Initial checkin of GCC 4.9.0 from trunk (r208799).

Change-Id: I48a3c08bb98542aa215912a75f03c0890e497dba

1 files changed, 856 insertions, 0 deletions

diff --git a/gcc-4.9/libsanitizer/sanitizer_common/sanitizer_linux.cc b/gcc-4.9/libsanitizer/sanitizer_common/sanitizer_linux.cc
new file mode 100644
index 000000000..69c9c1063
--- /dev/null
+++ b/gcc-4.9/libsanitizer/sanitizer_common/sanitizer_linux.cc
@@ -0,0 +1,856 @@
+//===-- sanitizer_linux.cc ------------------------------------------------===//
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between AddressSanitizer and ThreadSanitizer
+// run-time libraries and implements linux-specific functions from
+// sanitizer_libc.h.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_LINUX
+
+#include "sanitizer_common.h"
+#include "sanitizer_internal_defs.h"
+#include "sanitizer_libc.h"
+#include "sanitizer_linux.h"
+#include "sanitizer_mutex.h"
+#include "sanitizer_placement_new.h"
+#include "sanitizer_procmaps.h"
+#include "sanitizer_stacktrace.h"
+#include "sanitizer_symbolizer.h"
+
+#include <asm/param.h>
+#include <dlfcn.h>
+#include <errno.h>
+#include <fcntl.h>
+#if !SANITIZER_ANDROID
+#include <link.h>
+#endif
+#include <pthread.h>
+#include <sched.h>
+#include <sys/mman.h>
+#include <sys/ptrace.h>
+#include <sys/resource.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <unwind.h>
+
+#if !SANITIZER_ANDROID
+#include <sys/signal.h>
+#endif
+
+// <linux/time.h>
+struct kernel_timeval {
+  long tv_sec;
+  long tv_usec;
+};
+
+// <linux/futex.h> is broken on some linux distributions.
+const int FUTEX_WAIT = 0;
+const int FUTEX_WAKE = 1;
+
+// Are we using 32-bit or 64-bit syscalls?
+// x32 (which defines __x86_64__) has SANITIZER_WORDSIZE == 32
+// but it still needs to use 64-bit syscalls.
+#if defined(__x86_64__) || SANITIZER_WORDSIZE == 64
+# define SANITIZER_LINUX_USES_64BIT_SYSCALLS 1
+#else
+# define SANITIZER_LINUX_USES_64BIT_SYSCALLS 0
+#endif
+
+namespace __sanitizer {
+
+#ifdef __x86_64__
+#include "sanitizer_syscall_linux_x86_64.inc"
+#else
+#include "sanitizer_syscall_generic.inc"
+#endif
+
+// --------------- sanitizer_libc.h
+uptr internal_mmap(void *addr, uptr length, int prot, int flags,
+                    int fd, u64 offset) {
+#if SANITIZER_LINUX_USES_64BIT_SYSCALLS
+  return internal_syscall(__NR_mmap, (uptr)addr, length, prot, flags, fd,
+                          offset);
+#else
+  return internal_syscall(__NR_mmap2, addr, length, prot, flags, fd, offset);
+#endif
+}
+
+uptr internal_munmap(void *addr, uptr length) {
+  return internal_syscall(__NR_munmap, (uptr)addr, length);
+}
+
+uptr internal_close(fd_t fd) {
+  return internal_syscall(__NR_close, fd);
+}
+
+uptr internal_open(const char *filename, int flags) {
+  return internal_syscall(__NR_open, (uptr)filename, flags);
+}
+
+uptr internal_open(const char *filename, int flags, u32 mode) {
+  return internal_syscall(__NR_open, (uptr)filename, flags, mode);
+}
+
+uptr OpenFile(const char *filename, bool write) {
+  return internal_open(filename,
+      write ? O_WRONLY | O_CREAT /*| O_CLOEXEC*/ : O_RDONLY, 0660);
+}
+
+uptr internal_read(fd_t fd, void *buf, uptr count) {
+  sptr res;
+  HANDLE_EINTR(res, (sptr)internal_syscall(__NR_read, fd, (uptr)buf, count));
