chore(3p/abseil_cpp): unvendor abseil_cpp r/3786

we weren't actually using these sources anymore, okay?

Change-Id: If701571d9716de308d3512e1eb22c35db0877a66
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5248
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
Autosubmit: tazjin <tazjin@tvl.su>

1 files changed, 0 insertions, 1560 deletions

diff --git a/third_party/abseil_cpp/absl/debugging/symbolize_elf.inc b/third_party/abseil_cpp/absl/debugging/symbolize_elf.inc
deleted file mode 100644
index f4d5727bdeb5..000000000000
--- a/third_party/abseil_cpp/absl/debugging/symbolize_elf.inc
+++ /dev/null
@@ -1,1560 +0,0 @@
-// Copyright 2018 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-// This library provides Symbolize() function that symbolizes program
-// counters to their corresponding symbol names on linux platforms.
-// This library has a minimal implementation of an ELF symbol table
-// reader (i.e. it doesn't depend on libelf, etc.).
-//
-// The algorithm used in Symbolize() is as follows.
-//
-//   1. Go through a list of maps in /proc/self/maps and find the map
-//   containing the program counter.
-//
-//   2. Open the mapped file and find a regular symbol table inside.
-//   Iterate over symbols in the symbol table and look for the symbol
-//   containing the program counter.  If such a symbol is found,
-//   obtain the symbol name, and demangle the symbol if possible.
-//   If the symbol isn't found in the regular symbol table (binary is
-//   stripped), try the same thing with a dynamic symbol table.
-//
-// Note that Symbolize() is originally implemented to be used in
-// signal handlers, hence it doesn't use malloc() and other unsafe
-// operations.  It should be both thread-safe and async-signal-safe.
-//
-// Implementation note:
-//
-// We don't use heaps but only use stacks.  We want to reduce the
-// stack consumption so that the symbolizer can run on small stacks.
-//
-// Here are some numbers collected with GCC 4.1.0 on x86:
-// - sizeof(Elf32_Sym)  = 16
-// - sizeof(Elf32_Shdr) = 40
-// - sizeof(Elf64_Sym)  = 24
-// - sizeof(Elf64_Shdr) = 64
-//
-// This implementation is intended to be async-signal-safe but uses some
-// functions which are not guaranteed to be so, such as memchr() and
-// memmove().  We assume they are async-signal-safe.
-
-#include <dlfcn.h>
-#include <elf.h>
-#include <fcntl.h>
-#include <link.h>  // For ElfW() macro.
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <unistd.h>
-
-#include <algorithm>
-#include <array>
-#include <atomic>
-#include <cerrno>
-#include <cinttypes>
-#include <climits>
-#include <cstdint>
-#include <cstdio>
-#include <cstdlib>
-#include <cstring>
-
-#include "absl/base/casts.h"
-#include "absl/base/dynamic_annotations.h"
-#include "absl/base/internal/low_level_alloc.h"
-#include "absl/base/internal/raw_logging.h"
-#include "absl/base/internal/spinlock.h"
-#include "absl/base/port.h"
-#include "absl/debugging/internal/demangle.h"
-#include "absl/debugging/internal/vdso_support.h"
-#include "absl/strings/string_view.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-
-// Value of argv[0]. Used by MaybeInitializeObjFile().
-static char *argv0_value = nullptr;
-
-void InitializeSymbolizer(const char *argv0) {
-#ifdef ABSL_HAVE_VDSO_SUPPORT
-  // We need to make sure VDSOSupport::Init() is called before any setuid or
-  // chroot calls, so InitializeSymbolizer() should be called very early in the
-  // life of a program.
-  absl::debugging_internal::VDSOSupport::Init();
-#endif
-  if (argv0_value != nullptr) {
-    free(argv0_value);
-    argv0_value = nullptr;
-  }
-  if (argv0 != nullptr && argv0[0] != '\0') {
-    argv0_value = strdup(argv0);
-  }
-}
-
-namespace debugging_internal {
-namespace {
-
-// Re-runs fn until it doesn't cause EINTR.
-#define NO_INTR(fn) \
-  do {              \
-  } while ((fn) < 0 && errno == EINTR)
-
-// On Linux, ELF_ST_* are defined in <linux/elf.h>.  To make this portable
-// we define our own ELF_ST_BIND and ELF_ST_TYPE if not available.
-#ifndef ELF_ST_BIND
-#define ELF_ST_BIND(info) (((unsigned char)(info)) >> 4)
-#endif
-
-#ifndef ELF_ST_TYPE
-#define ELF_ST_TYPE(info) (((unsigned char)(info)) & 0xF)
-#endif
-
-// Some platforms use a special .opd section to store function pointers.
-const char kOpdSectionName[] = ".opd";
-
-#if (defined(__powerpc__) && !(_CALL_ELF > 1)) || defined(__ia64)
-// Use opd section for function descriptors on these platforms, the function
-// address is the first word of the descriptor.
-enum { kPlatformUsesOPDSections = 1 };
-#else  // not PPC or IA64
-enum { kPlatformUsesOPDSections = 0 };
-#endif
-
-// This works for PowerPC & IA64 only.  A function descriptor consist of two
-// pointers and the first one is the function's entry.
-const size_t kFunctionDescriptorSize = sizeof(void *) * 2;
-
-const int kMaxDecorators = 10;  // Seems like a reasonable upper limit.
-
-struct InstalledSymbolDecorator {
-  SymbolDecorator fn;
-  void *arg;
-  int ticket;
-};
-
-int g_num_decorators;
-InstalledSymbolDecorator g_decorators[kMaxDecorators];
-
-struct FileMappingHint {
-  const void *start;
-  const void *end;
-  uint64_t offset;
-  const char *filename;
-};
-
-// Protects g_decorators.
-// We are using SpinLock and not a Mutex here, because we may be called
-// from inside Mutex::Lock itself, and it prohibits recursive calls.
-// This happens in e.g. base/stacktrace_syscall_unittest.
-// Moreover, we are using only TryLock(), if the decorator list
-// is being modified (is busy), we skip all decorators, and possibly
-// loose some info. Sorry, that's the best we could do.
-ABSL_CONST_INIT absl::base_internal::SpinLock g_decorators_mu(
-    absl::kConstInit, absl::base_internal::SCHEDULE_KERNEL_ONLY);
-
-const int kMaxFileMappingHints = 8;
-int g_num_file_mapping_hints;
-FileMappingHint g_file_mapping_hints[kMaxFileMappingHints];
-// Protects g_file_mapping_hints.
-ABSL_CONST_INIT absl::base_internal::SpinLock g_file_mapping_mu(
-    absl::kConstInit, absl::base_internal::SCHEDULE_KERNEL_ONLY);
-
-// Async-signal-safe function to zero a buffer.
-// memset() is not guaranteed to be async-signal-safe.
-static void SafeMemZero(void* p, size_t size) {
-  unsigned char *c = static_cast<unsigned char *>(p);
-  while (size--) {
-    *c++ = 0;
-  }
-}
-
-struct ObjFile {
-  ObjFile()
-      : filename(nullptr),
-        start_addr(nullptr),
-        end_addr(nullptr),
-        offset(0),
-        fd(-1),
-        elf_type(-1) {
-    SafeMemZero(&elf_header, sizeof(elf_header));
-    SafeMemZero(&phdr[0], sizeof(phdr));
-  }
-
-  char *filename;
-  const void *start_addr;
-  const void *end_addr;
-  uint64_t offset;
-
-  // The following fields are initialized on the first access to the
-  // object file.
-  int fd;
-  int elf_type;
-  ElfW(Ehdr) elf_header;
-
-  // PT_LOAD program header describing executable code.
-  // Normally we expect just one, but SWIFT binaries have two.
-  std::array<ElfW(Phdr), 2> phdr;
-};
-
-// Build 4-way associative cache for symbols. Within each cache line, symbols
-// are replaced in LRU order.
