linux/md2core/minidump-2-core.cc

// Copyright (c) 2009, Google Inc.
// All rights reserved.
//
// 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 Inc. 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.

// Converts a minidump file to a core file which gdb can read.
// Large parts lifted from the userspace core dumper:
//   http://code.google.com/p/google-coredumper/
//
// Usage: minidump-2-core [-v] 1234.dmp > core

#include <elf.h>
#include <errno.h>
#include <link.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/user.h>
#include <unistd.h>

#include <map>
#include <string>
#include <vector>

#include "common/linux/memory_mapped_file.h"
#include "common/scoped_ptr.h"
#include "google_breakpad/common/minidump_format.h"
#include "third_party/lss/linux_syscall_support.h"
#include "tools/linux/md2core/minidump_memory_range.h"

#if __WORDSIZE == 64
  #define ELF_CLASS ELFCLASS64
#else
  #define ELF_CLASS ELFCLASS32
#endif
#define Ehdr   ElfW(Ehdr)
#define Phdr   ElfW(Phdr)
#define Shdr   ElfW(Shdr)
#define Nhdr   ElfW(Nhdr)
#define auxv_t ElfW(auxv_t)


#if defined(__x86_64__)
  #define ELF_ARCH  EM_X86_64
#elif defined(__i386__)
  #define ELF_ARCH  EM_386
#elif defined(__arm__)
  #define ELF_ARCH  EM_ARM
#elif defined(__mips__)
  #define ELF_ARCH  EM_MIPS
#endif

#if defined(__arm__)
// GLibc/ARM and Android/ARM both use 'user_regs' for the structure type
// containing core registers, while they use 'user_regs_struct' on other
// architectures. This file-local typedef simplifies the source code.
typedef user_regs user_regs_struct;
#endif

using google_breakpad::MemoryMappedFile;
using google_breakpad::MinidumpMemoryRange;

static const MDRVA kInvalidMDRVA = static_cast<MDRVA>(-1);
static bool verbose;
static std::string g_custom_so_basedir;

static int usage(const char* argv0) {
  fprintf(stderr, "Usage: %s [-v] <minidump file>\n", argv0);
  return 1;
}

// Write all of the given buffer, handling short writes and EINTR. Return true
// iff successful.
static bool
writea(int fd, const void* idata, size_t length) {
  const uint8_t* data = (const uint8_t*) idata;

  size_t done = 0;
  while (done < length) {
    ssize_t r;
    do {
      r = write(fd, data + done, length - done);
    } while (r == -1 && errno == EINTR);

    if (r < 1)
      return false;
    done += r;
  }

  return true;
}

/* Dynamically determines the byte sex of the system. Returns non-zero
 * for big-endian machines.
 */
static inline int sex() {
  int probe = 1;
  return !*(char *)&probe;
}

typedef struct elf_timeval {    /* Time value with microsecond resolution    */
  long tv_sec;                  /* Seconds                                   */
  long tv_usec;                 /* Microseconds                              */
} elf_timeval;

typedef struct elf_siginfo {    /* Information about signal (unused)         */
  int32_t si_signo;             /* Signal number                             */
  int32_t si_code;              /* Extra code                                */
  int32_t si_errno;             /* Errno                                     */
} elf_siginfo;

typedef struct prstatus {       /* Information about thread; includes CPU reg*/
  elf_siginfo    pr_info;       /* Info associated with signal               */
  uint16_t       pr_cursig;     /* Current signal                            */
  unsigned long  pr_sigpend;    /* Set of pending signals                    */
  unsigned long  pr_sighold;    /* Set of held signals                       */
  pid_t          pr_pid;        /* Process ID                                */
  pid_t          pr_ppid;       /* Parent's process ID                       */
  pid_t          pr_pgrp;       /* Group ID                                  */
  pid_t          pr_sid;        /* Session ID                                */
  elf_timeval    pr_utime;      /* User time                                 */
  elf_timeval    pr_stime;      /* System time                               */
  elf_timeval    pr_cutime;     /* Cumulative user time                      */
  elf_timeval    pr_cstime;     /* Cumulative system time                    */
  user_regs_struct pr_reg;      /* CPU registers                             */
  uint32_t       pr_fpvalid;    /* True if math co-processor being used      */
} prstatus;

typedef struct prpsinfo {       /* Information about process                 */
  unsigned char  pr_state;      /* Numeric process state                     */
  char           pr_sname;      /* Char for pr_state                         */
  unsigned char  pr_zomb;       /* Zombie                                    */
  signed char    pr_nice;       /* Nice val                                  */
  unsigned long  pr_flag;       /* Flags                                     */
#if defined(__x86_64__) || defined(__mips__)
  uint32_t       pr_uid;        /* User ID                                   */
  uint32_t       pr_gid;        /* Group ID                                  */
#else
  uint16_t       pr_uid;        /* User ID                                   */
  uint16_t       pr_gid;        /* Group ID                                  */
#endif
  pid_t          pr_pid;        /* Process ID                                */
  pid_t          pr_ppid;       /* Parent's process ID                       */
  pid_t          pr_pgrp;       /* Group ID                                  */
  pid_t          pr_sid;        /* Session ID                                */
  char           pr_fname[16];  /* Filename of executable                    */
  char           pr_psargs[80]; /* Initial part of arg list                  */
} prpsinfo;

// We parse the minidump file and keep the parsed information in this structure
struct CrashedProcess {
  CrashedProcess()
      : crashing_tid(-1),
        auxv(NULL),
        auxv_length(0) {
    memset(&prps, 0, sizeof(prps));
    prps.pr_sname = 'R';
    memset(&debug, 0, sizeof(debug));
  }

  struct Mapping {
    Mapping()
      : permissions(0xFFFFFFFF),
        start_address(0),
        end_address(0),
        offset(0) {
    }

    uint32_t permissions;
    uint64_t start_address, end_address, offset;
    std::string filename;
    std::string data;
  };
  std::map<uint64_t, Mapping> mappings;

  pid_t crashing_tid;
  int fatal_signal;

  struct Thread {
    pid_t tid;
    user_regs_struct regs;
#if defined(__i386__) || defined(__x86_64__) || defined(__mips__)
    user_fpregs_struct fpregs;
#endif
#if defined(__i386__)
    user_fpxregs_struct fpxregs;
#endif
    uintptr_t stack_addr;
    const uint8_t* stack;
    size_t stack_length;
  };
  std::vector<Thread> threads;

  const uint8_t* auxv;
  size_t auxv_length;

  prpsinfo prps;

  std::map<uintptr_t, std::string> signatures;

  std::string dynamic_data;
  MDRawDebug debug;
  std::vector<MDRawLinkMap> link_map;
};

