root/third_party/tcmalloc/vendor/src/base/sysinfo.cc

DEFINITIONS

1. GetenvBeforeMain
2. GetUniquePathFromEnv
3. SleepForMilliseconds
4. EstimateCyclesPerSecond
5. ReadIntFromFile
6. InitializeSystemInfo
7. CyclesPerSecond
8. NumCPUs
9. HasPosixThreads
10. ConstructFilename
11. NextExtMachHelper
12. Init
13. Valid
14. Next
15. NextExt
16. FormatLine
17. FillProcSelfMaps
18. DumpProcSelfMaps

// Copyright (c) 2006, 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.

#include <config.h>
#if (defined(_WIN32) || defined(__MINGW32__)) && !defined(__CYGWIN__) && !defined(__CYGWIN32)
# define PLATFORM_WINDOWS 1
#endif

#include <stdlib.h>   // for getenv()
#include <stdio.h>    // for snprintf(), sscanf()
#include <string.h>   // for memmove(), memchr(), etc.
#include <fcntl.h>    // for open()
#include <errno.h>    // for errno
#ifdef HAVE_UNISTD_H
#include <unistd.h>   // for read()
#endif
#if defined __MACH__          // Mac OS X, almost certainly
#include <mach-o/dyld.h>      // for iterating over dll's in ProcMapsIter
#include <mach-o/loader.h>    // for iterating over dll's in ProcMapsIter
#include <sys/types.h>
#include <sys/sysctl.h>       // how we figure out numcpu's on OS X
#elif defined __FreeBSD__
#include <sys/sysctl.h>
#elif defined __sun__         // Solaris
#include <procfs.h>           // for, e.g., prmap_t
#elif defined(PLATFORM_WINDOWS)
#include <process.h>          // for getpid() (actually, _getpid())
#include <shlwapi.h>          // for SHGetValueA()
#include <tlhelp32.h>         // for Module32First()
#endif
#include "base/sysinfo.h"
#include "base/commandlineflags.h"
#include "base/dynamic_annotations.h"   // for RunningOnValgrind
#include "base/logging.h"
#include "base/cycleclock.h"

#ifdef PLATFORM_WINDOWS
#ifdef MODULEENTRY32
// In a change from the usual W-A pattern, there is no A variant of
// MODULEENTRY32.  Tlhelp32.h #defines the W variant, but not the A.
// In unicode mode, tlhelp32.h #defines MODULEENTRY32 to be
// MODULEENTRY32W.  These #undefs are the only way I see to get back
// access to the original, ascii struct (and related functions).
#undef MODULEENTRY32
#undef Module32First
#undef Module32Next
#undef PMODULEENTRY32
#undef LPMODULEENTRY32
#endif  /* MODULEENTRY32 */
// MinGW doesn't seem to define this, perhaps some windowsen don't either.
#ifndef TH32CS_SNAPMODULE32
#define TH32CS_SNAPMODULE32  0
#endif  /* TH32CS_SNAPMODULE32 */
#endif  /* PLATFORM_WINDOWS */

// Re-run fn until it doesn't cause EINTR.
#define NO_INTR(fn)  do {} while ((fn) < 0 && errno == EINTR)

// open/read/close can set errno, which may be illegal at this
// time, so prefer making the syscalls directly if we can.
#ifdef HAVE_SYS_SYSCALL_H
# include <sys/syscall.h>
#endif
#ifdef SYS_open   // solaris 11, at least sometimes, only defines SYS_openat
# define safeopen(filename, mode)  syscall(SYS_open, filename, mode)
#else
# define safeopen(filename, mode)  open(filename, mode)
#endif
#ifdef SYS_read
# define saferead(fd, buffer, size)  syscall(SYS_read, fd, buffer, size)
#else
# define saferead(fd, buffer, size)  read(fd, buffer, size)
#endif
#ifdef SYS_close
# define safeclose(fd)  syscall(SYS_close, fd)
#else
# define safeclose(fd)  close(fd)
#endif

// ----------------------------------------------------------------------
// GetenvBeforeMain()
// GetUniquePathFromEnv()
//    Some non-trivial getenv-related functions.
// ----------------------------------------------------------------------

