    return;
+  }
+
+  char addr_desc[32]; // ", fault addr 0x1234"
+  if (signal_has_si_addr(si.si_signo, si.si_code)) {
+    snprintf(addr_desc, sizeof(addr_desc), "%p", si.si_addr);
+  } else {
+    snprintf(addr_desc, sizeof(addr_desc), "--------");
+  }
+
+  _LOG(log, logtype::HEADER, "signal %d (%s), code %d (%s), fault addr %s\n", si.si_signo,
+       get_signame(si.si_signo), si.si_code, get_sigcode(si.si_signo, si.si_code), addr_desc);
+}
+
+static void dump_thread_info(log_t* log, pid_t pid, pid_t tid) {
+  char path[64];
+  char threadnamebuf[1024];
+  char* threadname = nullptr;
+  FILE *fp;
+
+  snprintf(path, sizeof(path), "/proc/%d/comm", tid);
+  if ((fp = fopen(path, "r"))) {
+    threadname = fgets(threadnamebuf, sizeof(threadnamebuf), fp);
+    fclose(fp);
+    if (threadname) {
+      size_t len = strlen(threadname);
+      if (len && threadname[len - 1] == '\n') {
+        threadname[len - 1] = '\0';
+      }
+    }
+  }
+  // Blacklist logd, logd.reader, logd.writer, logd.auditd, logd.control ...
+  static const char logd[] = "logd";
+  if (threadname != nullptr && !strncmp(threadname, logd, sizeof(logd) - 1)
+      && (!threadname[sizeof(logd) - 1] || (threadname[sizeof(logd) - 1] == '.'))) {
+    log->should_retrieve_logcat = false;
+  }
+
+  char procnamebuf[1024];
+  char* procname = nullptr;
+
+  snprintf(path, sizeof(path), "/proc/%d/cmdline", pid);
+  if ((fp = fopen(path, "r"))) {
+    procname = fgets(procnamebuf, sizeof(procnamebuf), fp);
+    fclose(fp);
+  }
+
+  _LOG(log, logtype::HEADER, "pid: %d, tid: %d, name: %s  >>> %s <<<\n", pid, tid,
+       threadname ? threadname : "UNKNOWN", procname ? procname : "UNKNOWN");
+}
+
+static void dump_stack_segment(
+    Backtrace* backtrace, log_t* log, uintptr_t* sp, size_t words, int label) {
+  // Read the data all at once.
+  word_t stack_data[words];
+  size_t bytes_read = backtrace->Read(*sp, reinterpret_cast<uint8_t*>(&stack_data[0]), sizeof(word_t) * words);
+  words = bytes_read / sizeof(word_t);
+  std::string line;
+  for (size_t i = 0; i < words; i++) {
+    line = "    ";
+    if (i == 0 && label >= 0) {
+      // Print the label once.
+      line += android::base::StringPrintf("#%02d  ", label);
+    } else {
+      line += "     ";
+    }
+    line += android::base::StringPrintf("%" PRIPTR "  %" PRIPTR, *sp, stack_data[i]);
+
+    backtrace_map_t map;
+    backtrace->FillInMap(stack_data[i], &map);
+    if (BacktraceMap::IsValid(map) && !map.name.empty()) {
+      line += "  " + map.name;
+      uintptr_t offset = 0;
+      std::string func_name(backtrace->GetFunctionName(stack_data[i], &offset));
+      if (!func_name.empty()) {
+        line += " (" + func_name;
+        if (offset) {
+          line += android::base::StringPrintf("+%" PRIuPTR, offset);
+        }
+        line += ')';
+      }
+    }
+    _LOG(log, logtype::STACK, "%s\n", line.c_str());
+
+    *sp += sizeof(word_t);
+  }
+}
+
+static void dump_stack(Backtrace* backtrace, log_t* log) {
+  size_t first = 0, last;
+  for (size_t i = 0; i < backtrace->NumFrames(); i++) {
+    const backtrace_frame_data_t* frame = backtrace->GetFrame(i);
+    if (frame->sp) {
+      if (!first) {
+        first = i+1;
+      }
+      last = i;
+    }
+  }
+  if (!first) {
+    return;
+  }
+  first--;
+
+  // Dump a few words before the first frame.