#if defined(__i386__)
static uint32_t
U32(const uint8_t* data) {
  uint32_t v;
  memcpy(&v, data, sizeof(v));
  return v;
}

static uint16_t
U16(const uint8_t* data) {
  uint16_t v;
  memcpy(&v, data, sizeof(v));
  return v;
}

static void
ParseThreadRegisters(CrashedProcess::Thread* thread,
                     const MinidumpMemoryRange& range) {
  const MDRawContextX86* rawregs = range.GetData<MDRawContextX86>(0);

  thread->regs.ebx = rawregs->ebx;
  thread->regs.ecx = rawregs->ecx;
  thread->regs.edx = rawregs->edx;
  thread->regs.esi = rawregs->esi;
  thread->regs.edi = rawregs->edi;
  thread->regs.ebp = rawregs->ebp;
  thread->regs.eax = rawregs->eax;
  thread->regs.xds = rawregs->ds;
  thread->regs.xes = rawregs->es;
  thread->regs.xfs = rawregs->fs;
  thread->regs.xgs = rawregs->gs;
  thread->regs.orig_eax = rawregs->eax;
  thread->regs.eip = rawregs->eip;
  thread->regs.xcs = rawregs->cs;
  thread->regs.eflags = rawregs->eflags;
  thread->regs.esp = rawregs->esp;
  thread->regs.xss = rawregs->ss;

  thread->fpregs.cwd = rawregs->float_save.control_word;
  thread->fpregs.swd = rawregs->float_save.status_word;
  thread->fpregs.twd = rawregs->float_save.tag_word;
  thread->fpregs.fip = rawregs->float_save.error_offset;
  thread->fpregs.fcs = rawregs->float_save.error_selector;
  thread->fpregs.foo = rawregs->float_save.data_offset;
  thread->fpregs.fos = rawregs->float_save.data_selector;
  memcpy(thread->fpregs.st_space, rawregs->float_save.register_area,
         10 * 8);

  thread->fpxregs.cwd = rawregs->float_save.control_word;
  thread->fpxregs.swd = rawregs->float_save.status_word;
  thread->fpxregs.twd = rawregs->float_save.tag_word;
  thread->fpxregs.fop = U16(rawregs->extended_registers + 6);
  thread->fpxregs.fip = U16(rawregs->extended_registers + 8);
  thread->fpxregs.fcs = U16(rawregs->extended_registers + 12);
  thread->fpxregs.foo = U16(rawregs->extended_registers + 16);
  thread->fpxregs.fos = U16(rawregs->extended_registers + 20);
  thread->fpxregs.mxcsr = U32(rawregs->extended_registers + 24);
  memcpy(thread->fpxregs.st_space, rawregs->extended_registers + 32, 128);
  memcpy(thread->fpxregs.xmm_space, rawregs->extended_registers + 160, 128);
}
#elif defined(__x86_64__)
static void
ParseThreadRegisters(CrashedProcess::Thread* thread,
                     const MinidumpMemoryRange& range) {
  const MDRawContextAMD64* rawregs = range.GetData<MDRawContextAMD64>(0);

  thread->regs.r15 = rawregs->r15;
  thread->regs.r14 = rawregs->r14;
  thread->regs.r13 = rawregs->r13;
  thread->regs.r12 = rawregs->r12;
  thread->regs.rbp = rawregs->rbp;
  thread->regs.rbx = rawregs->rbx;
  thread->regs.r11 = rawregs->r11;
  thread->regs.r10 = rawregs->r10;
  thread->regs.r9 = rawregs->r9;
  thread->regs.r8 = rawregs->r8;
  thread->regs.rax = rawregs->rax;
  thread->regs.rcx = rawregs->rcx;
  thread->regs.rdx = rawregs->rdx;
  thread->regs.rsi = rawregs->rsi;
  thread->regs.rdi = rawregs->rdi;
  thread->regs.orig_rax = rawregs->rax;
  thread->regs.rip = rawregs->rip;
  thread->regs.cs  = rawregs->cs;
  thread->regs.eflags = rawregs->eflags;
  thread->regs.rsp = rawregs->rsp;
  thread->regs.ss = rawregs->ss;
  thread->regs.fs_base = 0;
  thread->regs.gs_base = 0;
  thread->regs.ds = rawregs->ds;
  thread->regs.es = rawregs->es;
  thread->regs.fs = rawregs->fs;
  thread->regs.gs = rawregs->gs;

  thread->fpregs.cwd = rawregs->flt_save.control_word;
  thread->fpregs.swd = rawregs->flt_save.status_word;
  thread->fpregs.ftw = rawregs->flt_save.tag_word;
  thread->fpregs.fop = rawregs->flt_save.error_opcode;
  thread->fpregs.rip = rawregs->flt_save.error_offset;
  thread->fpregs.rdp = rawregs->flt_save.data_offset;
  thread->fpregs.mxcsr = rawregs->flt_save.mx_csr;
  thread->fpregs.mxcr_mask = rawregs->flt_save.mx_csr_mask;
  memcpy(thread->fpregs.st_space, rawregs->flt_save.float_registers, 8 * 16);
  memcpy(thread->fpregs.xmm_space, rawregs->flt_save.xmm_registers, 16 * 16);
}
#elif defined(__arm__)
static void
ParseThreadRegisters(CrashedProcess::Thread* thread,
                     const MinidumpMemoryRange& range) {
  const MDRawContextARM* rawregs = range.GetData<MDRawContextARM>(0);

