// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// For linux_syscall_support.h. This makes it safe to call embedded system
// calls when in seccomp mode.

#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40285824): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif

#include "components/crash/core/app/breakpad_linux.h"

#include <fcntl.h>
#include <poll.h>
#include <signal.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

#include <algorithm>
#include <string>
#include <tuple>

#include "base/base_switches.h"
#include "base/command_line.h"
#include "base/containers/span.h"
#include "base/debug/dump_without_crashing.h"
#include "base/files/file_path.h"
#include "base/lazy_instance.h"
#include "base/linux_util.h"
#include "base/logging.h"
#include "base/path_service.h"
#include "base/posix/eintr_wrapper.h"
#include "base/posix/global_descriptors.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "base/strings/string_util.h"
#include "base/threading/thread_checker.h"
#include "build/branding_buildflags.h"
#include "build/build_config.h"
#include "components/crash/core/app/breakpad_linux_impl.h"
#include "components/crash/core/app/crash_reporter_client.h"
#include "components/crash/core/common/crash_keys.h"
#include "content/public/common/content_descriptors.h"
#include "partition_alloc/oom.h"
#include "third_party/breakpad/breakpad/src/client/linux/crash_generation/crash_generation_client.h"
#include "third_party/breakpad/breakpad/src/client/linux/handler/exception_handler.h"
#include "third_party/breakpad/breakpad/src/client/linux/minidump_writer/directory_reader.h"
#include "third_party/breakpad/breakpad/src/common/linux/linux_libc_support.h"
#include "third_party/breakpad/breakpad/src/common/memory_allocator.h"
#include "third_party/lss/linux_syscall_support.h"

#if defined(ADDRESS_SANITIZER)
#include <ucontext.h>  // for getcontext().
#endif

#define STAT_STRUCT struct kernel_stat
#define FSTAT_FUNC sys_fstat

// Some versions of gcc are prone to warn about unused return values. In cases
// where we either a) know the call cannot fail, or b) there is nothing we
// can do when a call fails, we mark the return code as ignored. This avoids
// spurious compiler warnings.
#define IGNORE_RET(x) std::ignore = x

using crash_reporter::GetCrashReporterClient;
using google_breakpad::ExceptionHandler;
using google_breakpad::MinidumpDescriptor;

namespace breakpad {

namespace {

char* g_upload_url = nullptr;
void SetUploadURL(const std::string& url) {
  DCHECK(!g_upload_url);
  g_upload_url = strdup(url.c_str());
}

bool g_is_crash_reporter_enabled = false;
uint64_t g_process_start_time = 0;
pid_t g_pid = 0;
char* g_crash_log_path = nullptr;
ExceptionHandler* g_breakpad = nullptr;

#if defined(ADDRESS_SANITIZER)
const char* g_asan_report_str = nullptr;
#endif

// Writes the value |v| as 16 hex characters to the memory pointed at by
// |output|.
void write_uint64_hex(char* output, uint64_t v) {
  static const char hextable[] = "0123456789abcdef";

  for (int i = 15; i >= 0; --i) {
    output[i] = hextable[v & 15];
    v >>= 4;
  }
}

// The following helper functions are for calculating uptime.

// Converts a struct timeval to milliseconds.
uint64_t timeval_to_ms(struct timeval *tv) {
  uint64_t ret = tv->tv_sec;  // Avoid overflow by explicitly using a uint64_t.
  ret *= 1000;
  ret += tv->tv_usec / 1000;
  return ret;
}

// Converts a struct timeval to milliseconds.
uint64_t kernel_timeval_to_ms(struct kernel_timeval *tv) {
  uint64_t ret = tv->tv_sec;  // Avoid overflow by explicitly using a uint64_t.
  ret *= 1000;
  ret += tv->tv_usec / 1000;
  return ret;
}

// String buffer size to use to convert a uint64_t to string.
const size_t kUint64StringSize = 21;

void SetProcessStartTime() {
  // Set the base process start time value.
  struct timeval tv;
  if (!gettimeofday(&tv, nullptr))
    g_process_start_time = timeval_to_ms(&tv);
  else
    g_process_start_time = 0;
}

// uint64_t version of my_int_len() from
// third_party/breakpad/breakpad/src/common/linux/linux_libc_support.h. Return
// the length of the given, non-negative integer when expressed in base 10.
unsigned my_uint64_len(uint64_t i) {
  if (!i)
    return 1;

  unsigned len = 0;
  while (i) {
    len++;
    i /= 10;
  }

  return len;
}

// uint64_t version of my_uitos() from
// third_party/breakpad/breakpad/src/common/linux/linux_libc_support.h. Convert
// a non-negative integer to a string (not null-terminated).
void my_uint64tos(char* output, uint64_t i, unsigned i_len) {
  for (unsigned index = i_len; index; --index, i /= 10)
    output[index - 1] = '0' + (i % 10);
}

size_t LengthWithoutTrailingSpaces(const char* str, size_t len) {
  while (len > 0 && str[len - 1] == ' ') {
    len--;
  }
  return len;
}

bool GetEnableCrashReporterSwitchParts(const base::CommandLine& command_line,
                                       std::vector<std::string>* switch_parts) {
  std::string switch_value =
      command_line.GetSwitchValueASCII(switches::kEnableCrashReporter);
  std::vector<std::string> parts = base::SplitString(switch_value,
                                                     ",",
                                                     base::KEEP_WHITESPACE,
                                                     base::SPLIT_WANT_ALL);
  if (parts.size() != 2)
    return false;

  *switch_parts = parts;
  return true;
}

void SetChannelFromCommandLine(const base::CommandLine& command_line) {
  std::vector<std::string> switch_parts;
  if (!GetEnableCrashReporterSwitchParts(command_line, &switch_parts))
    return;

  SetChannelCrashKey(switch_parts[1]);
}

void SetClientIdFromCommandLine(const base::CommandLine& command_line) {
  std::vector<std::string> switch_parts;
  if (!GetEnableCrashReporterSwitchParts(command_line, &switch_parts))
    return;