+  word_t sp = backtrace->GetFrame(first)->sp - STACK_WORDS * sizeof(word_t);
+  dump_stack_segment(backtrace, log, &sp, STACK_WORDS, -1);
+
+  // Dump a few words from all successive frames.
+  // Only log the first 3 frames, put the rest in the tombstone.
+  for (size_t i = first; i <= last; i++) {
+    const backtrace_frame_data_t* frame = backtrace->GetFrame(i);
+    if (sp != frame->sp) {
+      _LOG(log, logtype::STACK, "         ........  ........\n");
+      sp = frame->sp;
+    }
+    if (i == last) {
+      dump_stack_segment(backtrace, log, &sp, STACK_WORDS, i);
+      if (sp < frame->sp + frame->stack_size) {
+        _LOG(log, logtype::STACK, "         ........  ........\n");
+      }
+    } else {
+      size_t words = frame->stack_size / sizeof(word_t);
+      if (words == 0) {
+        words = 1;
+      } else if (words > STACK_WORDS) {
+        words = STACK_WORDS;
+      }
+      dump_stack_segment(backtrace, log, &sp, words, i);
+    }
+  }
+}
+
+static std::string get_addr_string(uintptr_t addr) {
+  std::string addr_str;
+#if defined(__LP64__)
+  addr_str = android::base::StringPrintf("%08x'%08x",
+                                         static_cast<uint32_t>(addr >> 32),
+                                         static_cast<uint32_t>(addr & 0xffffffff));
+#else
+  addr_str = android::base::StringPrintf("%08x", addr);
+#endif
+  return addr_str;
+}
+
+static void dump_abort_message(Backtrace* backtrace, log_t* log, uintptr_t address) {
+  if (address == 0) {
+    return;
+  }
+
+  address += sizeof(size_t);  // Skip the buffer length.
+
+  char msg[512];
+  memset(msg, 0, sizeof(msg));
+  char* p = &msg[0];
+  while (p < &msg[sizeof(msg)]) {
+    word_t data;
+    size_t len = sizeof(word_t);
+    if (!backtrace->ReadWord(address, &data)) {
+      break;
+    }
+    address += sizeof(word_t);
+
+    while (len > 0 && (*p++ = (data >> (sizeof(word_t) - len) * 8) & 0xff) != 0) {
+      len--;
+    }
+  }
+  msg[sizeof(msg) - 1] = '\0';
+
+  _LOG(log, logtype::HEADER, "Abort message: '%s'\n", msg);
+}
+
+static void dump_all_maps(Backtrace* backtrace, BacktraceMap* map, log_t* log, pid_t tid) {
+  bool print_fault_address_marker = false;
+  uintptr_t addr = 0;
+  siginfo_t si;
+  memset(&si, 0, sizeof(si));
+  if (ptrace(PTRACE_GETSIGINFO, tid, 0, &si) != -1) {
+    print_fault_address_marker = signal_has_si_addr(si.si_signo, si.si_code);
+    addr = reinterpret_cast<uintptr_t>(si.si_addr);
+  } else {
+    ALOGE("Cannot get siginfo for %d: %s\n", tid, strerror(errno));
+  }
+
+  ScopedBacktraceMapIteratorLock lock(map);
+  _LOG(log, logtype::MAPS, "\n");
+  if (!print_fault_address_marker) {
+    _LOG(log, logtype::MAPS, "memory map:\n");
+  } else {
+    _LOG(log, logtype::MAPS, "memory map: (fault address prefixed with --->)\n");
+    if (map->begin() != map->end() && addr < map->begin()->start) {
+      _LOG(log, logtype::MAPS, "--->Fault address falls at %s before any mapped regions\n",
+           get_addr_string(addr).c_str());
+      print_fault_address_marker = false;
+    }
+  }
+
+  std::string line;
+  for (BacktraceMap::const_iterator it = map->begin(); it != map->end(); ++it) {