  thread->regs.uregs[0] = rawregs->iregs[0];
  thread->regs.uregs[1] = rawregs->iregs[1];
  thread->regs.uregs[2] = rawregs->iregs[2];
  thread->regs.uregs[3] = rawregs->iregs[3];
  thread->regs.uregs[4] = rawregs->iregs[4];
  thread->regs.uregs[5] = rawregs->iregs[5];
  thread->regs.uregs[6] = rawregs->iregs[6];
  thread->regs.uregs[7] = rawregs->iregs[7];
  thread->regs.uregs[8] = rawregs->iregs[8];
  thread->regs.uregs[9] = rawregs->iregs[9];
  thread->regs.uregs[10] = rawregs->iregs[10];
  thread->regs.uregs[11] = rawregs->iregs[11];
  thread->regs.uregs[12] = rawregs->iregs[12];
  thread->regs.uregs[13] = rawregs->iregs[13];
  thread->regs.uregs[14] = rawregs->iregs[14];
  thread->regs.uregs[15] = rawregs->iregs[15];

  thread->regs.uregs[16] = rawregs->cpsr;
  thread->regs.uregs[17] = 0;  // what is ORIG_r0 exactly?
}
#elif defined(__mips__)
static void
ParseThreadRegisters(CrashedProcess::Thread* thread,
                     const MinidumpMemoryRange& range) {
  const MDRawContextMIPS* rawregs = range.GetData<MDRawContextMIPS>(0);

  for (int i = 0; i < MD_CONTEXT_MIPS_GPR_COUNT; ++i)
    thread->regs.regs[i] = rawregs->iregs[i];

  thread->regs.lo = rawregs->mdlo;
  thread->regs.hi = rawregs->mdhi;
  thread->regs.epc = rawregs->epc;
  thread->regs.badvaddr = rawregs->badvaddr;
  thread->regs.status = rawregs->status;
  thread->regs.cause = rawregs->cause;

  for (int i = 0; i < MD_FLOATINGSAVEAREA_MIPS_FPR_COUNT; ++i)
    thread->fpregs.regs[i] = rawregs->float_save.regs[i];

  thread->fpregs.fpcsr = rawregs->float_save.fpcsr;
  thread->fpregs.fir = rawregs->float_save.fir;
}
#else
#error "This code has not been ported to your platform yet"
#endif

static void
ParseThreadList(CrashedProcess* crashinfo, const MinidumpMemoryRange& range,
                const MinidumpMemoryRange& full_file) {
  const uint32_t num_threads = *range.GetData<uint32_t>(0);
  if (verbose) {
    fprintf(stderr,
            "MD_THREAD_LIST_STREAM:\n"
            "Found %d threads\n"
            "\n\n",
            num_threads);
  }
  for (unsigned i = 0; i < num_threads; ++i) {
    CrashedProcess::Thread thread;
    memset(&thread, 0, sizeof(thread));
    const MDRawThread* rawthread =
        range.GetArrayElement<MDRawThread>(sizeof(uint32_t), i);
    thread.tid = rawthread->thread_id;
    thread.stack_addr = rawthread->stack.start_of_memory_range;
    MinidumpMemoryRange stack_range =
        full_file.Subrange(rawthread->stack.memory);
    thread.stack = stack_range.data();
    thread.stack_length = rawthread->stack.memory.data_size;

    ParseThreadRegisters(&thread,
                         full_file.Subrange(rawthread->thread_context));

    crashinfo->threads.push_back(thread);
  }
}

static void
ParseSystemInfo(CrashedProcess* crashinfo, const MinidumpMemoryRange& range,
                const MinidumpMemoryRange& full_file) {
  const MDRawSystemInfo* sysinfo = range.GetData<MDRawSystemInfo>(0);
  if (!sysinfo) {
    fprintf(stderr, "Failed to access MD_SYSTEM_INFO_STREAM\n");
    _exit(1);
  }
#if defined(__i386__)
  if (sysinfo->processor_architecture != MD_CPU_ARCHITECTURE_X86) {
    fprintf(stderr,
            "This version of minidump-2-core only supports x86 (32bit)%s.\n",
            sysinfo->processor_architecture == MD_CPU_ARCHITECTURE_AMD64 ?
            ",\nbut the minidump file is from a 64bit machine" : "");
    _exit(1);
  }
#elif defined(__x86_64__)
  if (sysinfo->processor_architecture != MD_CPU_ARCHITECTURE_AMD64) {
    fprintf(stderr,
            "This version of minidump-2-core only supports x86 (64bit)%s.\n",
            sysinfo->processor_architecture == MD_CPU_ARCHITECTURE_X86 ?
            ",\nbut the minidump file is from a 32bit machine" : "");
    _exit(1);
  }
#elif defined(__arm__)
  if (sysinfo->processor_architecture != MD_CPU_ARCHITECTURE_ARM) {
    fprintf(stderr,
            "This version of minidump-2-core only supports ARM (32bit).\n");
    _exit(1);
  }
#elif defined(__mips__)
  if (sysinfo->processor_architecture != MD_CPU_ARCHITECTURE_MIPS) {
    fprintf(stderr,
            "This version of minidump-2-core only supports mips (32bit).\n");
    _exit(1);
  }
#else
#error "This code has not been ported to your platform yet"
#endif
  if (!strstr(full_file.GetAsciiMDString(sysinfo->csd_version_rva).c_str(),
              "Linux") &&
      sysinfo->platform_id != MD_OS_NACL) {
    fprintf(stderr, "This minidump was not generated by Linux or NaCl.\n");
    _exit(1);
  }