+  return res;
+}
+
+uptr internal_write(fd_t fd, const void *buf, uptr count) {
+  sptr res;
+  HANDLE_EINTR(res, (sptr)internal_syscall(__NR_write, fd, (uptr)buf, count));
+  return res;
+}
+
+#if !SANITIZER_LINUX_USES_64BIT_SYSCALLS
+static void stat64_to_stat(struct stat64 *in, struct stat *out) {
+  internal_memset(out, 0, sizeof(*out));
+  out->st_dev = in->st_dev;
+  out->st_ino = in->st_ino;
+  out->st_mode = in->st_mode;
+  out->st_nlink = in->st_nlink;
+  out->st_uid = in->st_uid;
+  out->st_gid = in->st_gid;
+  out->st_rdev = in->st_rdev;
+  out->st_size = in->st_size;
+  out->st_blksize = in->st_blksize;
+  out->st_blocks = in->st_blocks;
+  out->st_atime = in->st_atime;
+  out->st_mtime = in->st_mtime;
+  out->st_ctime = in->st_ctime;
+  out->st_ino = in->st_ino;
+}
+#endif
+
+uptr internal_stat(const char *path, void *buf) {
+#if SANITIZER_LINUX_USES_64BIT_SYSCALLS
+  return internal_syscall(__NR_stat, (uptr)path, (uptr)buf);
+#else
+  struct stat64 buf64;
+  int res = internal_syscall(__NR_stat64, path, &buf64);
+  stat64_to_stat(&buf64, (struct stat *)buf);
+  return res;
+#endif
+}
+
+uptr internal_lstat(const char *path, void *buf) {
+#if SANITIZER_LINUX_USES_64BIT_SYSCALLS
+  return internal_syscall(__NR_lstat, (uptr)path, (uptr)buf);
+#else
+  struct stat64 buf64;
+  int res = internal_syscall(__NR_lstat64, path, &buf64);
+  stat64_to_stat(&buf64, (struct stat *)buf);
+  return res;
+#endif
+}
+
+uptr internal_fstat(fd_t fd, void *buf) {
+#if SANITIZER_LINUX_USES_64BIT_SYSCALLS
+  return internal_syscall(__NR_fstat, fd, (uptr)buf);
+#else
+  struct stat64 buf64;
+  int res = internal_syscall(__NR_fstat64, fd, &buf64);
+  stat64_to_stat(&buf64, (struct stat *)buf);
+  return res;
+#endif
+}
+
+uptr internal_filesize(fd_t fd) {
+  struct stat st;
+  if (internal_fstat(fd, &st))
+    return -1;
+  return (uptr)st.st_size;
+}
+
+uptr internal_dup2(int oldfd, int newfd) {
+  return internal_syscall(__NR_dup2, oldfd, newfd);
+}
+
+uptr internal_readlink(const char *path, char *buf, uptr bufsize) {
+  return internal_syscall(__NR_readlink, (uptr)path, (uptr)buf, bufsize);
+}
+
+uptr internal_unlink(const char *path) {
+  return internal_syscall(__NR_unlink, (uptr)path);
+}
+
+uptr internal_sched_yield() {
+  return internal_syscall(__NR_sched_yield);
+}
+
+void internal__exit(int exitcode) {
+  internal_syscall(__NR_exit_group, exitcode);
+  Die();  // Unreachable.
+}
+
+uptr internal_execve(const char *filename, char *const argv[],
+                     char *const envp[]) {
+  return internal_syscall(__NR_execve, (uptr)filename, (uptr)argv, (uptr)envp);
+}
+
+// ----------------- sanitizer_common.h
+bool FileExists(const char *filename) {
+  struct stat st;
+  if (internal_stat(filename, &st))
+    return false;
+  // Sanity check: filename is a regular file.
+  return S_ISREG(st.st_mode);
+}
+
+uptr GetTid() {
+  return internal_syscall(__NR_gettid);
+}
+
+u64 NanoTime() {
+  kernel_timeval tv;
+  internal_memset(&tv, 0, sizeof(tv));
+  internal_syscall(__NR_gettimeofday, (uptr)&tv, 0);
+  return (u64)tv.tv_sec * 1000*1000*1000 + tv.tv_usec * 1000;
+}
+
+// Like getenv, but reads env directly from /proc and does not use libc.
