1 files changed, 1617 insertions, 0 deletions
diff --git a/externals/breakpad/src/client/linux/minidump_writer/minidump_writer.cc b/externals/breakpad/src/client/linux/minidump_writer/minidump_writer.cc
new file mode 100644
index 0000000000..27e10a4b54
--- /dev/null
+++ b/externals/breakpad/src/client/linux/minidump_writer/minidump_writer.cc
@@ -0,0 +1,1617 @@
+// 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.
+
+// This code writes out minidump files:
+//   http://msdn.microsoft.com/en-us/library/ms680378(VS.85,loband).aspx
+//
+// Minidumps are a Microsoft format which Breakpad uses for recording crash
+// dumps. This code has to run in a compromised environment (the address space
+// may have received SIGSEGV), thus the following rules apply:
+//   * You may not enter the dynamic linker. This means that we cannot call
+//     any symbols in a shared library (inc libc). Because of this we replace
+//     libc functions in linux_libc_support.h.
+//   * You may not call syscalls via the libc wrappers. This rule is a subset
+//     of the first rule but it bears repeating. We have direct wrappers
+//     around the system calls in linux_syscall_support.h.
+//   * You may not malloc. There's an alternative allocator in memory.h and
+//     a canonical instance in the LinuxDumper object. We use the placement
+//     new form to allocate objects and we don't delete them.
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>  // Must come first
+#endif
+
+#include "client/linux/handler/minidump_descriptor.h"
+#include "client/linux/minidump_writer/minidump_writer.h"
+#include "client/minidump_file_writer-inl.h"
+
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <link.h>
+#include <stdio.h>
+#if defined(__ANDROID__)
+#include <sys/system_properties.h>
+#endif
+#include <sys/types.h>
+#include <sys/ucontext.h>
+#include <sys/user.h>
+#include <sys/utsname.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <algorithm>
+
+#include "client/linux/dump_writer_common/thread_info.h"
+#include "client/linux/dump_writer_common/ucontext_reader.h"
+#include "client/linux/handler/exception_handler.h"
+#include "client/linux/minidump_writer/cpu_set.h"
+#include "client/linux/minidump_writer/line_reader.h"
+#include "client/linux/minidump_writer/linux_dumper.h"
+#include "client/linux/minidump_writer/linux_ptrace_dumper.h"
+#include "client/linux/minidump_writer/pe_file.h"
+#include "client/linux/minidump_writer/pe_structs.h"
+#include "client/linux/minidump_writer/proc_cpuinfo_reader.h"
+#include "client/minidump_file_writer.h"
+#include "common/linux/file_id.h"
+#include "common/linux/linux_libc_support.h"
+#include "common/minidump_type_helper.h"
+#include "google_breakpad/common/minidump_format.h"
+#include "third_party/lss/linux_syscall_support.h"
+
+namespace {
+
+using google_breakpad::AppMemoryList;
+using google_breakpad::auto_wasteful_vector;
+using google_breakpad::elf::kDefaultBuildIdSize;
+using google_breakpad::ExceptionHandler;
+using google_breakpad::CpuSet;
+using google_breakpad::LineReader;
+using google_breakpad::LinuxDumper;
+using google_breakpad::LinuxPtraceDumper;
+using google_breakpad::MDTypeHelper;
+using google_breakpad::MappingEntry;
+using google_breakpad::MappingInfo;
+using google_breakpad::MappingList;
+using google_breakpad::MinidumpFileWriter;
+using google_breakpad::PageAllocator;
+using google_breakpad::PEFile;
+using google_breakpad::PEFileFormat;
+using google_breakpad::ProcCpuInfoReader;
+using google_breakpad::RawContextCPU;
+using google_breakpad::RSDS_DEBUG_FORMAT;
+using google_breakpad::ThreadInfo;
+using google_breakpad::TypedMDRVA;
+using google_breakpad::UContextReader;
+using google_breakpad::UntypedMDRVA;
+using google_breakpad::wasteful_vector;
+
+typedef MDTypeHelper<sizeof(void*)>::MDRawDebug MDRawDebug;
+typedef MDTypeHelper<sizeof(void*)>::MDRawLinkMap MDRawLinkMap;
+
+class MinidumpWriter {
+ public:
+  // The following kLimit* constants are for when minidump_size_limit_ is set
+  // and the minidump size might exceed it.
+  //
+  // Estimate for how big each thread's stack will be (in bytes).
+  static const unsigned kLimitAverageThreadStackLength = 8 * 1024;
+  // Number of threads whose stack size we don't want to limit.  These base
+  // threads will simply be the first N threads returned by the dumper (although
+  // the crashing thread will never be limited).  Threads beyond this count are
+  // the extra threads.
+  static const unsigned kLimitBaseThreadCount = 20;
+  // Maximum stack size to dump for any extra thread (in bytes).
+  static const unsigned kLimitMaxExtraThreadStackLen = 2 * 1024;
+  // Make sure this number of additional bytes can fit in the minidump
+  // (exclude the stack data).
+  static const unsigned kLimitMinidumpFudgeFactor = 64 * 1024;
+
+  MinidumpWriter(const char* minidump_path,
+                 int minidump_fd,
+                 const ExceptionHandler::CrashContext* context,
+                 const MappingList& mappings,
+                 const AppMemoryList& appmem,
+                 bool skip_stacks_if_mapping_unreferenced,
+                 uintptr_t principal_mapping_address,
+                 bool sanitize_stacks,
+                 LinuxDumper* dumper)
+      : fd_(minidump_fd),
+        path_(minidump_path),
+        ucontext_(context ? &context->context : NULL),
+#if GOOGLE_BREAKPAD_CRASH_CONTEXT_HAS_FLOAT_STATE
+        float_state_(context ? &context->float_state : NULL),
+#endif
+        dumper_(dumper),
+        minidump_size_limit_(-1),
+        memory_blocks_(dumper_->allocator()),
+        mapping_list_(mappings),
+        app_memory_list_(appmem),
+        skip_stacks_if_mapping_unreferenced_(
+            skip_stacks_if_mapping_unreferenced),
+        principal_mapping_address_(principal_mapping_address),
+        principal_mapping_(nullptr),
+    sanitize_stacks_(sanitize_stacks) {
+    // Assert there should be either a valid fd or a valid path, not both.
+    assert(fd_ != -1 || minidump_path);
+    assert(fd_ == -1 || !minidump_path);
+  }
+
+  bool Init() {
+    if (!dumper_->Init())
+      return false;
+
+    if (!dumper_->ThreadsSuspend() || !dumper_->LateInit())
+      return false;
+
+    if (skip_stacks_if_mapping_unreferenced_) {
+      principal_mapping_ =
+          dumper_->FindMappingNoBias(principal_mapping_address_);
+      if (!CrashingThreadReferencesPrincipalMapping())
+        return false;
+    }
+
+    if (fd_ != -1)
+      minidump_writer_.SetFile(fd_);
+    else if (!minidump_writer_.Open(path_))
+      return false;
+
+    return true;
+  }
+
+  ~MinidumpWriter() {
+    // Don't close the file descriptor when it's been provided explicitly.
+    // Callers might still need to use it.
+    if (fd_ == -1)
+      minidump_writer_.Close();
+    dumper_->ThreadsResume();
+  }
+
+  bool CrashingThreadReferencesPrincipalMapping() {
+    if (!ucontext_ || !principal_mapping_)
+      return false;
+
+    const uintptr_t low_addr =
+        principal_mapping_->system_mapping_info.start_addr;
+    const uintptr_t high_addr =
+        principal_mapping_->system_mapping_info.end_addr;
+
+    const uintptr_t stack_pointer = UContextReader::GetStackPointer(ucontext_);
+    const uintptr_t pc = UContextReader::GetInstructionPointer(ucontext_);
+
+    if (pc >= low_addr && pc < high_addr)
+      return true;
+
+    uint8_t* stack_copy;
+    const void* stack;
+    size_t stack_len;
+
+    if (!dumper_->GetStackInfo(&stack, &stack_len, stack_pointer))
+      return false;
+
+    stack_copy = reinterpret_cast<uint8_t*>(Alloc(stack_len));
+    dumper_->CopyFromProcess(stack_copy, GetCrashThread(), stack, stack_len);
+
+    uintptr_t stack_pointer_offset =
+        stack_pointer - reinterpret_cast<uintptr_t>(stack);
+
+    return dumper_->StackHasPointerToMapping(
+        stack_copy, stack_len, stack_pointer_offset, *principal_mapping_);
+  }
+
+  bool Dump() {
+    // A minidump file contains a number of tagged streams. This is the number
+    // of stream which we write.