  if (verbose) {
    fprintf(stderr,
            "MD_SYSTEM_INFO_STREAM:\n"
            "Architecture: %s\n"
            "Number of processors: %d\n"
            "Processor level: %d\n"
            "Processor model: %d\n"
            "Processor stepping: %d\n",
            sysinfo->processor_architecture == MD_CPU_ARCHITECTURE_X86
            ? "i386"
            : sysinfo->processor_architecture == MD_CPU_ARCHITECTURE_AMD64
            ? "x86-64"
            : sysinfo->processor_architecture == MD_CPU_ARCHITECTURE_ARM
            ? "ARM"
            : sysinfo->processor_architecture == MD_CPU_ARCHITECTURE_MIPS
            ? "MIPS"
            : "???",
            sysinfo->number_of_processors,
            sysinfo->processor_level,
            sysinfo->processor_revision >> 8,
            sysinfo->processor_revision & 0xFF);
    if (sysinfo->processor_architecture == MD_CPU_ARCHITECTURE_X86 ||
        sysinfo->processor_architecture == MD_CPU_ARCHITECTURE_AMD64) {
      fputs("Vendor id: ", stderr);
      const char *nul =
        (const char *)memchr(sysinfo->cpu.x86_cpu_info.vendor_id, 0,
                             sizeof(sysinfo->cpu.x86_cpu_info.vendor_id));
      fwrite(sysinfo->cpu.x86_cpu_info.vendor_id,
             nul ? nul - (const char *)&sysinfo->cpu.x86_cpu_info.vendor_id[0]
             : sizeof(sysinfo->cpu.x86_cpu_info.vendor_id), 1, stderr);
      fputs("\n", stderr);
    }
    fprintf(stderr, "OS: %s\n",
            full_file.GetAsciiMDString(sysinfo->csd_version_rva).c_str());
    fputs("\n\n", stderr);
  }
}

static void
ParseCPUInfo(CrashedProcess* crashinfo, const MinidumpMemoryRange& range) {
  if (verbose) {
    fputs("MD_LINUX_CPU_INFO:\n", stderr);
    fwrite(range.data(), range.length(), 1, stderr);
    fputs("\n\n\n", stderr);
  }
}

static void
ParseProcessStatus(CrashedProcess* crashinfo,
                   const MinidumpMemoryRange& range) {
  if (verbose) {
    fputs("MD_LINUX_PROC_STATUS:\n", stderr);
    fwrite(range.data(), range.length(), 1, stderr);
    fputs("\n\n", stderr);
  }
}

static void
ParseLSBRelease(CrashedProcess* crashinfo, const MinidumpMemoryRange& range) {
  if (verbose) {
    fputs("MD_LINUX_LSB_RELEASE:\n", stderr);
    fwrite(range.data(), range.length(), 1, stderr);
    fputs("\n\n", stderr);
  }
}

static void
ParseMaps(CrashedProcess* crashinfo, const MinidumpMemoryRange& range) {
  if (verbose) {
    fputs("MD_LINUX_MAPS:\n", stderr);
    fwrite(range.data(), range.length(), 1, stderr);
  }
  for (const uint8_t* ptr = range.data();
       ptr < range.data() + range.length();) {
    const uint8_t* eol = (uint8_t*)memchr(ptr, '\n',
                                       range.data() + range.length() - ptr);
    std::string line((const char*)ptr,
                     eol ? eol - ptr : range.data() + range.length() - ptr);
    ptr = eol ? eol + 1 : range.data() + range.length();
    unsigned long long start, stop, offset;
    char* permissions = NULL;
    char* filename = NULL;
    sscanf(line.c_str(), "%llx-%llx %m[-rwxp] %llx %*[:0-9a-f] %*d %ms",
           &start, &stop, &permissions, &offset, &filename);
    if (filename && *filename == '/') {
      CrashedProcess::Mapping mapping;
      mapping.permissions = 0;
      if (strchr(permissions, 'r')) {
        mapping.permissions |= PF_R;
      }
      if (strchr(permissions, 'w')) {
        mapping.permissions |= PF_W;
      }
      if (strchr(permissions, 'x')) {
        mapping.permissions |= PF_X;
      }
      mapping.start_address = start;
      mapping.end_address = stop;
      mapping.offset = offset;
      if (filename) {
        mapping.filename = filename;
      }
      crashinfo->mappings[mapping.start_address] = mapping;
    }
    free(permissions);
    free(filename);
  }
  if (verbose) {
    fputs("\n\n\n", stderr);
  }
}

static void
ParseEnvironment(CrashedProcess* crashinfo, const MinidumpMemoryRange& range) {
  if (verbose) {
    fputs("MD_LINUX_ENVIRON:\n", stderr);
    char* env = new char[range.length()];
    memcpy(env, range.data(), range.length());
    int nul_count = 0;
    for (char *ptr = env;;) {
      ptr = (char *)memchr(ptr, '\000', range.length() - (ptr - env));
      if (!ptr) {
        break;
      }
      if (ptr > env && ptr[-1] == '\n') {
        if (++nul_count > 5) {
          // Some versions of Chrome try to rewrite the process' command line
          // in a way that causes the environment to be corrupted. Afterwards,
          // part of the environment will contain the trailing bit of the
          // command line. The rest of the environment will be filled with
          // NUL bytes.
          // We detect this corruption by counting the number of consecutive
          // NUL bytes. Normally, we would not expect any consecutive NUL
          // bytes. But we are conservative and only suppress printing of
          // the environment if we see at least five consecutive NULs.
          fputs("Environment has been corrupted; no data available", stderr);
          goto env_corrupted;
        }
      } else {
        nul_count = 0;
      }
      *ptr = '\n';
    }
    fwrite(env, range.length(), 1, stderr);
  env_corrupted:
    delete[] env;
    fputs("\n\n\n", stderr);
  }
}

static void
ParseAuxVector(CrashedProcess* crashinfo, const MinidumpMemoryRange& range) {
  // Some versions of Chrome erroneously used the MD_LINUX_AUXV stream value
  // when dumping /proc/$x/maps
  if (range.length() > 17) {
    // The AUXV vector contains binary data, whereas the maps always begin
    // with an 8+ digit hex address followed by a hyphen and another 8+ digit
    // address.
    char addresses[18];
    memcpy(addresses, range.data(), 17);
    addresses[17] = '\000';
    if (strspn(addresses, "0123456789abcdef-") == 17) {
      ParseMaps(crashinfo, range);
      return;
    }
  }