+// This function should be called first inside __asan_init.
+const char *GetEnv(const char *name) {
+  static char *environ;
+  static uptr len;
+  static bool inited;
+  if (!inited) {
+    inited = true;
+    uptr environ_size;
+    len = ReadFileToBuffer("/proc/self/environ",
+                           &environ, &environ_size, 1 << 26);
+  }
+  if (!environ || len == 0) return 0;
+  uptr namelen = internal_strlen(name);
+  const char *p = environ;
+  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*)internal_memchr(p, '\0', len - (p - environ));
+    if (endp == 0)  // this entry isn't NUL terminated
+      return 0;
+    else if (!internal_memcmp(p, name, namelen) && p[namelen] == '=')  // Match.
+      return p + namelen + 1;  // point after =
+    p = endp + 1;
+  }
+  return 0;  // Not found.
+}
+
+extern "C" {
+  SANITIZER_WEAK_ATTRIBUTE extern void *__libc_stack_end;
+}
+
+#if !SANITIZER_GO
+static void ReadNullSepFileToArray(const char *path, char ***arr,
+                                   int arr_size) {
+  char *buff;
+  uptr buff_size = 0;
+  *arr = (char **)MmapOrDie(arr_size * sizeof(char *), "NullSepFileArray");
+  ReadFileToBuffer(path, &buff, &buff_size, 1024 * 1024);
+  (*arr)[0] = buff;
+  int count, i;
+  for (count = 1, i = 1; ; i++) {
+    if (buff[i] == 0) {
+      if (buff[i+1] == 0) break;
+      (*arr)[count] = &buff[i+1];
+      CHECK_LE(count, arr_size - 1);  // FIXME: make this more flexible.
+      count++;
+    }
+  }
+  (*arr)[count] = 0;
+}
+#endif
+
+static void GetArgsAndEnv(char*** argv, char*** envp) {
+#if !SANITIZER_GO
+  if (&__libc_stack_end) {
+#endif
+    uptr* stack_end = (uptr*)__libc_stack_end;
+    int argc = *stack_end;
+    *argv = (char**)(stack_end + 1);
+    *envp = (char**)(stack_end + argc + 2);
+#if !SANITIZER_GO
+  } else {
+    static const int kMaxArgv = 2000, kMaxEnvp = 2000;
+    ReadNullSepFileToArray("/proc/self/cmdline", argv, kMaxArgv);
+    ReadNullSepFileToArray("/proc/self/environ", envp, kMaxEnvp);
+  }
+#endif
+}
+
+void ReExec() {
+  char **argv, **envp;
+  GetArgsAndEnv(&argv, &envp);
+  uptr rv = internal_execve("/proc/self/exe", argv, envp);
+  int rverrno;
+  CHECK_EQ(internal_iserror(rv, &rverrno), true);
+  Printf("execve failed, errno %d\n", rverrno);
+  Die();
+}
+
+void PrepareForSandboxing() {
+  // Some kinds of sandboxes may forbid filesystem access, so we won't be able
+  // to read the file mappings from /proc/self/maps. Luckily, neither the
+  // process will be able to load additional libraries, so it's fine to use the
+  // cached mappings.
+  MemoryMappingLayout::CacheMemoryMappings();
+  // Same for /proc/self/exe in the symbolizer.
+#if !SANITIZER_GO
+  if (Symbolizer *sym = Symbolizer::GetOrNull())
+    sym->PrepareForSandboxing();
+#endif
+}
+
+// ----------------- sanitizer_procmaps.h
+// Linker initialized.
+ProcSelfMapsBuff MemoryMappingLayout::cached_proc_self_maps_;
+StaticSpinMutex MemoryMappingLayout::cache_lock_;  // Linker initialized.
+
+MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
+  proc_self_maps_.len =
+      ReadFileToBuffer("/proc/self/maps", &proc_self_maps_.data,
+                       &proc_self_maps_.mmaped_size, 1 << 26);
+  if (cache_enabled) {
+    if (proc_self_maps_.mmaped_size == 0) {
+      LoadFromCache();
+      CHECK_GT(proc_self_maps_.len, 0);
+    }
+  } else {
+    CHECK_GT(proc_self_maps_.mmaped_size, 0);
+  }
+  Reset();
+  // FIXME: in the future we may want to cache the mappings on demand only.