  GetCrashReporterClient()->SetCrashReporterClientIdFromGUID(switch_parts[0]);
}

// MIME substrings.
const char g_rn[] = "\r\n";
const char g_form_data_msg[] = "Content-Disposition: form-data; name=\"";
const char g_quote_msg[] = "\"";
const char g_dashdash_msg[] = "--";
const char g_dump_msg[] = "upload_file_minidump\"; filename=\"dump\"";
#if defined(ADDRESS_SANITIZER)
const char g_log_msg[] = "upload_file_log\"; filename=\"log\"";
#endif
const char g_content_type_msg[] = "Content-Type: application/octet-stream";

// MimeWriter manages an iovec for writing MIMEs to a file.
class MimeWriter {
 public:
  static const int kIovCapacity = 30;
  static const size_t kMaxCrashChunkSize = 64;

  MimeWriter(int fd, const char* const mime_boundary);

  MimeWriter(const MimeWriter&) = delete;
  MimeWriter& operator=(const MimeWriter&) = delete;

  ~MimeWriter();

  // Append boundary.
  virtual void AddBoundary();

  // Append end of file boundary.
  virtual void AddEnd();

  // Append key/value pair with specified sizes.
  virtual void AddPairData(const char* msg_type,
                           size_t msg_type_size,
                           const char* msg_data,
                           size_t msg_data_size);

  // Append key/value pair.
  void AddPairString(const char* msg_type,
                     const char* msg_data) {
    AddPairData(msg_type, my_strlen(msg_type), msg_data, my_strlen(msg_data));
  }

  // Append key/value pair, splitting value into chunks no larger than
  // |chunk_size|. |chunk_size| cannot be greater than |kMaxCrashChunkSize|.
  // The msg_type string will have a counter suffix to distinguish each chunk.
  virtual void AddPairDataInChunks(const char* msg_type,
                                   size_t msg_type_size,
                                   const char* msg_data,
                                   size_t msg_data_size,
                                   size_t chunk_size,
                                   bool strip_trailing_spaces);

  // Add binary file contents to be uploaded with the specified filename.
  virtual void AddFileContents(const char* filename_msg,
                               uint8_t* file_data,
                               size_t file_size);

  // Flush any pending iovecs to the output file.
  void Flush() {
    IGNORE_RET(sys_writev(fd_, iov_, iov_index_));
    iov_index_ = 0;
  }

 protected:
  void AddItem(const void* base, size_t size);
  // Minor performance trade-off for easier-to-maintain code.
  void AddString(const char* str) {
    AddItem(str, my_strlen(str));
  }
  void AddItemWithoutTrailingSpaces(const void* base, size_t size);

  struct kernel_iovec iov_[kIovCapacity];
  int iov_index_;

  // Output file descriptor.
  int fd_;

  const char* const mime_boundary_;
};

MimeWriter::MimeWriter(int fd, const char* const mime_boundary)
    : iov_index_(0),
      fd_(fd),
      mime_boundary_(mime_boundary) {
}

MimeWriter::~MimeWriter() {
}

void MimeWriter::AddBoundary() {
  AddString(mime_boundary_);
  AddString(g_rn);
}

void MimeWriter::AddEnd() {
  AddString(mime_boundary_);
  AddString(g_dashdash_msg);
  AddString(g_rn);
}

void MimeWriter::AddPairData(const char* msg_type,
                             size_t msg_type_size,
                             const char* msg_data,
                             size_t msg_data_size) {
  AddString(g_form_data_msg);
  AddItem(msg_type, msg_type_size);
  AddString(g_quote_msg);
  AddString(g_rn);
  AddString(g_rn);
  AddItem(msg_data, msg_data_size);
  AddString(g_rn);
}

void MimeWriter::AddPairDataInChunks(const char* msg_type,
                                     size_t msg_type_size,
                                     const char* msg_data,
                                     size_t msg_data_size,
                                     size_t chunk_size,
                                     bool strip_trailing_spaces) {
  if (chunk_size > kMaxCrashChunkSize)
    return;

  unsigned i = 0;
  size_t done = 0, msg_length = msg_data_size;

  while (msg_length) {
    char num[kUint64StringSize];
    const unsigned num_len = my_uint_len(++i);
    my_uitos(num, i, num_len);

    size_t chunk_len = std::min(chunk_size, msg_length);

    AddString(g_form_data_msg);
    AddItem(msg_type, msg_type_size);
    AddItem(num, num_len);
    AddString(g_quote_msg);
    AddString(g_rn);
    AddString(g_rn);
    if (strip_trailing_spaces) {
      AddItemWithoutTrailingSpaces(msg_data + done, chunk_len);
    } else {
      AddItem(msg_data + done, chunk_len);
    }
    AddString(g_rn);
    AddBoundary();
    Flush();

    done += chunk_len;
    msg_length -= chunk_len;
  }
}

void MimeWriter::AddFileContents(const char* filename_msg, uint8_t* file_data,
                                 size_t file_size) {
  AddString(g_form_data_msg);
  AddString(filename_msg);
  AddString(g_rn);
  AddString(g_content_type_msg);
  AddString(g_rn);
  AddString(g_rn);
  AddItem(file_data, file_size);
  AddString(g_rn);
}

void MimeWriter::AddItem(const void* base, size_t size) {
  // Check if the iovec is full and needs to be flushed to output file.
  if (iov_index_ == kIovCapacity) {
    Flush();
  }
  iov_[iov_index_].iov_base = const_cast<void*>(base);
  iov_[iov_index_].iov_len = size;
  ++iov_index_;
}

void MimeWriter::AddItemWithoutTrailingSpaces(const void* base, size_t size) {
  AddItem(base, LengthWithoutTrailingSpaces(static_cast<const char*>(base),
                                            size));
}

size_t WriteLog(const char* buf, size_t nbytes) {
  return sys_write(2, buf, nbytes);
}

size_t WriteNewline() {
  return WriteLog("\n", 1);
}

bool CrashDone(const MinidumpDescriptor& minidump,
               const bool upload,
               const bool should_finalize,
               const bool succeeded) {
  // WARNING: this code runs in a compromised context. It may not call into
  // libc nor allocate memory normally.
  if (!succeeded) {
    const char msg[] = "Failed to generate minidump.";
    WriteLog(msg, sizeof(msg) - 1);
    return false;
  }