+    unsigned kNumWriters = 13;
+
+    TypedMDRVA<MDRawDirectory> dir(&minidump_writer_);
+    {
+      // Ensure the header gets flushed, as that happens in the destructor.
+      // If a crash occurs somewhere below, at least the header will be
+      // intact.
+      TypedMDRVA<MDRawHeader> header(&minidump_writer_);
+      if (!header.Allocate())
+        return false;
+
+      if (!dir.AllocateArray(kNumWriters))
+        return false;
+
+      my_memset(header.get(), 0, sizeof(MDRawHeader));
+
+      header.get()->signature = MD_HEADER_SIGNATURE;
+      header.get()->version = MD_HEADER_VERSION;
+      header.get()->time_date_stamp = time(NULL);
+      header.get()->stream_count = kNumWriters;
+      header.get()->stream_directory_rva = dir.position();
+    }
+
+    unsigned dir_index = 0;
+    MDRawDirectory dirent;
+
+    if (!WriteThreadListStream(&dirent))
+      return false;
+    dir.CopyIndex(dir_index++, &dirent);
+
+    if (!WriteMappings(&dirent))
+      return false;
+    dir.CopyIndex(dir_index++, &dirent);
+
+    if (!WriteAppMemory())
+      return false;
+
+    if (!WriteMemoryListStream(&dirent))
+      return false;
+    dir.CopyIndex(dir_index++, &dirent);
+
+    if (!WriteExceptionStream(&dirent))
+      return false;
+    dir.CopyIndex(dir_index++, &dirent);
+
+    if (!WriteSystemInfoStream(&dirent))
+      return false;
+    dir.CopyIndex(dir_index++, &dirent);
+
+    dirent.stream_type = MD_LINUX_CPU_INFO;
+    if (!WriteFile(&dirent.location, "/proc/cpuinfo"))
+      NullifyDirectoryEntry(&dirent);
+    dir.CopyIndex(dir_index++, &dirent);
+
+    dirent.stream_type = MD_LINUX_PROC_STATUS;
+    if (!WriteProcFile(&dirent.location, GetCrashThread(), "status"))
+      NullifyDirectoryEntry(&dirent);
+    dir.CopyIndex(dir_index++, &dirent);
+
+    dirent.stream_type = MD_LINUX_LSB_RELEASE;
+    if (!WriteFile(&dirent.location, "/etc/lsb-release"))
+      NullifyDirectoryEntry(&dirent);
+    dir.CopyIndex(dir_index++, &dirent);
+
+    dirent.stream_type = MD_LINUX_CMD_LINE;
+    if (!WriteProcFile(&dirent.location, GetCrashThread(), "cmdline"))
+      NullifyDirectoryEntry(&dirent);
+    dir.CopyIndex(dir_index++, &dirent);
+
+    dirent.stream_type = MD_LINUX_ENVIRON;
+    if (!WriteProcFile(&dirent.location, GetCrashThread(), "environ"))
+      NullifyDirectoryEntry(&dirent);
+    dir.CopyIndex(dir_index++, &dirent);
+
+    dirent.stream_type = MD_LINUX_AUXV;
+    if (!WriteProcFile(&dirent.location, GetCrashThread(), "auxv"))
+      NullifyDirectoryEntry(&dirent);
+    dir.CopyIndex(dir_index++, &dirent);
+
+    dirent.stream_type = MD_LINUX_MAPS;
+    if (!WriteProcFile(&dirent.location, GetCrashThread(), "maps"))
+      NullifyDirectoryEntry(&dirent);
+    dir.CopyIndex(dir_index++, &dirent);
+
+    dirent.stream_type = MD_LINUX_DSO_DEBUG;
+    if (!WriteDSODebugStream(&dirent))
+      NullifyDirectoryEntry(&dirent);
+    dir.CopyIndex(dir_index++, &dirent);
+
+    // If you add more directory entries, don't forget to update kNumWriters,
+    // above.
+
+    dumper_->ThreadsResume();
+    return true;
+  }
+
+  bool FillThreadStack(MDRawThread* thread, uintptr_t stack_pointer,
+                       uintptr_t pc, int max_stack_len, uint8_t** stack_copy) {
+    *stack_copy = NULL;
+    const void* stack;
+    size_t stack_len;
+
+    thread->stack.start_of_memory_range = stack_pointer;
+    thread->stack.memory.data_size = 0;
+    thread->stack.memory.rva = minidump_writer_.position();
+
+    if (dumper_->GetStackInfo(&stack, &stack_len, stack_pointer)) {
+      if (max_stack_len >= 0 &&
+          stack_len > static_cast<unsigned int>(max_stack_len)) {
+        stack_len = max_stack_len;
+        // Skip empty chunks of length max_stack_len.
+        uintptr_t int_stack = reinterpret_cast<uintptr_t>(stack);
+        if (max_stack_len > 0) {
+          while (int_stack + max_stack_len < stack_pointer) {
+            int_stack += max_stack_len;
+          }
+        }
+        stack = reinterpret_cast<const void*>(int_stack);
+      }
+      *stack_copy = reinterpret_cast<uint8_t*>(Alloc(stack_len));
+      dumper_->CopyFromProcess(*stack_copy, thread->thread_id, stack,
+                               stack_len);
+
+      uintptr_t stack_pointer_offset =
+          stack_pointer - reinterpret_cast<uintptr_t>(stack);
+      if (skip_stacks_if_mapping_unreferenced_) {
+        if (!principal_mapping_) {
+          return true;
+        }
+        uintptr_t low_addr = principal_mapping_->system_mapping_info.start_addr;
+        uintptr_t high_addr = principal_mapping_->system_mapping_info.end_addr;
+        if ((pc < low_addr || pc > high_addr) &&
+            !dumper_->StackHasPointerToMapping(*stack_copy, stack_len,
+                                               stack_pointer_offset,
+                                               *principal_mapping_)) {
+          return true;
+        }
+      }
+
+      if (sanitize_stacks_) {
+        dumper_->SanitizeStackCopy(*stack_copy, stack_len, stack_pointer,
+                                   stack_pointer_offset);
+      }
+
+      UntypedMDRVA memory(&minidump_writer_);
+      if (!memory.Allocate(stack_len))
+        return false;
+      memory.Copy(*stack_copy, stack_len);
+      thread->stack.start_of_memory_range = reinterpret_cast<uintptr_t>(stack);
+      thread->stack.memory = memory.location();
+      memory_blocks_.push_back(thread->stack);
+    }
+    return true;
+  }
+
+  // Write information about the threads.
+  bool WriteThreadListStream(MDRawDirectory* dirent) {
+    const unsigned num_threads = dumper_->threads().size();
+
+    TypedMDRVA<uint32_t> list(&minidump_writer_);
+    if (!list.AllocateObjectAndArray(num_threads, sizeof(MDRawThread)))
+      return false;
+
+    dirent->stream_type = MD_THREAD_LIST_STREAM;
+    dirent->location = list.location();
+
+    *list.get() = num_threads;
+
+    // If there's a minidump size limit, check if it might be exceeded.  Since
+    // most of the space is filled with stack data, just check against that.
+    // If this expects to exceed the limit, set extra_thread_stack_len such
+    // that any thread beyond the first kLimitBaseThreadCount threads will
+    // have only kLimitMaxExtraThreadStackLen bytes dumped.
+    int extra_thread_stack_len = -1;  // default to no maximum
+    if (minidump_size_limit_ >= 0) {
+      const unsigned estimated_total_stack_size = num_threads *
+          kLimitAverageThreadStackLength;
+      const off_t estimated_minidump_size = minidump_writer_.position() +
+          estimated_total_stack_size + kLimitMinidumpFudgeFactor;
+      if (estimated_minidump_size > minidump_size_limit_)
+        extra_thread_stack_len = kLimitMaxExtraThreadStackLen;
+    }
+
+    for (unsigned i = 0; i < num_threads; ++i) {
+      MDRawThread thread;
+      my_memset(&thread, 0, sizeof(thread));
+      thread.thread_id = dumper_->threads()[i];
+
+      // We have a different source of information for the crashing thread. If
+      // we used the actual state of the thread we would find it running in the
+      // signal handler with the alternative stack, which would be deeply
+      // unhelpful.