+  if (cache_enabled)
+    CacheMemoryMappings();
+}
+
+MemoryMappingLayout::~MemoryMappingLayout() {
+  // Only unmap the buffer if it is different from the cached one. Otherwise
+  // it will be unmapped when the cache is refreshed.
+  if (proc_self_maps_.data != cached_proc_self_maps_.data) {
+    UnmapOrDie(proc_self_maps_.data, proc_self_maps_.mmaped_size);
+  }
+}
+
+void MemoryMappingLayout::Reset() {
+  current_ = proc_self_maps_.data;
+}
+
+// static
+void MemoryMappingLayout::CacheMemoryMappings() {
+  SpinMutexLock l(&cache_lock_);
+  // Don't invalidate the cache if the mappings are unavailable.
+  ProcSelfMapsBuff old_proc_self_maps;
+  old_proc_self_maps = cached_proc_self_maps_;
+  cached_proc_self_maps_.len =
+      ReadFileToBuffer("/proc/self/maps", &cached_proc_self_maps_.data,
+                       &cached_proc_self_maps_.mmaped_size, 1 << 26);
+  if (cached_proc_self_maps_.mmaped_size == 0) {
+    cached_proc_self_maps_ = old_proc_self_maps;
+  } else {
+    if (old_proc_self_maps.mmaped_size) {
+      UnmapOrDie(old_proc_self_maps.data,
+                 old_proc_self_maps.mmaped_size);
+    }
+  }
+}
+
+void MemoryMappingLayout::LoadFromCache() {
+  SpinMutexLock l(&cache_lock_);
+  if (cached_proc_self_maps_.data) {
+    proc_self_maps_ = cached_proc_self_maps_;
+  }
+}
+
+// Parse a hex value in str and update str.
+static uptr ParseHex(char **str) {
+  uptr x = 0;
+  char *s;
+  for (s = *str; ; s++) {
+    char c = *s;
+    uptr v = 0;
+    if (c >= '0' && c <= '9')
+      v = c - '0';
+    else if (c >= 'a' && c <= 'f')
+      v = c - 'a' + 10;
+    else if (c >= 'A' && c <= 'F')
+      v = c - 'A' + 10;
+    else
+      break;
+    x = x * 16 + v;
+  }
+  *str = s;
+  return x;
+}
+
+static bool IsOneOf(char c, char c1, char c2) {
+  return c == c1 || c == c2;
+}
+
+static bool IsDecimal(char c) {
+  return c >= '0' && c <= '9';
+}
+
+static bool IsHex(char c) {
+  return (c >= '0' && c <= '9')
+      || (c >= 'a' && c <= 'f');
+}
+
+static uptr ReadHex(const char *p) {
+  uptr v = 0;
+  for (; IsHex(p[0]); p++) {
+    if (p[0] >= '0' && p[0] <= '9')
+      v = v * 16 + p[0] - '0';
+    else
+      v = v * 16 + p[0] - 'a' + 10;
+  }
+  return v;
+}
+
+static uptr ReadDecimal(const char *p) {
+  uptr v = 0;
+  for (; IsDecimal(p[0]); p++)
+    v = v * 10 + p[0] - '0';
+  return v;
+}
+
+
+bool MemoryMappingLayout::Next(uptr *start, uptr *end, uptr *offset,
+                               char filename[], uptr filename_size,
+                               uptr *protection) {
+  char *last = proc_self_maps_.data + proc_self_maps_.len;
+  if (current_ >= last) return false;
+  uptr dummy;
+  if (!start) start = &dummy;
+  if (!end) end = &dummy;
+  if (!offset) offset = &dummy;
+  char *next_line = (char*)internal_memchr(current_, '\n', last - current_);
+  if (next_line == 0)
+    next_line = last;
+  // Example: 08048000-08056000 r-xp 00000000 03:0c 64593   /foo/bar
+  *start = ParseHex(&current_);
+  CHECK_EQ(*current_++, '-');
+  *end = ParseHex(&current_);
+  CHECK_EQ(*current_++, ' ');
+  uptr local_protection = 0;
+  CHECK(IsOneOf(*current_, '-', 'r'));
+  if (*current_++ == 'r')
+    local_protection |= kProtectionRead;
+  CHECK(IsOneOf(*current_, '-', 'w'));
+  if (*current_++ == 'w')
+    local_protection |= kProtectionWrite;
+  CHECK(IsOneOf(*current_, '-', 'x'));
+  if (*current_++ == 'x')
+    local_protection |= kProtectionExecute;
+  CHECK(IsOneOf(*current_, 's', 'p'));
+  if (*current_++ == 's')
+    local_protection |= kProtectionShared;
+  if (protection) {
+    *protection = local_protection;
+  }
+  CHECK_EQ(*current_++, ' ');
+  *offset = ParseHex(&current_);
+  CHECK_EQ(*current_++, ' ');
+  ParseHex(&current_);
+  CHECK_EQ(*current_++, ':');
+  ParseHex(&current_);
+  CHECK_EQ(*current_++, ' ');
+  while (IsDecimal(*current_))
+    current_++;
+  // Qemu may lack the trailing space.
