Revert "Add utils to read elf binary and get Build id"

This reverts commit 61248f1a.

Reason for revert: Suspected breaking component builds (bug 837817)

Original change's description:
> Add utils to read elf binary and get Build id
> 
> Adds code to parse elf binary to get build id from
> .note.gnu.build-id section. The build ID is needed to symbolize
> heap dumps from the users.
> 
> BUG=734705
> 
> Change-Id: If4365e232c060ba96071ba1e1c43618f9807e39c
> Reviewed-on: https://chromium-review.googlesource.com/1028995
> Commit-Queue: Siddhartha S <ssid@chromium.org>
> Reviewed-by: Lei Zhang <thestig@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#554304}

TBR=thestig@chromium.org,ssid@chromium.org

Change-Id: If512434b55bcc912990e3997a86f6f93722b15fb
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 734705
Reviewed-on: https://chromium-review.googlesource.com/1033795Reviewed-by: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554532}

base/BUILD.gn

@@ -1164,11 +1164,7 @@ jumbo_component("base") {
     ]
 
     if (is_linux) {
-      sources += [
-        "base_paths_posix.cc",
-        "debug/elf_reader_linux.cc",
-        "debug/elf_reader_linux.h",
-      ]
+      sources += [ "base_paths_posix.cc" ]
     }
   }
 
@@ -1268,8 +1264,6 @@ jumbo_component("base") {
     # Android uses some Linux sources, put those back.
     set_sources_assignment_filter([])
     sources += [
-      "debug/elf_reader_linux.cc",
-      "debug/elf_reader_linux.h",
       "debug/proc_maps_linux.cc",
       "debug/proc_maps_linux.h",
       "files/file_path_watcher_linux.cc",
@@ -2143,7 +2137,6 @@ test("base_unittests") {
     "debug/alias_unittest.cc",
     "debug/crash_logging_unittest.cc",
     "debug/debugger_unittest.cc",
-    "debug/elf_reader_linux_unittest.cc",
     "debug/leak_tracker_unittest.cc",
     "debug/proc_maps_linux_unittest.cc",
     "debug/stack_trace_unittest.cc",
@@ -2585,7 +2578,6 @@ test("base_unittests") {
     deps += [ "//testing/android/native_test:native_test_native_code" ]
     set_sources_assignment_filter([])
     sources += [
-      "debug/elf_reader_linux_unittest.cc",
       "debug/proc_maps_linux_unittest.cc",
       "trace_event/trace_event_android_unittest.cc",
     ]