// It's not safe to call getenv() in the malloc hooks, because they
// might be called extremely early, before libc is done setting up
// correctly.  In particular, the thread library may not be done
// setting up errno.  So instead, we use the built-in __environ array
// if it exists, and otherwise read /proc/self/environ directly, using
// system calls to read the file, and thus avoid setting errno.
// /proc/self/environ has a limit of how much data it exports (around
// 8K), so it's not an ideal solution.
const char* GetenvBeforeMain(const char* name) {
#if defined(HAVE___ENVIRON)   // if we have it, it's declared in unistd.h
  if (__environ) {            // can exist but be NULL, if statically linked
    const int namelen = strlen(name);
    for (char** p = __environ; *p; p++) {
      if (!memcmp(*p, name, namelen) && (*p)[namelen] == '=')  // it's a match
        return *p + namelen+1;                                 // point after =
    }
    return NULL;
  }
#endif
#if defined(PLATFORM_WINDOWS)
  // TODO(mbelshe) - repeated calls to this function will overwrite the
  // contents of the static buffer.
  static char envvar_buf[1024];  // enough to hold any envvar we care about
  if (!GetEnvironmentVariableA(name, envvar_buf, sizeof(envvar_buf)-1))
    return NULL;
  return envvar_buf;
#endif
  // static is ok because this function should only be called before
  // main(), when we're single-threaded.
  static char envbuf[16<<10];
  if (*envbuf == '\0') {    // haven't read the environ yet
    int fd = safeopen("/proc/self/environ", O_RDONLY);
    // The -2 below guarantees the last two bytes of the buffer will be \0\0
    if (fd == -1 ||           // unable to open the file, fall back onto libc
        saferead(fd, envbuf, sizeof(envbuf) - 2) < 0) { // error reading file
      RAW_VLOG(1, "Unable to open /proc/self/environ, falling back "
               "on getenv(\"%s\"), which may not work", name);
      if (fd != -1) safeclose(fd);
      return getenv(name);
    }
    safeclose(fd);
  }
  const int namelen = strlen(name);
  const char* p = envbuf;
  while (*p != '\0') {    // will happen at the \0\0 that terminates the buffer
    // proc file has the format NAME=value\0NAME=value\0NAME=value\0...
    const char* endp = (char*)memchr(p, '\0', sizeof(envbuf) - (p - envbuf));
    if (endp == NULL)            // this entry isn't NUL terminated
      return NULL;
    else if (!memcmp(p, name, namelen) && p[namelen] == '=')    // it's a match
      return p + namelen+1;      // point after =
    p = endp + 1;
  }
  return NULL;                   // env var never found
}

// This takes as an argument an environment-variable name (like
// CPUPROFILE) whose value is supposed to be a file-path, and sets
// path to that path, and returns true.  If the env var doesn't exist,
// or is the empty string, leave path unchanged and returns false.
// The reason this is non-trivial is that this function handles munged
// pathnames.  Here's why:
//
// If we're a child process of the 'main' process, we can't just use
// getenv("CPUPROFILE") -- the parent process will be using that path.
// Instead we append our pid to the pathname.  How do we tell if we're a
// child process?  Ideally we'd set an environment variable that all
// our children would inherit.  But -- and this is seemingly a bug in
// gcc -- if you do a setenv() in a shared libarary in a global
// constructor, the environment setting is lost by the time main() is
// called.  The only safe thing we can do in such a situation is to
// modify the existing envvar.  So we do a hack: in the parent, we set
// the high bit of the 1st char of CPUPROFILE.  In the child, we
// notice the high bit is set and append the pid().  This works
// assuming cpuprofile filenames don't normally have the high bit set
// in their first character!  If that assumption is violated, we'll
// still get a profile, but one with an unexpected name.
// TODO(csilvers): set an envvar instead when we can do it reliably.
bool GetUniquePathFromEnv(const char* env_name, char* path) {
  char* envval = getenv(env_name);
  if (envval == NULL || *envval == '\0')
    return false;
  if (envval[0] & 128) {                  // high bit is set
    snprintf(path, PATH_MAX, "%c%s_%u",   // add pid and clear high bit
             envval[0] & 127, envval+1, (unsigned int)(getpid()));
  } else {
    snprintf(path, PATH_MAX, "%s", envval);
    envval[0] |= 128;                     // set high bit for kids to see
  }
  return true;
}

// ----------------------------------------------------------------------
// CyclesPerSecond()
// NumCPUs()
//    It's important this not call malloc! -- they may be called at
//    global-construct time, before we've set up all our proper malloc
//    hooks and such.
// ----------------------------------------------------------------------

static double cpuinfo_cycles_per_second = 1.0;  // 0.0 might be dangerous
static int cpuinfo_num_cpus = 1;  // Conservative guess

void SleepForMilliseconds(int milliseconds) {
#ifdef PLATFORM_WINDOWS
  _sleep(milliseconds);   // Windows's _sleep takes milliseconds argument
#else
  // Sleep for a few milliseconds
  struct timespec sleep_time;
  sleep_time.tv_sec = milliseconds / 1000;
  sleep_time.tv_nsec = (milliseconds % 1000) * 1000000;
  while (nanosleep(&sleep_time, &sleep_time) != 0 && errno == EINTR)
    ;  // Ignore signals and wait for the full interval to elapse.
#endif
}

// Helper function estimates cycles/sec by observing cycles elapsed during
// sleep(). Using small sleep time decreases accuracy significantly.
static int64 EstimateCyclesPerSecond(const int estimate_time_ms) {
  assert(estimate_time_ms > 0);
  if (estimate_time_ms <= 0)
    return 1;
  double multiplier = 1000.0 / (double)estimate_time_ms;  // scale by this much

  const int64 start_ticks = CycleClock::Now();
  SleepForMilliseconds(estimate_time_ms);
  const int64 guess = int64(multiplier * (CycleClock::Now() - start_ticks));
  return guess;
}

// ReadIntFromFile is only called on linux and cygwin platforms.
#if defined(__linux__) || defined(__CYGWIN__) || defined(__CYGWIN32__)
// Helper function for reading an int from a file. Returns true if successful
// and the memory location pointed to by value is set to the value read.
static bool ReadIntFromFile(const char *file, int *value) {
  bool ret = false;
  int fd = open(file, O_RDONLY);
  if (fd != -1) {
    char line[1024];
    char* err;
    memset(line, '\0', sizeof(line));
    read(fd, line, sizeof(line) - 1);
    const int temp_value = strtol(line, &err, 10);
    if (line[0] != '\0' && (*err == '\n' || *err == '\0')) {
      *value = temp_value;
      ret = true;
    }
    close(fd);
  }
  return ret;
}
#endif