  crashinfo->auxv = range.data();
  crashinfo->auxv_length = range.length();
}

static void
ParseCmdLine(CrashedProcess* crashinfo, const MinidumpMemoryRange& range) {
  // The command line is supposed to use NUL bytes to separate arguments.
  // As Chrome rewrites its own command line and (incorrectly) substitutes
  // spaces, this is often not the case in our minidump files.
  const char* cmdline = (const char*) range.data();
  if (verbose) {
    fputs("MD_LINUX_CMD_LINE:\n", stderr);
    unsigned i = 0;
    for (; i < range.length() && cmdline[i] && cmdline[i] != ' '; ++i) { }
    fputs("argv[0] = \"", stderr);
    fwrite(cmdline, i, 1, stderr);
    fputs("\"\n", stderr);
    for (unsigned j = ++i, argc = 1; j < range.length(); ++j) {
      if (!cmdline[j] || cmdline[j] == ' ') {
        fprintf(stderr, "argv[%d] = \"", argc++);
        fwrite(cmdline + i, j - i, 1, stderr);
        fputs("\"\n", stderr);
        i = j + 1;
      }
    }
    fputs("\n\n", stderr);
  }

  const char *binary_name = cmdline;
  for (size_t i = 0; i < range.length(); ++i) {
    if (cmdline[i] == '/') {
      binary_name = cmdline + i + 1;
    } else if (cmdline[i] == 0 || cmdline[i] == ' ') {
      static const size_t fname_len = sizeof(crashinfo->prps.pr_fname) - 1;
      static const size_t args_len = sizeof(crashinfo->prps.pr_psargs) - 1;
      memset(crashinfo->prps.pr_fname, 0, fname_len + 1);
      memset(crashinfo->prps.pr_psargs, 0, args_len + 1);
      unsigned len = cmdline + i - binary_name;
      memcpy(crashinfo->prps.pr_fname, binary_name,
               len > fname_len ? fname_len : len);

      len = range.length() > args_len ? args_len : range.length();
      memcpy(crashinfo->prps.pr_psargs, cmdline, len);
      for (unsigned j = 0; j < len; ++j) {
        if (crashinfo->prps.pr_psargs[j] == 0)
          crashinfo->prps.pr_psargs[j] = ' ';
      }
      break;
    }
  }
}

static void
ParseDSODebugInfo(CrashedProcess* crashinfo, const MinidumpMemoryRange& range,
                  const MinidumpMemoryRange& full_file) {
  const MDRawDebug* debug = range.GetData<MDRawDebug>(0);
  if (!debug) {
    return;
  }
  if (verbose) {
    fprintf(stderr,
            "MD_LINUX_DSO_DEBUG:\n"
            "Version: %d\n"
            "Number of DSOs: %d\n"
            "Brk handler: %p\n"
            "Dynamic loader at: %p\n"
            "_DYNAMIC: %p\n",
            debug->version,
            debug->dso_count,
            debug->brk,
            debug->ldbase,
            debug->dynamic);
  }
  crashinfo->debug = *debug;
  if (range.length() > sizeof(MDRawDebug)) {
    char* dynamic_data = (char*)range.data() + sizeof(MDRawDebug);
    crashinfo->dynamic_data.assign(dynamic_data,
                                   range.length() - sizeof(MDRawDebug));
  }
  if (debug->map != kInvalidMDRVA) {
    for (unsigned int i = 0; i < debug->dso_count; ++i) {
      const MDRawLinkMap* link_map =
          full_file.GetArrayElement<MDRawLinkMap>(debug->map, i);
      if (link_map) {
        if (verbose) {
          fprintf(stderr,
                  "#%03d: %p, %p, \"%s\"\n",
                  i, link_map->addr, link_map->ld,
                  full_file.GetAsciiMDString(link_map->name).c_str());
        }
        crashinfo->link_map.push_back(*link_map);
      }
    }
  }
  if (verbose) {
    fputs("\n\n", stderr);
  }
}

static void
ParseExceptionStream(CrashedProcess* crashinfo,
                     const MinidumpMemoryRange& range) {
  const MDRawExceptionStream* exp = range.GetData<MDRawExceptionStream>(0);
  crashinfo->crashing_tid = exp->thread_id;
  crashinfo->fatal_signal = (int) exp->exception_record.exception_code;
}

static bool
WriteThread(const CrashedProcess::Thread& thread, int fatal_signal) {
  struct prstatus pr;
  memset(&pr, 0, sizeof(pr));

  pr.pr_info.si_signo = fatal_signal;
  pr.pr_cursig = fatal_signal;
  pr.pr_pid = thread.tid;
  memcpy(&pr.pr_reg, &thread.regs, sizeof(user_regs_struct));

  Nhdr nhdr;
  memset(&nhdr, 0, sizeof(nhdr));
  nhdr.n_namesz = 5;
  nhdr.n_descsz = sizeof(struct prstatus);
  nhdr.n_type = NT_PRSTATUS;
  if (!writea(1, &nhdr, sizeof(nhdr)) ||
      !writea(1, "CORE\0\0\0\0", 8) ||
      !writea(1, &pr, sizeof(struct prstatus))) {
    return false;
  }

#if defined(__i386__) || defined(__x86_64__)
  nhdr.n_descsz = sizeof(user_fpregs_struct);
  nhdr.n_type = NT_FPREGSET;
  if (!writea(1, &nhdr, sizeof(nhdr)) ||
      !writea(1, "CORE\0\0\0\0", 8) ||
      !writea(1, &thread.fpregs, sizeof(user_fpregs_struct))) {
    return false;
  }
#endif

