1 files changed, 974 insertions, 0 deletions
diff --git a/externals/breakpad/src/client/linux/minidump_writer/linux_dumper.cc b/externals/breakpad/src/client/linux/minidump_writer/linux_dumper.cc
new file mode 100644
index 0000000000..5c4c389c39
--- /dev/null
+++ b/externals/breakpad/src/client/linux/minidump_writer/linux_dumper.cc
@@ -0,0 +1,974 @@
+// Copyright 2010 Google LLC
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google LLC nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// linux_dumper.cc: Implement google_breakpad::LinuxDumper.
+// See linux_dumper.h for details.
+
+// This code deals with the mechanics of getting information about a crashed
+// process. Since this code may run in a compromised address space, the same
+// rules apply as detailed at the top of minidump_writer.h: no libc calls and
+// use the alternative allocator.
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>  // Must come first
+#endif
+
+#include "client/linux/minidump_writer/linux_dumper.h"
+
+#include <assert.h>
+#include <elf.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stddef.h>
+#include <string.h>
+
+#include "client/linux/minidump_writer/line_reader.h"
+#include "common/linux/elfutils.h"
+#include "common/linux/file_id.h"
+#include "common/linux/linux_libc_support.h"
+#include "common/linux/memory_mapped_file.h"
+#include "common/linux/safe_readlink.h"
+#include "google_breakpad/common/minidump_exception_linux.h"
+#include "third_party/lss/linux_syscall_support.h"
+
+using google_breakpad::elf::FileID;
+
+#if defined(__ANDROID__)
+
+// Android packed relocations definitions are not yet available from the
+// NDK header files, so we have to provide them manually here.
+#ifndef DT_LOOS
+#define DT_LOOS 0x6000000d
+#endif
+#ifndef DT_ANDROID_REL
+static const int DT_ANDROID_REL = DT_LOOS + 2;
+#endif
+#ifndef DT_ANDROID_RELA
+static const int DT_ANDROID_RELA = DT_LOOS + 4;
+#endif
+
+#endif  // __ANDROID __
+
+static const char kMappedFileUnsafePrefix[] = "/dev/";
+static const char kDeletedSuffix[] = " (deleted)";
+
+inline static bool IsMappedFileOpenUnsafe(
+    const google_breakpad::MappingInfo& mapping) {
+  // It is unsafe to attempt to open a mapped file that lives under /dev,
+  // because the semantics of the open may be driver-specific so we'd risk
+  // hanging the crash dumper. And a file in /dev/ almost certainly has no
+  // ELF file identifier anyways.
+  return my_strncmp(mapping.name,
+                    kMappedFileUnsafePrefix,
+                    sizeof(kMappedFileUnsafePrefix) - 1) == 0;
+}
+
+namespace google_breakpad {
+
+namespace {
+
+bool MappingContainsAddress(const MappingInfo& mapping, uintptr_t address) {
+  return mapping.system_mapping_info.start_addr <= address &&
+         address < mapping.system_mapping_info.end_addr;
+}
+
+#if defined(__CHROMEOS__)
+
+// Recover memory mappings before writing dump on ChromeOS
+//
+// On Linux, breakpad relies on /proc/[pid]/maps to associate symbols from
+// addresses. ChromeOS' hugepage implementation replaces some segments with
+// anonymous private pages, which is a restriction of current implementation
+// in Linux kernel at the time of writing. Thus, breakpad can no longer
+// symbolize addresses from those text segments replaced with hugepages.
+//
+// This postprocess tries to recover the mappings. Because hugepages are always
+// inserted in between some .text sections, it tries to infer the names and
+// offsets of the segments, by looking at segments immediately precede and
+// succeed them.
+//
+// For example, a text segment before hugepage optimization
+//   02001000-03002000 r-xp /opt/google/chrome/chrome
+//
+// can be broken into
+//   02001000-02200000 r-xp /opt/google/chrome/chrome
+//   02200000-03000000 r-xp
+//   03000000-03002000 r-xp /opt/google/chrome/chrome
+//
+// For more details, see:
+// crbug.com/628040 ChromeOS' use of hugepages confuses crash symbolization
+
+// Copied from CrOS' hugepage implementation, which is unlikely to change.
+// The hugepage size is 2M.
+const unsigned int kHpageShift = 21;
+const size_t kHpageSize = (1 << kHpageShift);
+const size_t kHpageMask = (~(kHpageSize - 1));
+
+// Find and merge anonymous r-xp segments with surrounding named segments.
+// There are two cases:
+
+// Case 1: curr, next
+//   curr is anonymous
+//   curr is r-xp
+//   curr.size >= 2M
+//   curr.size is a multiple of 2M.
+//   next is backed by some file.
+//   curr and next are contiguous.
+//   offset(next) == sizeof(curr)
+void TryRecoverMappings(MappingInfo* curr, MappingInfo* next) {
+  // Merged segments are marked with size = 0.
