1// Copyright 2016 The Chromium OS Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "dso.h"
6
7#include <elf.h>
8#include <fcntl.h>
9#include <string.h>
10#include <sys/stat.h>
11#include <sys/sysmacros.h>
12#include <unistd.h>
13
14#include <algorithm>
15#include <vector>
16
17#include <build_id.h>
18#include <read_elf.h>
19
20#include "base/logging.h"
21#include "compat/string.h"
22#include "file_reader.h"
23
24namespace quipper {
25
26void InitializeLibelf() {
27  // Unnecessary.
28}
29
30bool ReadElfBuildId(const string &filename, string *buildid) {
31  BuildId id;
32  ElfStatus status = GetBuildIdFromElfFile(filename, &id);
33  if (status == ElfStatus::NO_ERROR) {
34    *buildid = id.ToString();
35    return true;
36  }
37  return false;
38}
39
40bool ReadElfBuildId(int fd, string *buildid) {
41  // TODO: Implement. b/74410255.
42  return false;
43}
44
45// read /sys/module/<module_name>/notes/.note.gnu.build-id
46bool ReadModuleBuildId(const string &module_name, string *buildid) {
47  string note_filename =
48      "/sys/module/" + module_name + "/notes/.note.gnu.build-id";
49
50  FileReader file(note_filename);
51  if (!file.IsOpen()) return false;
52
53  return ReadBuildIdNote(&file, buildid);
54}
55
56bool ReadBuildIdNote(DataReader *data, string *buildid) {
57  // Non-simpleperf implementation, as a reader is given.
58  Elf64_Nhdr note_header;
59
60  while (data->ReadData(sizeof(note_header), &note_header)) {
61    size_t name_size = Align<4>(note_header.n_namesz);
62    size_t desc_size = Align<4>(note_header.n_descsz);
63
64    string name;
65    if (!data->ReadString(name_size, &name)) return false;
66    string desc;
67    if (!data->ReadDataString(desc_size, &desc)) return false;
68    if (note_header.n_type == NT_GNU_BUILD_ID && name == ELF_NOTE_GNU) {
69      *buildid = desc;
70      return true;
71    }
72  }
73  return false;
74}
75
76bool IsKernelNonModuleName(string name) {
77  // List from kernel: tools/perf/util/dso.c : __kmod_path__parse()
78  static const std::vector<string> kKernelNonModuleNames{
79      "[kernel.kallsyms]",
80      "[guest.kernel.kallsyms",
81      "[vdso]",
82      "[vsyscall]",
83  };
84
85  for (const auto &n : kKernelNonModuleNames) {
86    if (name.compare(0, n.size(), n) == 0) return true;
87  }
88  return false;
89}
90
91// Do the |DSOInfo| and |struct stat| refer to the same inode?
92bool SameInode(const DSOInfo &dso, const struct stat *s) {
93  return dso.maj == major(s->st_dev) && dso.min == minor(s->st_dev) &&
94         dso.ino == s->st_ino;
95}
96
97}  // namespace quipper
98