  DCHECK(!(upload && minidump.IsFD()));

  BreakpadInfo info;
  info.filename = minidump.path();
  info.fd = minidump.fd();
#if defined(ADDRESS_SANITIZER)
  google_breakpad::PageAllocator allocator;
  const size_t log_path_len = my_strlen(minidump.path());
  char* log_path = reinterpret_cast<char*>(allocator.Alloc(log_path_len + 1));
  my_memcpy(log_path, minidump.path(), log_path_len);
  my_memcpy(log_path + log_path_len - 4, ".log", 4);
  log_path[log_path_len] = '\0';
  info.log_filename = log_path;
#endif
  info.process_type = "browser";
  info.process_type_length = 7;
  info.distro = base::g_linux_distro;
  info.distro_length = my_strlen(base::g_linux_distro);
  info.upload = upload;
  info.process_start_time = g_process_start_time;
  info.oom_size = partition_alloc::g_oom_size;
  info.pid = g_pid;
  info.crash_keys = crash_reporter::internal::GetCrashKeyStorage();
  HandleCrashDump(info);
  return true;
}

// Wrapper function, do not add more code here.
bool CrashDoneNoUpload(const MinidumpDescriptor& minidump,
                       void* context,
                       bool succeeded) {
  return CrashDone(minidump, false, true, succeeded);
}

// Wrapper function, do not add more code here.
bool CrashDoneUpload(const MinidumpDescriptor& minidump,
                     void* context,
                     bool succeeded) {
  return CrashDone(minidump, true, true, succeeded);
}

void DumpProcess() {
  if (g_breakpad)
    g_breakpad->WriteMinidump();
}

#if defined(ADDRESS_SANITIZER)
extern "C"
void __asan_set_error_report_callback(void (*cb)(const char*));

extern "C"
void AsanLinuxBreakpadCallback(const char* report) {
  g_asan_report_str = report;
  // Send minidump here.
  g_breakpad->SimulateSignalDelivery(SIGKILL);
}
#endif

void EnableCrashDumping(bool unattended) {
  g_is_crash_reporter_enabled = true;

  base::FilePath tmp_path("/tmp");
  base::PathService::Get(base::DIR_TEMP, &tmp_path);

  base::FilePath dumps_path(tmp_path);
  if (GetCrashReporterClient()->GetCrashDumpLocation(&dumps_path)) {
    base::FilePath logfile =
        dumps_path.Append(GetCrashReporterClient()->GetReporterLogFilename());
    std::string logfile_str = logfile.value();
    const size_t crash_log_path_len = logfile_str.size() + 1;
    g_crash_log_path = new char[crash_log_path_len];
    strncpy(g_crash_log_path, logfile_str.c_str(), crash_log_path_len);
  }
  DCHECK(!g_breakpad);
  MinidumpDescriptor minidump_descriptor(dumps_path.value());
  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kFullMemoryCrashReport)) {
    minidump_descriptor.set_size_limit(-1);  // unlimited.
  } else {
    minidump_descriptor.set_size_limit(kMaxMinidumpFileSize);
  }
  if (unattended) {
    g_breakpad = new ExceptionHandler(
        minidump_descriptor, nullptr, CrashDoneNoUpload, nullptr,
        true,  // Install handlers.
        -1);   // Server file descriptor. -1 for in-process.
    return;
  }

  // Attended mode
  g_breakpad = new ExceptionHandler(
      minidump_descriptor,
      nullptr,
      CrashDoneUpload,
      nullptr,
      true,  // Install handlers.
      -1);   // Server file descriptor. -1 for in-process.
}

// Non-Browser = Extension, Gpu, Plugins, Ppapi and Renderer
class NonBrowserCrashHandler : public google_breakpad::CrashGenerationClient {
 public:
  NonBrowserCrashHandler()
      : server_fd_(
            base::GlobalDescriptors::GetInstance()->Get(kCrashDumpSignal)) {}

  NonBrowserCrashHandler(const NonBrowserCrashHandler&) = delete;
  NonBrowserCrashHandler& operator=(const NonBrowserCrashHandler&) = delete;

  ~NonBrowserCrashHandler() override {}

  bool RequestDump(const void* crash_context,
                   size_t crash_context_size) override {
    int fds[2] = { -1, -1 };
    if (sys_socketpair(AF_UNIX, SOCK_STREAM, 0, fds) < 0) {
      static const char msg[] = "Failed to create socket for crash dumping.\n";
      WriteLog(msg, sizeof(msg) - 1);
      return false;
    }

    // Start constructing the message to send to the browser.
    char b;  // Dummy variable for sys_read below.
    const char* b_addr = &b;  // Get the address of |b| so we can create the
                              // expected /proc/[pid]/syscall content in the
                              // browser to convert namespace tids.