-enum {
-  ASSOCIATIVITY = 4,
-};
-struct SymbolCacheLine {
-  const void *pc[ASSOCIATIVITY];
-  char *name[ASSOCIATIVITY];
-
-  // age[i] is incremented when a line is accessed. it's reset to zero if the
-  // i'th entry is read.
-  uint32_t age[ASSOCIATIVITY];
-};
-
-// ---------------------------------------------------------------
-// An async-signal-safe arena for LowLevelAlloc
-static std::atomic<base_internal::LowLevelAlloc::Arena *> g_sig_safe_arena;
-
-static base_internal::LowLevelAlloc::Arena *SigSafeArena() {
-  return g_sig_safe_arena.load(std::memory_order_acquire);
-}
-
-static void InitSigSafeArena() {
-  if (SigSafeArena() == nullptr) {
-    base_internal::LowLevelAlloc::Arena *new_arena =
-        base_internal::LowLevelAlloc::NewArena(
-            base_internal::LowLevelAlloc::kAsyncSignalSafe);
-    base_internal::LowLevelAlloc::Arena *old_value = nullptr;
-    if (!g_sig_safe_arena.compare_exchange_strong(old_value, new_arena,
-                                                  std::memory_order_release,
-                                                  std::memory_order_relaxed)) {
-      // We lost a race to allocate an arena; deallocate.
-      base_internal::LowLevelAlloc::DeleteArena(new_arena);
-    }
-  }
-}
-
-// ---------------------------------------------------------------
-// An AddrMap is a vector of ObjFile, using SigSafeArena() for allocation.
-
-class AddrMap {
- public:
-  AddrMap() : size_(0), allocated_(0), obj_(nullptr) {}
-  ~AddrMap() { base_internal::LowLevelAlloc::Free(obj_); }
-  int Size() const { return size_; }
-  ObjFile *At(int i) { return &obj_[i]; }
-  ObjFile *Add();
-  void Clear();
-
- private:
-  int size_;       // count of valid elements (<= allocated_)
-  int allocated_;  // count of allocated elements
-  ObjFile *obj_;   // array of allocated_ elements
-  AddrMap(const AddrMap &) = delete;
-  AddrMap &operator=(const AddrMap &) = delete;
-};
-
-void AddrMap::Clear() {
-  for (int i = 0; i != size_; i++) {
-    At(i)->~ObjFile();
-  }
-  size_ = 0;
-}
-
-ObjFile *AddrMap::Add() {
-  if (size_ == allocated_) {
-    int new_allocated = allocated_ * 2 + 50;
-    ObjFile *new_obj_ =
-        static_cast<ObjFile *>(base_internal::LowLevelAlloc::AllocWithArena(
-            new_allocated * sizeof(*new_obj_), SigSafeArena()));
-    if (obj_) {
-      memcpy(new_obj_, obj_, allocated_ * sizeof(*new_obj_));
-      base_internal::LowLevelAlloc::Free(obj_);
-    }
-    obj_ = new_obj_;
-    allocated_ = new_allocated;
-  }
-  return new (&obj_[size_++]) ObjFile;
-}
-
-// ---------------------------------------------------------------
-
-enum FindSymbolResult { SYMBOL_NOT_FOUND = 1, SYMBOL_TRUNCATED, SYMBOL_FOUND };
-
-class Symbolizer {
- public:
-  Symbolizer();
-  ~Symbolizer();
-  const char *GetSymbol(const void *const pc);
-
- private:
-  char *CopyString(const char *s) {
-    int len = strlen(s);
-    char *dst = static_cast<char *>(
-        base_internal::LowLevelAlloc::AllocWithArena(len + 1, SigSafeArena()));
-    ABSL_RAW_CHECK(dst != nullptr, "out of memory");
-    memcpy(dst, s, len + 1);
-    return dst;
-  }
-  ObjFile *FindObjFile(const void *const start,
-                       size_t size) ABSL_ATTRIBUTE_NOINLINE;
-  static bool RegisterObjFile(const char *filename,
-                              const void *const start_addr,
-                              const void *const end_addr, uint64_t offset,
-                              void *arg);
-  SymbolCacheLine *GetCacheLine(const void *const pc);
-  const char *FindSymbolInCache(const void *const pc);
-  const char *InsertSymbolInCache(const void *const pc, const char *name);
-  void AgeSymbols(SymbolCacheLine *line);
-  void ClearAddrMap();
-  FindSymbolResult GetSymbolFromObjectFile(const ObjFile &obj,
-                                           const void *const pc,
-                                           const ptrdiff_t relocation,
-                                           char *out, int out_size,
-                                           char *tmp_buf, int tmp_buf_size);
-
-  enum {
-    SYMBOL_BUF_SIZE = 3072,
-    TMP_BUF_SIZE = 1024,
-    SYMBOL_CACHE_LINES = 128,
-  };
-
-  AddrMap addr_map_;
-
-  bool ok_;
-  bool addr_map_read_;
-
-  char symbol_buf_[SYMBOL_BUF_SIZE];
-
-  // tmp_buf_ will be used to store arrays of ElfW(Shdr) and ElfW(Sym)
-  // so we ensure that tmp_buf_ is properly aligned to store either.
-  alignas(16) char tmp_buf_[TMP_BUF_SIZE];
-  static_assert(alignof(ElfW(Shdr)) <= 16,
-                "alignment of tmp buf too small for Shdr");
-  static_assert(alignof(ElfW(Sym)) <= 16,
-                "alignment of tmp buf too small for Sym");
-
-  SymbolCacheLine symbol_cache_[SYMBOL_CACHE_LINES];
-};
-
-static std::atomic<Symbolizer *> g_cached_symbolizer;
-
-}  // namespace
-
-static int SymbolizerSize() {
-#if defined(__wasm__) || defined(__asmjs__)
-  int pagesize = getpagesize();
-#else
-  int pagesize = sysconf(_SC_PAGESIZE);
-#endif
-  return ((sizeof(Symbolizer) - 1) / pagesize + 1) * pagesize;
-}
-
-// Return (and set null) g_cached_symbolized_state if it is not null.
-// Otherwise return a new symbolizer.
-static Symbolizer *AllocateSymbolizer() {
-  InitSigSafeArena();
-  Symbolizer *symbolizer =
-      g_cached_symbolizer.exchange(nullptr, std::memory_order_acquire);
-  if (symbolizer != nullptr) {
-    return symbolizer;
-  }
-  return new (base_internal::LowLevelAlloc::AllocWithArena(
-      SymbolizerSize(), SigSafeArena())) Symbolizer();
-}
-
-// Set g_cached_symbolize_state to s if it is null, otherwise
-// delete s.
-static void FreeSymbolizer(Symbolizer *s) {
-  Symbolizer *old_cached_symbolizer = nullptr;
-  if (!g_cached_symbolizer.compare_exchange_strong(old_cached_symbolizer, s,
-                                                   std::memory_order_release,
-                                                   std::memory_order_relaxed)) {
-    s->~Symbolizer();
-    base_internal::LowLevelAlloc::Free(s);
-  }
-}
-
-Symbolizer::Symbolizer() : ok_(true), addr_map_read_(false) {
-  for (SymbolCacheLine &symbol_cache_line : symbol_cache_) {
-    for (size_t j = 0; j < ABSL_ARRAYSIZE(symbol_cache_line.name); ++j) {
-      symbol_cache_line.pc[j] = nullptr;
-      symbol_cache_line.name[j] = nullptr;
-      symbol_cache_line.age[j] = 0;
-    }
-  }
-}
-
-Symbolizer::~Symbolizer() {
-  for (SymbolCacheLine &symbol_cache_line : symbol_cache_) {
-    for (char *s : symbol_cache_line.name) {
-      base_internal::LowLevelAlloc::Free(s);
-    }
-  }
-  ClearAddrMap();
-}
-
-// We don't use assert() since it's not guaranteed to be
-// async-signal-safe.  Instead we define a minimal assertion
-// macro. So far, we don't need pretty printing for __FILE__, etc.