+  if (curr->size == 0 || next->size == 0)
+    return;
+
+  if (curr->size >= kHpageSize &&
+      curr->exec &&
+      (curr->size & kHpageMask) == curr->size &&
+      (curr->start_addr & kHpageMask) == curr->start_addr &&
+      curr->name[0] == '\0' &&
+      next->name[0] != '\0' &&
+      curr->start_addr + curr->size == next->start_addr &&
+      curr->size == next->offset) {
+
+    // matched
+    my_strlcpy(curr->name, next->name, NAME_MAX);
+    if (next->exec) {
+      // (curr, next)
+      curr->size += next->size;
+      next->size = 0;
+    }
+  }
+}
+
+// Case 2: prev, curr, next
+//   curr is anonymous
+//   curr is r-xp
+//   curr.size >= 2M
+//   curr.size is a multiple of 2M.
+//   next and prev are backed by the same file.
+//   prev, curr and next are contiguous.
+//   offset(next) == offset(prev) + sizeof(prev) + sizeof(curr)
+void TryRecoverMappings(MappingInfo* prev, MappingInfo* curr,
+                        MappingInfo* next) {
+  // Merged segments are marked with size = 0.
+  if (prev->size == 0 || curr->size == 0 || next->size == 0)
+    return;
+
+  if (curr->size >= kHpageSize &&
+      curr->exec &&
+      (curr->size & kHpageMask) == curr->size &&
+      (curr->start_addr & kHpageMask) == curr->start_addr &&
+      curr->name[0] == '\0' &&
+      next->name[0] != '\0' &&
+      curr->start_addr + curr->size == next->start_addr &&
+      prev->start_addr + prev->size == curr->start_addr &&
+      my_strncmp(prev->name, next->name, NAME_MAX) == 0 &&
+      next->offset == prev->offset + prev->size + curr->size) {
+
+    // matched
+    my_strlcpy(curr->name, prev->name, NAME_MAX);
+    if (prev->exec) {
+      curr->offset = prev->offset;
+      curr->start_addr = prev->start_addr;
+      if (next->exec) {
+        // (prev, curr, next)
+        curr->size += prev->size + next->size;
+        prev->size = 0;
+        next->size = 0;
+      } else {
+        // (prev, curr), next
+        curr->size += prev->size;
+        prev->size = 0;
+      }
+    } else {
+      curr->offset = prev->offset + prev->size;
+      if (next->exec) {
+        // prev, (curr, next)
+        curr->size += next->size;
+        next->size = 0;
+      } else {
+        // prev, curr, next
+      }
+    }
+  }
+}
+
+// mappings_ is sorted excepted for the first entry.
+// This function tries to merge segemnts into the first entry,
+// then check for other sorted entries.
+// See LinuxDumper::EnumerateMappings().
+void CrOSPostProcessMappings(wasteful_vector<MappingInfo*>& mappings) {
+  // Find the candidate "next" to first segment, which is the only one that
+  // could be out-of-order.
+  size_t l = 1;
+  size_t r = mappings.size();
+  size_t next = mappings.size();
+  while (l < r) {
+    int m = (l + r) / 2;
+    if (mappings[m]->start_addr > mappings[0]->start_addr)
+      r = next = m;
+    else
+      l = m + 1;
+  }
+
+  // Shows the range that contains the entry point is
+  // [first_start_addr, first_end_addr)
+  size_t first_start_addr = mappings[0]->start_addr;
+  size_t first_end_addr = mappings[0]->start_addr + mappings[0]->size;
+
+  // Put the out-of-order segment in order.
+  std::rotate(mappings.begin(), mappings.begin() + 1, mappings.begin() + next);
+
+  // Iterate through normal, sorted cases.
+  // Normal case 1.
+  for (size_t i = 0; i < mappings.size() - 1; i++)
+    TryRecoverMappings(mappings[i], mappings[i + 1]);
+
+  // Normal case 2.
+  for (size_t i = 0; i < mappings.size() - 2; i++)
+    TryRecoverMappings(mappings[i], mappings[i + 1], mappings[i + 2]);
+
+  // Collect merged (size == 0) segments.
+  size_t f, e;
+  for (f = e = 0; e < mappings.size(); e++)
+    if (mappings[e]->size > 0)
+      mappings[f++] = mappings[e];
+  mappings.resize(f);
+
+  // The entry point is in the first mapping. We want to find the location
+  // of the entry point after merging segment. To do this, we want to find
+  // the mapping that covers the first mapping from the original mapping list.
+  // If the mapping is not in the beginning, we move it to the begining via
+  // a right rotate by using reverse iterators.