    // The length of the control message:
    static const unsigned kControlMsgSize = sizeof(int);
    static const unsigned kControlMsgSpaceSize = CMSG_SPACE(kControlMsgSize);
    static const unsigned kControlMsgLenSize = CMSG_LEN(kControlMsgSize);

    struct kernel_msghdr msg;
    my_memset(&msg, 0, sizeof(struct kernel_msghdr));
    struct kernel_iovec iov[kCrashIovSize];
    iov[0].iov_base = const_cast<void*>(crash_context);
    iov[0].iov_len = crash_context_size;
    iov[1].iov_base = &b_addr;
    iov[1].iov_len = sizeof(b_addr);
    iov[2].iov_base = &fds[0];
    iov[2].iov_len = sizeof(fds[0]);
    iov[3].iov_base = &g_process_start_time;
    iov[3].iov_len = sizeof(g_process_start_time);
    iov[4].iov_base = &partition_alloc::g_oom_size;
    iov[4].iov_len = sizeof(partition_alloc::g_oom_size);
    google_breakpad::SerializedNonAllocatingMap* serialized_map;
    iov[5].iov_len = crash_reporter::internal::GetCrashKeyStorage()->Serialize(
        const_cast<const google_breakpad::SerializedNonAllocatingMap**>(
            &serialized_map));
    iov[5].iov_base = serialized_map;
#if !defined(ADDRESS_SANITIZER)
    static_assert(5 == kCrashIovSize - 1, "kCrashIovSize should equal 6");
#else
    if (g_asan_report_str != nullptr) {
      iov[6].iov_base = const_cast<char*>(g_asan_report_str);
    } else {
      static char empty_asan_report[kMaxAsanReportSize + 1];
      iov[6].iov_base = empty_asan_report;
    }
    iov[6].iov_len = kMaxAsanReportSize + 1;
    static_assert(6 == kCrashIovSize - 1, "kCrashIovSize should equal 7");
#endif

    msg.msg_iov = iov;
    msg.msg_iovlen = kCrashIovSize;
    char cmsg[kControlMsgSpaceSize];
    my_memset(cmsg, 0, kControlMsgSpaceSize);
    msg.msg_control = cmsg;
    msg.msg_controllen = sizeof(cmsg);

    struct cmsghdr *hdr = CMSG_FIRSTHDR(&msg);
    hdr->cmsg_level = SOL_SOCKET;
    hdr->cmsg_type = SCM_RIGHTS;
    hdr->cmsg_len = kControlMsgLenSize;
    ((int*)CMSG_DATA(hdr))[0] = fds[1];

    if (HANDLE_EINTR(sys_sendmsg(server_fd_, &msg, 0)) < 0) {
      static const char errmsg[] = "Failed to tell parent about crash.\n";
      WriteLog(errmsg, sizeof(errmsg) - 1);
      IGNORE_RET(sys_close(fds[0]));
      IGNORE_RET(sys_close(fds[1]));
      return false;
    }
    IGNORE_RET(sys_close(fds[1]));

    if (HANDLE_EINTR(sys_read(fds[0], &b, 1)) != 1) {
      static const char errmsg[] = "Parent failed to complete crash dump.\n";
      WriteLog(errmsg, sizeof(errmsg) - 1);
    }
    IGNORE_RET(sys_close(fds[0]));

    return true;
  }

 private:
  // The pipe FD to the browser process, which will handle the crash dumping.
  const int server_fd_;
};

void EnableNonBrowserCrashDumping() {
  g_is_crash_reporter_enabled = true;
  // We deliberately leak this object.
  DCHECK(!g_breakpad);

  g_breakpad = new ExceptionHandler(
      MinidumpDescriptor("/tmp"),  // Unused but needed or Breakpad will assert.
      nullptr,
      nullptr,
      nullptr,
      true,
      -1);
  g_breakpad->set_crash_generation_client(new NonBrowserCrashHandler());
}

// GetCrashReporterClient() cannot call any Set methods until after
// InitCrashKeys().
void InitCrashKeys() {
  crash_reporter::InitializeCrashKeys();
}

// Miscellaneous initialization functions to call after Breakpad has been
// enabled.
void PostEnableBreakpadInitialization(
    const std::string& process_type,
    const base::CommandLine& parsed_command_line) {
  SetProcessStartTime();
  g_pid = getpid();

  base::debug::SetDumpWithoutCrashingFunction(&DumpProcess);
#if defined(ADDRESS_SANITIZER)
  // Register the callback for AddressSanitizer error reporting.
  __asan_set_error_report_callback(AsanLinuxBreakpadCallback);
#endif
}

}  // namespace

void LoadDataFromFD(google_breakpad::PageAllocator& allocator,
                    int fd, bool close_fd, uint8_t** file_data, size_t* size) {
  STAT_STRUCT st;
  if (FSTAT_FUNC(fd, &st) != 0) {
    static const char msg[] = "Cannot upload crash dump: stat failed\n";
    WriteLog(msg, sizeof(msg) - 1);
    if (close_fd)
      IGNORE_RET(sys_close(fd));
    return;
  }

  *file_data = reinterpret_cast<uint8_t*>(allocator.Alloc(st.st_size));
  if (!(*file_data)) {
    static const char msg[] = "Cannot upload crash dump: cannot alloc\n";
    WriteLog(msg, sizeof(msg) - 1);
    if (close_fd)
      IGNORE_RET(sys_close(fd));
    return;
  }
  my_memset(*file_data, 0xf, st.st_size);

  *size = st.st_size;
  int byte_read = sys_read(fd, *file_data, *size);
  if (byte_read == -1) {
    static const char msg[] = "Cannot upload crash dump: read failed\n";
    WriteLog(msg, sizeof(msg) - 1);
    if (close_fd)
      IGNORE_RET(sys_close(fd));
    return;
  }

  if (close_fd)
    IGNORE_RET(sys_close(fd));
}

void LoadDataFromFile(google_breakpad::PageAllocator& allocator,
                      const char* filename,
                      int* fd, uint8_t** file_data, size_t* size) {
  // WARNING: this code runs in a compromised context. It may not call into
  // libc nor allocate memory normally.
  *fd = sys_open(filename, O_RDONLY, 0);
  *size = 0;

  if (*fd < 0) {
    static const char msg[] = "Cannot upload crash dump: failed to open\n";
    WriteLog(msg, sizeof(msg) - 1);
    return;
  }