+      if (static_cast<pid_t>(thread.thread_id) == GetCrashThread() &&
+          ucontext_ &&
+          !dumper_->IsPostMortem()) {
+        uint8_t* stack_copy;
+        const uintptr_t stack_ptr = UContextReader::GetStackPointer(ucontext_);
+        if (!FillThreadStack(&thread, stack_ptr,
+                             UContextReader::GetInstructionPointer(ucontext_),
+                             -1, &stack_copy))
+          return false;
+
+        // Copy 256 bytes around crashing instruction pointer to minidump.
+        const size_t kIPMemorySize = 256;
+        uint64_t ip = UContextReader::GetInstructionPointer(ucontext_);
+        // Bound it to the upper and lower bounds of the memory map
+        // it's contained within. If it's not in mapped memory,
+        // don't bother trying to write it.
+        bool ip_is_mapped = false;
+        MDMemoryDescriptor ip_memory_d;
+        for (unsigned j = 0; j < dumper_->mappings().size(); ++j) {
+          const MappingInfo& mapping = *dumper_->mappings()[j];
+          if (ip >= mapping.start_addr &&
+              ip < mapping.start_addr + mapping.size) {
+            ip_is_mapped = true;
+            // Try to get 128 bytes before and after the IP, but
+            // settle for whatever's available.
+            ip_memory_d.start_of_memory_range =
+              std::max(mapping.start_addr,
+                       uintptr_t(ip - (kIPMemorySize / 2)));
+            uintptr_t end_of_range =
+              std::min(uintptr_t(ip + (kIPMemorySize / 2)),
+                       uintptr_t(mapping.start_addr + mapping.size));
+            ip_memory_d.memory.data_size =
+              end_of_range - ip_memory_d.start_of_memory_range;
+            break;
+          }
+        }
+
+        if (ip_is_mapped) {
+          UntypedMDRVA ip_memory(&minidump_writer_);
+          if (!ip_memory.Allocate(ip_memory_d.memory.data_size))
+            return false;
+          uint8_t* memory_copy =
+              reinterpret_cast<uint8_t*>(Alloc(ip_memory_d.memory.data_size));
+          dumper_->CopyFromProcess(
+              memory_copy,
+              thread.thread_id,
+              reinterpret_cast<void*>(ip_memory_d.start_of_memory_range),
+              ip_memory_d.memory.data_size);
+          ip_memory.Copy(memory_copy, ip_memory_d.memory.data_size);
+          ip_memory_d.memory = ip_memory.location();
+          memory_blocks_.push_back(ip_memory_d);
+        }
+
+        TypedMDRVA<RawContextCPU> cpu(&minidump_writer_);
+        if (!cpu.Allocate())
+          return false;
+        my_memset(cpu.get(), 0, sizeof(RawContextCPU));
+#if GOOGLE_BREAKPAD_CRASH_CONTEXT_HAS_FLOAT_STATE
+        UContextReader::FillCPUContext(cpu.get(), ucontext_, float_state_);
+#else
+        UContextReader::FillCPUContext(cpu.get(), ucontext_);
+#endif
+        thread.thread_context = cpu.location();
+        crashing_thread_context_ = cpu.location();
+      } else {
+        ThreadInfo info;
+        if (!dumper_->GetThreadInfoByIndex(i, &info))
+          return false;
+
+        uint8_t* stack_copy;
+        int max_stack_len = -1;  // default to no maximum for this thread
+        if (minidump_size_limit_ >= 0 && i >= kLimitBaseThreadCount)
+          max_stack_len = extra_thread_stack_len;
+        if (!FillThreadStack(&thread, info.stack_pointer,
+                             info.GetInstructionPointer(), max_stack_len,
+                             &stack_copy))
+          return false;
+
+        TypedMDRVA<RawContextCPU> cpu(&minidump_writer_);
+        if (!cpu.Allocate())
+          return false;
+        my_memset(cpu.get(), 0, sizeof(RawContextCPU));
+        info.FillCPUContext(cpu.get());
+        thread.thread_context = cpu.location();
+        if (dumper_->threads()[i] == GetCrashThread()) {
+          crashing_thread_context_ = cpu.location();
+          if (!dumper_->IsPostMortem()) {
+            // This is the crashing thread of a live process, but
+            // no context was provided, so set the crash address
+            // while the instruction pointer is already here.
+            dumper_->set_crash_address(info.GetInstructionPointer());
+          }
+        }
+      }
+
+      list.CopyIndexAfterObject(i, &thread, sizeof(thread));
+    }
+
+    return true;
+  }
+
+  // Write application-provided memory regions.
+  bool WriteAppMemory() {
+    for (AppMemoryList::const_iterator iter = app_memory_list_.begin();
+         iter != app_memory_list_.end();
+         ++iter) {
+      uint8_t* data_copy =
+        reinterpret_cast<uint8_t*>(dumper_->allocator()->Alloc(iter->length));
+      dumper_->CopyFromProcess(data_copy, GetCrashThread(), iter->ptr,
+                               iter->length);
+
+      UntypedMDRVA memory(&minidump_writer_);
+      if (!memory.Allocate(iter->length)) {
+        return false;
+      }
+      memory.Copy(data_copy, iter->length);
+      MDMemoryDescriptor desc;
+      desc.start_of_memory_range = reinterpret_cast<uintptr_t>(iter->ptr);
+      desc.memory = memory.location();
+      memory_blocks_.push_back(desc);
+    }
+
+    return true;
+  }
+
+  static bool ShouldIncludeMapping(const MappingInfo& mapping) {
+    if (mapping.name[0] == 0 ||  // only want modules with filenames.
+        // Only want to include one mapping per shared lib.
+        // Avoid filtering executable mappings.
+        (mapping.offset != 0 && !mapping.exec) ||
+        mapping.size < 4096 ||  // too small to get a signature for.
+        mapping.size > 0xFFFFFFFFULL) { // too large to include in the dump.
+      return false;
+    }
+
+    return true;
+  }
+
+  // If there is caller-provided information about this mapping
+  // in the mapping_list_ list, return true. Otherwise, return false.
+  bool HaveMappingInfo(const MappingInfo& mapping) {
+    for (MappingList::const_iterator iter = mapping_list_.begin();
+         iter != mapping_list_.end();
+         ++iter) {
+      // Ignore any mappings that are wholly contained within
+      // mappings in the mapping_info_ list.
+      if (mapping.start_addr >= iter->first.start_addr &&
+          (mapping.start_addr + mapping.size) <=
+          (iter->first.start_addr + iter->first.size)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  // Write information about the mappings in effect. Because we are using the
+  // minidump format, the information about the mappings is pretty limited.
+  // Because of this, we also include the full, unparsed, /proc/$x/maps file in
+  // another stream in the file.
+  bool WriteMappings(MDRawDirectory* dirent) {
+    const unsigned num_mappings = dumper_->mappings().size();
+    unsigned num_output_mappings = mapping_list_.size();
+
+    for (unsigned i = 0; i < dumper_->mappings().size(); ++i) {
+      const MappingInfo& mapping = *dumper_->mappings()[i];
+      if (ShouldIncludeMapping(mapping) && !HaveMappingInfo(mapping))
+        num_output_mappings++;
+    }
+
+    TypedMDRVA<uint32_t> list(&minidump_writer_);
+    if (num_output_mappings) {
+      if (!list.AllocateObjectAndArray(num_output_mappings, MD_MODULE_SIZE))
+        return false;
+    } else {
+      // Still create the module list stream, although it will have zero
+      // modules.