+  // http://code.google.com/p/address-sanitizer/issues/detail?id=160
+  // CHECK_EQ(*current_++, ' ');
+  // Skip spaces.
+  while (current_ < next_line && *current_ == ' ')
+    current_++;
+  // Fill in the filename.
+  uptr i = 0;
+  while (current_ < next_line) {
+    if (filename && i < filename_size - 1)
+      filename[i++] = *current_;
+    current_++;
+  }
+  if (filename && i < filename_size)
+    filename[i] = 0;
+  current_ = next_line + 1;
+  return true;
+}
+
+// Gets the object name and the offset by walking MemoryMappingLayout.
+bool MemoryMappingLayout::GetObjectNameAndOffset(uptr addr, uptr *offset,
+                                                 char filename[],
+                                                 uptr filename_size,
+                                                 uptr *protection) {
+  return IterateForObjectNameAndOffset(addr, offset, filename, filename_size,
+                                       protection);
+}
+
+void GetMemoryProfile(fill_profile_f cb, uptr *stats, uptr stats_size) {
+  char *smaps = 0;
+  uptr smaps_cap = 0;
+  uptr smaps_len = ReadFileToBuffer("/proc/self/smaps",
+      &smaps, &smaps_cap, 64<<20);
+  uptr start = 0;
+  bool file = false;
+  const char *pos = smaps;
+  while (pos < smaps + smaps_len) {
+    if (IsHex(pos[0])) {
+      start = ReadHex(pos);
+      for (; *pos != '/' && *pos > '\n'; pos++) {}
+      file = *pos == '/';
+    } else if (internal_strncmp(pos, "Rss:", 4) == 0) {
+      for (; *pos < '0' || *pos > '9'; pos++) {}
+      uptr rss = ReadDecimal(pos) * 1024;
+      cb(start, rss, file, stats, stats_size);
+    }
+    while (*pos++ != '\n') {}
+  }
+  UnmapOrDie(smaps, smaps_cap);
+}
+
+enum MutexState {
+  MtxUnlocked = 0,
+  MtxLocked = 1,
+  MtxSleeping = 2
+};
+
+BlockingMutex::BlockingMutex(LinkerInitialized) {
+  CHECK_EQ(owner_, 0);
+}
+
+BlockingMutex::BlockingMutex() {
+  internal_memset(this, 0, sizeof(*this));
+}
+
+void BlockingMutex::Lock() {
+  atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
+  if (atomic_exchange(m, MtxLocked, memory_order_acquire) == MtxUnlocked)
+    return;
+  while (atomic_exchange(m, MtxSleeping, memory_order_acquire) != MtxUnlocked)
+    internal_syscall(__NR_futex, (uptr)m, FUTEX_WAIT, MtxSleeping, 0, 0, 0);
+}
+
+void BlockingMutex::Unlock() {
+  atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
+  u32 v = atomic_exchange(m, MtxUnlocked, memory_order_relaxed);
+  CHECK_NE(v, MtxUnlocked);
+  if (v == MtxSleeping)
+    internal_syscall(__NR_futex, (uptr)m, FUTEX_WAKE, 1, 0, 0, 0);
+}
+
+void BlockingMutex::CheckLocked() {
+  atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
+  CHECK_NE(MtxUnlocked, atomic_load(m, memory_order_relaxed));
+}
+
+// ----------------- sanitizer_linux.h
+// The actual size of this structure is specified by d_reclen.