  LoadDataFromFD(allocator, *fd, true, file_data, size);
}

// Concatenates a |prefix| and a |number| to get a string like "--foo=123" or
// "/dev/fd/4". Safe to run in a compromised context. The returned memory is
// internally owned by |allocator|.
char* StringFromPrefixAndUint(const char* prefix,
                              uint64_t number,
                              google_breakpad::PageAllocator* allocator) {
  // Convert the number to a string.
  char number_buf[kUint64StringSize];
  const unsigned number_len = my_uint64_len(number);
  my_uint64tos(number_buf, number, number_len);
  number_buf[number_len] = '\0';

  // Concatenate the prefix and number.
  size_t output_len = my_strlen(prefix) + my_strlen(number_buf) + 1;
  char* output = reinterpret_cast<char*>(allocator->Alloc(output_len));
  my_strlcpy(output, prefix, output_len);
  my_strlcat(output, number_buf, output_len);
  return output;
}

// Spawn the appropriate upload process for the current OS:
// - generic Linux invokes wget.
// |dumpfile| is the path to the dump data file.
// |mime_boundary| is only used on Linux.
// |upload_status_fd| is the file descriptor of a pipe that will receive:
// - On Linux, the crash report id
void ExecUploadProcessOrTerminate(const BreakpadInfo& info,
                                  const char* dumpfile,
                                  const char* mime_boundary,
                                  int upload_status_fd,
                                  google_breakpad::PageAllocator* allocator) {
  // Compress |dumpfile| with gzip.
  const pid_t gzip_child = sys_fork();
  if (gzip_child < 0) {
    static const char msg[] = "sys_fork() for gzip process failed.\n";
    WriteLog(msg, sizeof(msg) - 1);
    sys__exit(1);
  }
  if (!gzip_child) {
    // gzip process.
    const char* args[] = {
      "/bin/gzip",
      "-f",  // Do not prompt to verify before overwriting.
      dumpfile,
      nullptr,
    };
    execve(args[0], const_cast<char**>(args), environ);
    static const char msg[] = "Cannot exec gzip.\n";
    WriteLog(msg, sizeof(msg) - 1);
    sys__exit(1);
  }
  // Wait for gzip process.
  int status = 0;
  if (sys_waitpid(gzip_child, &status, 0) != gzip_child ||
      !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
    static const char msg[] = "sys_waitpid() for gzip process failed.\n";
    WriteLog(msg, sizeof(msg) - 1);
    sys_kill(gzip_child, SIGKILL);
    sys__exit(1);
  }

  static const char kGzipExtension[] = ".gz";
  const size_t gzip_file_size = my_strlen(dumpfile) + sizeof(kGzipExtension);
  char* const gzip_file = reinterpret_cast<char*>(allocator->Alloc(
      gzip_file_size));
  my_strlcpy(gzip_file, dumpfile, gzip_file_size);
  my_strlcat(gzip_file, kGzipExtension, gzip_file_size);

  // Rename |gzip_file| to |dumpfile| (the original file was deleted by gzip).
  if (rename(gzip_file, dumpfile)) {
    static const char msg[] = "Failed to rename gzipped file.\n";
    WriteLog(msg, sizeof(msg) - 1);
    sys__exit(1);
  }

  // The --header argument to wget looks like:
  //   --header=Content-Encoding: gzip
  //   --header=Content-Type: multipart/form-data; boundary=XYZ
  // where the boundary has two fewer leading '-' chars
  static const char header_content_encoding[] =
      "--header=Content-Encoding: gzip";
  static const char header_msg[] =
      "--header=Content-Type: multipart/form-data; boundary=";
  const size_t header_content_type_size =
      sizeof(header_msg) - 1 + my_strlen(mime_boundary) - 2 + 1;
  char* const header_content_type = reinterpret_cast<char*>(allocator->Alloc(
      header_content_type_size));
  my_strlcpy(header_content_type, header_msg, header_content_type_size);
  my_strlcat(header_content_type, mime_boundary + 2, header_content_type_size);

  // The --post-file argument to wget looks like:
  //   --post-file=/tmp/...
  static const char post_file_msg[] = "--post-file=";
  const size_t post_file_size =
      sizeof(post_file_msg) - 1 + my_strlen(dumpfile) + 1;
  char* const post_file = reinterpret_cast<char*>(allocator->Alloc(
      post_file_size));
  my_strlcpy(post_file, post_file_msg, post_file_size);
  my_strlcat(post_file, dumpfile, post_file_size);

  // Write the wget status output to the status pipe file descriptor path.
  char* status_fd_path =
      StringFromPrefixAndUint("/dev/fd/", upload_status_fd, allocator);

  static const char kWgetBinary[] = "/usr/bin/wget";
  const char* args[] = {
      kWgetBinary,
      header_content_encoding,
      header_content_type,
      post_file,
      g_upload_url,
      "--timeout=10",  // Set a timeout so we don't hang forever.
      "--tries=1",     // Don't retry if the upload fails.
      "-O",            // Output reply to the file descriptor path.
      status_fd_path,
      nullptr,
  };
  static const char msg[] = "Cannot upload crash dump: cannot exec "
                            "/usr/bin/wget\n";

  execve(args[0], const_cast<char**>(args), environ);
  WriteLog(msg, sizeof(msg) - 1);
  sys__exit(1);
}

// Runs in the helper process to wait for the upload process running
// ExecUploadProcessOrTerminate() to finish. Returns the number of bytes written
// to |fd| and save the written contents to |buf|.
// |buf| needs to be big enough to hold |bytes_to_read| + 1 characters.
size_t WaitForCrashReportUploadProcess(int fd, size_t bytes_to_read,
                                       char* buf) {
  size_t bytes_read = 0;