// WARNING: logging calls back to InitializeSystemInfo() so it must
// not invoke any logging code.  Also, InitializeSystemInfo() can be
// called before main() -- in fact it *must* be since already_called
// isn't protected -- before malloc hooks are properly set up, so
// we make an effort not to call any routines which might allocate
// memory.

static void InitializeSystemInfo() {
  static bool already_called = false;   // safe if we run before threads
  if (already_called)  return;
  already_called = true;

  bool saw_mhz = false;

  if (RunningOnValgrind()) {
    // Valgrind may slow the progress of time artificially (--scale-time=N
    // option). We thus can't rely on CPU Mhz info stored in /sys or /proc
    // files. Thus, actually measure the cps.
    cpuinfo_cycles_per_second = EstimateCyclesPerSecond(100);
    saw_mhz = true;
  }

#if defined(__linux__) || defined(__CYGWIN__) || defined(__CYGWIN32__)
  char line[1024];
  char* err;
  int freq;

  // If the kernel is exporting the tsc frequency use that. There are issues
  // where cpuinfo_max_freq cannot be relied on because the BIOS may be
  // exporintg an invalid p-state (on x86) or p-states may be used to put the
  // processor in a new mode (turbo mode). Essentially, those frequencies
  // cannot always be relied upon. The same reasons apply to /proc/cpuinfo as
  // well.
  if (!saw_mhz &&
      ReadIntFromFile("/sys/devices/system/cpu/cpu0/tsc_freq_khz", &freq)) {
      // The value is in kHz (as the file name suggests).  For example, on a
      // 2GHz warpstation, the file contains the value "2000000".
      cpuinfo_cycles_per_second = freq * 1000.0;
      saw_mhz = true;
  }

  // If CPU scaling is in effect, we want to use the *maximum* frequency,
  // not whatever CPU speed some random processor happens to be using now.
  if (!saw_mhz &&
      ReadIntFromFile("/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq",
                      &freq)) {
    // The value is in kHz.  For example, on a 2GHz machine, the file
    // contains the value "2000000".
    cpuinfo_cycles_per_second = freq * 1000.0;
    saw_mhz = true;
  }

  // Read /proc/cpuinfo for other values, and if there is no cpuinfo_max_freq.
  const char* pname = "/proc/cpuinfo";
  int fd = open(pname, O_RDONLY);
  if (fd == -1) {
    perror(pname);
    if (!saw_mhz) {
      cpuinfo_cycles_per_second = EstimateCyclesPerSecond(1000);
    }
    return;          // TODO: use generic tester instead?
  }

  double bogo_clock = 1.0;
  bool saw_bogo = false;
  int num_cpus = 0;
  line[0] = line[1] = '\0';
  int chars_read = 0;
  do {   // we'll exit when the last read didn't read anything
    // Move the next line to the beginning of the buffer
    const int oldlinelen = strlen(line);
    if (sizeof(line) == oldlinelen + 1)    // oldlinelen took up entire line
      line[0] = '\0';
    else                                   // still other lines left to save
      memmove(line, line + oldlinelen+1, sizeof(line) - (oldlinelen+1));
    // Terminate the new line, reading more if we can't find the newline
    char* newline = strchr(line, '\n');
    if (newline == NULL) {
      const int linelen = strlen(line);
      const int bytes_to_read = sizeof(line)-1 - linelen;
      assert(bytes_to_read > 0);  // because the memmove recovered >=1 bytes
      chars_read = read(fd, line + linelen, bytes_to_read);
      line[linelen + chars_read] = '\0';
      newline = strchr(line, '\n');
    }
    if (newline != NULL)
      *newline = '\0';

    // When parsing the "cpu MHz" and "bogomips" (fallback) entries, we only
    // accept postive values. Some environments (virtual machines) report zero,
    // which would cause infinite looping in WallTime_Init.
    if (!saw_mhz && strncasecmp(line, "cpu MHz", sizeof("cpu MHz")-1) == 0) {
      const char* freqstr = strchr(line, ':');
      if (freqstr) {
        cpuinfo_cycles_per_second = strtod(freqstr+1, &err) * 1000000.0;
        if (freqstr[1] != '\0' && *err == '\0' && cpuinfo_cycles_per_second > 0)
          saw_mhz = true;
      }
    } else if (strncasecmp(line, "bogomips", sizeof("bogomips")-1) == 0) {
      const char* freqstr = strchr(line, ':');
      if (freqstr) {
        bogo_clock = strtod(freqstr+1, &err) * 1000000.0;
        if (freqstr[1] != '\0' && *err == '\0' && bogo_clock > 0)
          saw_bogo = true;
      }
    } else if (strncasecmp(line, "processor", sizeof("processor")-1) == 0) {
      num_cpus++;  // count up every time we see an "processor :" entry
    }
  } while (chars_read > 0);
  close(fd);

  if (!saw_mhz) {
    if (saw_bogo) {
      // If we didn't find anything better, we'll use bogomips, but
      // we're not happy about it.
      cpuinfo_cycles_per_second = bogo_clock;
    } else {
      // If we don't even have bogomips, we'll use the slow estimation.
      cpuinfo_cycles_per_second = EstimateCyclesPerSecond(1000);
    }
  }
  if (cpuinfo_cycles_per_second == 0.0) {
    cpuinfo_cycles_per_second = 1.0;   // maybe unnecessary, but safe
  }
  if (num_cpus > 0) {
    cpuinfo_num_cpus = num_cpus;
  }

