llvm/lib/Object/BuildID.cpp

   1 //===- llvm/Object/BuildID.cpp - Build ID ---------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 ///
   9 /// \file
  10 /// This file defines a library for handling Build IDs and using them to find
  11 /// debug info.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/Object/BuildID.h"
  16
  17 #include "llvm/Object/ELFObjectFile.h"
  18 #include "llvm/Support/FileSystem.h"
  19 #include "llvm/Support/Path.h"
  20
  21 using namespace llvm;
  22 using namespace llvm::object;
  23
  24 namespace {
  25
  26 template <typename ELFT> BuildIDRef getBuildID(const ELFFile<ELFT> &Obj) {
  27   auto PhdrsOrErr = Obj.program_headers();
  28   if (!PhdrsOrErr) {
  29     consumeError(PhdrsOrErr.takeError());
  30     return {};
  31   }
  32   for (const auto &P : *PhdrsOrErr) {
  33     if (P.p_type != ELF::PT_NOTE)
  34       continue;
  35     Error Err = Error::success();
  36     for (auto N : Obj.notes(P, Err))
  37       if (N.getType() == ELF::NT_GNU_BUILD_ID &&
  38           N.getName() == ELF::ELF_NOTE_GNU)
  39         return N.getDesc(P.p_align);
  40     consumeError(std::move(Err));
  41   }
  42   return {};
  43 }
  44
  45 } // namespace
  46
  47 BuildID llvm::object::parseBuildID(StringRef Str) {
  48   std::string Bytes;
  49   if (!tryGetFromHex(Str, Bytes))
  50     return {};
  51   ArrayRef<uint8_t> BuildID(reinterpret_cast<const uint8_t *>(Bytes.data()),
  52                             Bytes.size());
  53   return SmallVector<uint8_t>(BuildID.begin(), BuildID.end());
  54 }
  55
  56 BuildIDRef llvm::object::getBuildID(const ObjectFile *Obj) {
  57   if (auto *O = dyn_cast<ELFObjectFile<ELF32LE>>(Obj))
  58     return ::getBuildID(O->getELFFile());
  59   if (auto *O = dyn_cast<ELFObjectFile<ELF32BE>>(Obj))
  60     return ::getBuildID(O->getELFFile());
  61   if (auto *O = dyn_cast<ELFObjectFile<ELF64LE>>(Obj))
  62     return ::getBuildID(O->getELFFile());
  63   if (auto *O = dyn_cast<ELFObjectFile<ELF64BE>>(Obj))
  64     return ::getBuildID(O->getELFFile());
  65   return std::nullopt;
  66 }
  67
  68 std::optional<std::string> BuildIDFetcher::fetch(BuildIDRef BuildID) const {
  69   auto GetDebugPath = [&](StringRef Directory) {
  70     SmallString<128> Path{Directory};
  71     sys::path::append(Path, ".build-id",
  72                       llvm::toHex(BuildID[0], /*LowerCase=*/true),
  73                       llvm::toHex(BuildID.slice(1), /*LowerCase=*/true));
  74     Path += ".debug";
  75     return Path;
  76   };
  77   if (DebugFileDirectories.empty()) {
  78     SmallString<128> Path = GetDebugPath(
  79 #if defined(__NetBSD__)
  80         // Try /usr/libdata/debug/.build-id/../...
  81         "/usr/libdata/debug"
  82 #else
  83         // Try /usr/lib/debug/.build-id/../...
  84         "/usr/lib/debug"
  85 #endif
  86     );
  87     if (llvm::sys::fs::exists(Path))
  88       return std::string(Path);
  89   } else {
  90     for (const auto &Directory : DebugFileDirectories) {
  91       // Try <debug-file-directory>/.build-id/../...
  92       SmallString<128> Path = GetDebugPath(Directory);
  93       if (llvm::sys::fs::exists(Path))
  94         return std::string(Path);
  95     }
  96   }
  97   return std::nullopt;
  98 }