  // Upload should finish in about 10 seconds. Add a few more 500 ms
  // internals to account for process startup time.
  for (size_t wait_count = 0; wait_count < 24; ++wait_count) {
    struct kernel_pollfd poll_fd;
    poll_fd.fd = fd;
    poll_fd.events = POLLIN | POLLPRI | POLLERR;
    int ret = sys_poll(&poll_fd, 1, 500);
    if (ret < 0) {
      // Error
      break;
    }
    if (ret > 0) {
      // There is data to read.
      ssize_t len = HANDLE_EINTR(
          sys_read(fd, buf + bytes_read, bytes_to_read - bytes_read));
      if (len < 0)
        break;
      bytes_read += len;
      if (bytes_read == bytes_to_read)
        break;
    }
    // |ret| == 0 -> timed out, continue waiting.
    // or |bytes_read| < |bytes_to_read| still, keep reading.
  }
  buf[bytes_to_read] = 0;  // Always NUL terminate the buffer.
  return bytes_read;
}

// |buf| should be |expected_len| + 1 characters in size and nullptr terminated.
bool IsValidCrashReportId(const char* buf, size_t bytes_read,
                          size_t expected_len) {
  if (bytes_read != expected_len) {
    static const char msg[] = "Unexpected crash report id length\n";
    WriteLog(msg, sizeof(msg) - 1);
    return false;
  }
  return std::ranges::all_of(base::span(buf, bytes_read),
                             base::IsHexDigit<char>);
}

// |buf| should be |expected_len| + 1 characters in size and nullptr terminated.
void HandleCrashReportId(const char* buf, size_t bytes_read,
                         size_t expected_len) {
  WriteNewline();
  if (!IsValidCrashReportId(buf, bytes_read, expected_len)) {
    static const char msg[] = "Failed to get crash dump id.";
    WriteLog(msg, sizeof(msg) - 1);
    WriteNewline();

    static const char id_msg[] = "Report Id: ";
    WriteLog(id_msg, sizeof(id_msg) - 1);
    WriteLog(buf, bytes_read);
    WriteNewline();
    return;
  }

  // Write crash dump id to stderr.
  static const char msg[] = "Crash dump id: ";
  WriteLog(msg, sizeof(msg) - 1);
  WriteLog(buf, my_strlen(buf));
  WriteNewline();

  // Write crash dump id to crash log as: seconds_since_epoch,crash_id
  struct kernel_timeval tv;
  if (g_crash_log_path && !sys_gettimeofday(&tv, nullptr)) {
    uint64_t time = kernel_timeval_to_ms(&tv) / 1000;
    char time_str[kUint64StringSize];
    const unsigned time_len = my_uint64_len(time);
    my_uint64tos(time_str, time, time_len);

    const int kLogOpenFlags = O_CREAT | O_WRONLY | O_APPEND | O_CLOEXEC;
    int log_fd = sys_open(g_crash_log_path, kLogOpenFlags, 0600);
    if (log_fd > 0) {
      sys_write(log_fd, time_str, time_len);
      sys_write(log_fd, ",", 1);
      sys_write(log_fd, buf, my_strlen(buf));
      sys_write(log_fd, "\n", 1);
      IGNORE_RET(sys_close(log_fd));
    }
  }
}

// Attempts to close all open file descriptors other than stdin, stdout and
// stderr (0, 1, and 2).
void CloseAllFileDescriptors() {
  const int fd = sys_open("/proc/self/fd", O_DIRECTORY | O_RDONLY, 0);
  if (fd < 0) {
    for (unsigned i = 3; i < 8192; ++i)
      IGNORE_RET(sys_close(i));
  } else {
    google_breakpad::DirectoryReader reader(fd);
    const char* name;
    while (reader.GetNextEntry(&name)) {
      int i;
      if (my_strtoui(&i, name) && i > 2 && i != fd)
        IGNORE_RET(sys_close(i));
      reader.PopEntry();
    }

    IGNORE_RET(sys_close(fd));
  }
}

void HandleCrashDump(const BreakpadInfo& info) {
  int dumpfd;
  bool keep_fd = false;
  size_t dump_size;
  uint8_t* dump_data;
  google_breakpad::PageAllocator allocator;

  if (GetCrashReporterClient()->HandleCrashDump(info.filename, info.pid)) {
    return;
  }

  if (info.fd != -1) {
    // Dump is provided with an open FD.
    keep_fd = true;
    dumpfd = info.fd;

    // The FD is pointing to the end of the file.
    // Rewind, we'll read the data next.
    if (lseek(dumpfd, 0, SEEK_SET) == -1) {
      static const char msg[] = "Cannot upload crash dump: failed to "
          "reposition minidump FD\n";
      WriteLog(msg, sizeof(msg) - 1);
      IGNORE_RET(sys_close(dumpfd));
      return;
    }
    LoadDataFromFD(allocator, info.fd, false, &dump_data, &dump_size);
  } else {
    // Dump is provided with a path.
    keep_fd = false;
    LoadDataFromFile(allocator, info.filename, &dumpfd, &dump_data, &dump_size);
  }

  // TODO(jcivelli): make log work when using FDs.
#if defined(ADDRESS_SANITIZER)
  int logfd;
  size_t log_size;
  uint8_t* log_data;
  // Load the AddressSanitizer log into log_data.
  LoadDataFromFile(allocator, info.log_filename, &logfd, &log_data, &log_size);
#endif