+      if (!list.Allocate())
+        return false;
+    }
+
+    dirent->stream_type = MD_MODULE_LIST_STREAM;
+    dirent->location = list.location();
+    *list.get() = num_output_mappings;
+
+    // First write all the mappings from the dumper
+    unsigned int j = 0;
+    for (unsigned i = 0; i < num_mappings; ++i) {
+      const MappingInfo& mapping = *dumper_->mappings()[i];
+      if (!ShouldIncludeMapping(mapping) || HaveMappingInfo(mapping))
+        continue;
+
+      MDRawModule mod;
+      if (!FillRawModule(mapping, true, i, &mod, NULL))
+        return false;
+      list.CopyIndexAfterObject(j++, &mod, MD_MODULE_SIZE);
+    }
+    // Next write all the mappings provided by the caller
+    for (MappingList::const_iterator iter = mapping_list_.begin();
+         iter != mapping_list_.end();
+         ++iter) {
+      MDRawModule mod;
+      if (!FillRawModule(iter->first, false, 0, &mod, iter->second))
+        return false;
+      list.CopyIndexAfterObject(j++, &mod, MD_MODULE_SIZE);
+    }
+
+    return true;
+  }
+
+  // Fill the MDRawModule |mod| with information about the provided
+  // |mapping|. If |identifier| is non-NULL, use it instead of calculating
+  // a file ID from the mapping.
+  bool FillRawModule(const MappingInfo& mapping,
+                     bool member,
+                     unsigned int mapping_id,
+                     MDRawModule* mod,
+                     const uint8_t* identifier) {
+    my_memset(mod, 0, MD_MODULE_SIZE);
+
+    mod->base_of_image = mapping.start_addr;
+    mod->size_of_image = mapping.size;
+
+    char file_name[NAME_MAX];
+    char file_path[NAME_MAX];
+
+    dumper_->GetMappingEffectiveNameAndPath(mapping, file_path,
+                                            sizeof(file_path), file_name,
+                                            sizeof(file_name));
+
+    RSDS_DEBUG_FORMAT rsds;
+    PEFileFormat file_format = PEFile::TryGetDebugInfo(file_path, &rsds);
+
+    if (file_format == PEFileFormat::notPeCoff) {
+      // The module is not a PE/COFF file, process as an ELF.
+      auto_wasteful_vector<uint8_t, kDefaultBuildIdSize> identifier_bytes(
+          dumper_->allocator());
+
+      if (identifier) {
+        // GUID was provided by caller.
+        identifier_bytes.insert(identifier_bytes.end(), identifier,
+                                identifier + sizeof(MDGUID));
+      } else {
+        // Note: ElfFileIdentifierForMapping() can manipulate the
+        // |mapping.name|, that is why we need to call the method
+        // GetMappingEffectiveNameAndPath again.
+        dumper_->ElfFileIdentifierForMapping(mapping, member, mapping_id,
+                                             identifier_bytes);
+        dumper_->GetMappingEffectiveNameAndPath(mapping, file_path,
+                                                sizeof(file_path), file_name,
+                                                sizeof(file_name));
+      }
+
+      if (!identifier_bytes.empty()) {
+        UntypedMDRVA cv(&minidump_writer_);
+        if (!cv.Allocate(MDCVInfoELF_minsize + identifier_bytes.size()))
+          return false;
+
+        const uint32_t cv_signature = MD_CVINFOELF_SIGNATURE;
+        cv.Copy(&cv_signature, sizeof(cv_signature));
+        cv.Copy(cv.position() + sizeof(cv_signature), &identifier_bytes[0],
+                identifier_bytes.size());
+
+        mod->cv_record = cv.location();
+      }
+    } else {
+      // The module is a PE/COFF file. Create MDCVInfoPDB70 struct for it.
+      size_t file_name_length = strlen(file_name);
+      TypedMDRVA<MDCVInfoPDB70> cv(&minidump_writer_);
+      if (!cv.AllocateObjectAndArray(file_name_length + 1, sizeof(uint8_t)))
+        return false;
+      if (!cv.CopyIndexAfterObject(0, file_name, file_name_length))
+        return false;
+      MDCVInfoPDB70* cv_ptr = cv.get();
+      cv_ptr->cv_signature = MD_CVINFOPDB70_SIGNATURE;
+      if (file_format == PEFileFormat::peWithBuildId) {
+        // Populate BuildId and age using RSDS instance.
+        cv_ptr->signature.data1 = static_cast<uint32_t>(rsds.guid[0]) << 24 |
+                                  static_cast<uint32_t>(rsds.guid[1]) << 16 |
+                                  static_cast<uint32_t>(rsds.guid[2]) << 8 |
+                                  static_cast<uint32_t>(rsds.guid[3]);
+        cv_ptr->signature.data2 =
+            static_cast<uint16_t>(rsds.guid[4]) << 8 | rsds.guid[5];
+        cv_ptr->signature.data3 =
+            static_cast<uint16_t>(rsds.guid[6]) << 8 | rsds.guid[7];
+        cv_ptr->signature.data4[0] = rsds.guid[8];
+        cv_ptr->signature.data4[1] = rsds.guid[9];
+        cv_ptr->signature.data4[2] = rsds.guid[10];
+        cv_ptr->signature.data4[3] = rsds.guid[11];
+        cv_ptr->signature.data4[4] = rsds.guid[12];
+        cv_ptr->signature.data4[5] = rsds.guid[13];
+        cv_ptr->signature.data4[6] = rsds.guid[14];
+        cv_ptr->signature.data4[7] = rsds.guid[15];
+        // The Age field should be reverted as well.
+        cv_ptr->age = static_cast<uint32_t>(rsds.age[0]) << 24 |
+                      static_cast<uint32_t>(rsds.age[1]) << 16 |
+                      static_cast<uint32_t>(rsds.age[2]) << 8 |
+                      static_cast<uint32_t>(rsds.age[3]);
+      } else {
+        cv_ptr->age = 0;
+      }
+
+      mod->cv_record = cv.location();
+    }
+
+    MDLocationDescriptor ld;
+    if (!minidump_writer_.WriteString(file_path, my_strlen(file_path), &ld))
+      return false;
+    mod->module_name_rva = ld.rva;
+    return true;
+  }
+
+  bool WriteMemoryListStream(MDRawDirectory* dirent) {
+    TypedMDRVA<uint32_t> list(&minidump_writer_);
+    if (memory_blocks_.size()) {
+      if (!list.AllocateObjectAndArray(memory_blocks_.size(),
+                                       sizeof(MDMemoryDescriptor)))
+        return false;
+    } else {
+      // Still create the memory list stream, although it will have zero
+      // memory blocks.
+      if (!list.Allocate())
+        return false;
+    }
+
+    dirent->stream_type = MD_MEMORY_LIST_STREAM;
+    dirent->location = list.location();
+
+    *list.get() = memory_blocks_.size();
+
+    for (size_t i = 0; i < memory_blocks_.size(); ++i) {
+      list.CopyIndexAfterObject(i, &memory_blocks_[i],
+                                sizeof(MDMemoryDescriptor));
+    }
+    return true;
+  }
+
+  bool WriteExceptionStream(MDRawDirectory* dirent) {
+    TypedMDRVA<MDRawExceptionStream> exc(&minidump_writer_);
+    if (!exc.Allocate())
+      return false;
+
+    MDRawExceptionStream* stream = exc.get();
+    my_memset(stream, 0, sizeof(MDRawExceptionStream));
+
+    dirent->stream_type = MD_EXCEPTION_STREAM;
+    dirent->location = exc.location();
+
+    stream->thread_id = GetCrashThread();
+    stream->exception_record.exception_code = dumper_->crash_signal();
+    stream->exception_record.exception_flags = dumper_->crash_signal_code();
+    stream->exception_record.exception_address = dumper_->crash_address();
+    const std::vector<uint64_t> crash_exception_info =
+        dumper_->crash_exception_info();
+    stream->exception_record.number_parameters = crash_exception_info.size();
+    memcpy(stream->exception_record.exception_information,
+           crash_exception_info.data(),
+           sizeof(uint64_t) * crash_exception_info.size());
+    stream->thread_context = crashing_thread_context_;
+
+    return true;
+  }
+
+  bool WriteSystemInfoStream(MDRawDirectory* dirent) {
+    TypedMDRVA<MDRawSystemInfo> si(&minidump_writer_);
+    if (!si.Allocate())
+      return false;
+    my_memset(si.get(), 0, sizeof(MDRawSystemInfo));
+
+    dirent->stream_type = MD_SYSTEM_INFO_STREAM;
+    dirent->location = si.location();
+
+    WriteCPUInformation(si.get());
+    WriteOSInformation(si.get());
+
+    return true;
+  }
+
+  bool WriteDSODebugStream(MDRawDirectory* dirent) {
+    ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(dumper_->auxv()[AT_PHDR]);
+    char* base;
+    int phnum = dumper_->auxv()[AT_PHNUM];
+    if (!phnum || !phdr)
+      return false;
+
+    // Assume the program base is at the beginning of the same page as the PHDR
+    base = reinterpret_cast<char*>(reinterpret_cast<uintptr_t>(phdr) & ~0xfff);
+
+    // Search for the program PT_DYNAMIC segment
+    ElfW(Addr) dyn_addr = 0;
+    for (; phnum >= 0; phnum--, phdr++) {
+      ElfW(Phdr) ph;
+      if (!dumper_->CopyFromProcess(&ph, GetCrashThread(), phdr, sizeof(ph)))
+        return false;
+
+      // Adjust base address with the virtual address of the PT_LOAD segment
+      // corresponding to offset 0
+      if (ph.p_type == PT_LOAD && ph.p_offset == 0) {
+        base -= ph.p_vaddr;
+      }
+      if (ph.p_type == PT_DYNAMIC) {
+        dyn_addr = ph.p_vaddr;
+      }
+    }
+    if (!dyn_addr)
+      return false;
+
+    ElfW(Dyn)* dynamic = reinterpret_cast<ElfW(Dyn)*>(dyn_addr + base);
+
+    // The dynamic linker makes information available that helps gdb find all
+    // DSOs loaded into the program. If this information is indeed available,
+    // dump it to a MD_LINUX_DSO_DEBUG stream.