#elif defined __FreeBSD__
  // For this sysctl to work, the machine must be configured without
  // SMP, APIC, or APM support.  hz should be 64-bit in freebsd 7.0
  // and later.  Before that, it's a 32-bit quantity (and gives the
  // wrong answer on machines faster than 2^32 Hz).  See
  //  http://lists.freebsd.org/pipermail/freebsd-i386/2004-November/001846.html
  // But also compare FreeBSD 7.0:
  //  http://fxr.watson.org/fxr/source/i386/i386/tsc.c?v=RELENG70#L223
  //  231         error = sysctl_handle_quad(oidp, &freq, 0, req);
  // To FreeBSD 6.3 (it's the same in 6-STABLE):
  //  http://fxr.watson.org/fxr/source/i386/i386/tsc.c?v=RELENG6#L131
  //  139         error = sysctl_handle_int(oidp, &freq, sizeof(freq), req);
#if __FreeBSD__ >= 7
  uint64_t hz = 0;
#else
  unsigned int hz = 0;
#endif
  size_t sz = sizeof(hz);
  const char *sysctl_path = "machdep.tsc_freq";
  if ( sysctlbyname(sysctl_path, &hz, &sz, NULL, 0) != 0 ) {
    fprintf(stderr, "Unable to determine clock rate from sysctl: %s: %s\n",
            sysctl_path, strerror(errno));
    cpuinfo_cycles_per_second = EstimateCyclesPerSecond(1000);
  } else {
    cpuinfo_cycles_per_second = hz;
  }
  // TODO(csilvers): also figure out cpuinfo_num_cpus

#elif defined(PLATFORM_WINDOWS)
# pragma comment(lib, "shlwapi.lib")  // for SHGetValue()
  // In NT, read MHz from the registry. If we fail to do so or we're in win9x
  // then make a crude estimate.
  OSVERSIONINFO os;
  os.dwOSVersionInfoSize = sizeof(os);
  DWORD data, data_size = sizeof(data);
  if (GetVersionEx(&os) &&
      os.dwPlatformId == VER_PLATFORM_WIN32_NT &&
      SUCCEEDED(SHGetValueA(HKEY_LOCAL_MACHINE,
                         "HARDWARE\\DESCRIPTION\\System\\CentralProcessor\\0",
                           "~MHz", NULL, &data, &data_size)))
    cpuinfo_cycles_per_second = (int64)data * (int64)(1000 * 1000); // was mhz
  else
    cpuinfo_cycles_per_second = EstimateCyclesPerSecond(500); // TODO <500?

  // Get the number of processors.
  SYSTEM_INFO info;
  GetSystemInfo(&info);
  cpuinfo_num_cpus = info.dwNumberOfProcessors;

#elif defined(__MACH__) && defined(__APPLE__)
  // returning "mach time units" per second. the current number of elapsed
  // mach time units can be found by calling uint64 mach_absolute_time();
  // while not as precise as actual CPU cycles, it is accurate in the face
  // of CPU frequency scaling and multi-cpu/core machines.
  // Our mac users have these types of machines, and accuracy
  // (i.e. correctness) trumps precision.
  // See cycleclock.h: CycleClock::Now(), which returns number of mach time
  // units on Mac OS X.
  mach_timebase_info_data_t timebase_info;
  mach_timebase_info(&timebase_info);
  double mach_time_units_per_nanosecond =
      static_cast<double>(timebase_info.denom) /
      static_cast<double>(timebase_info.numer);
  cpuinfo_cycles_per_second = mach_time_units_per_nanosecond * 1e9;

  int num_cpus = 0;
  size_t size = sizeof(num_cpus);
  int numcpus_name[] = { CTL_HW, HW_NCPU };
  if (::sysctl(numcpus_name, arraysize(numcpus_name), &num_cpus, &size, 0, 0)
      == 0
      && (size == sizeof(num_cpus)))
    cpuinfo_num_cpus = num_cpus;

#else
  // Generic cycles per second counter
  cpuinfo_cycles_per_second = EstimateCyclesPerSecond(1000);
#endif
}

double CyclesPerSecond(void) {
  InitializeSystemInfo();
  return cpuinfo_cycles_per_second;
}

int NumCPUs(void) {
  InitializeSystemInfo();
  return cpuinfo_num_cpus;
}

// ----------------------------------------------------------------------
// HasPosixThreads()
//      Return true if we're running POSIX (e.g., NPTL on Linux)
//      threads, as opposed to a non-POSIX thread libary.  The thing
//      that we care about is whether a thread's pid is the same as
//      the thread that spawned it.  If so, this function returns
//      true.
// ----------------------------------------------------------------------
bool HasPosixThreads() {
#if defined(__linux__)
#ifndef _CS_GNU_LIBPTHREAD_VERSION
#define _CS_GNU_LIBPTHREAD_VERSION 3
#endif
  char buf[32];
  //  We assume that, if confstr() doesn't know about this name, then
  //  the same glibc is providing LinuxThreads.
  if (confstr(_CS_GNU_LIBPTHREAD_VERSION, buf, sizeof(buf)) == 0)
    return false;
  return strncmp(buf, "NPTL", 4) == 0;
#elif defined(PLATFORM_WINDOWS) || defined(__CYGWIN__) || defined(__CYGWIN32__)
  return false;
#else  // other OS
  return true;      //  Assume that everything else has Posix
#endif  // else OS_LINUX
}