  // We need to build a MIME block for uploading to the server. Since we are
  // going to fork and run wget, it needs to be written to a temp file.
  const int ufd = sys_open("/dev/urandom", O_RDONLY, 0);
  if (ufd < 0) {
    static const char msg[] = "Cannot upload crash dump because /dev/urandom"
                              " is missing\n";
    WriteLog(msg, sizeof(msg) - 1);
    return;
  }

  static const char temp_file_template[] =
      "/tmp/chromium-upload-XXXXXXXXXXXXXXXX";
  char temp_file[sizeof(temp_file_template)];
  int temp_file_fd = -1;
  if (keep_fd) {
    temp_file_fd = dumpfd;
    // Rewind the destination, we are going to overwrite it.
    if (lseek(dumpfd, 0, SEEK_SET) == -1) {
      static const char msg[] = "Cannot upload crash dump: failed to "
          "reposition minidump FD (2)\n";
      WriteLog(msg, sizeof(msg) - 1);
      IGNORE_RET(sys_close(dumpfd));
      return;
    }
  } else {
    if (info.upload) {
      my_memcpy(temp_file, temp_file_template, sizeof(temp_file_template));

      for (unsigned i = 0; i < 10; ++i) {
        uint64_t t;
        sys_read(ufd, &t, sizeof(t));
        write_uint64_hex(temp_file + sizeof(temp_file) - (16 + 1), t);

        temp_file_fd = sys_open(temp_file, O_WRONLY | O_CREAT | O_EXCL, 0600);
        if (temp_file_fd >= 0)
          break;
      }

      if (temp_file_fd < 0) {
        static const char msg[] = "Failed to create temporary file in /tmp: "
            "cannot upload crash dump\n";
        WriteLog(msg, sizeof(msg) - 1);
        IGNORE_RET(sys_close(ufd));
        return;
      }
    } else {
      temp_file_fd = sys_open(info.filename, O_WRONLY, 0600);
      if (temp_file_fd < 0) {
        static const char msg[] = "Failed to save crash dump: failed to open\n";
        WriteLog(msg, sizeof(msg) - 1);
        IGNORE_RET(sys_close(ufd));
        return;
      }
    }
  }

  // The MIME boundary is 28 hyphens, followed by a 64-bit nonce and a NUL.
  char mime_boundary[28 + 16 + 1];
  my_memset(mime_boundary, '-', 28);
  uint64_t boundary_rand;
  sys_read(ufd, &boundary_rand, sizeof(boundary_rand));
  write_uint64_hex(mime_boundary + 28, boundary_rand);
  mime_boundary[28 + 16] = 0;
  IGNORE_RET(sys_close(ufd));

  // The MIME block looks like this:
  //   BOUNDARY \r\n
  //   Content-Disposition: form-data; name="prod" \r\n \r\n
  //   Chrome_Linux \r\n
  //   BOUNDARY \r\n
  //   Content-Disposition: form-data; name="ver" \r\n \r\n
  //   1.2.3.4 \r\n
  //   BOUNDARY \r\n
  //
  //   zero or one:
  //   Content-Disposition: form-data; name="ptime" \r\n \r\n
  //   abcdef \r\n
  //   BOUNDARY \r\n
  //
  //   zero or one:
  //   Content-Disposition: form-data; name="ptype" \r\n \r\n
  //   abcdef \r\n
  //   BOUNDARY \r\n
  //
  //   zero or one:
  //   Content-Disposition: form-data; name="lsb-release" \r\n \r\n
  //   abcdef \r\n
  //   BOUNDARY \r\n
  //
  //   zero or one:
  //   Content-Disposition: form-data; name="oom-size" \r\n \r\n
  //   1234567890 \r\n
  //   BOUNDARY \r\n
  //
  //   zero or more (up to CrashKeyStorage::num_entries = 64):
  //   Content-Disposition: form-data; name=crash-key-name \r\n
  //   crash-key-value \r\n
  //   BOUNDARY \r\n
  //
  //   Content-Disposition: form-data; name="dump"; filename="dump" \r\n
  //   Content-Type: application/octet-stream \r\n \r\n
  //   <dump contents>
  //   \r\n BOUNDARY -- \r\n

  MimeWriter writer(temp_file_fd, mime_boundary);
  {
    crash_reporter::ProductInfo product_info;
    GetCrashReporterClient()->GetProductInfo(&product_info);

    writer.AddBoundary();
    writer.AddPairString("prod", product_info.product_name.c_str());
    writer.AddBoundary();
    writer.AddPairString("ver", product_info.version.c_str());
    writer.AddBoundary();
    if (info.pid > 0) {
      char pid_value_buf[kUint64StringSize];
      uint64_t pid_value_len = my_uint64_len(info.pid);
      my_uint64tos(pid_value_buf, info.pid, pid_value_len);
      static const char pid_key_name[] = "pid";
      writer.AddPairData(pid_key_name, sizeof(pid_key_name) - 1,
                         pid_value_buf, pid_value_len);
      writer.AddBoundary();
    }
    writer.Flush();
  }

  if (info.process_start_time > 0) {
    struct kernel_timeval tv;
    if (!sys_gettimeofday(&tv, nullptr)) {
      uint64_t time = kernel_timeval_to_ms(&tv);
      if (time > info.process_start_time) {
        time -= info.process_start_time;
        char time_str[kUint64StringSize];
        const unsigned time_len = my_uint64_len(time);
        my_uint64tos(time_str, time, time_len);

        static const char process_time_msg[] = "ptime";
        writer.AddPairData(process_time_msg, sizeof(process_time_msg) - 1,
                           time_str, time_len);
        writer.AddBoundary();
        writer.Flush();
      }
    }
  }

  if (info.process_type_length) {
    writer.AddPairString("ptype", info.process_type);
    writer.AddBoundary();
    writer.Flush();
  }

  if (info.distro_length) {
    static const char distro_msg[] = "lsb-release";
    writer.AddPairString(distro_msg, info.distro);
    writer.AddBoundary();
    writer.Flush();
  }

  if (info.oom_size) {
    char oom_size_str[kUint64StringSize];
    const unsigned oom_size_len = my_uint64_len(info.oom_size);
    my_uint64tos(oom_size_str, info.oom_size, oom_size_len);
    static const char oom_size_msg[] = "oom-size";
    writer.AddPairData(oom_size_msg, sizeof(oom_size_msg) - 1,
                       oom_size_str, oom_size_len);
    writer.AddBoundary();
    writer.Flush();
  }