+    struct r_debug* r_debug = NULL;
+    uint32_t dynamic_length = 0;
+
+    for (int i = 0; ; ++i) {
+      ElfW(Dyn) dyn;
+      dynamic_length += sizeof(dyn);
+      if (!dumper_->CopyFromProcess(&dyn, GetCrashThread(), dynamic + i,
+                                    sizeof(dyn))) {
+        return false;
+      }
+
+#ifdef __mips__
+      const int32_t debug_tag = DT_MIPS_RLD_MAP;
+#else
+      const int32_t debug_tag = DT_DEBUG;
+#endif
+      if (dyn.d_tag == debug_tag) {
+        r_debug = reinterpret_cast<struct r_debug*>(dyn.d_un.d_ptr);
+        continue;
+      } else if (dyn.d_tag == DT_NULL) {
+        break;
+      }
+    }
+
+    // The "r_map" field of that r_debug struct contains a linked list of all
+    // loaded DSOs.
+    // Our list of DSOs potentially is different from the ones in the crashing
+    // process. So, we have to be careful to never dereference pointers
+    // directly. Instead, we use CopyFromProcess() everywhere.
+    // See <link.h> for a more detailed discussion of the how the dynamic
+    // loader communicates with debuggers.
+
+    // Count the number of loaded DSOs
+    int dso_count = 0;
+    struct r_debug debug_entry;
+    if (!dumper_->CopyFromProcess(&debug_entry, GetCrashThread(), r_debug,
+                                  sizeof(debug_entry))) {
+      return false;
+    }
+    for (struct link_map* ptr = debug_entry.r_map; ptr; ) {
+      struct link_map map;
+      if (!dumper_->CopyFromProcess(&map, GetCrashThread(), ptr, sizeof(map)))
+        return false;
+
+      ptr = map.l_next;
+      dso_count++;
+    }
+
+    MDRVA linkmap_rva = minidump_writer_.kInvalidMDRVA;
+    if (dso_count > 0) {
+      // If we have at least one DSO, create an array of MDRawLinkMap
+      // entries in the minidump file.
+      TypedMDRVA<MDRawLinkMap> linkmap(&minidump_writer_);
+      if (!linkmap.AllocateArray(dso_count))
+        return false;
+      linkmap_rva = linkmap.location().rva;
+      int idx = 0;
+
+      // Iterate over DSOs and write their information to mini dump
+      for (struct link_map* ptr = debug_entry.r_map; ptr; ) {
+        struct link_map map;
+        if (!dumper_->CopyFromProcess(&map, GetCrashThread(), ptr, sizeof(map)))
+          return  false;
+
+        ptr = map.l_next;
+        char filename[257] = { 0 };
+        if (map.l_name) {
+          dumper_->CopyFromProcess(filename, GetCrashThread(), map.l_name,
+                                   sizeof(filename) - 1);
+        }
+        MDLocationDescriptor location;
+        if (!minidump_writer_.WriteString(filename, 0, &location))
+          return false;
+        MDRawLinkMap entry;
+        entry.name = location.rva;
+        entry.addr = map.l_addr;
+        entry.ld = reinterpret_cast<uintptr_t>(map.l_ld);
+        linkmap.CopyIndex(idx++, &entry);
+      }
+    }
+
+    // Write MD_LINUX_DSO_DEBUG record
+    TypedMDRVA<MDRawDebug> debug(&minidump_writer_);
+    if (!debug.AllocateObjectAndArray(1, dynamic_length))
+      return false;
+    my_memset(debug.get(), 0, sizeof(MDRawDebug));
+    dirent->stream_type = MD_LINUX_DSO_DEBUG;
+    dirent->location = debug.location();
+
+    debug.get()->version = debug_entry.r_version;
+    debug.get()->map = linkmap_rva;
+    debug.get()->dso_count = dso_count;
+    debug.get()->brk = debug_entry.r_brk;
+    debug.get()->ldbase = debug_entry.r_ldbase;
+    debug.get()->dynamic = reinterpret_cast<uintptr_t>(dynamic);
+
+    wasteful_vector<char> dso_debug_data(dumper_->allocator(), dynamic_length);
+    // The passed-in size to the constructor (above) is only a hint.
+    // Must call .resize() to do actual initialization of the elements.
+    dso_debug_data.resize(dynamic_length);
+    dumper_->CopyFromProcess(&dso_debug_data[0], GetCrashThread(), dynamic,
+                             dynamic_length);
+    debug.CopyIndexAfterObject(0, &dso_debug_data[0], dynamic_length);
+
+    return true;
+  }
+
+  void set_minidump_size_limit(off_t limit) { minidump_size_limit_ = limit; }
+
+ private:
+  void* Alloc(unsigned bytes) {
+    return dumper_->allocator()->Alloc(bytes);
+  }
+
+  pid_t GetCrashThread() const {
+    return dumper_->crash_thread();
+  }
+
+  void NullifyDirectoryEntry(MDRawDirectory* dirent) {
+    dirent->stream_type = 0;
+    dirent->location.data_size = 0;
+    dirent->location.rva = 0;
+  }
+
+#if defined(__i386__) || defined(__x86_64__) || defined(__mips__)
+  bool WriteCPUInformation(MDRawSystemInfo* sys_info) {
+    char vendor_id[sizeof(sys_info->cpu.x86_cpu_info.vendor_id) + 1] = {0};
+    static const char vendor_id_name[] = "vendor_id";
+
+    struct CpuInfoEntry {
+      const char* info_name;
+      int value;
+      bool found;
+    } cpu_info_table[] = {
+      { "processor", -1, false },
+#if defined(__i386__) || defined(__x86_64__)
+      { "model", 0, false },
+      { "stepping",  0, false },
+      { "cpu family", 0, false },
+#endif
+    };
+
+    // processor_architecture should always be set, do this first
+    sys_info->processor_architecture =
+#if defined(__mips__)
+# if _MIPS_SIM == _ABIO32
+        MD_CPU_ARCHITECTURE_MIPS;
+# elif _MIPS_SIM == _ABI64
+        MD_CPU_ARCHITECTURE_MIPS64;
+# else
+#  error "This mips ABI is currently not supported (n32)"
+#endif
+#elif defined(__i386__)
+        MD_CPU_ARCHITECTURE_X86;
+#else
+        MD_CPU_ARCHITECTURE_AMD64;
+#endif
+
+    const int fd = sys_open("/proc/cpuinfo", O_RDONLY, 0);
+    if (fd < 0)
+      return false;
+
+    {
+      PageAllocator allocator;
+      ProcCpuInfoReader* const reader = new(allocator) ProcCpuInfoReader(fd);
+      const char* field;
+      while (reader->GetNextField(&field)) {
+        bool is_first_entry = true;
+        for (CpuInfoEntry& entry : cpu_info_table) {
+          if (!is_first_entry && entry.found) {
+            // except for the 'processor' field, ignore repeated values.