base/debug/elf_reader_linux.cc

-// Copyright 2018 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "base/debug/elf_reader_linux.h"
-
-#include <arpa/inet.h>
-#include <elf.h>
-
-#include <vector>
-
-#include "base/bits.h"
-#include "base/containers/span.h"
-#include "base/sha1.h"
-#include "base/strings/stringprintf.h"
-
-extern char __executable_start;
-
-namespace base {
-namespace debug {
-
-namespace {
-
-#if __SIZEOF_POINTER__ == 4
-using Ehdr = Elf32_Ehdr;
-using Half = Elf32_Half;
-using Nhdr = Elf32_Nhdr;
-using Phdr = Elf32_Phdr;
-#else
-using Ehdr = Elf64_Ehdr;
-using Half = Elf64_Half;
-using Nhdr = Elf64_Nhdr;
-using Phdr = Elf64_Phdr;
-#endif
-
-using ElfSegment = span<const char>;
-
-Optional<std::string> ElfSegmentBuildIDNoteAsString(const ElfSegment& segment) {
-  const void* section_end = segment.data() + segment.size_bytes();
-  const Nhdr* note_header = reinterpret_cast<const Nhdr*>(segment.data());
-  while (note_header < section_end) {
-    if (note_header->n_type == NT_GNU_BUILD_ID)
-      break;
-    note_header = reinterpret_cast<const Nhdr*>(
-        reinterpret_cast<const char*>(note_header) + sizeof(Nhdr) +
-        bits::Align(note_header->n_namesz, 4) +
-        bits::Align(note_header->n_descsz, 4));
-  }
-
-  if (note_header >= section_end || note_header->n_descsz != kSHA1Length)
-    return nullopt;
-
-  const uint8_t* guid = reinterpret_cast<const uint8_t*>(note_header) +
-                        sizeof(Nhdr) + bits::Align(note_header->n_namesz, 4);
-
-  uint32_t dword = htonl(*reinterpret_cast<const int32_t*>(guid));
-  uint16_t word1 = htons(*reinterpret_cast<const int16_t*>(guid + 4));
-  uint16_t word2 = htons(*reinterpret_cast<const int16_t*>(guid + 6));
-  std::string identifier;
-  identifier.reserve(kSHA1Length * 2);  // as hex string
-  SStringPrintf(&identifier, "%08X%04X%04X", dword, word1, word2);
-  for (size_t i = 8; i < note_header->n_descsz; ++i)
-    StringAppendF(&identifier, "%02X", guid[i]);
-
-  return identifier;
-}
-
-std::vector<ElfSegment> FindElfSegments(const char* elf_base,
-                                        uint32_t segment_type) {
-  if (strncmp(static_cast<const char*>(elf_base), ELFMAG, SELFMAG) != 0)
-    return std::vector<ElfSegment>();
-
-  const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base);
-  const Phdr* phdrs =
-      reinterpret_cast<const Phdr*>(elf_base + elf_header->e_phoff);
-  std::vector<ElfSegment> segments;
-  for (Half i = 0; i < elf_header->e_phnum; ++i) {
-    if (phdrs[i].p_type == segment_type)
-      segments.push_back({elf_base + phdrs[i].p_offset, phdrs[i].p_filesz});
-  }
-  return segments;
-}
-
-}  // namespace
-
-Optional<std::string> ReadElfBuildId() {
-  // Elf program headers can have multiple PT_NOTE arrays.
-  std::vector<ElfSegment> segs = FindElfSegments(&__executable_start, PT_NOTE);
-  if (segs.empty())
-    return nullopt;
-  Optional<std::string> id;
-  for (const ElfSegment& seg : segs) {
-    id = ElfSegmentBuildIDNoteAsString(seg);
-    if (id)
-      return id;
-  }
-
-  return nullopt;
-}
-
-}  // namespace debug
-}  // namespace base

base/debug/elf_reader_linux.h

-// Copyright 2018 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef BASE_DEBUG_ELF_READER_LINUX_H_
-#define BASE_DEBUG_ELF_READER_LINUX_H_
-
-#include <string>
-
-#include "base/base_export.h"
-#include "base/optional.h"
-
-namespace base {
-namespace debug {
-
-// Returns the ELF section .note.gnu.build-id from current executable file, if
-// present.
-Optional<std::string> BASE_EXPORT ReadElfBuildId();
-
-}  // namespace debug
-}  // namespace base
-
-#endif  // BASE_DEBUG_ELF_READER_LINUX_H_

base/debug/elf_reader_linux_unittest.cc

-// Copyright 2018 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "base/debug/elf_reader_linux.h"
-
-#include "base/strings/string_util.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-namespace base {
-namespace debug {
-
-// The linker flag --build-id is passed only on official builds. Clang does not
-// enable it by default and we do not have build id section in non-official
-// builds.
-#if defined(OFFICIAL_BUILD)
-TEST(ElfReaderTest, ReadElfBuildId) {
-  Optional<std::string> build_id = ReadElfBuildId();
-  ASSERT_TRUE(build_id);
-  const size_t kGuidBytes = 20;
-  EXPECT_EQ(2 * kGuidBytes, build_id.value().size());
-  for (char c : *build_id) {
-    EXPECT_TRUE(IsHexDigit(c));
-    EXPECT_FALSE(IsAsciiLower(c));
-  }
-}
-#endif
-
-}  // namespace debug
-}  // namespace base