-#define SAFE_ASSERT(expr) ((expr) ? static_cast<void>(0) : abort())
-
-// Read up to "count" bytes from file descriptor "fd" into the buffer
-// starting at "buf" while handling short reads and EINTR.  On
-// success, return the number of bytes read.  Otherwise, return -1.
-static ssize_t ReadPersistent(int fd, void *buf, size_t count) {
-  SAFE_ASSERT(fd >= 0);
-  SAFE_ASSERT(count <= SSIZE_MAX);
-  char *buf0 = reinterpret_cast<char *>(buf);
-  size_t num_bytes = 0;
-  while (num_bytes < count) {
-    ssize_t len;
-    NO_INTR(len = read(fd, buf0 + num_bytes, count - num_bytes));
-    if (len < 0) {  // There was an error other than EINTR.
-      ABSL_RAW_LOG(WARNING, "read failed: errno=%d", errno);
-      return -1;
-    }
-    if (len == 0) {  // Reached EOF.
-      break;
-    }
-    num_bytes += len;
-  }
-  SAFE_ASSERT(num_bytes <= count);
-  return static_cast<ssize_t>(num_bytes);
-}
-
-// Read up to "count" bytes from "offset" in the file pointed by file
-// descriptor "fd" into the buffer starting at "buf".  On success,
-// return the number of bytes read.  Otherwise, return -1.
-static ssize_t ReadFromOffset(const int fd, void *buf, const size_t count,
-                              const off_t offset) {
-  off_t off = lseek(fd, offset, SEEK_SET);
-  if (off == (off_t)-1) {
-    ABSL_RAW_LOG(WARNING, "lseek(%d, %ju, SEEK_SET) failed: errno=%d", fd,
-                 static_cast<uintmax_t>(offset), errno);
-    return -1;
-  }
-  return ReadPersistent(fd, buf, count);
-}
-
-// Try reading exactly "count" bytes from "offset" bytes in a file
-// pointed by "fd" into the buffer starting at "buf" while handling
-// short reads and EINTR.  On success, return true. Otherwise, return
-// false.
-static bool ReadFromOffsetExact(const int fd, void *buf, const size_t count,
-                                const off_t offset) {
-  ssize_t len = ReadFromOffset(fd, buf, count, offset);
-  return len >= 0 && static_cast<size_t>(len) == count;
-}
-
-// Returns elf_header.e_type if the file pointed by fd is an ELF binary.
-static int FileGetElfType(const int fd) {
-  ElfW(Ehdr) elf_header;
-  if (!ReadFromOffsetExact(fd, &elf_header, sizeof(elf_header), 0)) {
-    return -1;
-  }
-  if (memcmp(elf_header.e_ident, ELFMAG, SELFMAG) != 0) {
-    return -1;
-  }
-  return elf_header.e_type;
-}
-
-// Read the section headers in the given ELF binary, and if a section
-// of the specified type is found, set the output to this section header
-// and return true.  Otherwise, return false.
-// To keep stack consumption low, we would like this function to not get
-// inlined.
-static ABSL_ATTRIBUTE_NOINLINE bool GetSectionHeaderByType(
-    const int fd, ElfW(Half) sh_num, const off_t sh_offset, ElfW(Word) type,
-    ElfW(Shdr) * out, char *tmp_buf, int tmp_buf_size) {
-  ElfW(Shdr) *buf = reinterpret_cast<ElfW(Shdr) *>(tmp_buf);
-  const int buf_entries = tmp_buf_size / sizeof(buf[0]);
-  const int buf_bytes = buf_entries * sizeof(buf[0]);
-
-  for (int i = 0; i < sh_num;) {
-    const ssize_t num_bytes_left = (sh_num - i) * sizeof(buf[0]);
-    const ssize_t num_bytes_to_read =
-        (buf_bytes > num_bytes_left) ? num_bytes_left : buf_bytes;
-    const off_t offset = sh_offset + i * sizeof(buf[0]);
-    const ssize_t len = ReadFromOffset(fd, buf, num_bytes_to_read, offset);
-    if (len % sizeof(buf[0]) != 0) {
-      ABSL_RAW_LOG(
-          WARNING,
-          "Reading %zd bytes from offset %ju returned %zd which is not a "
-          "multiple of %zu.",
-          num_bytes_to_read, static_cast<uintmax_t>(offset), len,
-          sizeof(buf[0]));
-      return false;
-    }
-    const ssize_t num_headers_in_buf = len / sizeof(buf[0]);
-    SAFE_ASSERT(num_headers_in_buf <= buf_entries);
-    for (int j = 0; j < num_headers_in_buf; ++j) {
-      if (buf[j].sh_type == type) {
-        *out = buf[j];
-        return true;
-      }
-    }
-    i += num_headers_in_buf;
-  }
-  return false;
-}
-
-// There is no particular reason to limit section name to 63 characters,
-// but there has (as yet) been no need for anything longer either.
-const int kMaxSectionNameLen = 64;
-
-bool ForEachSection(int fd,
-                    const std::function<bool(absl::string_view name,
-                                             const ElfW(Shdr) &)> &callback) {
-  ElfW(Ehdr) elf_header;
-  if (!ReadFromOffsetExact(fd, &elf_header, sizeof(elf_header), 0)) {
-    return false;
-  }
-
-  ElfW(Shdr) shstrtab;
-  off_t shstrtab_offset =
-      (elf_header.e_shoff + elf_header.e_shentsize * elf_header.e_shstrndx);
-  if (!ReadFromOffsetExact(fd, &shstrtab, sizeof(shstrtab), shstrtab_offset)) {
-    return false;
-  }
-
-  for (int i = 0; i < elf_header.e_shnum; ++i) {
-    ElfW(Shdr) out;
-    off_t section_header_offset =
-        (elf_header.e_shoff + elf_header.e_shentsize * i);
-    if (!ReadFromOffsetExact(fd, &out, sizeof(out), section_header_offset)) {
-      return false;
-    }
-    off_t name_offset = shstrtab.sh_offset + out.sh_name;
-    char header_name[kMaxSectionNameLen];
-    ssize_t n_read =
-        ReadFromOffset(fd, &header_name, kMaxSectionNameLen, name_offset);
-    if (n_read == -1) {
-      return false;
-    } else if (n_read > kMaxSectionNameLen) {
-      // Long read?
-      return false;
-    }
-
-    absl::string_view name(header_name, strnlen(header_name, n_read));
-    if (!callback(name, out)) {
-      break;
-    }
-  }
-  return true;
-}
-
-// name_len should include terminating '\0'.
-bool GetSectionHeaderByName(int fd, const char *name, size_t name_len,
-                            ElfW(Shdr) * out) {
-  char header_name[kMaxSectionNameLen];
-  if (sizeof(header_name) < name_len) {
-    ABSL_RAW_LOG(WARNING,
-                 "Section name '%s' is too long (%zu); "
-                 "section will not be found (even if present).",
-                 name, name_len);
-    // No point in even trying.
-    return false;
-  }
-
-  ElfW(Ehdr) elf_header;
-  if (!ReadFromOffsetExact(fd, &elf_header, sizeof(elf_header), 0)) {
-    return false;
-  }
-
-  ElfW(Shdr) shstrtab;
-  off_t shstrtab_offset =
-      (elf_header.e_shoff + elf_header.e_shentsize * elf_header.e_shstrndx);
-  if (!ReadFromOffsetExact(fd, &shstrtab, sizeof(shstrtab), shstrtab_offset)) {
-    return false;
-  }
-
-  for (int i = 0; i < elf_header.e_shnum; ++i) {
-    off_t section_header_offset =
-        (elf_header.e_shoff + elf_header.e_shentsize * i);
-    if (!ReadFromOffsetExact(fd, out, sizeof(*out), section_header_offset)) {
-      return false;
-    }
-    off_t name_offset = shstrtab.sh_offset + out->sh_name;
-    ssize_t n_read = ReadFromOffset(fd, &header_name, name_len, name_offset);
-    if (n_read < 0) {
-      return false;
-    } else if (static_cast<size_t>(n_read) != name_len) {
-      // Short read -- name could be at end of file.