// ----------------------------------------------------------------------

#if defined __linux__ || defined __FreeBSD__ || defined __sun__ || defined __CYGWIN__ || defined __CYGWIN32__
static void ConstructFilename(const char* spec, pid_t pid,
                              char* buf, int buf_size) {
  CHECK_LT(snprintf(buf, buf_size,
                    spec,
                    static_cast<int>(pid ? pid : getpid())), buf_size);
}
#endif

// A templatized helper function instantiated for Mach (OS X) only.
// It can handle finding info for both 32 bits and 64 bits.
// Returns true if it successfully handled the hdr, false else.
#ifdef __MACH__          // Mac OS X, almost certainly
template<uint32_t kMagic, uint32_t kLCSegment,
         typename MachHeader, typename SegmentCommand>
static bool NextExtMachHelper(const mach_header* hdr,
                              int current_image, int current_load_cmd,
                              uint64 *start, uint64 *end, char **flags,
                              uint64 *offset, int64 *inode, char **filename,
                              uint64 *file_mapping, uint64 *file_pages,
                              uint64 *anon_mapping, uint64 *anon_pages,
                              dev_t *dev) {
  static char kDefaultPerms[5] = "r-xp";
  if (hdr->magic != kMagic)
    return false;
  const char* lc = (const char *)hdr + sizeof(MachHeader);
  // TODO(csilvers): make this not-quadradic (increment and hold state)
  for (int j = 0; j < current_load_cmd; j++)  // advance to *our* load_cmd
    lc += ((const load_command *)lc)->cmdsize;
  if (((const load_command *)lc)->cmd == kLCSegment) {
    const intptr_t dlloff = _dyld_get_image_vmaddr_slide(current_image);
    const SegmentCommand* sc = (const SegmentCommand *)lc;
    if (start) *start = sc->vmaddr + dlloff;
    if (end) *end = sc->vmaddr + sc->vmsize + dlloff;
    if (flags) *flags = kDefaultPerms;  // can we do better?
    if (offset) *offset = sc->fileoff;
    if (inode) *inode = 0;
    if (filename)
      *filename = const_cast<char*>(_dyld_get_image_name(current_image));
    if (file_mapping) *file_mapping = 0;
    if (file_pages) *file_pages = 0;   // could we use sc->filesize?
    if (anon_mapping) *anon_mapping = 0;
    if (anon_pages) *anon_pages = 0;
    if (dev) *dev = 0;
    return true;
  }

  return false;
}
#endif

ProcMapsIterator::ProcMapsIterator(pid_t pid) {
  Init(pid, NULL, false);
}

ProcMapsIterator::ProcMapsIterator(pid_t pid, Buffer *buffer) {
  Init(pid, buffer, false);
}

ProcMapsIterator::ProcMapsIterator(pid_t pid, Buffer *buffer,
                                   bool use_maps_backing) {
  Init(pid, buffer, use_maps_backing);
}

void ProcMapsIterator::Init(pid_t pid, Buffer *buffer,
                            bool use_maps_backing) {
  pid_ = pid;
  using_maps_backing_ = use_maps_backing;
  dynamic_buffer_ = NULL;
  if (!buffer) {
    // If the user didn't pass in any buffer storage, allocate it
    // now. This is the normal case; the signal handler passes in a
    // static buffer.
    buffer = dynamic_buffer_ = new Buffer;
  } else {
    dynamic_buffer_ = NULL;
  }

  ibuf_ = buffer->buf_;

  stext_ = etext_ = nextline_ = ibuf_;
  ebuf_ = ibuf_ + Buffer::kBufSize - 1;
  nextline_ = ibuf_;

#if defined(__linux__) || defined(__CYGWIN__) || defined(__CYGWIN32__)
  if (use_maps_backing) {  // don't bother with clever "self" stuff in this case
    ConstructFilename("/proc/%d/maps_backing", pid, ibuf_, Buffer::kBufSize);
  } else if (pid == 0) {
    // We have to kludge a bit to deal with the args ConstructFilename
    // expects.  The 1 is never used -- it's only impt. that it's not 0.
    ConstructFilename("/proc/self/maps", 1, ibuf_, Buffer::kBufSize);
  } else {
    ConstructFilename("/proc/%d/maps", pid, ibuf_, Buffer::kBufSize);
  }
  // No error logging since this can be called from the crash dump
  // handler at awkward moments. Users should call Valid() before
  // using.
  NO_INTR(fd_ = open(ibuf_, O_RDONLY));
#elif defined(__FreeBSD__)
  // We don't support maps_backing on freebsd
  if (pid == 0) {
    ConstructFilename("/proc/curproc/map", 1, ibuf_, Buffer::kBufSize);
  } else {
    ConstructFilename("/proc/%d/map", pid, ibuf_, Buffer::kBufSize);
  }
  NO_INTR(fd_ = open(ibuf_, O_RDONLY));
#elif defined(__sun__)
  if (pid == 0) {
    ConstructFilename("/proc/self/map", 1, ibuf_, Buffer::kBufSize);
  } else {
    ConstructFilename("/proc/%d/map", pid, ibuf_, Buffer::kBufSize);
  }
  NO_INTR(fd_ = open(ibuf_, O_RDONLY));
#elif defined(__MACH__)
  current_image_ = _dyld_image_count();   // count down from the top
  current_load_cmd_ = -1;
#elif defined(PLATFORM_WINDOWS)
  snapshot_ = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE |
                                       TH32CS_SNAPMODULE32,
                                       GetCurrentProcessId());
  memset(&module_, 0, sizeof(module_));
#else
  fd_ = -1;   // so Valid() is always false
#endif