+// Note that getdents64 uses a different structure format. We only provide the
+// 32-bit syscall here.
+struct linux_dirent {
+  unsigned long      d_ino;
+  unsigned long      d_off;
+  unsigned short     d_reclen;
+  char               d_name[256];
+};
+
+// Syscall wrappers.
+uptr internal_ptrace(int request, int pid, void *addr, void *data) {
+  return internal_syscall(__NR_ptrace, request, pid, (uptr)addr, (uptr)data);
+}
+
+uptr internal_waitpid(int pid, int *status, int options) {
+  return internal_syscall(__NR_wait4, pid, (uptr)status, options,
+                          0 /* rusage */);
+}
+
+uptr internal_getpid() {
+  return internal_syscall(__NR_getpid);
+}
+
+uptr internal_getppid() {
+  return internal_syscall(__NR_getppid);
+}
+
+uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count) {
+  return internal_syscall(__NR_getdents, fd, (uptr)dirp, count);
+}
+
+uptr internal_lseek(fd_t fd, OFF_T offset, int whence) {
+  return internal_syscall(__NR_lseek, fd, offset, whence);
+}
+
+uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5) {
+  return internal_syscall(__NR_prctl, option, arg2, arg3, arg4, arg5);
+}
+
+uptr internal_sigaltstack(const struct sigaltstack *ss,
+                         struct sigaltstack *oss) {
+  return internal_syscall(__NR_sigaltstack, (uptr)ss, (uptr)oss);
+}
+
+uptr internal_sigaction(int signum, const __sanitizer_kernel_sigaction_t *act,
+    __sanitizer_kernel_sigaction_t *oldact) {
+  return internal_syscall(__NR_rt_sigaction, signum, act, oldact,
+      sizeof(__sanitizer_kernel_sigset_t));
+}
+
+uptr internal_sigprocmask(int how, __sanitizer_kernel_sigset_t *set,
+    __sanitizer_kernel_sigset_t *oldset) {
+  return internal_syscall(__NR_rt_sigprocmask, (uptr)how, &set->sig[0],
+      &oldset->sig[0], sizeof(__sanitizer_kernel_sigset_t));
+}
+
+void internal_sigfillset(__sanitizer_kernel_sigset_t *set) {
+  internal_memset(set, 0xff, sizeof(*set));
+}
+
+void internal_sigdelset(__sanitizer_kernel_sigset_t *set, int signum) {
+  signum -= 1;
+  CHECK_GE(signum, 0);
+  CHECK_LT(signum, sizeof(*set) * 8);
+  const uptr idx = signum / (sizeof(set->sig[0]) * 8);
+  const uptr bit = signum % (sizeof(set->sig[0]) * 8);
+  set->sig[idx] &= ~(1 << bit);
+}
+
+// ThreadLister implementation.
+ThreadLister::ThreadLister(int pid)
+  : pid_(pid),
+    descriptor_(-1),
+    buffer_(4096),
+    error_(true),
+    entry_((struct linux_dirent *)buffer_.data()),
+    bytes_read_(0) {
+  char task_directory_path[80];
+  internal_snprintf(task_directory_path, sizeof(task_directory_path),
+                    "/proc/%d/task/", pid);
+  uptr openrv = internal_open(task_directory_path, O_RDONLY | O_DIRECTORY);
+  if (internal_iserror(openrv)) {
+    error_ = true;
+    Report("Can't open /proc/%d/task for reading.\n", pid);
+  } else {
+    error_ = false;
+    descriptor_ = openrv;
+  }
+}
+
+int ThreadLister::GetNextTID() {
+  int tid = -1;
+  do {
+    if (error_)
+      return -1;
+    if ((char *)entry_ >= &buffer_[bytes_read_] && !GetDirectoryEntries())
+      return -1;
+    if (entry_->d_ino != 0 && entry_->d_name[0] >= '0' &&
+        entry_->d_name[0] <= '9') {
+      // Found a valid tid.
