1 //===- PublicsStream.cpp - PDB Public Symbol Stream -----------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // The data structures defined in this file are based on the reference
11 // implementation which is available at
12 // https://github.com/Microsoft/microsoft-pdb/blob/master/PDB/dbi/gsi.h
13 //
14 // When you are reading the reference source code, you'd find the
15 // information below useful.
16 //
17 //  - ppdb1->m_fMinimalDbgInfo seems to be always true.
18 //  - SMALLBUCKETS macro is defined.
19 //
20 // The reference doesn't compile, so I learned just by reading code.
21 // It's not guaranteed to be correct.
22 //
23 //===----------------------------------------------------------------------===//
24 
25 #include "llvm/DebugInfo/PDB/Native/PublicsStream.h"
26 #include "GSI.h"
27 #include "llvm/ADT/iterator_range.h"
28 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
29 #include "llvm/DebugInfo/MSF/MappedBlockStream.h"
30 #include "llvm/DebugInfo/PDB/Native/PDBFile.h"
31 #include "llvm/DebugInfo/PDB/Native/RawError.h"
32 #include "llvm/DebugInfo/PDB/Native/SymbolStream.h"
33 #include "llvm/Support/BinaryStreamReader.h"
34 #include "llvm/Support/Endian.h"
35 #include "llvm/Support/Error.h"
36 #include <algorithm>
37 #include <cstdint>
38 
39 using namespace llvm;
40 using namespace llvm::msf;
41 using namespace llvm::support;
42 using namespace llvm::pdb;
43 
44 PublicsStream::PublicsStream(PDBFile &File,
45                              std::unique_ptr<MappedBlockStream> Stream)
46     : Pdb(File), Stream(std::move(Stream)) {}
47 
48 PublicsStream::~PublicsStream() = default;
49 
50 uint32_t PublicsStream::getSymHash() const { return Header->SymHash; }
51 uint32_t PublicsStream::getAddrMap() const { return Header->AddrMap; }
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.
58 Error 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 and GSIHashHdr structs.
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   if (auto EC = readGSIHashHeader(HashHdr, Reader))
73     return EC;
74 
75   if (auto EC = readGSIHashRecords(HashRecords, HashHdr, Reader))
76     return EC;
77 
78   if (auto EC = readGSIHashBuckets(HashBuckets, HashBitmap, HashHdr, Reader))
79     return EC;
80   NumBuckets = HashBuckets.size();
81 
82   // Something called "address map" follows.
83   uint32_t NumAddressMapEntries = Header->AddrMap / sizeof(uint32_t);
84   if (auto EC = Reader.readArray(AddressMap, NumAddressMapEntries))
85     return joinErrors(std::move(EC),
86                       make_error<RawError>(raw_error_code::corrupt_file,
87                                            "Could not read an address map."));
88 
89   // Something called "thunk map" follows.
90   if (auto EC = Reader.readArray(ThunkMap, Header->NumThunks))
91     return joinErrors(std::move(EC),
92                       make_error<RawError>(raw_error_code::corrupt_file,
93                                            "Could not read a thunk map."));
94 
95   // Something called "section map" follows.
96   if (Reader.bytesRemaining() > 0) {
97     if (auto EC = Reader.readArray(SectionOffsets, Header->NumSections))
98       return joinErrors(std::move(EC),
99                         make_error<RawError>(raw_error_code::corrupt_file,
100                                              "Could not read a section map."));
101   }
102 
103   if (Reader.bytesRemaining() > 0)
104     return make_error<RawError>(raw_error_code::corrupt_file,
105                                 "Corrupted publics stream.");
106   return Error::success();
107 }
108 
109 iterator_range<codeview::CVSymbolArray::Iterator>
110 PublicsStream::getSymbols(bool *HadError) const {
111   auto SymbolS = Pdb.getPDBSymbolStream();
112   if (SymbolS.takeError()) {
113     codeview::CVSymbolArray::Iterator Iter;
114     return make_range(Iter, Iter);
115   }
116   SymbolStream &SS = SymbolS.get();
117 
118   return SS.getSymbols(HadError);
119 }
120 
121 Expected<const codeview::CVSymbolArray &>
122 PublicsStream::getSymbolArray() const {
123   auto SymbolS = Pdb.getPDBSymbolStream();
124   if (!SymbolS)
125     return SymbolS.takeError();
126 
127   return SymbolS->getSymbolArray();
128 }
129 
130 Error PublicsStream::commit() { return Error::success(); }
131