+            continue;
+          }
+          is_first_entry = false;
+          if (!my_strcmp(field, entry.info_name)) {
+            size_t value_len;
+            const char* value = reader->GetValueAndLen(&value_len);
+            if (value_len == 0)
+              continue;
+
+            uintptr_t val;
+            if (my_read_decimal_ptr(&val, value) == value)
+              continue;
+
+            entry.value = static_cast<int>(val);
+            entry.found = true;
+          }
+        }
+
+        // special case for vendor_id
+        if (!my_strcmp(field, vendor_id_name)) {
+          size_t value_len;
+          const char* value = reader->GetValueAndLen(&value_len);
+          if (value_len > 0)
+            my_strlcpy(vendor_id, value, sizeof(vendor_id));
+        }
+      }
+      sys_close(fd);
+    }
+
+    // make sure we got everything we wanted
+    for (const CpuInfoEntry& entry : cpu_info_table) {
+      if (!entry.found) {
+        return false;
+      }
+    }
+    // cpu_info_table[0] holds the last cpu id listed in /proc/cpuinfo,
+    // assuming this is the highest id, change it to the number of CPUs
+    // by adding one.
+    cpu_info_table[0].value++;
+
+    sys_info->number_of_processors = cpu_info_table[0].value;
+#if defined(__i386__) || defined(__x86_64__)
+    sys_info->processor_level      = cpu_info_table[3].value;
+    sys_info->processor_revision   = cpu_info_table[1].value << 8 |
+                                     cpu_info_table[2].value;
+#endif
+
+    if (vendor_id[0] != '\0') {
+      my_memcpy(sys_info->cpu.x86_cpu_info.vendor_id, vendor_id,
+                sizeof(sys_info->cpu.x86_cpu_info.vendor_id));
+    }
+    return true;
+  }
+#elif defined(__arm__) || defined(__aarch64__)
+  bool WriteCPUInformation(MDRawSystemInfo* sys_info) {
+    // The CPUID value is broken up in several entries in /proc/cpuinfo.
+    // This table is used to rebuild it from the entries.
+    const struct CpuIdEntry {
+      const char* field;
+      char        format;
+      char        bit_lshift;
+      char        bit_length;
+    } cpu_id_entries[] = {
+      { "CPU implementer", 'x', 24, 8 },
+      { "CPU variant", 'x', 20, 4 },
+      { "CPU part", 'x', 4, 12 },
+      { "CPU revision", 'd', 0, 4 },
+    };
+
+    // The ELF hwcaps are listed in the "Features" entry as textual tags.
+    // This table is used to rebuild them.
+    const struct CpuFeaturesEntry {
+      const char* tag;
+      uint32_t hwcaps;
+    } cpu_features_entries[] = {
+#if defined(__arm__)
+      { "swp",  MD_CPU_ARM_ELF_HWCAP_SWP },
+      { "half", MD_CPU_ARM_ELF_HWCAP_HALF },
+      { "thumb", MD_CPU_ARM_ELF_HWCAP_THUMB },
+      { "26bit", MD_CPU_ARM_ELF_HWCAP_26BIT },
+      { "fastmult", MD_CPU_ARM_ELF_HWCAP_FAST_MULT },
+      { "fpa", MD_CPU_ARM_ELF_HWCAP_FPA },
+      { "vfp", MD_CPU_ARM_ELF_HWCAP_VFP },
+      { "edsp", MD_CPU_ARM_ELF_HWCAP_EDSP },
+      { "java", MD_CPU_ARM_ELF_HWCAP_JAVA },
+      { "iwmmxt", MD_CPU_ARM_ELF_HWCAP_IWMMXT },
+      { "crunch", MD_CPU_ARM_ELF_HWCAP_CRUNCH },
+      { "thumbee", MD_CPU_ARM_ELF_HWCAP_THUMBEE },
+      { "neon", MD_CPU_ARM_ELF_HWCAP_NEON },
+      { "vfpv3", MD_CPU_ARM_ELF_HWCAP_VFPv3 },
+      { "vfpv3d16", MD_CPU_ARM_ELF_HWCAP_VFPv3D16 },
+      { "tls", MD_CPU_ARM_ELF_HWCAP_TLS },
+      { "vfpv4", MD_CPU_ARM_ELF_HWCAP_VFPv4 },
+      { "idiva", MD_CPU_ARM_ELF_HWCAP_IDIVA },
+      { "idivt", MD_CPU_ARM_ELF_HWCAP_IDIVT },
+      { "idiv", MD_CPU_ARM_ELF_HWCAP_IDIVA | MD_CPU_ARM_ELF_HWCAP_IDIVT },
+#elif defined(__aarch64__)
+      // No hwcaps on aarch64.
+#endif
+    };
+
+    // processor_architecture should always be set, do this first
+    sys_info->processor_architecture =
+#if defined(__aarch64__)
+        MD_CPU_ARCHITECTURE_ARM64_OLD;
+#else
+        MD_CPU_ARCHITECTURE_ARM;
+#endif
+
+    // /proc/cpuinfo is not readable under various sandboxed environments
+    // (e.g. Android services with the android:isolatedProcess attribute)
+    // prepare for this by setting default values now, which will be
+    // returned when this happens.
+    //
+    // Note: Bogus values are used to distinguish between failures (to
+    //       read /sys and /proc files) and really badly configured kernels.
+    sys_info->number_of_processors = 0;
+    sys_info->processor_level = 1U;  // There is no ARMv1
+    sys_info->processor_revision = 42;
+    sys_info->cpu.arm_cpu_info.cpuid = 0;
+    sys_info->cpu.arm_cpu_info.elf_hwcaps = 0;
+
+    // Counting the number of CPUs involves parsing two sysfs files,
+    // because the content of /proc/cpuinfo will only mirror the number
+    // of 'online' cores, and thus will vary with time.
+    // See http://www.kernel.org/doc/Documentation/cputopology.txt
+    {
+      CpuSet cpus_present;
+      CpuSet cpus_possible;
+
+      int fd = sys_open("/sys/devices/system/cpu/present", O_RDONLY, 0);
+      if (fd >= 0) {
+        cpus_present.ParseSysFile(fd);
+        sys_close(fd);
+
+        fd = sys_open("/sys/devices/system/cpu/possible", O_RDONLY, 0);
+        if (fd >= 0) {
+          cpus_possible.ParseSysFile(fd);
+          sys_close(fd);
+
+          cpus_present.IntersectWith(cpus_possible);
+          int cpu_count = std::min(255, cpus_present.GetCount());
+          sys_info->number_of_processors = static_cast<uint8_t>(cpu_count);
+        }
+      }
+    }
+
+    // Parse /proc/cpuinfo to reconstruct the CPUID value, as well
+    // as the ELF hwcaps field. For the latter, it would be easier to
+    // read /proc/self/auxv but unfortunately, this file is not always
+    // readable from regular Android applications on later versions
+    // (>= 4.1) of the Android platform.
+    const int fd = sys_open("/proc/cpuinfo", O_RDONLY, 0);
+    if (fd < 0) {
+      // Do not return false here to allow the minidump generation
+      // to happen properly.
+      return true;
+    }
+
+    {
+      PageAllocator allocator;
+      ProcCpuInfoReader* const reader =
+          new(allocator) ProcCpuInfoReader(fd);
+      const char* field;
+      while (reader->GetNextField(&field)) {
+        for (const CpuIdEntry& entry : cpu_id_entries) {
+          if (my_strcmp(entry.field, field) != 0)
+            continue;
+          uintptr_t result = 0;
+          const char* value = reader->GetValue();
+          const char* p = value;
+          if (value[0] == '0' && value[1] == 'x') {
+            p = my_read_hex_ptr(&result, value+2);
+          } else if (entry.format == 'x') {
+            p = my_read_hex_ptr(&result, value);
+          } else {
+            p = my_read_decimal_ptr(&result, value);
+          }
+          if (p == value)
+            continue;
+
+          result &= (1U << entry.bit_length)-1;
+          result <<= entry.bit_lshift;
+          sys_info->cpu.arm_cpu_info.cpuid |=
+              static_cast<uint32_t>(result);
+        }
+#if defined(__arm__)
+        // Get the architecture version from the "Processor" field.