+    line = "    ";
+    if (print_fault_address_marker) {
+      if (addr < it->start) {
+        _LOG(log, logtype::MAPS, "--->Fault address falls at %s between mapped regions\n",
+             get_addr_string(addr).c_str());
+        print_fault_address_marker = false;
+      } else if (addr >= it->start && addr < it->end) {
+        line = "--->";
+        print_fault_address_marker = false;
+      }
+    }
+    line += get_addr_string(it->start) + '-' + get_addr_string(it->end - 1) + ' ';
+    if (it->flags & PROT_READ) {
+      line += 'r';
+    } else {
+      line += '-';
+    }
+    if (it->flags & PROT_WRITE) {
+      line += 'w';
+    } else {
+      line += '-';
+    }
+    if (it->flags & PROT_EXEC) {
+      line += 'x';
+    } else {
+      line += '-';
+    }
+    line += android::base::StringPrintf("  %8" PRIxPTR "  %8" PRIxPTR,
+                                        it->offset, it->end - it->start);
+    bool space_needed = true;
+    if (it->name.length() > 0) {
+      space_needed = false;
+      line += "  " + it->name;
+      std::string build_id;
+      if ((it->flags & PROT_READ) && elf_get_build_id(backtrace, it->start, &build_id)) {
+        line += " (BuildId: " + build_id + ")";
+      }
+    }
+    if (it->load_base != 0) {
+      if (space_needed) {
+        line += ' ';
+      }
+      line += android::base::StringPrintf(" (load base 0x%" PRIxPTR ")", it->load_base);
+    }
+    _LOG(log, logtype::MAPS, "%s\n", line.c_str());
+  }
+  if (print_fault_address_marker) {
+    _LOG(log, logtype::MAPS, "--->Fault address falls at %s after any mapped regions\n",
+         get_addr_string(addr).c_str());
+  }
+}
+
+static void dump_backtrace_and_stack(Backtrace* backtrace, log_t* log) {
+  if (backtrace->NumFrames()) {
+    _LOG(log, logtype::BACKTRACE, "\nbacktrace:\n");
+    dump_backtrace_to_log(backtrace, log, "    ");
+
+    _LOG(log, logtype::STACK, "\nstack:\n");
+    dump_stack(backtrace, log);
+  }
+}
+
+static void dump_thread(log_t* log, pid_t pid, pid_t tid, BacktraceMap* map,
+                        uintptr_t abort_msg_address, bool primary_thread) {
+  log->current_tid = tid;
+  if (!primary_thread) {
+    _LOG(log, logtype::THREAD, "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
+  }
+  dump_thread_info(log, pid, tid);
+  dump_signal_info(log, tid);
+
+  std::unique_ptr<Backtrace> backtrace(Backtrace::Create(pid, tid, map));
+  if (primary_thread) {
+    dump_abort_message(backtrace.get(), log, abort_msg_address);
+  }
+  dump_registers(log, tid);
+  if (backtrace->Unwind(0)) {
+    dump_backtrace_and_stack(backtrace.get(), log);
+  } else {
+    ALOGE("Unwind failed: pid = %d, tid = %d", pid, tid);
+  }
+
+  if (primary_thread) {
+    dump_memory_and_code(log, backtrace.get());
+    if (map) {
+      dump_all_maps(backtrace.get(), map, log, tid);
+    }
+  }
+
+  log->current_tid = log->crashed_tid;
+}
+
+// Reads the contents of the specified log device, filters out the entries
+// that don't match the specified pid, and writes them to the tombstone file.
+//
+// If "tail" is non-zero, log the last "tail" number of lines.
