Squashed 'third_party/gperftools/' content from commit 54505f1

Change-Id: Id02e833828732b0efe7dac722b8485279e67c5fa
git-subtree-dir: third_party/gperftools
git-subtree-split: 54505f1d50c2d1f4676f5e87090b64a117fd980e
diff --git a/src/base/sysinfo.cc b/src/base/sysinfo.cc
new file mode 100644
index 0000000..cad751b
--- /dev/null
+++ b/src/base/sysinfo.cc
@@ -0,0 +1,1153 @@
+// -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
+// 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 <ctype.h>    // for isspace()
+#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 (strlen(*p) < namelen) {
+        continue;
+      }
+      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
+}
+
+extern "C" {
+  const char* TCMallocGetenvSafe(const char* name) {
+    return GetenvBeforeMain(name);
+  }
+}
+
+// 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';
+
+#if defined(__powerpc__) || defined(__ppc__)
+    // PowerPC cpus report the frequency in "clock" line
+    if (strncasecmp(line, "clock", sizeof("clock")-1) == 0) {
+      const char* freqstr = strchr(line, ':');
+      if (freqstr) {
+	// PowerPC frequencies are only reported as MHz (check 'show_cpuinfo'
+	// function at arch/powerpc/kernel/setup-common.c)
+	char *endp = strstr(line, "MHz");
+	if (endp) {
+	  *endp = 0;
+	  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
+    // 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;
+      }
+#endif
+    } 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 library.  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
+
+// Finds |c| in |text|, and assign '\0' at the found position.
+// The original character at the modified position should be |c|.
+// A pointer to the modified position is stored in |endptr|.
+// |endptr| should not be NULL.
+static bool ExtractUntilChar(char *text, int c, char **endptr) {
+  CHECK_NE(text, NULL);
+  CHECK_NE(endptr, NULL);
+  char *found;
+  found = strchr(text, c);
+  if (found == NULL) {
+    *endptr = NULL;
+    return false;
+  }
+
+  *endptr = found;
+  *found = '\0';
+  return true;
+}
+
+// Increments |*text_pointer| while it points a whitespace character.
+// It is to follow sscanf's whilespace handling.
+static void SkipWhileWhitespace(char **text_pointer, int c) {
+  if (isspace(c)) {
+    while (isspace(**text_pointer) && isspace(*((*text_pointer) + 1))) {
+      ++(*text_pointer);
+    }
+  }
+}
+
+template<class T>
+static T StringToInteger(char *text, char **endptr, int base) {
+  assert(false);
+  return T();
+}
+
+template<>
+int StringToInteger<int>(char *text, char **endptr, int base) {
+  return strtol(text, endptr, base);
+}
+
+template<>
+int64 StringToInteger<int64>(char *text, char **endptr, int base) {
+  return strtoll(text, endptr, base);
+}
+
+template<>
+uint64 StringToInteger<uint64>(char *text, char **endptr, int base) {
+  return strtoull(text, endptr, base);
+}
+
+template<typename T>
+static T StringToIntegerUntilChar(
+    char *text, int base, int c, char **endptr_result) {
+  CHECK_NE(endptr_result, NULL);
+  *endptr_result = NULL;
+
+  char *endptr_extract;
+  if (!ExtractUntilChar(text, c, &endptr_extract))
+    return 0;
+
+  T result;
+  char *endptr_strto;
+  result = StringToInteger<T>(text, &endptr_strto, base);
+  *endptr_extract = c;
+
+  if (endptr_extract != endptr_strto)
+    return 0;
+
+  *endptr_result = endptr_extract;
+  SkipWhileWhitespace(endptr_result, c);
+
+  return result;
+}
+
+static char *CopyStringUntilChar(
+    char *text, unsigned out_len, int c, char *out) {
+  char *endptr;
+  if (!ExtractUntilChar(text, c, &endptr))
+    return NULL;
+
+  strncpy(out, text, out_len);
+  out[out_len-1] = '\0';
+  *endptr = c;
+
+  SkipWhileWhitespace(&endptr, c);
+  return endptr;
+}
+
+template<typename T>
+static bool StringToIntegerUntilCharWithCheck(
+    T *outptr, char *text, int base, int c, char **endptr) {
+  *outptr = StringToIntegerUntilChar<T>(*endptr, base, c, endptr);
+  if (*endptr == NULL || **endptr == '\0') return false;
+  ++(*endptr);
+  return true;
+}
+
+static bool ParseProcMapsLine(char *text, uint64 *start, uint64 *end,
+                              char *flags, uint64 *offset,
+                              int *major, int *minor, int64 *inode,
+                              unsigned *filename_offset) {
+#if defined(__linux__)
+  /*
+   * It's similar to:
+   * sscanf(text, "%"SCNx64"-%"SCNx64" %4s %"SCNx64" %x:%x %"SCNd64" %n",
+   *        start, end, flags, offset, major, minor, inode, filename_offset)
+   */
+  char *endptr = text;
+  if (endptr == NULL || *endptr == '\0')  return false;
+
+  if (!StringToIntegerUntilCharWithCheck(start, endptr, 16, '-', &endptr))
+    return false;
+
+  if (!StringToIntegerUntilCharWithCheck(end, endptr, 16, ' ', &endptr))
+    return false;
+
+  endptr = CopyStringUntilChar(endptr, 5, ' ', flags);
+  if (endptr == NULL || *endptr == '\0')  return false;
+  ++endptr;
+
+  if (!StringToIntegerUntilCharWithCheck(offset, endptr, 16, ' ', &endptr))
+    return false;
+
+  if (!StringToIntegerUntilCharWithCheck(major, endptr, 16, ':', &endptr))
+    return false;
+
+  if (!StringToIntegerUntilCharWithCheck(minor, endptr, 16, ' ', &endptr))
+    return false;
+
+  if (!StringToIntegerUntilCharWithCheck(inode, endptr, 10, ' ', &endptr))
+    return false;
+
+  *filename_offset = (endptr - text);
+  return true;
+#else
+  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 (!ParseProcMapsLine(
+        stext_,
+        start ? start : &tmpstart,
+        end ? end : &tmpend,
+        flags_,
+        offset ? offset : &tmpoffset,
+        &major, &minor,
+        inode ? inode : &tmpinode, &filename_offset)) 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