+        // Note that it is also available in the "CPU architecture" field,
+        // however, some existing kernels are misconfigured and will report
+        // invalid values here (e.g. 6, while the CPU is ARMv7-A based).
+        // The "Processor" field doesn't have this issue.
+        if (!my_strcmp(field, "Processor")) {
+          size_t value_len;
+          const char* value = reader->GetValueAndLen(&value_len);
+          // Expected format: <text> (v<level><endian>)
+          // Where <text> is some text like "ARMv7 Processor rev 2"
+          // and <level> is a decimal corresponding to the ARM
+          // architecture number. <endian> is either 'l' or 'b'
+          // and corresponds to the endianess, it is ignored here.
+          while (value_len > 0 && my_isspace(value[value_len-1]))
+            value_len--;
+
+          size_t nn = value_len;
+          while (nn > 0 && value[nn-1] != '(')
+            nn--;
+          if (nn > 0 && value[nn] == 'v') {
+            uintptr_t arch_level = 5;
+            my_read_decimal_ptr(&arch_level, value + nn + 1);
+            sys_info->processor_level = static_cast<uint16_t>(arch_level);
+          }
+        }
+#elif defined(__aarch64__)
+        // The aarch64 architecture does not provide the architecture level
+        // in the Processor field, so we instead check the "CPU architecture"
+        // field.
+        if (!my_strcmp(field, "CPU architecture")) {
+          uintptr_t arch_level = 0;
+          const char* value = reader->GetValue();
+          const char* p = value;
+          p = my_read_decimal_ptr(&arch_level, value);
+          if (p == value)
+            continue;
+          sys_info->processor_level = static_cast<uint16_t>(arch_level);
+        }
+#endif
+        // Rebuild the ELF hwcaps from the 'Features' field.
+        if (!my_strcmp(field, "Features")) {
+          size_t value_len;
+          const char* value = reader->GetValueAndLen(&value_len);
+
+          // Parse each space-separated tag.
+          while (value_len > 0) {
+            const char* tag = value;
+            size_t tag_len = value_len;
+            const char* p = my_strchr(tag, ' ');
+            if (p) {
+              tag_len = static_cast<size_t>(p - tag);
+              value += tag_len + 1;
+              value_len -= tag_len + 1;
+            } else {
+              tag_len = strlen(tag);
+              value_len = 0;
+            }
+            for (const CpuFeaturesEntry& entry : cpu_features_entries) {
+              if (tag_len == strlen(entry.tag) &&
+                  !memcmp(tag, entry.tag, tag_len)) {
+                sys_info->cpu.arm_cpu_info.elf_hwcaps |= entry.hwcaps;
+                break;
+              }
+            }
+          }
+        }
+      }
+      sys_close(fd);
+    }
+
+    return true;
+  }
+#elif defined(__riscv)
+  bool WriteCPUInformation(MDRawSystemInfo* sys_info) {
+    // processor_architecture should always be set, do this first
+# if __riscv_xlen == 32
+    sys_info->processor_architecture = MD_CPU_ARCHITECTURE_RISCV;
+# elif __riscv_xlen == 64
+    sys_info->processor_architecture = MD_CPU_ARCHITECTURE_RISCV64;
+# else
+#  error "Unexpected __riscv_xlen"
+# endif
+
+    // /proc/cpuinfo is not readable under various sandboxed environments
+    // (e.g. Android services with the android:isolatedProcess attribute)
+    // prepare for this by setting default values now, which will be
+    // returned when this happens.
+    //
+    // Note: Bogus values are used to distinguish between failures (to
+    //       read /sys and /proc files) and really badly configured kernels.
+    sys_info->number_of_processors = 0;
+    sys_info->processor_level = 0U;
+    sys_info->processor_revision = 42;
+    sys_info->cpu.other_cpu_info.processor_features[0] = 0;
+    sys_info->cpu.other_cpu_info.processor_features[1] = 0;
+
+    // Counting the number of CPUs involves parsing two sysfs files,
+    // because the content of /proc/cpuinfo will only mirror the number
+    // of 'online' cores, and thus will vary with time.
+    // See http://www.kernel.org/doc/Documentation/cputopology.txt
+    {
+      CpuSet cpus_present;
+      CpuSet cpus_possible;
+
+      int fd = sys_open("/sys/devices/system/cpu/present",
+                        O_RDONLY | O_CLOEXEC, 0);
+      if (fd >= 0) {
+        cpus_present.ParseSysFile(fd);
+        sys_close(fd);
+
+        fd = sys_open("/sys/devices/system/cpu/possible",
+                      O_RDONLY | O_CLOEXEC, 0);
+        if (fd >= 0) {
+          cpus_possible.ParseSysFile(fd);
+          sys_close(fd);
+
+          cpus_present.IntersectWith(cpus_possible);
+          int cpu_count = std::min(255, cpus_present.GetCount());
+          sys_info->number_of_processors = static_cast<uint8_t>(cpu_count);
+        }
+      }
+    }
+
+    return true;
+  }
+#else
+#  error "Unsupported CPU"
+#endif
+
+  bool WriteFile(MDLocationDescriptor* result, const char* filename) {
+    const int fd = sys_open(filename, O_RDONLY, 0);
+    if (fd < 0)
+      return false;
+
+    // We can't stat the files because several of the files that we want to
+    // read are kernel seqfiles, which always have a length of zero. So we have
+    // to read as much as we can into a buffer.
+    static const unsigned kBufSize = 1024 - 2*sizeof(void*);
+    struct Buffers {
+      Buffers* next;
+      size_t len;
+      uint8_t data[kBufSize];
+    }* buffers = reinterpret_cast<Buffers*>(Alloc(sizeof(Buffers)));
+    buffers->next = NULL;
+    buffers->len = 0;
+
+    size_t total = 0;
+    for (Buffers* bufptr = buffers;;) {
+      ssize_t r;
+      do {
+        r = sys_read(fd, &bufptr->data[bufptr->len], kBufSize - bufptr->len);
+      } while (r == -1 && errno == EINTR);
+
+      if (r < 1)
+        break;
+
+      total += r;
+      bufptr->len += r;
+      if (bufptr->len == kBufSize) {
+        bufptr->next = reinterpret_cast<Buffers*>(Alloc(sizeof(Buffers)));
+        bufptr = bufptr->next;
+        bufptr->next = NULL;
+        bufptr->len = 0;
+      }
+    }
+    sys_close(fd);
+
+    if (!total)
+      return false;
+
+    UntypedMDRVA memory(&minidump_writer_);
+    if (!memory.Allocate(total))
+      return false;
+    for (MDRVA pos = memory.position(); buffers; buffers = buffers->next) {
+      // Check for special case of a zero-length buffer.  This should only
+      // occur if a file's size happens to be a multiple of the buffer's
+      // size, in which case the final sys_read() will have resulted in
+      // zero bytes being read after the final buffer was just allocated.
+      if (buffers->len == 0) {
+        // This can only occur with final buffer.
+        assert(buffers->next == NULL);
+        continue;
+      }
+      memory.Copy(pos, &buffers->data, buffers->len);
+      pos += buffers->len;
+    }
+    *result = memory.location();
+    return true;
+  }
+
+  bool WriteOSInformation(MDRawSystemInfo* sys_info) {
+#if defined(__ANDROID__)
+    sys_info->platform_id = MD_OS_ANDROID;
+#else
+    sys_info->platform_id = MD_OS_LINUX;
+#endif
+
+    struct utsname uts;
+    if (uname(&uts))
+      return false;
+
+    static const size_t buf_len = 512;
+    char buf[buf_len] = {0};
+    size_t space_left = buf_len - 1;
+    const char* info_table[] = {
+      uts.sysname,
+      uts.release,
+      uts.version,
+      uts.machine,
+      NULL
+    };
+    bool first_item = true;
+    for (const char** cur_info = info_table; *cur_info; cur_info++) {
+      static const char separator[] = " ";
+      size_t separator_len = sizeof(separator) - 1;
+      size_t info_len = my_strlen(*cur_info);
+      if (info_len == 0)
+        continue;
+
+      if (space_left < info_len + (first_item ? 0 : separator_len))
+        break;
+
+      if (!first_item) {
+        my_strlcat(buf, separator, sizeof(buf));
+        space_left -= separator_len;
+      }
+
+      first_item = false;
+      my_strlcat(buf, *cur_info, sizeof(buf));
+      space_left -= info_len;
+    }
+
+    MDLocationDescriptor location;
+    if (!minidump_writer_.WriteString(buf, 0, &location))
+      return false;
+    sys_info->csd_version_rva = location.rva;
+
+    return true;
+  }
+
+  bool WriteProcFile(MDLocationDescriptor* result, pid_t pid,
+                     const char* filename) {
+    char buf[NAME_MAX];
+    if (!dumper_->BuildProcPath(buf, pid, filename))
+      return false;
+    return WriteFile(result, buf);
+  }
+
+  // Only one of the 2 member variables below should be set to a valid value.