#if defined(__i386__)
  nhdr.n_descsz = sizeof(user_fpxregs_struct);
  nhdr.n_type = NT_PRXFPREG;
  if (!writea(1, &nhdr, sizeof(nhdr)) ||
      !writea(1, "LINUX\0\0\0", 8) ||
      !writea(1, &thread.fpxregs, sizeof(user_fpxregs_struct))) {
    return false;
  }
#endif

  return true;
}

static void
ParseModuleStream(CrashedProcess* crashinfo, const MinidumpMemoryRange& range,
                  const MinidumpMemoryRange& full_file) {
  if (verbose) {
    fputs("MD_MODULE_LIST_STREAM:\n", stderr);
  }
  const uint32_t num_mappings = *range.GetData<uint32_t>(0);
  for (unsigned i = 0; i < num_mappings; ++i) {
    CrashedProcess::Mapping mapping;
    const MDRawModule* rawmodule = reinterpret_cast<const MDRawModule*>(
        range.GetArrayElement(sizeof(uint32_t), MD_MODULE_SIZE, i));
    mapping.start_address = rawmodule->base_of_image;
    mapping.end_address = rawmodule->size_of_image + rawmodule->base_of_image;

    if (crashinfo->mappings.find(mapping.start_address) ==
        crashinfo->mappings.end()) {
      // We prefer data from MD_LINUX_MAPS over MD_MODULE_LIST_STREAM, as
      // the former is a strict superset of the latter.
      crashinfo->mappings[mapping.start_address] = mapping;
    }

    const MDCVInfoPDB70* record = reinterpret_cast<const MDCVInfoPDB70*>(
        full_file.GetData(rawmodule->cv_record.rva, MDCVInfoPDB70_minsize));
    char guid[40];
    sprintf(guid, "%08X-%04X-%04X-%02X%02X-%02X%02X%02X%02X%02X%02X",
            record->signature.data1, record->signature.data2,
            record->signature.data3,
            record->signature.data4[0], record->signature.data4[1],
            record->signature.data4[2], record->signature.data4[3],
            record->signature.data4[4], record->signature.data4[5],
            record->signature.data4[6], record->signature.data4[7]);
    std::string filename =
        full_file.GetAsciiMDString(rawmodule->module_name_rva);
    size_t slash = filename.find_last_of('/');
    std::string basename = slash == std::string::npos ?
      filename : filename.substr(slash + 1);
    if (strcmp(guid, "00000000-0000-0000-0000-000000000000")) {
      std::string prefix;
      if (!g_custom_so_basedir.empty())
        prefix = g_custom_so_basedir;
      else
        prefix = std::string("/var/lib/breakpad/") + guid + "-" + basename;

      crashinfo->signatures[rawmodule->base_of_image] = prefix + basename;
    }

    if (verbose) {
      fprintf(stderr, "0x%08llX-0x%08llX, ChkSum: 0x%08X, GUID: %s, \"%s\"\n",
              (unsigned long long)rawmodule->base_of_image,
              (unsigned long long)rawmodule->base_of_image +
              rawmodule->size_of_image,
              rawmodule->checksum, guid, filename.c_str());
    }
  }
  if (verbose) {
    fputs("\n\n", stderr);
  }
}

static void
AddDataToMapping(CrashedProcess* crashinfo, const std::string& data,
                 uintptr_t addr) {
  for (std::map<uint64_t, CrashedProcess::Mapping>::iterator
         iter = crashinfo->mappings.begin();
       iter != crashinfo->mappings.end();
       ++iter) {
    if (addr >= iter->second.start_address &&
        addr < iter->second.end_address) {
      CrashedProcess::Mapping mapping = iter->second;
      if ((addr & ~4095) != iter->second.start_address) {
        // If there are memory pages in the mapping prior to where the
        // data starts, truncate the existing mapping so that it ends with
        // the page immediately preceding the data region.
        iter->second.end_address = addr & ~4095;
        if (!mapping.filename.empty()) {
          // "mapping" is a copy of "iter->second". We are splitting the
          // existing mapping into two separate ones when we write the data
          // to the core file. The first one does not have any associated
          // data in the core file, the second one is backed by data that is
          // included with the core file.
          // If this mapping wasn't supposed to be anonymous, then we also
          // have to update the file offset upon splitting the mapping.
          mapping.offset += iter->second.end_address -
            iter->second.start_address;
        }
      }
      // Create a new mapping that contains the data contents. We often
      // limit the amount of data that is actually written to the core
      // file. But it is OK if the mapping itself extends past the end of
      // the data.
      mapping.start_address = addr & ~4095;
      mapping.data.assign(addr & 4095, 0).append(data);
      mapping.data.append(-mapping.data.size() & 4095, 0);
      crashinfo->mappings[mapping.start_address] = mapping;
      return;
    }
  }
  // Didn't find a suitable existing mapping for the data. Create a new one.
  CrashedProcess::Mapping mapping;
  mapping.permissions = PF_R | PF_W;
  mapping.start_address = addr & ~4095;
  mapping.end_address =
    (addr + data.size() + 4095) & ~4095;
  mapping.data.assign(addr & 4095, 0).append(data);
  mapping.data.append(-mapping.data.size() & 4095, 0);
  crashinfo->mappings[mapping.start_address] = mapping;
}

static void
AugmentMappings(CrashedProcess* crashinfo,
                const MinidumpMemoryRange& full_file) {
  // For each thread, find the memory mapping that matches the thread's stack.
  // Then adjust the mapping to include the stack dump.
  for (unsigned i = 0; i < crashinfo->threads.size(); ++i) {
    const CrashedProcess::Thread& thread = crashinfo->threads[i];
    AddDataToMapping(crashinfo,
                     std::string((char *)thread.stack, thread.stack_length),
                     thread.stack_addr);
  }