  if (info.crash_keys) {
    using CrashKeyStorage =
        crash_reporter::internal::TransitionalCrashKeyStorage;
    CrashKeyStorage::Iterator crash_key_iterator(*info.crash_keys);
    const CrashKeyStorage::Entry* entry;
    while ((entry = crash_key_iterator.Next())) {
      size_t key_size, value_size;
      // Check for malformed messages.
      key_size = entry->key[CrashKeyStorage::key_size - 1] != '\0'
                     ? CrashKeyStorage::key_size - 1
                     : my_strlen(entry->key);
      value_size = entry->value[CrashKeyStorage::value_size - 1] != '\0'
                       ? CrashKeyStorage::value_size - 1
                       : my_strlen(entry->value);

      writer.AddPairData(entry->key, key_size, entry->value, value_size);
      writer.AddBoundary();
      writer.Flush();
    }
  }

  writer.AddFileContents(g_dump_msg, dump_data, dump_size);
#if defined(ADDRESS_SANITIZER)
  // Append a multipart boundary and the contents of the AddressSanitizer log.
  writer.AddBoundary();
  writer.AddFileContents(g_log_msg, log_data, log_size);
#endif
  writer.AddEnd();
  writer.Flush();

  IGNORE_RET(sys_close(temp_file_fd));

  if (!info.upload)
    return;

  const pid_t child = sys_fork();
  if (!child) {
    // Spawned helper process.
    //
    // This code is called both when a browser is crashing (in which case,
    // nothing really matters any more) and when a renderer/plugin crashes, in
    // which case we need to continue.
    //
    // Since we are a multithreaded app, if we were just to fork(), we might
    // grab file descriptors which have just been created in another thread and
    // hold them open for too long.
    //
    // Thus, we have to loop and try and close everything.
    CloseAllFileDescriptors();

    IGNORE_RET(sys_setsid());

    // Leave one end of a pipe in the upload process and watch for it getting
    // closed by the upload process exiting.
    int fds[2];
    if (sys_pipe(fds) >= 0) {
      const pid_t upload_child = sys_fork();
      if (!upload_child) {
        // Upload process.
        IGNORE_RET(sys_close(fds[0]));  // Close read end of pipe.
        // Write status to the pipe.
        ExecUploadProcessOrTerminate(info, temp_file, mime_boundary, fds[1],
                                     &allocator);
      }

      // Helper process.
      if (upload_child > 0) {
        IGNORE_RET(sys_close(fds[1]));  // Close write end of pipe.

        const size_t kCrashIdLength = 16;
        char id_buf[kCrashIdLength + 1];
        size_t bytes_read =
            WaitForCrashReportUploadProcess(fds[0], kCrashIdLength, id_buf);
        HandleCrashReportId(id_buf, bytes_read, kCrashIdLength);

        if (sys_waitpid(upload_child, nullptr, WNOHANG) == 0) {
          // Upload process is still around, kill it.
          sys_kill(upload_child, SIGKILL);
        }
      }
    }

    // Helper process.
    IGNORE_RET(sys_unlink(info.filename));
#if defined(ADDRESS_SANITIZER)
    IGNORE_RET(sys_unlink(info.log_filename));
#endif
    IGNORE_RET(sys_unlink(temp_file));
    sys__exit(0);
  }

  // Main browser process.
  if (child <= 0)
    return;
  (void) HANDLE_EINTR(sys_waitpid(child, nullptr, 0));
}

void InitCrashReporter(const std::string& process_type) {
  // Determine the process type and take appropriate action.
  const base::CommandLine& parsed_command_line =
      *base::CommandLine::ForCurrentProcess();
  if (parsed_command_line.HasSwitch(switches::kDisableBreakpad))
    return;

  bool is_browser_process =
      process_type.empty();

  SetUploadURL(GetCrashReporterClient()->GetUploadUrl());

  if (is_browser_process) {
    bool enable_breakpad = GetCrashReporterClient()->GetCollectStatsConsent() ||
                           GetCrashReporterClient()->IsRunningUnattended();
    enable_breakpad &=
        !parsed_command_line.HasSwitch(switches::kDisableBreakpad);
    if (!enable_breakpad) {
      enable_breakpad = parsed_command_line.HasSwitch(
          switches::kEnableCrashReporterForTesting);
    }
    if (!enable_breakpad) {
      VLOG(1) << "Breakpad disabled";
      return;
    }

    InitCrashKeys();
    EnableCrashDumping(GetCrashReporterClient()->IsRunningUnattended());
  } else if (GetCrashReporterClient()->EnableBreakpadForProcess(process_type)) {
    // We might be chrooted in a zygote or renderer process so we cannot call
    // GetCollectStatsConsent because that needs access the the user's home
    // dir. Instead, we set a command line flag for these processes.
    // Even though plugins are not chrooted, we share the same code path for
    // simplicity.
    if (!parsed_command_line.HasSwitch(switches::kEnableCrashReporter))
      return;

    InitCrashKeys();
    SetChannelFromCommandLine(parsed_command_line);
    SetClientIdFromCommandLine(parsed_command_line);
    EnableNonBrowserCrashDumping();
    VLOG(1) << "Non Browser crash dumping enabled for: " << process_type;
  }

  PostEnableBreakpadInitialization(process_type, parsed_command_line);
}

void SetChannelCrashKey(const std::string& channel) {
  static crash_reporter::CrashKeyString<16> channel_key("channel");
  channel_key.Set(channel);
#if BUILDFLAG(GOOGLE_CHROME_BRANDING)
  if (channel == "extended") {
    // Extended stable reports as stable (empty string) with an extra bool.
    static crash_reporter::CrashKeyString<5> extended_stable_key(
        "extended_stable_channel");
    extended_stable_key.Set("true");
    channel_key.Set("");
  }
#endif
}

bool IsCrashReporterEnabled() {
  return g_is_crash_reporter_enabled;
}

void SetFirstChanceExceptionHandler(bool (*handler)(int, siginfo_t*, void*)) {
  google_breakpad::SetFirstChanceExceptionHandler(handler);
}

}  // namespace breakpad