+  for (l = 0; l < mappings.size(); l++) {
+    if (mappings[l]->start_addr <= first_start_addr
+        && (mappings[l]->start_addr + mappings[l]->size >= first_end_addr))
+      break;
+  }
+  if (l > 0) {
+    r = mappings.size();
+    std::rotate(mappings.rbegin() + r - l - 1, mappings.rbegin() + r - l,
+                mappings.rend());
+  }
+}
+
+#endif  // __CHROMEOS__
+
+}  // namespace
+
+// All interesting auvx entry types are below AT_SYSINFO_EHDR
+#define AT_MAX AT_SYSINFO_EHDR
+
+LinuxDumper::LinuxDumper(pid_t pid, const char* root_prefix)
+    : pid_(pid),
+      root_prefix_(root_prefix),
+      crash_address_(0),
+      crash_signal_(0),
+      crash_signal_code_(0),
+      crash_thread_(pid),
+      threads_(&allocator_, 8),
+      mappings_(&allocator_),
+      auxv_(&allocator_, AT_MAX + 1) {
+  assert(root_prefix_ && my_strlen(root_prefix_) < PATH_MAX);
+  // The passed-in size to the constructor (above) is only a hint.
+  // Must call .resize() to do actual initialization of the elements.
+  auxv_.resize(AT_MAX + 1);
+}
+
+LinuxDumper::~LinuxDumper() {
+}
+
+bool LinuxDumper::Init() {
+  return ReadAuxv() && EnumerateThreads() && EnumerateMappings();
+}
+
+bool LinuxDumper::LateInit() {
+#if defined(__ANDROID__)
+  LatePostprocessMappings();
+#endif
+
+#if defined(__CHROMEOS__)
+  CrOSPostProcessMappings(mappings_);
+#endif
+
+  return true;
+}
+
+bool
+LinuxDumper::ElfFileIdentifierForMapping(const MappingInfo& mapping,
+                                         bool member,
+                                         unsigned int mapping_id,
+                                         wasteful_vector<uint8_t>& identifier) {
+  assert(!member || mapping_id < mappings_.size());
+  if (IsMappedFileOpenUnsafe(mapping))
+    return false;
+
+  // Special-case linux-gate because it's not a real file.
+  if (my_strcmp(mapping.name, kLinuxGateLibraryName) == 0) {
+    void* linux_gate = NULL;
+    if (pid_ == sys_getpid()) {
+      linux_gate = reinterpret_cast<void*>(mapping.start_addr);
+    } else {
+      linux_gate = allocator_.Alloc(mapping.size);
+      CopyFromProcess(linux_gate, pid_,
+                      reinterpret_cast<const void*>(mapping.start_addr),
+                      mapping.size);
+    }
+    return FileID::ElfFileIdentifierFromMappedFile(linux_gate, identifier);
+  }
+
+  char filename[PATH_MAX];
+  if (!GetMappingAbsolutePath(mapping, filename))
+    return false;
+  bool filename_modified = HandleDeletedFileInMapping(filename);
+
+  MemoryMappedFile mapped_file(filename, 0);
+  if (!mapped_file.data() || mapped_file.size() < SELFMAG)
+    return false;
+
+  bool success =
+      FileID::ElfFileIdentifierFromMappedFile(mapped_file.data(), identifier);
+  if (success && member && filename_modified) {
+    mappings_[mapping_id]->name[my_strlen(mapping.name) -
+                                sizeof(kDeletedSuffix) + 1] = '\0';
+  }
+
+  return success;
+}
+
+void LinuxDumper::SetCrashInfoFromSigInfo(const siginfo_t& siginfo) {
+  set_crash_address(reinterpret_cast<uintptr_t>(siginfo.si_addr));
+  set_crash_signal(siginfo.si_signo);
+  set_crash_signal_code(siginfo.si_code);
+}
+
+const char* LinuxDumper::GetCrashSignalString() const {
+  switch (static_cast<unsigned int>(crash_signal_)) {
+    case MD_EXCEPTION_CODE_LIN_SIGHUP:
+      return "SIGHUP";
+    case MD_EXCEPTION_CODE_LIN_SIGINT:
+      return "SIGINT";
+    case MD_EXCEPTION_CODE_LIN_SIGQUIT:
+      return "SIGQUIT";
+    case MD_EXCEPTION_CODE_LIN_SIGILL:
+      return "SIGILL";
+    case MD_EXCEPTION_CODE_LIN_SIGTRAP:
+      return "SIGTRAP";
+    case MD_EXCEPTION_CODE_LIN_SIGABRT:
+      return "SIGABRT";
+    case MD_EXCEPTION_CODE_LIN_SIGBUS:
+      return "SIGBUS";
+    case MD_EXCEPTION_CODE_LIN_SIGFPE:
+      return "SIGFPE";
+    case MD_EXCEPTION_CODE_LIN_SIGKILL:
+      return "SIGKILL";
+    case MD_EXCEPTION_CODE_LIN_SIGUSR1:
+      return "SIGUSR1";
+    case MD_EXCEPTION_CODE_LIN_SIGSEGV:
+      return "SIGSEGV";
+    case MD_EXCEPTION_CODE_LIN_SIGUSR2:
+      return "SIGUSR2";
+    case MD_EXCEPTION_CODE_LIN_SIGPIPE:
+      return "SIGPIPE";
+    case MD_EXCEPTION_CODE_LIN_SIGALRM:
+      return "SIGALRM";
+    case MD_EXCEPTION_CODE_LIN_SIGTERM:
+      return "SIGTERM";
+    case MD_EXCEPTION_CODE_LIN_SIGSTKFLT:
+      return "SIGSTKFLT";
+    case MD_EXCEPTION_CODE_LIN_SIGCHLD:
+      return "SIGCHLD";
+    case MD_EXCEPTION_CODE_LIN_SIGCONT:
+      return "SIGCONT";
+    case MD_EXCEPTION_CODE_LIN_SIGSTOP:
+      return "SIGSTOP";
+    case MD_EXCEPTION_CODE_LIN_SIGTSTP:
+      return "SIGTSTP";
+    case MD_EXCEPTION_CODE_LIN_SIGTTIN:
+      return "SIGTTIN";
+    case MD_EXCEPTION_CODE_LIN_SIGTTOU:
+      return "SIGTTOU";
+    case MD_EXCEPTION_CODE_LIN_SIGURG:
+      return "SIGURG";
+    case MD_EXCEPTION_CODE_LIN_SIGXCPU:
+      return "SIGXCPU";
+    case MD_EXCEPTION_CODE_LIN_SIGXFSZ:
+      return "SIGXFSZ";
+    case MD_EXCEPTION_CODE_LIN_SIGVTALRM:
+      return "SIGVTALRM";
+    case MD_EXCEPTION_CODE_LIN_SIGPROF:
+      return "SIGPROF";
+    case MD_EXCEPTION_CODE_LIN_SIGWINCH:
+      return "SIGWINCH";
+    case MD_EXCEPTION_CODE_LIN_SIGIO:
+      return "SIGIO";
+    case MD_EXCEPTION_CODE_LIN_SIGPWR:
+      return "SIGPWR";
+    case MD_EXCEPTION_CODE_LIN_SIGSYS:
+      return "SIGSYS";
+    case MD_EXCEPTION_CODE_LIN_DUMP_REQUESTED:
+      return "DUMP_REQUESTED";
+    default:
+      return "UNKNOWN";
+  }
+}
+
+bool LinuxDumper::GetMappingAbsolutePath(const MappingInfo& mapping,
+                                         char path[PATH_MAX]) const {
+  return my_strlcpy(path, root_prefix_, PATH_MAX) < PATH_MAX &&
+         my_strlcat(path, mapping.name, PATH_MAX) < PATH_MAX;
+}
+
+namespace {
+// Find the shared object name (SONAME) by examining the ELF information
+// for |mapping|. If the SONAME is found copy it into the passed buffer
+// |soname| and return true. The size of the buffer is |soname_size|.
+// The SONAME will be truncated if it is too long to fit in the buffer.
+bool ElfFileSoName(const LinuxDumper& dumper,
+    const MappingInfo& mapping, char* soname, size_t soname_size) {
+  if (IsMappedFileOpenUnsafe(mapping)) {
+    // Not safe
+    return false;
+  }
+
+  char filename[PATH_MAX];
+  if (!dumper.GetMappingAbsolutePath(mapping, filename))
+    return false;
+
+  MemoryMappedFile mapped_file(filename, 0);
+  if (!mapped_file.data() || mapped_file.size() < SELFMAG) {
+    // mmap failed
+    return false;
+  }
+
+  return ElfFileSoNameFromMappedFile(mapped_file.data(), soname, soname_size);
+}
+
+}  // namespace
+
+
+void LinuxDumper::GetMappingEffectiveNameAndPath(const MappingInfo& mapping,
+                                                 char* file_path,
+                                                 size_t file_path_size,
+                                                 char* file_name,
+                                                 size_t file_name_size) {
+  my_strlcpy(file_path, mapping.name, file_path_size);
+
+  // Tools such as minidump_stackwalk use the name of the module to look up
+  // symbols produced by dump_syms. dump_syms will prefer to use a module's
+  // DT_SONAME as the module name, if one exists, and will fall back to the
+  // filesystem name of the module.
+
+  // Just use the filesystem name if no SONAME is present.
+  if (!ElfFileSoName(*this, mapping, file_name, file_name_size)) {
+    //   file_path := /path/to/libname.so
+    //   file_name := libname.so
+    const char* basename = my_strrchr(file_path, '/');
+    basename = basename == NULL ? file_path : (basename + 1);
+    my_strlcpy(file_name, basename, file_name_size);
+    return;
+  }
+
+  if (mapping.exec && mapping.offset != 0) {
+    // If an executable is mapped from a non-zero offset, this is likely because
+    // the executable was loaded directly from inside an archive file (e.g., an
+    // apk on Android).
+    // In this case, we append the file_name to the mapped archive path:
+    //   file_name := libname.so
+    //   file_path := /path/to/ARCHIVE.APK/libname.so
+    if (my_strlen(file_path) + 1 + my_strlen(file_name) < file_path_size) {
+      my_strlcat(file_path, "/", file_path_size);
+      my_strlcat(file_path, file_name, file_path_size);
+    }
+  } else {
+    // Otherwise, replace the basename with the SONAME.