  // Create a new link map with information about DSOs. We move this map to
  // the beginning of the address space, as this area should always be
  // available.
  static const uintptr_t start_addr = 4096;
  std::string data;
  struct r_debug debug = { 0 };
  debug.r_version = crashinfo->debug.version;
  debug.r_brk = (ElfW(Addr))crashinfo->debug.brk;
  debug.r_state = r_debug::RT_CONSISTENT;
  debug.r_ldbase = (ElfW(Addr))crashinfo->debug.ldbase;
  debug.r_map = crashinfo->debug.dso_count > 0 ?
    (struct link_map*)(start_addr + sizeof(debug)) : 0;
  data.append((char*)&debug, sizeof(debug));

  struct link_map* prev = 0;
  for (std::vector<MDRawLinkMap>::iterator iter = crashinfo->link_map.begin();
       iter != crashinfo->link_map.end();
       ++iter) {
    struct link_map link_map = { 0 };
    link_map.l_addr = (ElfW(Addr))iter->addr;
    link_map.l_name = (char*)(start_addr + data.size() + sizeof(link_map));
    link_map.l_ld = (ElfW(Dyn)*)iter->ld;
    link_map.l_prev = prev;
    prev = (struct link_map*)(start_addr + data.size());
    std::string filename = full_file.GetAsciiMDString(iter->name);

    // Look up signature for this filename. If available, change filename
    // to point to GUID, instead.
    std::map<uintptr_t, std::string>::const_iterator guid =
      crashinfo->signatures.find((uintptr_t)iter->addr);
    if (guid != crashinfo->signatures.end()) {
      filename = guid->second;
    }

    if (std::distance(iter, crashinfo->link_map.end()) == 1) {
      link_map.l_next = 0;
    } else {
      link_map.l_next = (struct link_map*)(start_addr + data.size() +
                                           sizeof(link_map) +
                                           ((filename.size() + 8) & ~7));
    }
    data.append((char*)&link_map, sizeof(link_map));
    data.append(filename);
    data.append(8 - (filename.size() & 7), 0);
  }
  AddDataToMapping(crashinfo, data, start_addr);

  // Map the page containing the _DYNAMIC array
  if (!crashinfo->dynamic_data.empty()) {
    // Make _DYNAMIC DT_DEBUG entry point to our link map
    for (int i = 0;; ++i) {
      ElfW(Dyn) dyn;
      if ((i+1)*sizeof(dyn) > crashinfo->dynamic_data.length()) {
      no_dt_debug:
        if (verbose) {
          fprintf(stderr, "No DT_DEBUG entry found\n");
        }
        return;
      }
      memcpy(&dyn, crashinfo->dynamic_data.c_str() + i*sizeof(dyn),
             sizeof(dyn));
      if (dyn.d_tag == DT_DEBUG) {
        crashinfo->dynamic_data.replace(i*sizeof(dyn) +
                                       offsetof(ElfW(Dyn), d_un.d_ptr),
                                       sizeof(start_addr),
                                       (char*)&start_addr, sizeof(start_addr));
        break;
      } else if (dyn.d_tag == DT_NULL) {
        goto no_dt_debug;
      }
    }
    AddDataToMapping(crashinfo, crashinfo->dynamic_data,
                     (uintptr_t)crashinfo->debug.dynamic);
  }
}

int
main(int argc, char** argv) {
  int argi = 1;
  while (argi < argc && argv[argi][0] == '-') {
    if (!strcmp(argv[argi], "-v")) {
      verbose = true;
    } else if (!strcmp(argv[argi], "--sobasedir")) {
      argi++;
      if (argi >= argc) {
        fprintf(stderr, "--sobasedir expects an argument.");
        return usage(argv[0]);
      }

      g_custom_so_basedir = argv[argi];
    } else {
      return usage(argv[0]);
    }
    argi++;
  }

  if (argc != argi + 1)
    return usage(argv[0]);

  MemoryMappedFile mapped_file(argv[argi]);
  if (!mapped_file.data()) {
    fprintf(stderr, "Failed to mmap dump file\n");
    return 1;
  }

  MinidumpMemoryRange dump(mapped_file.data(), mapped_file.size());

  const MDRawHeader* header = dump.GetData<MDRawHeader>(0);

  CrashedProcess crashinfo;

  // Always check the system info first, as that allows us to tell whether
  // this is a minidump file that is compatible with our converter.
  bool ok = false;
  for (unsigned i = 0; i < header->stream_count; ++i) {
    const MDRawDirectory* dirent =
        dump.GetArrayElement<MDRawDirectory>(header->stream_directory_rva, i);
    switch (dirent->stream_type) {
      case MD_SYSTEM_INFO_STREAM:
        ParseSystemInfo(&crashinfo, dump.Subrange(dirent->location), dump);
        ok = true;
        break;
      default:
        break;
    }
  }
  if (!ok) {
    fprintf(stderr, "Cannot determine input file format.\n");
    _exit(1);
  }

  for (unsigned i = 0; i < header->stream_count; ++i) {
    const MDRawDirectory* dirent =
        dump.GetArrayElement<MDRawDirectory>(header->stream_directory_rva, i);
    switch (dirent->stream_type) {
      case MD_THREAD_LIST_STREAM:
        ParseThreadList(&crashinfo, dump.Subrange(dirent->location), dump);
        break;
      case MD_LINUX_CPU_INFO:
        ParseCPUInfo(&crashinfo, dump.Subrange(dirent->location));
        break;
      case MD_LINUX_PROC_STATUS:
        ParseProcessStatus(&crashinfo, dump.Subrange(dirent->location));
        break;
      case MD_LINUX_LSB_RELEASE:
        ParseLSBRelease(&crashinfo, dump.Subrange(dirent->location));
        break;
      case MD_LINUX_ENVIRON:
        ParseEnvironment(&crashinfo, dump.Subrange(dirent->location));
        break;
      case MD_LINUX_MAPS:
        ParseMaps(&crashinfo, dump.Subrange(dirent->location));
        break;
      case MD_LINUX_AUXV:
        ParseAuxVector(&crashinfo, dump.Subrange(dirent->location));
        break;
      case MD_LINUX_CMD_LINE:
        ParseCmdLine(&crashinfo, dump.Subrange(dirent->location));
        break;
      case MD_LINUX_DSO_DEBUG:
        ParseDSODebugInfo(&crashinfo, dump.Subrange(dirent->location), dump);
        break;
      case MD_EXCEPTION_STREAM:
        ParseExceptionStream(&crashinfo, dump.Subrange(dirent->location));
        break;
      case MD_MODULE_LIST_STREAM:
        ParseModuleStream(&crashinfo, dump.Subrange(dirent->location), dump);
        break;
      default:
        if (verbose)
          fprintf(stderr, "Skipping %x\n", dirent->stream_type);
    }
  }