}

ProcMapsIterator::~ProcMapsIterator() {
#if defined(PLATFORM_WINDOWS)
  if (snapshot_ != INVALID_HANDLE_VALUE) CloseHandle(snapshot_);
#elif defined(__MACH__)
  // no cleanup necessary!
#else
  if (fd_ >= 0) NO_INTR(close(fd_));
#endif
  delete dynamic_buffer_;
}

bool ProcMapsIterator::Valid() const {
#if defined(PLATFORM_WINDOWS)
  return snapshot_ != INVALID_HANDLE_VALUE;
#elif defined(__MACH__)
  return 1;
#else
  return fd_ != -1;
#endif
}

bool ProcMapsIterator::Next(uint64 *start, uint64 *end, char **flags,
                            uint64 *offset, int64 *inode, char **filename) {
  return NextExt(start, end, flags, offset, inode, filename, NULL, NULL,
                 NULL, NULL, NULL);
}

// This has too many arguments.  It should really be building
// a map object and returning it.  The problem is that this is called
// when the memory allocator state is undefined, hence the arguments.
bool ProcMapsIterator::NextExt(uint64 *start, uint64 *end, char **flags,
                               uint64 *offset, int64 *inode, char **filename,
                               uint64 *file_mapping, uint64 *file_pages,
                               uint64 *anon_mapping, uint64 *anon_pages,
                               dev_t *dev) {

#if defined(__linux__) || defined(__FreeBSD__) || defined(__CYGWIN__) || defined(__CYGWIN32__)
  do {
    // Advance to the start of the next line
    stext_ = nextline_;

    // See if we have a complete line in the buffer already
    nextline_ = static_cast<char *>(memchr (stext_, '\n', etext_ - stext_));
    if (!nextline_) {
      // Shift/fill the buffer so we do have a line
      int count = etext_ - stext_;

      // Move the current text to the start of the buffer
      memmove(ibuf_, stext_, count);
      stext_ = ibuf_;
      etext_ = ibuf_ + count;

      int nread = 0;            // fill up buffer with text
      while (etext_ < ebuf_) {
        NO_INTR(nread = read(fd_, etext_, ebuf_ - etext_));
        if (nread > 0)
          etext_ += nread;
        else
          break;
      }

      // Zero out remaining characters in buffer at EOF to avoid returning
      // garbage from subsequent calls.
      if (etext_ != ebuf_ && nread == 0) {
        memset(etext_, 0, ebuf_ - etext_);
      }
      *etext_ = '\n';   // sentinel; safe because ibuf extends 1 char beyond ebuf
      nextline_ = static_cast<char *>(memchr (stext_, '\n', etext_ + 1 - stext_));
    }
    *nextline_ = 0;                // turn newline into nul
    nextline_ += ((nextline_ < etext_)? 1 : 0);  // skip nul if not end of text
    // stext_ now points at a nul-terminated line
    uint64 tmpstart, tmpend, tmpoffset;
    int64 tmpinode;
    int major, minor;
    unsigned filename_offset = 0;
#if defined(__linux__)
    // for now, assume all linuxes have the same format
    if (sscanf(stext_, "%"SCNx64"-%"SCNx64" %4s %"SCNx64" %x:%x %"SCNd64" %n",
               start ? start : &tmpstart,
               end ? end : &tmpend,
               flags_,
               offset ? offset : &tmpoffset,
               &major, &minor,
               inode ? inode : &tmpinode, &filename_offset) != 7) continue;
#elif defined(__CYGWIN__) || defined(__CYGWIN32__)
    // cygwin is like linux, except the third field is the "entry point"
    // rather than the offset (see format_process_maps at
    // http://cygwin.com/cgi-bin/cvsweb.cgi/src/winsup/cygwin/fhandler_process.cc?rev=1.89&content-type=text/x-cvsweb-markup&cvsroot=src
    // Offset is always be 0 on cygwin: cygwin implements an mmap
    // by loading the whole file and then calling NtMapViewOfSection.
    // Cygwin also seems to set its flags kinda randomly; use windows default.
    char tmpflags[5];
    if (offset)
      *offset = 0;
    strcpy(flags_, "r-xp");
    if (sscanf(stext_, "%llx-%llx %4s %llx %x:%x %lld %n",
               start ? start : &tmpstart,
               end ? end : &tmpend,
               tmpflags,
               &tmpoffset,
               &major, &minor,
               inode ? inode : &tmpinode, &filename_offset) != 7) continue;
#elif defined(__FreeBSD__)
    // For the format, see http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/fs/procfs/procfs_map.c?rev=1.31&content-type=text/x-cvsweb-markup
    tmpstart = tmpend = tmpoffset = 0;
    tmpinode = 0;
    major = minor = 0;   // can't get this info in freebsd
    if (inode)
      *inode = 0;        // nor this
    if (offset)
      *offset = 0;       // seems like this should be in there, but maybe not
    // start end resident privateresident obj(?) prot refcnt shadowcnt
    // flags copy_on_write needs_copy type filename:
    // 0x8048000 0x804a000 2 0 0xc104ce70 r-x 1 0 0x0 COW NC vnode /bin/cat
    if (sscanf(stext_, "0x%"SCNx64" 0x%"SCNx64" %*d %*d %*p %3s %*d %*d 0x%*x %*s %*s %*s %n",
               start ? start : &tmpstart,
               end ? end : &tmpend,
               flags_,
               &filename_offset) != 3) continue;
#endif