+    char* basename = const_cast<char*>(my_strrchr(file_path, '/'));
+    if (basename) {
+      my_strlcpy(basename + 1, file_name,
+                 file_path_size - my_strlen(file_path) +
+                     my_strlen(basename + 1));
+    } else {
+      my_strlcpy(file_path, file_name, file_path_size);
+    }
+  }
+}
+
+bool LinuxDumper::ReadAuxv() {
+  char auxv_path[NAME_MAX];
+  if (!BuildProcPath(auxv_path, pid_, "auxv")) {
+    return false;
+  }
+
+  int fd = sys_open(auxv_path, O_RDONLY, 0);
+  if (fd < 0) {
+    return false;
+  }
+
+  elf_aux_entry one_aux_entry;
+  bool res = false;
+  while (sys_read(fd,
+                  &one_aux_entry,
+                  sizeof(elf_aux_entry)) == sizeof(elf_aux_entry) &&
+         one_aux_entry.a_type != AT_NULL) {
+    if (one_aux_entry.a_type <= AT_MAX) {
+      auxv_[one_aux_entry.a_type] = one_aux_entry.a_un.a_val;
+      res = true;
+    }
+  }
+  sys_close(fd);
+  return res;
+}
+
+bool LinuxDumper::EnumerateMappings() {
+  char maps_path[NAME_MAX];
+  if (!BuildProcPath(maps_path, pid_, "maps"))
+    return false;
+
+  // linux_gate_loc is the beginning of the kernel's mapping of
+  // linux-gate.so in the process.  It doesn't actually show up in the
+  // maps list as a filename, but it can be found using the AT_SYSINFO_EHDR
+  // aux vector entry, which gives the information necessary to special
+  // case its entry when creating the list of mappings.
+  // See http://www.trilithium.com/johan/2005/08/linux-gate/ for more
+  // information.
+  const void* linux_gate_loc =
+      reinterpret_cast<void*>(auxv_[AT_SYSINFO_EHDR]);
+  // Although the initial executable is usually the first mapping, it's not
+  // guaranteed (see http://crosbug.com/25355); therefore, try to use the
+  // actual entry point to find the mapping.
+  const void* entry_point_loc = reinterpret_cast<void*>(auxv_[AT_ENTRY]);
+
+  const int fd = sys_open(maps_path, O_RDONLY, 0);
+  if (fd < 0)
+    return false;
+  LineReader* const line_reader = new(allocator_) LineReader(fd);
+
+  const char* line;
+  unsigned line_len;
+  while (line_reader->GetNextLine(&line, &line_len)) {
+    uintptr_t start_addr, end_addr, offset;
+
+    const char* i1 = my_read_hex_ptr(&start_addr, line);
+    if (*i1 == '-') {
+      const char* i2 = my_read_hex_ptr(&end_addr, i1 + 1);
+      if (*i2 == ' ') {
+        bool exec = (*(i2 + 3) == 'x');
+        const char* i3 = my_read_hex_ptr(&offset, i2 + 6 /* skip ' rwxp ' */);
+        if (*i3 == ' ') {
+          const char* name = NULL;
+          // Only copy name if the name is a valid path name, or if
+          // it's the VDSO image.
+          if (((name = my_strchr(line, '/')) == NULL) &&
+              linux_gate_loc &&
+              reinterpret_cast<void*>(start_addr) == linux_gate_loc) {
+            name = kLinuxGateLibraryName;
+            offset = 0;
+          }
+          // Merge adjacent mappings into one module, assuming they're a single
+          // library mapped by the dynamic linker. Do this only if their name
+          // matches and either they have the same +x protection flag, or if the
+          // previous mapping is not executable and the new one is, to handle
+          // lld's output (see crbug.com/716484).
+          if (name && !mappings_.empty()) {
+            MappingInfo* module = mappings_.back();
+            if ((start_addr == module->start_addr + module->size) &&
+                (my_strlen(name) == my_strlen(module->name)) &&
+                (my_strncmp(name, module->name, my_strlen(name)) == 0) &&
+                ((exec == module->exec) || (!module->exec && exec))) {
+              module->system_mapping_info.end_addr = end_addr;
+              module->size = end_addr - module->start_addr;
+              module->exec |= exec;
+              line_reader->PopLine(line_len);
+              continue;
+            }
+          }
+          MappingInfo* const module = new(allocator_) MappingInfo;
+          mappings_.push_back(module);
+          my_memset(module, 0, sizeof(MappingInfo));
+          module->system_mapping_info.start_addr = start_addr;
+          module->system_mapping_info.end_addr = end_addr;
+          module->start_addr = start_addr;
+          module->size = end_addr - start_addr;
+          module->offset = offset;
+          module->exec = exec;
+          if (name != NULL) {
+            const unsigned l = my_strlen(name);
+            if (l < sizeof(module->name))
+              my_memcpy(module->name, name, l);
+          }
+        }
+      }
+    }
+    line_reader->PopLine(line_len);
+  }
+
+  if (entry_point_loc) {
+    for (size_t i = 0; i < mappings_.size(); ++i) {
+      MappingInfo* module = mappings_[i];
+
+      // If this module contains the entry-point, and it's not already the first
+      // one, then we need to make it be first.  This is because the minidump
+      // format assumes the first module is the one that corresponds to the main
+      // executable (as codified in
+      // processor/minidump.cc:MinidumpModuleList::GetMainModule()).