+      tid = (int)internal_atoll(entry_->d_name);
+    }
+    entry_ = (struct linux_dirent *)(((char *)entry_) + entry_->d_reclen);
+  } while (tid < 0);
+  return tid;
+}
+
+void ThreadLister::Reset() {
+  if (error_ || descriptor_ < 0)
+    return;
+  internal_lseek(descriptor_, 0, SEEK_SET);
+}
+
+ThreadLister::~ThreadLister() {
+  if (descriptor_ >= 0)
+    internal_close(descriptor_);
+}
+
+bool ThreadLister::error() { return error_; }
+
+bool ThreadLister::GetDirectoryEntries() {
+  CHECK_GE(descriptor_, 0);
+  CHECK_NE(error_, true);
+  bytes_read_ = internal_getdents(descriptor_,
+                                  (struct linux_dirent *)buffer_.data(),
+                                  buffer_.size());
+  if (internal_iserror(bytes_read_)) {
+    Report("Can't read directory entries from /proc/%d/task.\n", pid_);
+    error_ = true;
+    return false;
+  } else if (bytes_read_ == 0) {
+    return false;
+  }
+  entry_ = (struct linux_dirent *)buffer_.data();
+  return true;
+}
+
+uptr GetPageSize() {
+#if defined(__x86_64__) || defined(__i386__)
+  return EXEC_PAGESIZE;
+#else
+  return sysconf(_SC_PAGESIZE);  // EXEC_PAGESIZE may not be trustworthy.
+#endif
+}
+
+static char proc_self_exe_cache_str[kMaxPathLength];
+static uptr proc_self_exe_cache_len = 0;
+
+uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
+  uptr module_name_len = internal_readlink(
+      "/proc/self/exe", buf, buf_len);
+  int readlink_error;
+  if (internal_iserror(module_name_len, &readlink_error)) {
+    if (proc_self_exe_cache_len) {
+      // If available, use the cached module name.
+      CHECK_LE(proc_self_exe_cache_len, buf_len);
+      internal_strncpy(buf, proc_self_exe_cache_str, buf_len);
+      module_name_len = internal_strlen(proc_self_exe_cache_str);
+    } else {
+      // We can't read /proc/self/exe for some reason, assume the name of the
+      // binary is unknown.
+      Report("WARNING: readlink(\"/proc/self/exe\") failed with errno %d, "
+             "some stack frames may not be symbolized\n", readlink_error);
+      module_name_len = internal_snprintf(buf, buf_len, "/proc/self/exe");
+    }
+    CHECK_LT(module_name_len, buf_len);
+    buf[module_name_len] = '\0';
+  }
+  return module_name_len;
+}
+
+void CacheBinaryName() {
+  if (!proc_self_exe_cache_len) {
+    proc_self_exe_cache_len =
+        ReadBinaryName(proc_self_exe_cache_str, kMaxPathLength);
+  }
+}
+
+// Match full names of the form /path/to/base_name{-,.}*
+bool LibraryNameIs(const char *full_name, const char *base_name) {
+  const char *name = full_name;
+  // Strip path.
+  while (*name != '\0') name++;
+  while (name > full_name && *name != '/') name--;
+  if (*name == '/') name++;
+  uptr base_name_length = internal_strlen(base_name);
+  if (internal_strncmp(name, base_name, base_name_length)) return false;
+  return (name[base_name_length] == '-' || name[base_name_length] == '.');
+}
+
+#if !SANITIZER_ANDROID
+// Call cb for each region mapped by map.
+void ForEachMappedRegion(link_map *map, void (*cb)(const void *, uptr)) {
+  typedef ElfW(Phdr) Elf_Phdr;
+  typedef ElfW(Ehdr) Elf_Ehdr;
+  char *base = (char *)map->l_addr;
+  Elf_Ehdr *ehdr = (Elf_Ehdr *)base;
+  char *phdrs = base + ehdr->e_phoff;
+  char *phdrs_end = phdrs + ehdr->e_phnum * ehdr->e_phentsize;
+
+  // Find the segment with the minimum base so we can "relocate" the p_vaddr
+  // fields.  Typically ET_DYN objects (DSOs) have base of zero and ET_EXEC
+  // objects have a non-zero base.
