1//===- PublicsStream.cpp - PDB Public Symbol Stream -----------------------===//
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// The data structures defined in this file are based on the reference
10// implementation which is available at
11// https://github.com/Microsoft/microsoft-pdb/blob/master/PDB/dbi/gsi.h
12//
13// When you are reading the reference source code, you'd find the
14// information below useful.
15//
16//  - ppdb1->m_fMinimalDbgInfo seems to be always true.
17//  - SMALLBUCKETS macro is defined.
18//
19// The reference doesn't compile, so I learned just by reading code.
20// It's not guaranteed to be correct.
21//
22//===----------------------------------------------------------------------===//
23
24#include "llvm/DebugInfo/PDB/Native/PublicsStream.h"
25#include "llvm/ADT/iterator_range.h"
26#include "llvm/DebugInfo/CodeView/SymbolRecord.h"
27#include "llvm/DebugInfo/MSF/MappedBlockStream.h"
28#include "llvm/DebugInfo/PDB/Native/RawError.h"
29#include "llvm/Support/BinaryStreamReader.h"
30#include "llvm/Support/Endian.h"
31#include "llvm/Support/Error.h"
32#include <algorithm>
33#include <cstdint>
34
35using namespace llvm;
36using namespace llvm::msf;
37using namespace llvm::support;
38using namespace llvm::pdb;
39
40PublicsStream::PublicsStream(std::unique_ptr<MappedBlockStream> Stream)
41    : Stream(std::move(Stream)) {}
42
43PublicsStream::~PublicsStream() = default;
44
45uint32_t PublicsStream::getSymHash() const { return Header->SymHash; }
46uint16_t PublicsStream::getThunkTableSection() const {
47  return Header->ISectThunkTable;
48}
49uint32_t PublicsStream::getThunkTableOffset() const {
50  return Header->OffThunkTable;
51}
52
53// Publics stream contains fixed-size headers and a serialized hash table.
54// This implementation is not complete yet. It reads till the end of the
55// stream so that we verify the stream is at least not corrupted. However,
56// we skip over the hash table which we believe contains information about
57// public symbols.
58Error PublicsStream::reload() {
59  BinaryStreamReader Reader(*Stream);
60
61  // Check stream size.
62  if (Reader.bytesRemaining() <
63      sizeof(PublicsStreamHeader) + sizeof(GSIHashHeader))
64    return make_error<RawError>(raw_error_code::corrupt_file,
65                                "Publics Stream does not contain a header.");
66
67  // Read PSGSIHDR struct.
68  if (Reader.readObject(Header))
69    return make_error<RawError>(raw_error_code::corrupt_file,
70                                "Publics Stream does not contain a header.");
71
72  // Read the hash table.
73  if (auto E = PublicsTable.read(Reader))
74    return E;
75
76  // Something called "address map" follows.
77  uint32_t NumAddressMapEntries = Header->AddrMap / sizeof(uint32_t);
78  if (auto EC = Reader.readArray(AddressMap, NumAddressMapEntries))
79    return joinErrors(std::move(EC),
80                      make_error<RawError>(raw_error_code::corrupt_file,
81                                           "Could not read an address map."));
82
83  // Something called "thunk map" follows.
84  if (auto EC = Reader.readArray(ThunkMap, Header->NumThunks))
85    return joinErrors(std::move(EC),
86                      make_error<RawError>(raw_error_code::corrupt_file,
87                                           "Could not read a thunk map."));
88
89  // Something called "section map" follows.
90  if (Reader.bytesRemaining() > 0) {
91    if (auto EC = Reader.readArray(SectionOffsets, Header->NumSections))
92      return joinErrors(std::move(EC),
93                        make_error<RawError>(raw_error_code::corrupt_file,
94                                             "Could not read a section map."));
95  }
96
97  if (Reader.bytesRemaining() > 0)
98    return make_error<RawError>(raw_error_code::corrupt_file,
99                                "Corrupted publics stream.");
100  return Error::success();
101}
102