+      if ((entry_point_loc >= reinterpret_cast<void*>(module->start_addr)) &&
+          (entry_point_loc <
+           reinterpret_cast<void*>(module->start_addr + module->size))) {
+        for (size_t j = i; j > 0; j--)
+          mappings_[j] = mappings_[j - 1];
+        mappings_[0] = module;
+        break;
+      }
+    }
+  }
+
+  sys_close(fd);
+
+  return !mappings_.empty();
+}
+
+#if defined(__ANDROID__)
+
+bool LinuxDumper::GetLoadedElfHeader(uintptr_t start_addr, ElfW(Ehdr)* ehdr) {
+  CopyFromProcess(ehdr, pid_,
+                  reinterpret_cast<const void*>(start_addr),
+                  sizeof(*ehdr));
+  return my_memcmp(&ehdr->e_ident, ELFMAG, SELFMAG) == 0;
+}
+
+void LinuxDumper::ParseLoadedElfProgramHeaders(ElfW(Ehdr)* ehdr,
+                                               uintptr_t start_addr,
+                                               uintptr_t* min_vaddr_ptr,
+                                               uintptr_t* dyn_vaddr_ptr,
+                                               size_t* dyn_count_ptr) {
+  uintptr_t phdr_addr = start_addr + ehdr->e_phoff;
+
+  const uintptr_t max_addr = UINTPTR_MAX;
+  uintptr_t min_vaddr = max_addr;
+  uintptr_t dyn_vaddr = 0;
+  size_t dyn_count = 0;
+
+  for (size_t i = 0; i < ehdr->e_phnum; ++i) {
+    ElfW(Phdr) phdr;
+    CopyFromProcess(&phdr, pid_,
+                    reinterpret_cast<const void*>(phdr_addr),
+                    sizeof(phdr));
+    if (phdr.p_type == PT_LOAD && phdr.p_vaddr < min_vaddr) {
+      min_vaddr = phdr.p_vaddr;
+    }
+    if (phdr.p_type == PT_DYNAMIC) {
+      dyn_vaddr = phdr.p_vaddr;
+      dyn_count = phdr.p_memsz / sizeof(ElfW(Dyn));
+    }
+    phdr_addr += sizeof(phdr);
+  }
+
+  *min_vaddr_ptr = min_vaddr;
+  *dyn_vaddr_ptr = dyn_vaddr;
+  *dyn_count_ptr = dyn_count;
+}
+
+bool LinuxDumper::HasAndroidPackedRelocations(uintptr_t load_bias,
+                                              uintptr_t dyn_vaddr,
+                                              size_t dyn_count) {
+  uintptr_t dyn_addr = load_bias + dyn_vaddr;
+  for (size_t i = 0; i < dyn_count; ++i) {
+    ElfW(Dyn) dyn;
+    CopyFromProcess(&dyn, pid_,
+                    reinterpret_cast<const void*>(dyn_addr),
+                    sizeof(dyn));
+    if (dyn.d_tag == DT_ANDROID_REL || dyn.d_tag == DT_ANDROID_RELA) {
+      return true;
+    }
+    dyn_addr += sizeof(dyn);
+  }
+  return false;
+}
+
+uintptr_t LinuxDumper::GetEffectiveLoadBias(ElfW(Ehdr)* ehdr,
+                                            uintptr_t start_addr) {
+  uintptr_t min_vaddr = 0;
+  uintptr_t dyn_vaddr = 0;
+  size_t dyn_count = 0;
+  ParseLoadedElfProgramHeaders(ehdr, start_addr,
+                               &min_vaddr, &dyn_vaddr, &dyn_count);
+  // If |min_vaddr| is non-zero and we find Android packed relocation tags,
+  // return the effective load bias.
+  if (min_vaddr != 0) {
+    const uintptr_t load_bias = start_addr - min_vaddr;
+    if (HasAndroidPackedRelocations(load_bias, dyn_vaddr, dyn_count)) {
+      return load_bias;
+    }
+  }
+  // Either |min_vaddr| is zero, or it is non-zero but we did not find the
+  // expected Android packed relocations tags.
+  return start_addr;
+}
+
+void LinuxDumper::LatePostprocessMappings() {
+  for (size_t i = 0; i < mappings_.size(); ++i) {
+    // Only consider exec mappings that indicate a file path was mapped, and
+    // where the ELF header indicates a mapped shared library.
+    MappingInfo* mapping = mappings_[i];
+    if (!(mapping->exec && mapping->name[0] == '/')) {
+      continue;
+    }
+    ElfW(Ehdr) ehdr;
+    if (!GetLoadedElfHeader(mapping->start_addr, &ehdr)) {
+      continue;
+    }
+    if (ehdr.e_type == ET_DYN) {
+      // Compute the effective load bias for this mapped library, and update
+      // the mapping to hold that rather than |start_addr|, at the same time
+      // adjusting |size| to account for the change in |start_addr|. Where
+      // the library does not contain Android packed relocations,
+      // GetEffectiveLoadBias() returns |start_addr| and the mapping entry
+      // is not changed.