+static EventTagMap* g_eventTagMap = NULL;
+
+static void dump_log_file(
+    log_t* log, pid_t pid, const char* filename, unsigned int tail) {
+  bool first = true;
+  struct logger_list* logger_list;
+
+  if (!log->should_retrieve_logcat) {
+    return;
+  }
+
+  logger_list = android_logger_list_open(
+      android_name_to_log_id(filename), ANDROID_LOG_RDONLY | ANDROID_LOG_NONBLOCK, tail, pid);
+
+  if (!logger_list) {
+    ALOGE("Unable to open %s: %s\n", filename, strerror(errno));
+    return;
+  }
+
+  struct log_msg log_entry;
+
+  while (true) {
+    ssize_t actual = android_logger_list_read(logger_list, &log_entry);
+    struct logger_entry* entry;
+
+    if (actual < 0) {
+      if (actual == -EINTR) {
+        // interrupted by signal, retry
+        continue;
+      } else if (actual == -EAGAIN) {
+        // non-blocking EOF; we're done
+        break;
+      } else {
+        ALOGE("Error while reading log: %s\n", strerror(-actual));
+        break;
+      }
+    } else if (actual == 0) {
+      ALOGE("Got zero bytes while reading log: %s\n", strerror(errno));
+      break;
+    }
+
+    // NOTE: if you ALOGV something here, this will spin forever,
+    // because you will be writing as fast as you're reading.  Any
+    // high-frequency debug diagnostics should just be written to
+    // the tombstone file.
+
+    entry = &log_entry.entry_v1;
+
+    if (first) {
+      _LOG(log, logtype::LOGS, "--------- %slog %s\n",
+        tail ? "tail end of " : "", filename);
+      first = false;
+    }
+
+    // Msg format is: <priority:1><tag:N>\0<message:N>\0
+    //
+    // We want to display it in the same format as "logcat -v threadtime"
+    // (although in this case the pid is redundant).
+    static const char* kPrioChars = "!.VDIWEFS";
+    unsigned hdr_size = log_entry.entry.hdr_size;
+    if (!hdr_size) {
+      hdr_size = sizeof(log_entry.entry_v1);
+    }
+    if ((hdr_size < sizeof(log_entry.entry_v1)) ||
+        (hdr_size > sizeof(log_entry.entry))) {
+      continue;
+    }
+    char* msg = reinterpret_cast<char*>(log_entry.buf) + hdr_size;
+
+    char timeBuf[32];
+    time_t sec = static_cast<time_t>(entry->sec);
+    struct tm tmBuf;
+    struct tm* ptm;
+    ptm = localtime_r(&sec, &tmBuf);
+    strftime(timeBuf, sizeof(timeBuf), "%m-%d %H:%M:%S", ptm);
+
+    if (log_entry.id() == LOG_ID_EVENTS) {
+      if (!g_eventTagMap) {
+        g_eventTagMap = android_openEventTagMap(NULL);
+      }
+      AndroidLogEntry e;
+      char buf[512];
+      android_log_processBinaryLogBuffer(entry, &e, g_eventTagMap, buf, sizeof(buf));
+      _LOG(log, logtype::LOGS, "%s.%03d %5d %5d %c %-8.*s: %s\n",
+         timeBuf, entry->nsec / 1000000, entry->pid, entry->tid,
+         'I', (int)e.tagLen, e.tag, e.message);
+      continue;
+    }
+
+    unsigned char prio = msg[0];
+    char* tag = msg + 1;
+    msg = tag + strlen(tag) + 1;
+
+    // consume any trailing newlines
+    char* nl = msg + strlen(msg) - 1;
+    while (nl >= msg && *nl == '\n') {
+      *nl-- = '\0';
+    }
+
+    char prioChar = (prio < strlen(kPrioChars) ? kPrioChars[prio] : '?');
+
+    // Look for line breaks ('\n') and display each text line
+    // on a separate line, prefixed with the header, like logcat does.
+    do {
+      nl = strchr(msg, '\n');
+      if (nl) {
+        *nl = '\0';
+        ++nl;
+      }
+
+      _LOG(log, logtype::LOGS, "%s.%03d %5d %5d %c %-8s: %s\n",
+         timeBuf, entry->nsec / 1000000, entry->pid, entry->tid,
+         prioChar, tag, msg);
+    } while ((msg = nl));
+  }
+
+  android_logger_list_free(logger_list);
+}
+
+// Dumps the logs generated by the specified pid to the tombstone, from both
+// "system" and "main" log devices.  Ideally we'd interleave the output.
+static void dump_logs(log_t* log, pid_t pid, unsigned int tail) {
+  dump_log_file(log, pid, "system", tail);
+  dump_log_file(log, pid, "main", tail);
+}
+
+// Dumps all information about the specified pid to the tombstone.