    // Depending on the Linux kernel being used, there may or may not be a space
    // after the inode if there is no filename.  sscanf will in such situations
    // nondeterministically either fill in filename_offset or not (the results
    // differ on multiple calls in the same run even with identical arguments).
    // We don't want to wander off somewhere beyond the end of the string.
    size_t stext_length = strlen(stext_);
    if (filename_offset == 0 || filename_offset > stext_length)
      filename_offset = stext_length;

    // We found an entry
    if (flags) *flags = flags_;
    if (filename) *filename = stext_ + filename_offset;
    if (dev) *dev = minor | (major << 8);

    if (using_maps_backing_) {
      // Extract and parse physical page backing info.
      char *backing_ptr = stext_ + filename_offset +
          strlen(stext_+filename_offset);

      // find the second '('
      int paren_count = 0;
      while (--backing_ptr > stext_) {
        if (*backing_ptr == '(') {
          ++paren_count;
          if (paren_count >= 2) {
            uint64 tmp_file_mapping;
            uint64 tmp_file_pages;
            uint64 tmp_anon_mapping;
            uint64 tmp_anon_pages;

            sscanf(backing_ptr+1, "F %"SCNx64" %"SCNd64") (A %"SCNx64" %"SCNd64")",
                   file_mapping ? file_mapping : &tmp_file_mapping,
                   file_pages ? file_pages : &tmp_file_pages,
                   anon_mapping ? anon_mapping : &tmp_anon_mapping,
                   anon_pages ? anon_pages : &tmp_anon_pages);
            // null terminate the file name (there is a space
            // before the first (.
            backing_ptr[-1] = 0;
            break;
          }
        }
      }
    }

    return true;
  } while (etext_ > ibuf_);
#elif defined(__sun__)
  // This is based on MA_READ == 4, MA_WRITE == 2, MA_EXEC == 1
  static char kPerms[8][4] = { "---", "--x", "-w-", "-wx",
                               "r--", "r-x", "rw-", "rwx" };
  COMPILE_ASSERT(MA_READ == 4, solaris_ma_read_must_equal_4);
  COMPILE_ASSERT(MA_WRITE == 2, solaris_ma_write_must_equal_2);
  COMPILE_ASSERT(MA_EXEC == 1, solaris_ma_exec_must_equal_1);
  Buffer object_path;
  int nread = 0;            // fill up buffer with text
  NO_INTR(nread = read(fd_, ibuf_, sizeof(prmap_t)));
  if (nread == sizeof(prmap_t)) {
    long inode_from_mapname = 0;
    prmap_t* mapinfo = reinterpret_cast<prmap_t*>(ibuf_);
    // Best-effort attempt to get the inode from the filename.  I think the
    // two middle ints are major and minor device numbers, but I'm not sure.
    sscanf(mapinfo->pr_mapname, "ufs.%*d.%*d.%ld", &inode_from_mapname);

    if (pid_ == 0) {
      CHECK_LT(snprintf(object_path.buf_, Buffer::kBufSize,
                        "/proc/self/path/%s", mapinfo->pr_mapname),
               Buffer::kBufSize);
    } else {
      CHECK_LT(snprintf(object_path.buf_, Buffer::kBufSize,
                        "/proc/%d/path/%s",
                        static_cast<int>(pid_), mapinfo->pr_mapname),
               Buffer::kBufSize);
    }
    ssize_t len = readlink(object_path.buf_, current_filename_, PATH_MAX);
    CHECK_LT(len, PATH_MAX);
    if (len < 0)
      len = 0;
    current_filename_[len] = '\0';

    if (start) *start = mapinfo->pr_vaddr;
    if (end) *end = mapinfo->pr_vaddr + mapinfo->pr_size;
    if (flags) *flags = kPerms[mapinfo->pr_mflags & 7];
    if (offset) *offset = mapinfo->pr_offset;
    if (inode) *inode = inode_from_mapname;
    if (filename) *filename = current_filename_;
    if (file_mapping) *file_mapping = 0;
    if (file_pages) *file_pages = 0;
    if (anon_mapping) *anon_mapping = 0;
    if (anon_pages) *anon_pages = 0;
    if (dev) *dev = 0;
    return true;
  }
#elif defined(__MACH__)
  // We return a separate entry for each segment in the DLL. (TODO(csilvers):
  // can we do better?)  A DLL ("image") has load-commands, some of which
  // talk about segment boundaries.
  // cf image_for_address from http://svn.digium.com/view/asterisk/team/oej/minivoicemail/dlfcn.c?revision=53912
  for (; current_image_ >= 0; current_image_--) {
    const mach_header* hdr = _dyld_get_image_header(current_image_);
    if (!hdr) continue;
    if (current_load_cmd_ < 0)   // set up for this image
      current_load_cmd_ = hdr->ncmds;  // again, go from the top down