+      const uintptr_t load_bias = GetEffectiveLoadBias(&ehdr,
+                                                       mapping->start_addr);
+      mapping->size += mapping->start_addr - load_bias;
+      mapping->start_addr = load_bias;
+    }
+  }
+}
+
+#endif  // __ANDROID__
+
+// Get information about the stack, given the stack pointer. We don't try to
+// walk the stack since we might not have all the information needed to do
+// unwind. So we just grab, up to, 32k of stack.
+bool LinuxDumper::GetStackInfo(const void** stack, size_t* stack_len,
+                               uintptr_t int_stack_pointer) {
+  // Move the stack pointer to the bottom of the page that it's in.
+  const uintptr_t page_size = getpagesize();
+
+  uint8_t* const stack_pointer =
+      reinterpret_cast<uint8_t*>(int_stack_pointer & ~(page_size - 1));
+
+  // The number of bytes of stack which we try to capture.
+  static const ptrdiff_t kStackToCapture = 32 * 1024;
+
+  const MappingInfo* mapping = FindMapping(stack_pointer);
+  if (!mapping)
+    return false;
+  const ptrdiff_t offset = stack_pointer -
+      reinterpret_cast<uint8_t*>(mapping->start_addr);
+  const ptrdiff_t distance_to_end =
+      static_cast<ptrdiff_t>(mapping->size) - offset;
+  *stack_len = distance_to_end > kStackToCapture ?
+      kStackToCapture : distance_to_end;
+  *stack = stack_pointer;
+  return true;
+}
+
+void LinuxDumper::SanitizeStackCopy(uint8_t* stack_copy, size_t stack_len,
+                                    uintptr_t stack_pointer,
+                                    uintptr_t sp_offset) {
+  // We optimize the search for containing mappings in three ways:
+  // 1) We expect that pointers into the stack mapping will be common, so
+  //    we cache that address range.
+  // 2) The last referenced mapping is a reasonable predictor for the next
+  //    referenced mapping, so we test that first.
+  // 3) We precompute a bitfield based upon bits 32:32-n of the start and
+  //    stop addresses, and use that to short circuit any values that can
+  //    not be pointers. (n=11)
+  const uintptr_t defaced =
+#if defined(__LP64__)
+      0x0defaced0defaced;
+#else
+      0x0defaced;
+#endif
+  // the bitfield length is 2^test_bits long.
+  const unsigned int test_bits = 11;
+  // byte length of the corresponding array.
+  const unsigned int array_size = 1 << (test_bits - 3);
+  const unsigned int array_mask = array_size - 1;
+  // The amount to right shift pointers by. This captures the top bits
+  // on 32 bit architectures. On 64 bit architectures this would be
+  // uninformative so we take the same range of bits.
+  const unsigned int shift = 32 - 11;
+  const MappingInfo* last_hit_mapping = nullptr;
+  const MappingInfo* hit_mapping = nullptr;
+  const MappingInfo* stack_mapping = FindMappingNoBias(stack_pointer);
+  // The magnitude below which integers are considered to be to be
+  // 'small', and not constitute a PII risk. These are included to
+  // avoid eliding useful register values.
+  const ssize_t small_int_magnitude = 4096;
+
+  char could_hit_mapping[array_size];
+  my_memset(could_hit_mapping, 0, array_size);
+
+  // Initialize the bitfield such that if the (pointer >> shift)'th
+  // bit, modulo the bitfield size, is not set then there does not
+  // exist a mapping in mappings_ that would contain that pointer.
+  for (size_t i = 0; i < mappings_.size(); ++i) {
+    if (!mappings_[i]->exec) continue;
+    // For each mapping, work out the (unmodulo'ed) range of bits to
+    // set.
+    uintptr_t start = mappings_[i]->start_addr;
+    uintptr_t end = start + mappings_[i]->size;
+    start >>= shift;
+    end >>= shift;
+    for (size_t bit = start; bit <= end; ++bit) {
+      // Set each bit in the range, applying the modulus.
+      could_hit_mapping[(bit >> 3) & array_mask] |= 1 << (bit & 7);
+    }
+  }
+
+  // Zero memory that is below the current stack pointer.
+  const uintptr_t offset =
+      (sp_offset + sizeof(uintptr_t) - 1) & ~(sizeof(uintptr_t) - 1);
+  if (offset) {
+    my_memset(stack_copy, 0, offset);
+  }
+
+  // Apply sanitization to each complete pointer-aligned word in the
+  // stack.