+  uptr preferred_base = (uptr)-1;
+  for (char *iter = phdrs; iter != phdrs_end; iter += ehdr->e_phentsize) {
+    Elf_Phdr *phdr = (Elf_Phdr *)iter;
+    if (phdr->p_type == PT_LOAD && preferred_base > (uptr)phdr->p_vaddr)
+      preferred_base = (uptr)phdr->p_vaddr;
+  }
+
+  // Compute the delta from the real base to get a relocation delta.
+  sptr delta = (uptr)base - preferred_base;
+  // Now we can figure out what the loader really mapped.
+  for (char *iter = phdrs; iter != phdrs_end; iter += ehdr->e_phentsize) {
+    Elf_Phdr *phdr = (Elf_Phdr *)iter;
+    if (phdr->p_type == PT_LOAD) {
+      uptr seg_start = phdr->p_vaddr + delta;
+      uptr seg_end = seg_start + phdr->p_memsz;
+      // None of these values are aligned.  We consider the ragged edges of the
+      // load command as defined, since they are mapped from the file.
+      seg_start = RoundDownTo(seg_start, GetPageSizeCached());
+      seg_end = RoundUpTo(seg_end, GetPageSizeCached());
+      cb((void *)seg_start, seg_end - seg_start);
+    }
+  }
+}
+#endif
+
+#if defined(__x86_64__)
+// We cannot use glibc's clone wrapper, because it messes with the child
+// task's TLS. It writes the PID and TID of the child task to its thread
+// descriptor, but in our case the child task shares the thread descriptor with
+// the parent (because we don't know how to allocate a new thread
+// descriptor to keep glibc happy). So the stock version of clone(), when
+// used with CLONE_VM, would end up corrupting the parent's thread descriptor.
+uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
+                    int *parent_tidptr, void *newtls, int *child_tidptr) {
+  long long res;
+  if (!fn || !child_stack)
+    return -EINVAL;
+  CHECK_EQ(0, (uptr)child_stack % 16);
+  child_stack = (char *)child_stack - 2 * sizeof(unsigned long long);
+  ((unsigned long long *)child_stack)[0] = (uptr)fn;
+  ((unsigned long long *)child_stack)[1] = (uptr)arg;
+  register void *r8 __asm__("r8") = newtls;
+  register int *r10 __asm__("r10") = child_tidptr;
+  __asm__ __volatile__(
+                       /* %rax = syscall(%rax = __NR_clone,
+                        *                %rdi = flags,
+                        *                %rsi = child_stack,
+                        *                %rdx = parent_tidptr,
+                        *                %r8  = new_tls,
+                        *                %r10 = child_tidptr)
+                        */
+                       "syscall\n"
+
+                       /* if (%rax != 0)
+                        *   return;
+                        */
+                       "testq  %%rax,%%rax\n"
+                       "jnz    1f\n"
+
+                       /* In the child. Terminate unwind chain. */
+                       // XXX: We should also terminate the CFI unwind chain
+                       // here. Unfortunately clang 3.2 doesn't support the
+                       // necessary CFI directives, so we skip that part.
+                       "xorq   %%rbp,%%rbp\n"
+
+                       /* Call "fn(arg)". */
+                       "popq   %%rax\n"
+                       "popq   %%rdi\n"
+                       "call   *%%rax\n"
+
+                       /* Call _exit(%rax). */
+                       "movq   %%rax,%%rdi\n"
+                       "movq   %2,%%rax\n"
+                       "syscall\n"
+
+                       /* Return to parent. */
+                     "1:\n"
+                       : "=a" (res)
+                       : "a"(__NR_clone), "i"(__NR_exit),
+                         "S"(child_stack),
+                         "D"(flags),
+                         "d"(parent_tidptr),
+                         "r"(r8),
+                         "r"(r10)
+                       : "rsp", "memory", "r11", "rcx");
+  return res;
+}
+#endif  // defined(__x86_64__)
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_LINUX