-      continue;
-    }
-    if (memcmp(header_name, name, name_len) == 0) {
-      return true;
-    }
-  }
-  return false;
-}
-
-// Compare symbols at in the same address.
-// Return true if we should pick symbol1.
-static bool ShouldPickFirstSymbol(const ElfW(Sym) & symbol1,
-                                  const ElfW(Sym) & symbol2) {
-  // If one of the symbols is weak and the other is not, pick the one
-  // this is not a weak symbol.
-  char bind1 = ELF_ST_BIND(symbol1.st_info);
-  char bind2 = ELF_ST_BIND(symbol1.st_info);
-  if (bind1 == STB_WEAK && bind2 != STB_WEAK) return false;
-  if (bind2 == STB_WEAK && bind1 != STB_WEAK) return true;
-
-  // If one of the symbols has zero size and the other is not, pick the
-  // one that has non-zero size.
-  if (symbol1.st_size != 0 && symbol2.st_size == 0) {
-    return true;
-  }
-  if (symbol1.st_size == 0 && symbol2.st_size != 0) {
-    return false;
-  }
-
-  // If one of the symbols has no type and the other is not, pick the
-  // one that has a type.
-  char type1 = ELF_ST_TYPE(symbol1.st_info);
-  char type2 = ELF_ST_TYPE(symbol1.st_info);
-  if (type1 != STT_NOTYPE && type2 == STT_NOTYPE) {
-    return true;
-  }
-  if (type1 == STT_NOTYPE && type2 != STT_NOTYPE) {
-    return false;
-  }
-
-  // Pick the first one, if we still cannot decide.
-  return true;
-}
-
-// Return true if an address is inside a section.
-static bool InSection(const void *address, const ElfW(Shdr) * section) {
-  const char *start = reinterpret_cast<const char *>(section->sh_addr);
-  size_t size = static_cast<size_t>(section->sh_size);
-  return start <= address && address < (start + size);
-}
-
-static const char *ComputeOffset(const char *base, ptrdiff_t offset) {
-  // Note: cast to uintptr_t to avoid undefined behavior when base evaluates to
-  // zero and offset is non-zero.
-  return reinterpret_cast<const char *>(
-      reinterpret_cast<uintptr_t>(base) + offset);
-}
-
-// Read a symbol table and look for the symbol containing the
-// pc. Iterate over symbols in a symbol table and look for the symbol
-// containing "pc".  If the symbol is found, and its name fits in
-// out_size, the name is written into out and SYMBOL_FOUND is returned.
-// If the name does not fit, truncated name is written into out,
-// and SYMBOL_TRUNCATED is returned. Out is NUL-terminated.
-// If the symbol is not found, SYMBOL_NOT_FOUND is returned;
-// To keep stack consumption low, we would like this function to not get
-// inlined.
-static ABSL_ATTRIBUTE_NOINLINE FindSymbolResult FindSymbol(
-    const void *const pc, const int fd, char *out, int out_size,
-    ptrdiff_t relocation, const ElfW(Shdr) * strtab, const ElfW(Shdr) * symtab,
-    const ElfW(Shdr) * opd, char *tmp_buf, int tmp_buf_size) {
-  if (symtab == nullptr) {
-    return SYMBOL_NOT_FOUND;
-  }
-
-  // Read multiple symbols at once to save read() calls.
-  ElfW(Sym) *buf = reinterpret_cast<ElfW(Sym) *>(tmp_buf);
-  const int buf_entries = tmp_buf_size / sizeof(buf[0]);
-
-  const int num_symbols = symtab->sh_size / symtab->sh_entsize;
-
-  // On platforms using an .opd section (PowerPC & IA64), a function symbol
-  // has the address of a function descriptor, which contains the real
-  // starting address.  However, we do not always want to use the real
-  // starting address because we sometimes want to symbolize a function
-  // pointer into the .opd section, e.g. FindSymbol(&foo,...).
-  const bool pc_in_opd =
-      kPlatformUsesOPDSections && opd != nullptr && InSection(pc, opd);
-  const bool deref_function_descriptor_pointer =
-      kPlatformUsesOPDSections && opd != nullptr && !pc_in_opd;
-
-  ElfW(Sym) best_match;
-  SafeMemZero(&best_match, sizeof(best_match));
-  bool found_match = false;
-  for (int i = 0; i < num_symbols;) {
-    off_t offset = symtab->sh_offset + i * symtab->sh_entsize;
-    const int num_remaining_symbols = num_symbols - i;
-    const int entries_in_chunk = std::min(num_remaining_symbols, buf_entries);
-    const int bytes_in_chunk = entries_in_chunk * sizeof(buf[0]);
-    const ssize_t len = ReadFromOffset(fd, buf, bytes_in_chunk, offset);
-    SAFE_ASSERT(len % sizeof(buf[0]) == 0);
-    const ssize_t num_symbols_in_buf = len / sizeof(buf[0]);
-    SAFE_ASSERT(num_symbols_in_buf <= entries_in_chunk);
-    for (int j = 0; j < num_symbols_in_buf; ++j) {
-      const ElfW(Sym) &symbol = buf[j];
-
-      // For a DSO, a symbol address is relocated by the loading address.
-      // We keep the original address for opd redirection below.
-      const char *const original_start_address =
-          reinterpret_cast<const char *>(symbol.st_value);
-      const char *start_address =
-          ComputeOffset(original_start_address, relocation);
-
-      if (deref_function_descriptor_pointer &&
-          InSection(original_start_address, opd)) {
-        // The opd section is mapped into memory.  Just dereference
-        // start_address to get the first double word, which points to the
-        // function entry.
-        start_address = *reinterpret_cast<const char *const *>(start_address);
-      }
-
-      // If pc is inside the .opd section, it points to a function descriptor.
-      const size_t size = pc_in_opd ? kFunctionDescriptorSize : symbol.st_size;
-      const void *const end_address = ComputeOffset(start_address, size);
-      if (symbol.st_value != 0 &&  // Skip null value symbols.
-          symbol.st_shndx != 0 &&  // Skip undefined symbols.
-#ifdef STT_TLS
-          ELF_ST_TYPE(symbol.st_info) != STT_TLS &&  // Skip thread-local data.
-#endif                                               // STT_TLS
-          ((start_address <= pc && pc < end_address) ||
-           (start_address == pc && pc == end_address))) {
-        if (!found_match || ShouldPickFirstSymbol(symbol, best_match)) {
-          found_match = true;
-          best_match = symbol;
-        }
-      }
-    }
-    i += num_symbols_in_buf;
-  }
-
-  if (found_match) {
-    const size_t off = strtab->sh_offset + best_match.st_name;
-    const ssize_t n_read = ReadFromOffset(fd, out, out_size, off);
-    if (n_read <= 0) {
-      // This should never happen.
-      ABSL_RAW_LOG(WARNING,
-                   "Unable to read from fd %d at offset %zu: n_read = %zd", fd,
-                   off, n_read);
-      return SYMBOL_NOT_FOUND;
-    }
-    ABSL_RAW_CHECK(n_read <= out_size, "ReadFromOffset read too much data.");
-
-    // strtab->sh_offset points into .strtab-like section that contains
-    // NUL-terminated strings: '\0foo\0barbaz\0...".
-    //
-    // sh_offset+st_name points to the start of symbol name, but we don't know
-    // how long the symbol is, so we try to read as much as we have space for,
-    // and usually over-read (i.e. there is a NUL somewhere before n_read).
-    if (memchr(out, '\0', n_read) == nullptr) {
-      // Either out_size was too small (n_read == out_size and no NUL), or
-      // we tried to read past the EOF (n_read < out_size) and .strtab is
-      // corrupt (missing terminating NUL; should never happen for valid ELF).