+static void dump_crash(log_t* log, BacktraceMap* map,
+                       const OpenFilesList& open_files, pid_t pid, pid_t tid,
+                       const std::set<pid_t>& siblings, uintptr_t abort_msg_address) {
+  // don't copy log messages to tombstone unless this is a dev device
+  char value[PROPERTY_VALUE_MAX];
+  property_get("ro.debuggable", value, "0");
+  bool want_logs = (value[0] == '1');
+
+  _LOG(log, logtype::HEADER,
+       "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
+  dump_header_info(log);
+  dump_thread(log, pid, tid, map, abort_msg_address, true);
+  if (want_logs) {
+    dump_logs(log, pid, 5);
+  }
+
+  if (!siblings.empty()) {
+    for (pid_t sibling : siblings) {
+      dump_thread(log, pid, sibling, map, 0, false);
+    }
+  }
+
+  _LOG(log, logtype::OPEN_FILES, "\nopen files:\n");
+  dump_open_files_list_to_log(open_files, log, "    ");
+
+  if (want_logs) {
+    dump_logs(log, pid, 0);
+  }
+}
+
+// open_tombstone - find an available tombstone slot, if any, of the
+// form tombstone_XX where XX is 00 to MAX_TOMBSTONES-1, inclusive. If no
+// file is available, we reuse the least-recently-modified file.
+int open_tombstone(std::string* out_path) {
+  // In a single pass, find an available slot and, in case none
+  // exist, find and record the least-recently-modified file.
+  char path[128];
+  int fd = -1;
+  int oldest = -1;
+  struct stat oldest_sb;
+  for (int i = 0; i < MAX_TOMBSTONES; i++) {
+    snprintf(path, sizeof(path), TOMBSTONE_TEMPLATE, i);
+
+    struct stat sb;
+    if (stat(path, &sb) == 0) {
+      if (oldest < 0 || sb.st_mtime < oldest_sb.st_mtime) {
+        oldest = i;
+        oldest_sb.st_mtime = sb.st_mtime;
+      }
+      continue;
+    }
+    if (errno != ENOENT) continue;
+
+    fd = open(path, O_CREAT | O_EXCL | O_WRONLY | O_NOFOLLOW | O_CLOEXEC, 0600);
+    if (fd < 0) continue;  // raced ?
+
+    if (out_path) {
+      *out_path = path;
+    }
+    fchown(fd, AID_SYSTEM, AID_SYSTEM);
+    return fd;
+  }
+
+  if (oldest < 0) {
+    ALOGE("debuggerd: failed to find a valid tombstone, default to using tombstone 0.\n");
+    oldest = 0;
+  }
+
+  // we didn't find an available file, so we clobber the oldest one
+  snprintf(path, sizeof(path), TOMBSTONE_TEMPLATE, oldest);
+  fd = open(path, O_CREAT | O_TRUNC | O_WRONLY | O_NOFOLLOW | O_CLOEXEC, 0600);
+  if (fd < 0) {
+    ALOGE("debuggerd: failed to open tombstone file '%s': %s\n", path, strerror(errno));
+    return -1;
+  }
+
+  if (out_path) {
+    *out_path = path;
+  }
+  fchown(fd, AID_SYSTEM, AID_SYSTEM);
+  return fd;
+}
+
+void engrave_tombstone(int tombstone_fd, BacktraceMap* map,
+                       const OpenFilesList& open_files, pid_t pid, pid_t tid,
+                       const std::set<pid_t>& siblings, uintptr_t abort_msg_address,
+                       std::string* amfd_data) {
+  log_t log;
+  log.current_tid = tid;
+  log.crashed_tid = tid;
+
+  if (tombstone_fd < 0) {
+    ALOGE("debuggerd: skipping tombstone write, nothing to do.\n");
+    return;
+  }
+
+  log.tfd = tombstone_fd;
+  log.amfd_data = amfd_data;
+  dump_crash(&log, map, open_files, pid, tid, siblings, abort_msg_address);
+}