  AugmentMappings(&crashinfo, dump);

  // Write the ELF header. The file will look like:
  //   ELF header
  //   Phdr for the PT_NOTE
  //   Phdr for each of the thread stacks
  //   PT_NOTE
  //   each of the thread stacks
  Ehdr ehdr;
  memset(&ehdr, 0, sizeof(Ehdr));
  ehdr.e_ident[0] = ELFMAG0;
  ehdr.e_ident[1] = ELFMAG1;
  ehdr.e_ident[2] = ELFMAG2;
  ehdr.e_ident[3] = ELFMAG3;
  ehdr.e_ident[4] = ELF_CLASS;
  ehdr.e_ident[5] = sex() ? ELFDATA2MSB : ELFDATA2LSB;
  ehdr.e_ident[6] = EV_CURRENT;
  ehdr.e_type     = ET_CORE;
  ehdr.e_machine  = ELF_ARCH;
  ehdr.e_version  = EV_CURRENT;
  ehdr.e_phoff    = sizeof(Ehdr);
  ehdr.e_ehsize   = sizeof(Ehdr);
  ehdr.e_phentsize= sizeof(Phdr);
  ehdr.e_phnum    = 1 +                         // PT_NOTE
                    crashinfo.mappings.size();  // memory mappings
  ehdr.e_shentsize= sizeof(Shdr);
  if (!writea(1, &ehdr, sizeof(Ehdr)))
    return 1;

  size_t offset = sizeof(Ehdr) + ehdr.e_phnum * sizeof(Phdr);
  size_t filesz = sizeof(Nhdr) + 8 + sizeof(prpsinfo) +
                  // sizeof(Nhdr) + 8 + sizeof(user) +
                  sizeof(Nhdr) + 8 + crashinfo.auxv_length +
                  crashinfo.threads.size() * (
                    (sizeof(Nhdr) + 8 + sizeof(prstatus))
#if defined(__i386__) || defined(__x86_64__)
                   + sizeof(Nhdr) + 8 + sizeof(user_fpregs_struct)
#endif
#if defined(__i386__)
                   + sizeof(Nhdr) + 8 + sizeof(user_fpxregs_struct)
#endif
                    );

  Phdr phdr;
  memset(&phdr, 0, sizeof(Phdr));
  phdr.p_type = PT_NOTE;
  phdr.p_offset = offset;
  phdr.p_filesz = filesz;
  if (!writea(1, &phdr, sizeof(phdr)))
    return 1;

  phdr.p_type = PT_LOAD;
  phdr.p_align = 4096;
  size_t note_align = phdr.p_align - ((offset+filesz) % phdr.p_align);
  if (note_align == phdr.p_align)
    note_align = 0;
  offset += note_align;

  for (std::map<uint64_t, CrashedProcess::Mapping>::const_iterator iter =
         crashinfo.mappings.begin();
       iter != crashinfo.mappings.end(); ++iter) {
    const CrashedProcess::Mapping& mapping = iter->second;
    if (mapping.permissions == 0xFFFFFFFF) {
      // This is a map that we found in MD_MODULE_LIST_STREAM (as opposed to
      // MD_LINUX_MAPS). It lacks some of the information that we would like
      // to include.
      phdr.p_flags = PF_R;
    } else {
      phdr.p_flags = mapping.permissions;
    }
    phdr.p_vaddr = mapping.start_address;
    phdr.p_memsz = mapping.end_address - mapping.start_address;
    if (mapping.data.size()) {
      offset += filesz;
      filesz = mapping.data.size();
      phdr.p_filesz = mapping.data.size();
      phdr.p_offset = offset;
    } else {
      phdr.p_filesz = 0;
      phdr.p_offset = 0;
    }
    if (!writea(1, &phdr, sizeof(phdr)))
      return 1;
  }

  Nhdr nhdr;
  memset(&nhdr, 0, sizeof(nhdr));
  nhdr.n_namesz = 5;
  nhdr.n_descsz = sizeof(prpsinfo);
  nhdr.n_type = NT_PRPSINFO;
  if (!writea(1, &nhdr, sizeof(nhdr)) ||
      !writea(1, "CORE\0\0\0\0", 8) ||
      !writea(1, &crashinfo.prps, sizeof(prpsinfo))) {
    return 1;
  }

  nhdr.n_descsz = crashinfo.auxv_length;
  nhdr.n_type = NT_AUXV;
  if (!writea(1, &nhdr, sizeof(nhdr)) ||
      !writea(1, "CORE\0\0\0\0", 8) ||
      !writea(1, crashinfo.auxv, crashinfo.auxv_length)) {
    return 1;
  }

  for (unsigned i = 0; i < crashinfo.threads.size(); ++i) {
    if (crashinfo.threads[i].tid == crashinfo.crashing_tid) {
      WriteThread(crashinfo.threads[i], crashinfo.fatal_signal);
      break;
    }
  }

  for (unsigned i = 0; i < crashinfo.threads.size(); ++i) {
    if (crashinfo.threads[i].tid != crashinfo.crashing_tid)
      WriteThread(crashinfo.threads[i], 0);
  }

  if (note_align) {
    google_breakpad::scoped_array<char> scratch(new char[note_align]);
    memset(scratch.get(), 0, note_align);
    if (!writea(1, scratch.get(), note_align))
      return 1;
  }

  for (std::map<uint64_t, CrashedProcess::Mapping>::const_iterator iter =
         crashinfo.mappings.begin();
       iter != crashinfo.mappings.end(); ++iter) {
    const CrashedProcess::Mapping& mapping = iter->second;
    if (mapping.data.size()) {
      if (!writea(1, mapping.data.c_str(), mapping.data.size()))
        return 1;
    }
  }

  return 0;
}