-      out[n_read - 1] = '\0';
-      return SYMBOL_TRUNCATED;
-    }
-    return SYMBOL_FOUND;
-  }
-
-  return SYMBOL_NOT_FOUND;
-}
-
-// Get the symbol name of "pc" from the file pointed by "fd".  Process
-// both regular and dynamic symbol tables if necessary.
-// See FindSymbol() comment for description of return value.
-FindSymbolResult Symbolizer::GetSymbolFromObjectFile(
-    const ObjFile &obj, const void *const pc, const ptrdiff_t relocation,
-    char *out, int out_size, char *tmp_buf, int tmp_buf_size) {
-  ElfW(Shdr) symtab;
-  ElfW(Shdr) strtab;
-  ElfW(Shdr) opd;
-  ElfW(Shdr) *opd_ptr = nullptr;
-
-  // On platforms using an .opd sections for function descriptor, read
-  // the section header.  The .opd section is in data segment and should be
-  // loaded but we check that it is mapped just to be extra careful.
-  if (kPlatformUsesOPDSections) {
-    if (GetSectionHeaderByName(obj.fd, kOpdSectionName,
-                               sizeof(kOpdSectionName) - 1, &opd) &&
-        FindObjFile(reinterpret_cast<const char *>(opd.sh_addr) + relocation,
-                    opd.sh_size) != nullptr) {
-      opd_ptr = &opd;
-    } else {
-      return SYMBOL_NOT_FOUND;
-    }
-  }
-
-  // Consult a regular symbol table, then fall back to the dynamic symbol table.
-  for (const auto symbol_table_type : {SHT_SYMTAB, SHT_DYNSYM}) {
-    if (!GetSectionHeaderByType(obj.fd, obj.elf_header.e_shnum,
-                                obj.elf_header.e_shoff, symbol_table_type,
-                                &symtab, tmp_buf, tmp_buf_size)) {
-      continue;
-    }
-    if (!ReadFromOffsetExact(
-            obj.fd, &strtab, sizeof(strtab),
-            obj.elf_header.e_shoff + symtab.sh_link * sizeof(symtab))) {
-      continue;
-    }
-    const FindSymbolResult rc =
-        FindSymbol(pc, obj.fd, out, out_size, relocation, &strtab, &symtab,
-                   opd_ptr, tmp_buf, tmp_buf_size);
-    if (rc != SYMBOL_NOT_FOUND) {
-      return rc;
-    }
-  }
-
-  return SYMBOL_NOT_FOUND;
-}
-
-namespace {
-// Thin wrapper around a file descriptor so that the file descriptor
-// gets closed for sure.
-class FileDescriptor {
- public:
-  explicit FileDescriptor(int fd) : fd_(fd) {}
-  FileDescriptor(const FileDescriptor &) = delete;
-  FileDescriptor &operator=(const FileDescriptor &) = delete;
-
-  ~FileDescriptor() {
-    if (fd_ >= 0) {
-      NO_INTR(close(fd_));
-    }
-  }
-
-  int get() const { return fd_; }
-
- private:
-  const int fd_;
-};
-
-// Helper class for reading lines from file.
-//
-// Note: we don't use ProcMapsIterator since the object is big (it has
-// a 5k array member) and uses async-unsafe functions such as sscanf()
-// and snprintf().
-class LineReader {
- public:
-  explicit LineReader(int fd, char *buf, int buf_len)
-      : fd_(fd),
-        buf_len_(buf_len),
-        buf_(buf),
-        bol_(buf),
-        eol_(buf),
-        eod_(buf) {}
-
-  LineReader(const LineReader &) = delete;
-  LineReader &operator=(const LineReader &) = delete;
-
-  // Read '\n'-terminated line from file.  On success, modify "bol"
-  // and "eol", then return true.  Otherwise, return false.
-  //
-  // Note: if the last line doesn't end with '\n', the line will be
-  // dropped.  It's an intentional behavior to make the code simple.
-  bool ReadLine(const char **bol, const char **eol) {
-    if (BufferIsEmpty()) {  // First time.
-      const ssize_t num_bytes = ReadPersistent(fd_, buf_, buf_len_);
-      if (num_bytes <= 0) {  // EOF or error.
-        return false;
-      }
-      eod_ = buf_ + num_bytes;
-      bol_ = buf_;
-    } else {
-      bol_ = eol_ + 1;            // Advance to the next line in the buffer.
-      SAFE_ASSERT(bol_ <= eod_);  // "bol_" can point to "eod_".
-      if (!HasCompleteLine()) {
-        const int incomplete_line_length = eod_ - bol_;
-        // Move the trailing incomplete line to the beginning.
-        memmove(buf_, bol_, incomplete_line_length);
-        // Read text from file and append it.
-        char *const append_pos = buf_ + incomplete_line_length;
-        const int capacity_left = buf_len_ - incomplete_line_length;
-        const ssize_t num_bytes =
-            ReadPersistent(fd_, append_pos, capacity_left);
-        if (num_bytes <= 0) {  // EOF or error.
-          return false;
-        }
-        eod_ = append_pos + num_bytes;
-        bol_ = buf_;
-      }
-    }
-    eol_ = FindLineFeed();
-    if (eol_ == nullptr) {  // '\n' not found.  Malformed line.
-      return false;
-    }
-    *eol_ = '\0';  // Replace '\n' with '\0'.
-
-    *bol = bol_;
-    *eol = eol_;
-    return true;
-  }
-
- private:
-  char *FindLineFeed() const {
-    return reinterpret_cast<char *>(memchr(bol_, '\n', eod_ - bol_));
-  }
-
-  bool BufferIsEmpty() const { return buf_ == eod_; }
-
-  bool HasCompleteLine() const {
-    return !BufferIsEmpty() && FindLineFeed() != nullptr;
-  }
-
-  const int fd_;
-  const int buf_len_;
-  char *const buf_;
-  char *bol_;
-  char *eol_;
-  const char *eod_;  // End of data in "buf_".
-};
-}  // namespace
-
-// Place the hex number read from "start" into "*hex".  The pointer to
-// the first non-hex character or "end" is returned.
-static const char *GetHex(const char *start, const char *end,
-                          uint64_t *const value) {
-  uint64_t hex = 0;
-  const char *p;
-  for (p = start; p < end; ++p) {
-    int ch = *p;
-    if ((ch >= '0' && ch <= '9') || (ch >= 'A' && ch <= 'F') ||
-        (ch >= 'a' && ch <= 'f')) {
-      hex = (hex << 4) | (ch < 'A' ? ch - '0' : (ch & 0xF) + 9);
-    } else {  // Encountered the first non-hex character.
-      break;
-    }
-  }
-  SAFE_ASSERT(p <= end);
-  *value = hex;
-  return p;
-}
-
-static const char *GetHex(const char *start, const char *end,
-                          const void **const addr) {
-  uint64_t hex = 0;
-  const char *p = GetHex(start, end, &hex);
-  *addr = reinterpret_cast<void *>(hex);
-  return p;
-}
-
-// Normally we are only interested in "r?x" maps.
-// On the PowerPC, function pointers point to descriptors in the .opd
-// section.  The descriptors themselves are not executable code, so
-// we need to relax the check below to "r??".
-static bool ShouldUseMapping(const char *const flags) {
-  return flags[0] == 'r' && (kPlatformUsesOPDSections || flags[2] == 'x');
-}
-
-// Read /proc/self/maps and run "callback" for each mmapped file found.  If
-// "callback" returns false, stop scanning and return true. Else continue
-// scanning /proc/self/maps. Return true if no parse error is found.
-static ABSL_ATTRIBUTE_NOINLINE bool ReadAddrMap(
-    bool (*callback)(const char *filename, const void *const start_addr,
-                     const void *const end_addr, uint64_t offset, void *arg),
-    void *arg, void *tmp_buf, int tmp_buf_size) {
-  // Use /proc/self/task/<pid>/maps instead of /proc/self/maps. The latter
-  // requires kernel to stop all threads, and is significantly slower when there
-  // are 1000s of threads.