+  uint8_t* sp;
+  for (sp = stack_copy + offset;
+       sp <= stack_copy + stack_len - sizeof(uintptr_t);
+       sp += sizeof(uintptr_t)) {
+    uintptr_t addr;
+    my_memcpy(&addr, sp, sizeof(uintptr_t));
+    if (static_cast<intptr_t>(addr) <= small_int_magnitude &&
+        static_cast<intptr_t>(addr) >= -small_int_magnitude) {
+      continue;
+    }
+    if (stack_mapping && MappingContainsAddress(*stack_mapping, addr)) {
+      continue;
+    }
+    if (last_hit_mapping && MappingContainsAddress(*last_hit_mapping, addr)) {
+      continue;
+    }
+    uintptr_t test = addr >> shift;
+    if (could_hit_mapping[(test >> 3) & array_mask] & (1 << (test & 7)) &&
+        (hit_mapping = FindMappingNoBias(addr)) != nullptr &&
+        hit_mapping->exec) {
+      last_hit_mapping = hit_mapping;
+      continue;
+    }
+    my_memcpy(sp, &defaced, sizeof(uintptr_t));
+  }
+  // Zero any partial word at the top of the stack, if alignment is
+  // such that that is required.
+  if (sp < stack_copy + stack_len) {
+    my_memset(sp, 0, stack_copy + stack_len - sp);
+  }
+}
+
+bool LinuxDumper::StackHasPointerToMapping(const uint8_t* stack_copy,
+                                           size_t stack_len,
+                                           uintptr_t sp_offset,
+                                           const MappingInfo& mapping) {
+  // Loop over all stack words that would have been on the stack in
+  // the target process (i.e. are word aligned, and at addresses >=
+  // the stack pointer).  Regardless of the alignment of |stack_copy|,
+  // the memory starting at |stack_copy| + |offset| represents an
+  // aligned word in the target process.
+  const uintptr_t low_addr = mapping.system_mapping_info.start_addr;
+  const uintptr_t high_addr = mapping.system_mapping_info.end_addr;
+  const uintptr_t offset =
+      (sp_offset + sizeof(uintptr_t) - 1) & ~(sizeof(uintptr_t) - 1);
+
+  for (const uint8_t* sp = stack_copy + offset;
+       sp <= stack_copy + stack_len - sizeof(uintptr_t);
+       sp += sizeof(uintptr_t)) {
+    uintptr_t addr;
+    my_memcpy(&addr, sp, sizeof(uintptr_t));
+    if (low_addr <= addr && addr <= high_addr)
+      return true;
+  }
+  return false;
+}
+
+// Find the mapping which the given memory address falls in.
+const MappingInfo* LinuxDumper::FindMapping(const void* address) const {
+  const uintptr_t addr = (uintptr_t) address;
+
+  for (size_t i = 0; i < mappings_.size(); ++i) {
+    const uintptr_t start = static_cast<uintptr_t>(mappings_[i]->start_addr);
+    if (addr >= start && addr - start < mappings_[i]->size)
+      return mappings_[i];
+  }
+
+  return NULL;
+}
+
+// Find the mapping which the given memory address falls in. Uses the
+// unadjusted mapping address range from the kernel, rather than the
+// biased range.
+const MappingInfo* LinuxDumper::FindMappingNoBias(uintptr_t address) const {
+  for (size_t i = 0; i < mappings_.size(); ++i) {
+    if (address >= mappings_[i]->system_mapping_info.start_addr &&
+        address < mappings_[i]->system_mapping_info.end_addr) {
+      return mappings_[i];
+    }
+  }
+  return NULL;
+}
+
+bool LinuxDumper::HandleDeletedFileInMapping(char* path) const {
+  static const size_t kDeletedSuffixLen = sizeof(kDeletedSuffix) - 1;
+
+  // Check for ' (deleted)' in |path|.
+  // |path| has to be at least as long as "/x (deleted)".
+  const size_t path_len = my_strlen(path);
+  if (path_len < kDeletedSuffixLen + 2)
+    return false;
+  if (my_strncmp(path + path_len - kDeletedSuffixLen, kDeletedSuffix,
+                 kDeletedSuffixLen) != 0) {
+    return false;
+  }
+
+  // Check |path| against the /proc/pid/exe 'symlink'.
+  char exe_link[NAME_MAX];
+  if (!BuildProcPath(exe_link, pid_, "exe"))
+    return false;
+  MappingInfo new_mapping = {0};
+  if (!SafeReadLink(exe_link, new_mapping.name))
+    return false;
+  char new_path[PATH_MAX];
+  if (!GetMappingAbsolutePath(new_mapping, new_path))
+    return false;
+  if (my_strcmp(path, new_path) != 0)
+    return false;
+
+  // Check to see if someone actually named their executable 'foo (deleted)'.
+  struct kernel_stat exe_stat;
+  struct kernel_stat new_path_stat;
+  if (sys_stat(exe_link, &exe_stat) == 0 &&
+      sys_stat(new_path, &new_path_stat) == 0 &&
+      exe_stat.st_dev == new_path_stat.st_dev &&
+      exe_stat.st_ino == new_path_stat.st_ino) {
+    return false;
+  }
+
+  my_memcpy(path, exe_link, NAME_MAX);
+  return true;
+}
+
+}  // namespace google_breakpad