    // We start with the next load command (we've already looked at this one).
    for (current_load_cmd_--; current_load_cmd_ >= 0; current_load_cmd_--) {
#ifdef MH_MAGIC_64
      if (NextExtMachHelper<MH_MAGIC_64, LC_SEGMENT_64,
                            struct mach_header_64, struct segment_command_64>(
                                hdr, current_image_, current_load_cmd_,
                                start, end, flags, offset, inode, filename,
                                file_mapping, file_pages, anon_mapping,
                                anon_pages, dev)) {
        return true;
      }
#endif
      if (NextExtMachHelper<MH_MAGIC, LC_SEGMENT,
                            struct mach_header, struct segment_command>(
                                hdr, current_image_, current_load_cmd_,
                                start, end, flags, offset, inode, filename,
                                file_mapping, file_pages, anon_mapping,
                                anon_pages, dev)) {
        return true;
      }
    }
    // If we get here, no more load_cmd's in this image talk about
    // segments.  Go on to the next image.
  }
#elif defined(PLATFORM_WINDOWS)
  static char kDefaultPerms[5] = "r-xp";
  BOOL ok;
  if (module_.dwSize == 0) {  // only possible before first call
    module_.dwSize = sizeof(module_);
    ok = Module32First(snapshot_, &module_);
  } else {
    ok = Module32Next(snapshot_, &module_);
  }
  if (ok) {
    uint64 base_addr = reinterpret_cast<DWORD_PTR>(module_.modBaseAddr);
    if (start) *start = base_addr;
    if (end) *end = base_addr + module_.modBaseSize;
    if (flags) *flags = kDefaultPerms;
    if (offset) *offset = 0;
    if (inode) *inode = 0;
    if (filename) *filename = module_.szExePath;
    if (file_mapping) *file_mapping = 0;
    if (file_pages) *file_pages = 0;
    if (anon_mapping) *anon_mapping = 0;
    if (anon_pages) *anon_pages = 0;
    if (dev) *dev = 0;
    return true;
  }
#endif

  // We didn't find anything
  return false;
}

int ProcMapsIterator::FormatLine(char* buffer, int bufsize,
                                 uint64 start, uint64 end, const char *flags,
                                 uint64 offset, int64 inode,
                                 const char *filename, dev_t dev) {
  // We assume 'flags' looks like 'rwxp' or 'rwx'.
  char r = (flags && flags[0] == 'r') ? 'r' : '-';
  char w = (flags && flags[0] && flags[1] == 'w') ? 'w' : '-';
  char x = (flags && flags[0] && flags[1] && flags[2] == 'x') ? 'x' : '-';
  // p always seems set on linux, so we set the default to 'p', not '-'
  char p = (flags && flags[0] && flags[1] && flags[2] && flags[3] != 'p')
      ? '-' : 'p';

  const int rc = snprintf(buffer, bufsize,
                          "%08"PRIx64"-%08"PRIx64" %c%c%c%c %08"PRIx64" %02x:%02x %-11"PRId64" %s\n",
                          start, end, r,w,x,p, offset,
                          static_cast<int>(dev/256), static_cast<int>(dev%256),
                          inode, filename);
  return (rc < 0 || rc >= bufsize) ? 0 : rc;
}

namespace tcmalloc {

// Helper to add the list of mapped shared libraries to a profile.
// Fill formatted "/proc/self/maps" contents into buffer 'buf' of size 'size'
// and return the actual size occupied in 'buf'.  We fill wrote_all to true
// if we successfully wrote all proc lines to buf, false else.
// We do not provision for 0-terminating 'buf'.
int FillProcSelfMaps(char buf[], int size, bool* wrote_all) {
  ProcMapsIterator::Buffer iterbuf;
  ProcMapsIterator it(0, &iterbuf);   // 0 means "current pid"

  uint64 start, end, offset;
  int64 inode;
  char *flags, *filename;
  int bytes_written = 0;
  *wrote_all = true;
  while (it.Next(&start, &end, &flags, &offset, &inode, &filename)) {
    const int line_length = it.FormatLine(buf + bytes_written,
                                          size - bytes_written,
                                          start, end, flags, offset,
                                          inode, filename, 0);
    if (line_length == 0)
      *wrote_all = false;     // failed to write this line out
    else
      bytes_written += line_length;

  }
  return bytes_written;
}

// Dump the same data as FillProcSelfMaps reads to fd.
// It seems easier to repeat parts of FillProcSelfMaps here than to
// reuse it via a call.
void DumpProcSelfMaps(RawFD fd) {
  ProcMapsIterator::Buffer iterbuf;
  ProcMapsIterator it(0, &iterbuf);   // 0 means "current pid"

  uint64 start, end, offset;
  int64 inode;
  char *flags, *filename;
  ProcMapsIterator::Buffer linebuf;
  while (it.Next(&start, &end, &flags, &offset, &inode, &filename)) {
    int written = it.FormatLine(linebuf.buf_, sizeof(linebuf.buf_),
                                start, end, flags, offset, inode, filename,
                                0);
    RawWrite(fd, linebuf.buf_, written);
  }
}

}  // namespace tcmalloc