-  char maps_path[80];
-  snprintf(maps_path, sizeof(maps_path), "/proc/self/task/%d/maps", getpid());
-
-  int maps_fd;
-  NO_INTR(maps_fd = open(maps_path, O_RDONLY));
-  FileDescriptor wrapped_maps_fd(maps_fd);
-  if (wrapped_maps_fd.get() < 0) {
-    ABSL_RAW_LOG(WARNING, "%s: errno=%d", maps_path, errno);
-    return false;
-  }
-
-  // Iterate over maps and look for the map containing the pc.  Then
-  // look into the symbol tables inside.
-  LineReader reader(wrapped_maps_fd.get(), static_cast<char *>(tmp_buf),
-                    tmp_buf_size);
-  while (true) {
-    const char *cursor;
-    const char *eol;
-    if (!reader.ReadLine(&cursor, &eol)) {  // EOF or malformed line.
-      break;
-    }
-
-    const char *line = cursor;
-    const void *start_address;
-    // Start parsing line in /proc/self/maps.  Here is an example:
-    //
-    // 08048000-0804c000 r-xp 00000000 08:01 2142121    /bin/cat
-    //
-    // We want start address (08048000), end address (0804c000), flags
-    // (r-xp) and file name (/bin/cat).
-
-    // Read start address.
-    cursor = GetHex(cursor, eol, &start_address);
-    if (cursor == eol || *cursor != '-') {
-      ABSL_RAW_LOG(WARNING, "Corrupt /proc/self/maps line: %s", line);
-      return false;
-    }
-    ++cursor;  // Skip '-'.
-
-    // Read end address.
-    const void *end_address;
-    cursor = GetHex(cursor, eol, &end_address);
-    if (cursor == eol || *cursor != ' ') {
-      ABSL_RAW_LOG(WARNING, "Corrupt /proc/self/maps line: %s", line);
-      return false;
-    }
-    ++cursor;  // Skip ' '.
-
-    // Read flags.  Skip flags until we encounter a space or eol.
-    const char *const flags_start = cursor;
-    while (cursor < eol && *cursor != ' ') {
-      ++cursor;
-    }
-    // We expect at least four letters for flags (ex. "r-xp").
-    if (cursor == eol || cursor < flags_start + 4) {
-      ABSL_RAW_LOG(WARNING, "Corrupt /proc/self/maps: %s", line);
-      return false;
-    }
-
-    // Check flags.
-    if (!ShouldUseMapping(flags_start)) {
-      continue;  // We skip this map.
-    }
-    ++cursor;  // Skip ' '.
-
-    // Read file offset.
-    uint64_t offset;
-    cursor = GetHex(cursor, eol, &offset);
-    ++cursor;  // Skip ' '.
-
-    // Skip to file name.  "cursor" now points to dev.  We need to skip at least
-    // two spaces for dev and inode.
-    int num_spaces = 0;
-    while (cursor < eol) {
-      if (*cursor == ' ') {
-        ++num_spaces;
-      } else if (num_spaces >= 2) {
-        // The first non-space character after  skipping two spaces
-        // is the beginning of the file name.
-        break;
-      }
-      ++cursor;
-    }
-
-    // Check whether this entry corresponds to our hint table for the true
-    // filename.
-    bool hinted =
-        GetFileMappingHint(&start_address, &end_address, &offset, &cursor);
-    if (!hinted && (cursor == eol || cursor[0] == '[')) {
-      // not an object file, typically [vdso] or [vsyscall]
-      continue;
-    }
-    if (!callback(cursor, start_address, end_address, offset, arg)) break;
-  }
-  return true;
-}
-
-// Find the objfile mapped in address region containing [addr, addr + len).
-ObjFile *Symbolizer::FindObjFile(const void *const addr, size_t len) {
-  for (int i = 0; i < 2; ++i) {
-    if (!ok_) return nullptr;
-
-    // Read /proc/self/maps if necessary
-    if (!addr_map_read_) {
-      addr_map_read_ = true;
-      if (!ReadAddrMap(RegisterObjFile, this, tmp_buf_, TMP_BUF_SIZE)) {
-        ok_ = false;
-        return nullptr;
-      }
-    }
-
-    int lo = 0;
-    int hi = addr_map_.Size();
-    while (lo < hi) {
-      int mid = (lo + hi) / 2;
-      if (addr < addr_map_.At(mid)->end_addr) {
-        hi = mid;
-      } else {
-        lo = mid + 1;
-      }
-    }
-    if (lo != addr_map_.Size()) {
-      ObjFile *obj = addr_map_.At(lo);
-      SAFE_ASSERT(obj->end_addr > addr);
-      if (addr >= obj->start_addr &&
-          reinterpret_cast<const char *>(addr) + len <= obj->end_addr)
-        return obj;
-    }
-
-    // The address mapping may have changed since it was last read.  Retry.
-    ClearAddrMap();
-  }
-  return nullptr;
-}
-
-void Symbolizer::ClearAddrMap() {
-  for (int i = 0; i != addr_map_.Size(); i++) {
-    ObjFile *o = addr_map_.At(i);
-    base_internal::LowLevelAlloc::Free(o->filename);
-    if (o->fd >= 0) {
-      NO_INTR(close(o->fd));
-    }
-  }
-  addr_map_.Clear();
-  addr_map_read_ = false;
-}
-
-// Callback for ReadAddrMap to register objfiles in an in-memory table.
-bool Symbolizer::RegisterObjFile(const char *filename,
-                                 const void *const start_addr,
-                                 const void *const end_addr, uint64_t offset,
-                                 void *arg) {
-  Symbolizer *impl = static_cast<Symbolizer *>(arg);
-
-  // Files are supposed to be added in the increasing address order.  Make
-  // sure that's the case.
-  int addr_map_size = impl->addr_map_.Size();
-  if (addr_map_size != 0) {
-    ObjFile *old = impl->addr_map_.At(addr_map_size - 1);
-    if (old->end_addr > end_addr) {
-      ABSL_RAW_LOG(ERROR,
-                   "Unsorted addr map entry: 0x%" PRIxPTR ": %s <-> 0x%" PRIxPTR
-                   ": %s",
-                   reinterpret_cast<uintptr_t>(end_addr), filename,
-                   reinterpret_cast<uintptr_t>(old->end_addr), old->filename);
-      return true;
-    } else if (old->end_addr == end_addr) {
-      // The same entry appears twice. This sometimes happens for [vdso].
-      if (old->start_addr != start_addr ||
-          strcmp(old->filename, filename) != 0) {
-        ABSL_RAW_LOG(ERROR,
-                     "Duplicate addr 0x%" PRIxPTR ": %s <-> 0x%" PRIxPTR ": %s",
-                     reinterpret_cast<uintptr_t>(end_addr), filename,
-                     reinterpret_cast<uintptr_t>(old->end_addr), old->filename);
-      }
-      return true;
-    }
-  }
-  ObjFile *obj = impl->addr_map_.Add();
-  obj->filename = impl->CopyString(filename);
-  obj->start_addr = start_addr;
-  obj->end_addr = end_addr;
-  obj->offset = offset;
-  obj->elf_type = -1;  // filled on demand
-  obj->fd = -1;        // opened on demand
-  return true;
-}
-
-// This function wraps the Demangle function to provide an interface
-// where the input symbol is demangled in-place.
-// To keep stack consumption low, we would like this function to not
-// get inlined.
-static ABSL_ATTRIBUTE_NOINLINE void DemangleInplace(char *out, int out_size,
-                                                    char *tmp_buf,
-                                                    int tmp_buf_size) {
-  if (Demangle(out, tmp_buf, tmp_buf_size)) {
-    // Demangling succeeded. Copy to out if the space allows.
-    int len = strlen(tmp_buf);
-    if (len + 1 <= out_size) {  // +1 for '\0'.