+  const int fd_;  // File descriptor where the minidum should be written.
+  const char* path_;  // Path to the file where the minidum should be written.
+
+  const ucontext_t* const ucontext_;  // also from the signal handler
+#if GOOGLE_BREAKPAD_CRASH_CONTEXT_HAS_FLOAT_STATE
+  const google_breakpad::fpstate_t* const float_state_;  // ditto
+#endif
+  LinuxDumper* dumper_;
+  MinidumpFileWriter minidump_writer_;
+  off_t minidump_size_limit_;
+  MDLocationDescriptor crashing_thread_context_;
+  // Blocks of memory written to the dump. These are all currently
+  // written while writing the thread list stream, but saved here
+  // so a memory list stream can be written afterwards.
+  wasteful_vector<MDMemoryDescriptor> memory_blocks_;
+  // Additional information about some mappings provided by the caller.
+  const MappingList& mapping_list_;
+  // Additional memory regions to be included in the dump,
+  // provided by the caller.
+  const AppMemoryList& app_memory_list_;
+  // If set, skip recording any threads that do not reference the
+  // mapping containing principal_mapping_address_.
+  bool skip_stacks_if_mapping_unreferenced_;
+  uintptr_t principal_mapping_address_;
+  const MappingInfo* principal_mapping_;
+  // If true, apply stack sanitization to stored stack data.
+  bool sanitize_stacks_;
+};
+
+
+bool WriteMinidumpImpl(const char* minidump_path,
+                       int minidump_fd,
+                       off_t minidump_size_limit,
+                       pid_t crashing_process,
+                       const void* blob, size_t blob_size,
+                       const MappingList& mappings,
+                       const AppMemoryList& appmem,
+                       bool skip_stacks_if_mapping_unreferenced,
+                       uintptr_t principal_mapping_address,
+                       bool sanitize_stacks) {
+  LinuxPtraceDumper dumper(crashing_process);
+  const ExceptionHandler::CrashContext* context = NULL;
+  if (blob) {
+    if (blob_size != sizeof(ExceptionHandler::CrashContext))
+      return false;
+    context = reinterpret_cast<const ExceptionHandler::CrashContext*>(blob);
+    dumper.SetCrashInfoFromSigInfo(context->siginfo);
+    dumper.set_crash_thread(context->tid);
+  }
+  MinidumpWriter writer(minidump_path, minidump_fd, context, mappings,
+                        appmem, skip_stacks_if_mapping_unreferenced,
+                        principal_mapping_address, sanitize_stacks, &dumper);
+  // Set desired limit for file size of minidump (-1 means no limit).
+  writer.set_minidump_size_limit(minidump_size_limit);
+  if (!writer.Init())
+    return false;
+  return writer.Dump();
+}
+
+}  // namespace
+
+namespace google_breakpad {
+
+bool WriteMinidump(const char* minidump_path, pid_t crashing_process,
+                   const void* blob, size_t blob_size,
+                   bool skip_stacks_if_mapping_unreferenced,
+                   uintptr_t principal_mapping_address,
+                   bool sanitize_stacks) {
+  return WriteMinidumpImpl(minidump_path, -1, -1,
+                           crashing_process, blob, blob_size,
+                           MappingList(), AppMemoryList(),
+                           skip_stacks_if_mapping_unreferenced,
+                           principal_mapping_address,
+                           sanitize_stacks);
+}
+
+bool WriteMinidump(int minidump_fd, pid_t crashing_process,
+                   const void* blob, size_t blob_size,
+                   bool skip_stacks_if_mapping_unreferenced,
+                   uintptr_t principal_mapping_address,
+                   bool sanitize_stacks) {
+  return WriteMinidumpImpl(NULL, minidump_fd, -1,
+                           crashing_process, blob, blob_size,
+                           MappingList(), AppMemoryList(),
+                           skip_stacks_if_mapping_unreferenced,
+                           principal_mapping_address,
+                           sanitize_stacks);
+}
+
+bool WriteMinidump(const char* minidump_path, pid_t process,
+                   pid_t process_blamed_thread) {
+  LinuxPtraceDumper dumper(process);
+  // MinidumpWriter will set crash address
+  dumper.set_crash_signal(MD_EXCEPTION_CODE_LIN_DUMP_REQUESTED);
+  dumper.set_crash_thread(process_blamed_thread);
+  MappingList mapping_list;
+  AppMemoryList app_memory_list;
+  MinidumpWriter writer(minidump_path, -1, NULL, mapping_list,
+                        app_memory_list, false, 0, false, &dumper);
+  if (!writer.Init())
+    return false;
+  return writer.Dump();
+}
+
+bool WriteMinidump(const char* minidump_path, pid_t crashing_process,
+                   const void* blob, size_t blob_size,
+                   const MappingList& mappings,
+                   const AppMemoryList& appmem,
+                   bool skip_stacks_if_mapping_unreferenced,
+                   uintptr_t principal_mapping_address,
+                   bool sanitize_stacks) {
+  return WriteMinidumpImpl(minidump_path, -1, -1, crashing_process,
+                           blob, blob_size,
+                           mappings, appmem,
+                           skip_stacks_if_mapping_unreferenced,
+                           principal_mapping_address,
+                           sanitize_stacks);
+}
+
+bool WriteMinidump(int minidump_fd, pid_t crashing_process,
+                   const void* blob, size_t blob_size,
+                   const MappingList& mappings,
+                   const AppMemoryList& appmem,
+                   bool skip_stacks_if_mapping_unreferenced,
+                   uintptr_t principal_mapping_address,
+                   bool sanitize_stacks) {
+  return WriteMinidumpImpl(NULL, minidump_fd, -1, crashing_process,
+                           blob, blob_size,
+                           mappings, appmem,
+                           skip_stacks_if_mapping_unreferenced,
+                           principal_mapping_address,
+                           sanitize_stacks);
+}
+
+bool WriteMinidump(const char* minidump_path, off_t minidump_size_limit,
+                   pid_t crashing_process,
+                   const void* blob, size_t blob_size,
+                   const MappingList& mappings,
+                   const AppMemoryList& appmem,
+                   bool skip_stacks_if_mapping_unreferenced,
+                   uintptr_t principal_mapping_address,
+                   bool sanitize_stacks) {
+  return WriteMinidumpImpl(minidump_path, -1, minidump_size_limit,
+                           crashing_process, blob, blob_size,
+                           mappings, appmem,
+                           skip_stacks_if_mapping_unreferenced,
+                           principal_mapping_address,
+                           sanitize_stacks);
+}
+
+bool WriteMinidump(int minidump_fd, off_t minidump_size_limit,
+                   pid_t crashing_process,
+                   const void* blob, size_t blob_size,
+                   const MappingList& mappings,
+                   const AppMemoryList& appmem,
+                   bool skip_stacks_if_mapping_unreferenced,
+                   uintptr_t principal_mapping_address,
+                   bool sanitize_stacks) {
+  return WriteMinidumpImpl(NULL, minidump_fd, minidump_size_limit,
+                           crashing_process, blob, blob_size,
+                           mappings, appmem,
+                           skip_stacks_if_mapping_unreferenced,
+                           principal_mapping_address,
+                           sanitize_stacks);
+}
+
+bool WriteMinidump(const char* filename,
+                   const MappingList& mappings,
+                   const AppMemoryList& appmem,
+                   LinuxDumper* dumper) {
+  MinidumpWriter writer(filename, -1, NULL, mappings, appmem,
+                        false, 0, false, dumper);
+  if (!writer.Init())
+    return false;
+  return writer.Dump();
+}
+
+}  // namespace google_breakpad