-      SAFE_ASSERT(len < tmp_buf_size);
-      memmove(out, tmp_buf, len + 1);
-    }
-  }
-}
-
-SymbolCacheLine *Symbolizer::GetCacheLine(const void *const pc) {
-  uintptr_t pc0 = reinterpret_cast<uintptr_t>(pc);
-  pc0 >>= 3;  // drop the low 3 bits
-
-  // Shuffle bits.
-  pc0 ^= (pc0 >> 6) ^ (pc0 >> 12) ^ (pc0 >> 18);
-  return &symbol_cache_[pc0 % SYMBOL_CACHE_LINES];
-}
-
-void Symbolizer::AgeSymbols(SymbolCacheLine *line) {
-  for (uint32_t &age : line->age) {
-    ++age;
-  }
-}
-
-const char *Symbolizer::FindSymbolInCache(const void *const pc) {
-  if (pc == nullptr) return nullptr;
-
-  SymbolCacheLine *line = GetCacheLine(pc);
-  for (size_t i = 0; i < ABSL_ARRAYSIZE(line->pc); ++i) {
-    if (line->pc[i] == pc) {
-      AgeSymbols(line);
-      line->age[i] = 0;
-      return line->name[i];
-    }
-  }
-  return nullptr;
-}
-
-const char *Symbolizer::InsertSymbolInCache(const void *const pc,
-                                            const char *name) {
-  SAFE_ASSERT(pc != nullptr);
-
-  SymbolCacheLine *line = GetCacheLine(pc);
-  uint32_t max_age = 0;
-  int oldest_index = -1;
-  for (size_t i = 0; i < ABSL_ARRAYSIZE(line->pc); ++i) {
-    if (line->pc[i] == nullptr) {
-      AgeSymbols(line);
-      line->pc[i] = pc;
-      line->name[i] = CopyString(name);
-      line->age[i] = 0;
-      return line->name[i];
-    }
-    if (line->age[i] >= max_age) {
-      max_age = line->age[i];
-      oldest_index = i;
-    }
-  }
-
-  AgeSymbols(line);
-  ABSL_RAW_CHECK(oldest_index >= 0, "Corrupt cache");
-  base_internal::LowLevelAlloc::Free(line->name[oldest_index]);
-  line->pc[oldest_index] = pc;
-  line->name[oldest_index] = CopyString(name);
-  line->age[oldest_index] = 0;
-  return line->name[oldest_index];
-}
-
-static void MaybeOpenFdFromSelfExe(ObjFile *obj) {
-  if (memcmp(obj->start_addr, ELFMAG, SELFMAG) != 0) {
-    return;
-  }
-  int fd = open("/proc/self/exe", O_RDONLY);
-  if (fd == -1) {
-    return;
-  }
-  // Verify that contents of /proc/self/exe matches in-memory image of
-  // the binary. This can fail if the "deleted" binary is in fact not
-  // the main executable, or for binaries that have the first PT_LOAD
-  // segment smaller than 4K. We do it in four steps so that the
-  // buffer is smaller and we don't consume too much stack space.
-  const char *mem = reinterpret_cast<const char *>(obj->start_addr);
-  for (int i = 0; i < 4; ++i) {
-    char buf[1024];
-    ssize_t n = read(fd, buf, sizeof(buf));
-    if (n != sizeof(buf) || memcmp(buf, mem, sizeof(buf)) != 0) {
-      close(fd);
-      return;
-    }
-    mem += sizeof(buf);
-  }
-  obj->fd = fd;
-}
-
-static bool MaybeInitializeObjFile(ObjFile *obj) {
-  if (obj->fd < 0) {
-    obj->fd = open(obj->filename, O_RDONLY);
-
-    if (obj->fd < 0) {
-      // Getting /proc/self/exe here means that we were hinted.
-      if (strcmp(obj->filename, "/proc/self/exe") == 0) {
-        // /proc/self/exe may be inaccessible (due to setuid, etc.), so try
-        // accessing the binary via argv0.
-        if (argv0_value != nullptr) {
-          obj->fd = open(argv0_value, O_RDONLY);
-        }
-      } else {
-        MaybeOpenFdFromSelfExe(obj);
-      }
-    }
-
-    if (obj->fd < 0) {
-      ABSL_RAW_LOG(WARNING, "%s: open failed: errno=%d", obj->filename, errno);
-      return false;
-    }
-    obj->elf_type = FileGetElfType(obj->fd);
-    if (obj->elf_type < 0) {
-      ABSL_RAW_LOG(WARNING, "%s: wrong elf type: %d", obj->filename,
-                   obj->elf_type);
-      return false;
-    }
-
-    if (!ReadFromOffsetExact(obj->fd, &obj->elf_header, sizeof(obj->elf_header),
-                             0)) {
-      ABSL_RAW_LOG(WARNING, "%s: failed to read elf header", obj->filename);
-      return false;
-    }
-    const int phnum = obj->elf_header.e_phnum;
-    const int phentsize = obj->elf_header.e_phentsize;
-    size_t phoff = obj->elf_header.e_phoff;
-    size_t num_executable_load_segments = 0;
-    for (int j = 0; j < phnum; j++) {
-      ElfW(Phdr) phdr;
-      if (!ReadFromOffsetExact(obj->fd, &phdr, sizeof(phdr), phoff)) {
-        ABSL_RAW_LOG(WARNING, "%s: failed to read program header %d",
-                     obj->filename, j);
-        return false;
-      }
-      phoff += phentsize;
-      constexpr int rx = PF_X | PF_R;
-      if (phdr.p_type != PT_LOAD || (phdr.p_flags & rx) != rx) {
-        // Not a LOAD segment, or not executable code.
-        continue;
-      }
-      if (num_executable_load_segments < obj->phdr.size()) {
-        memcpy(&obj->phdr[num_executable_load_segments++], &phdr, sizeof(phdr));
-      } else {
-        ABSL_RAW_LOG(WARNING, "%s: too many executable LOAD segments",
-                     obj->filename);
-        break;
-      }
-    }
-    if (num_executable_load_segments == 0) {
-      // This object has no "r-x" LOAD segments. That's unexpected.
-      ABSL_RAW_LOG(WARNING, "%s: no executable LOAD segments", obj->filename);
-      return false;
-    }
-  }
-  return true;
-}
-
-// The implementation of our symbolization routine.  If it
-// successfully finds the symbol containing "pc" and obtains the
-// symbol name, returns pointer to that symbol. Otherwise, returns nullptr.
-// If any symbol decorators have been installed via InstallSymbolDecorator(),
-// they are called here as well.
-// To keep stack consumption low, we would like this function to not
-// get inlined.
-const char *Symbolizer::GetSymbol(const void *const pc) {
-  const char *entry = FindSymbolInCache(pc);
-  if (entry != nullptr) {
-    return entry;
-  }
-  symbol_buf_[0] = '\0';
-
-  ObjFile *const obj = FindObjFile(pc, 1);
-  ptrdiff_t relocation = 0;
-  int fd = -1;
-  if (obj != nullptr) {
-    if (MaybeInitializeObjFile(obj)) {
-      const size_t start_addr = reinterpret_cast<size_t>(obj->start_addr);
-      if (obj->elf_type == ET_DYN && start_addr >= obj->offset) {
-        // This object was relocated.
-        //
-        // For obj->offset > 0, adjust the relocation since a mapping at offset
-        // X in the file will have a start address of [true relocation]+X.
-        relocation = start_addr - obj->offset;
-
-        // Note: some binaries have multiple "rx" LOAD segments. We must
-        // find the right one.
-        ElfW(Phdr) *phdr = nullptr;
-        for (size_t j = 0; j < obj->phdr.size(); j++) {
-          ElfW(Phdr) &p = obj->phdr[j];
-          if (p.p_type != PT_LOAD) {
-            // We only expect PT_LOADs. This must be PT_NULL that we didn't
-            // write over (i.e. we exhausted all interesting PT_LOADs).
-            ABSL_RAW_CHECK(p.p_type == PT_NULL, "unexpected p_type");
-            break;
-          }
-          if (pc < reinterpret_cast<void *>(start_addr + p.p_memsz)) {
-            phdr = &p;
-            break;
-          }
-        }
-        if (phdr == nullptr) {
-          // That's unexpected. Hope for the best.
-          ABSL_RAW_LOG(
-              WARNING,
-              "%s: unable to find LOAD segment for pc: %p, start_addr: %zx",
-              obj->filename, pc, start_addr);
-        } else {
-          // Adjust relocation in case phdr.p_vaddr != 0.
-          // This happens for binaries linked with `lld --rosegment`, and for
-          // binaries linked with BFD `ld -z separate-code`.
-          relocation -= phdr->p_vaddr - phdr->p_offset;
-        }
-      }
-
-      fd = obj->fd;
-      if (GetSymbolFromObjectFile(*obj, pc, relocation, symbol_buf_,
-                                  sizeof(symbol_buf_), tmp_buf_,
-                                  sizeof(tmp_buf_)) == SYMBOL_FOUND) {
-        // Only try to demangle the symbol name if it fit into symbol_buf_.
-        DemangleInplace(symbol_buf_, sizeof(symbol_buf_), tmp_buf_,
-                        sizeof(tmp_buf_));
-      }
-    }
-  } else {
-#if ABSL_HAVE_VDSO_SUPPORT
-    VDSOSupport vdso;
-    if (vdso.IsPresent()) {
-      VDSOSupport::SymbolInfo symbol_info;
-      if (vdso.LookupSymbolByAddress(pc, &symbol_info)) {
-        // All VDSO symbols are known to be short.
-        size_t len = strlen(symbol_info.name);
-        ABSL_RAW_CHECK(len + 1 < sizeof(symbol_buf_),
-                       "VDSO symbol unexpectedly long");
-        memcpy(symbol_buf_, symbol_info.name, len + 1);
-      }
-    }
-#endif
-  }
-
-  if (g_decorators_mu.TryLock()) {
-    if (g_num_decorators > 0) {
-      SymbolDecoratorArgs decorator_args = {
-          pc,       relocation,       fd,     symbol_buf_, sizeof(symbol_buf_),
-          tmp_buf_, sizeof(tmp_buf_), nullptr};
-      for (int i = 0; i < g_num_decorators; ++i) {
-        decorator_args.arg = g_decorators[i].arg;
-        g_decorators[i].fn(&decorator_args);
-      }
-    }
-    g_decorators_mu.Unlock();
-  }
-  if (symbol_buf_[0] == '\0') {
-    return nullptr;
-  }
-  symbol_buf_[sizeof(symbol_buf_) - 1] = '\0';  // Paranoia.
-  return InsertSymbolInCache(pc, symbol_buf_);
-}
-
-bool RemoveAllSymbolDecorators(void) {
-  if (!g_decorators_mu.TryLock()) {
-    // Someone else is using decorators. Get out.
-    return false;
-  }
-  g_num_decorators = 0;
-  g_decorators_mu.Unlock();
-  return true;
-}
-
-bool RemoveSymbolDecorator(int ticket) {
-  if (!g_decorators_mu.TryLock()) {
-    // Someone else is using decorators. Get out.
-    return false;
-  }
-  for (int i = 0; i < g_num_decorators; ++i) {
-    if (g_decorators[i].ticket == ticket) {
-      while (i < g_num_decorators - 1) {
-        g_decorators[i] = g_decorators[i + 1];
-        ++i;
-      }
-      g_num_decorators = i;
-      break;
-    }
-  }
-  g_decorators_mu.Unlock();
-  return true;  // Decorator is known to be removed.
-}
-
-int InstallSymbolDecorator(SymbolDecorator decorator, void *arg) {
-  static int ticket = 0;
-
-  if (!g_decorators_mu.TryLock()) {
-    // Someone else is using decorators. Get out.
-    return -2;
-  }
-  int ret = ticket;
-  if (g_num_decorators >= kMaxDecorators) {
-    ret = -1;
-  } else {
-    g_decorators[g_num_decorators] = {decorator, arg, ticket++};
-    ++g_num_decorators;
-  }
-  g_decorators_mu.Unlock();
-  return ret;
-}
-
-bool RegisterFileMappingHint(const void *start, const void *end, uint64_t offset,
-                             const char *filename) {
-  SAFE_ASSERT(start <= end);
-  SAFE_ASSERT(filename != nullptr);
-
-  InitSigSafeArena();
-
-  if (!g_file_mapping_mu.TryLock()) {
-    return false;
-  }
-
-  bool ret = true;
-  if (g_num_file_mapping_hints >= kMaxFileMappingHints) {
-    ret = false;
-  } else {
-    // TODO(ckennelly): Move this into a string copy routine.
-    int len = strlen(filename);
-    char *dst = static_cast<char *>(
-        base_internal::LowLevelAlloc::AllocWithArena(len + 1, SigSafeArena()));
-    ABSL_RAW_CHECK(dst != nullptr, "out of memory");
-    memcpy(dst, filename, len + 1);
-
-    auto &hint = g_file_mapping_hints[g_num_file_mapping_hints++];
-    hint.start = start;
-    hint.end = end;
-    hint.offset = offset;
-    hint.filename = dst;
-  }
-
-  g_file_mapping_mu.Unlock();
-  return ret;
-}
-
-bool GetFileMappingHint(const void **start, const void **end, uint64_t *offset,
-                        const char **filename) {
-  if (!g_file_mapping_mu.TryLock()) {
-    return false;
-  }
-  bool found = false;
-  for (int i = 0; i < g_num_file_mapping_hints; i++) {
-    if (g_file_mapping_hints[i].start <= *start &&
-        *end <= g_file_mapping_hints[i].end) {
-      // We assume that the start_address for the mapping is the base
-      // address of the ELF section, but when [start_address,end_address) is
-      // not strictly equal to [hint.start, hint.end), that assumption is
-      // invalid.
-      //
-      // This uses the hint's start address (even though hint.start is not
-      // necessarily equal to start_address) to ensure the correct
-      // relocation is computed later.
-      *start = g_file_mapping_hints[i].start;
-      *end = g_file_mapping_hints[i].end;
-      *offset = g_file_mapping_hints[i].offset;
-      *filename = g_file_mapping_hints[i].filename;
-      found = true;
-      break;
-    }
-  }
-  g_file_mapping_mu.Unlock();
-  return found;
-}
-
-}  // namespace debugging_internal
-
-bool Symbolize(const void *pc, char *out, int out_size) {
-  // Symbolization is very slow under tsan.
-  ABSL_ANNOTATE_IGNORE_READS_AND_WRITES_BEGIN();
-  SAFE_ASSERT(out_size >= 0);
-  debugging_internal::Symbolizer *s = debugging_internal::AllocateSymbolizer();
-  const char *name = s->GetSymbol(pc);
-  bool ok = false;
-  if (name != nullptr && out_size > 0) {
-    strncpy(out, name, out_size);
-    ok = true;
-    if (out[out_size - 1] != '\0') {
-      // strncpy() does not '\0' terminate when it truncates.  Do so, with
-      // trailing ellipsis.
-      static constexpr char kEllipsis[] = "...";
-      int ellipsis_size =
-          std::min(implicit_cast<int>(strlen(kEllipsis)), out_size - 1);
-      memcpy(out + out_size - ellipsis_size - 1, kEllipsis, ellipsis_size);
-      out[out_size - 1] = '\0';
-    }
-  }
-  debugging_internal::FreeSymbolizer(s);
-  ABSL_ANNOTATE_IGNORE_READS_AND_WRITES_END();
-  return ok;
-}
-
-ABSL_NAMESPACE_END
-}  // namespace absl
-
-extern "C" bool AbslInternalGetFileMappingHint(const void **start,
-                                               const void **end, uint64_t *offset,
-                                               const char **filename) {
-  return absl::debugging_internal::GetFileMappingHint(start, end, offset,
-                                                      filename);
-}