1 //===- PDBStringTable.cpp - PDB String Table ---------------------*- C++-*-===//
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 #include "llvm/DebugInfo/PDB/Native/PDBStringTable.h"
10 
11 #include "llvm/DebugInfo/PDB/Native/Hash.h"
12 #include "llvm/DebugInfo/PDB/Native/RawError.h"
13 #include "llvm/DebugInfo/PDB/Native/RawTypes.h"
14 #include "llvm/Support/BinaryStreamReader.h"
15 #include "llvm/Support/Endian.h"
16 
17 using namespace llvm;
18 using namespace llvm::support;
19 using namespace llvm::pdb;
20 
21 uint32_t PDBStringTable::getByteSize() const { return Header->ByteSize; }
22 uint32_t PDBStringTable::getNameCount() const { return NameCount; }
23 uint32_t PDBStringTable::getHashVersion() const { return Header->HashVersion; }
24 uint32_t PDBStringTable::getSignature() const { return Header->Signature; }
25 
26 Error PDBStringTable::readHeader(BinaryStreamReader &Reader) {
27   if (auto EC = Reader.readObject(Header))
28     return EC;
29 
30   if (Header->Signature != PDBStringTableSignature)
31     return make_error<RawError>(raw_error_code::corrupt_file,
32                                 "Invalid hash table signature");
33   if (Header->HashVersion != 1 && Header->HashVersion != 2)
34     return make_error<RawError>(raw_error_code::corrupt_file,
35                                 "Unsupported hash version");
36 
37   assert(Reader.bytesRemaining() == 0);
38   return Error::success();
39 }
40 
41 Error PDBStringTable::readStrings(BinaryStreamReader &Reader) {
42   BinaryStreamRef Stream;
43   if (auto EC = Reader.readStreamRef(Stream))
44     return EC;
45 
46   if (auto EC = Strings.initialize(Stream)) {
47     return joinErrors(std::move(EC),
48                       make_error<RawError>(raw_error_code::corrupt_file,
49                                            "Invalid hash table byte length"));
50   }
51 
52   assert(Reader.bytesRemaining() == 0);
53   return Error::success();
54 }
55 
56 const codeview::DebugStringTableSubsectionRef &
57 PDBStringTable::getStringTable() const {
58   return Strings;
59 }
60 
61 Error PDBStringTable::readHashTable(BinaryStreamReader &Reader) {
62   const support::ulittle32_t *HashCount;
63   if (auto EC = Reader.readObject(HashCount))
64     return EC;
65 
66   if (auto EC = Reader.readArray(IDs, *HashCount)) {
67     return joinErrors(std::move(EC),
68                       make_error<RawError>(raw_error_code::corrupt_file,
69                                            "Could not read bucket array"));
70   }
71 
72   return Error::success();
73 }
74 
75 Error PDBStringTable::readEpilogue(BinaryStreamReader &Reader) {
76   if (auto EC = Reader.readInteger(NameCount))
77     return EC;
78 
79   assert(Reader.bytesRemaining() == 0);
80   return Error::success();
81 }
82 
83 Error PDBStringTable::reload(BinaryStreamReader &Reader) {
84 
85   BinaryStreamReader SectionReader;
86 
87   std::tie(SectionReader, Reader) = Reader.split(sizeof(PDBStringTableHeader));
88   if (auto EC = readHeader(SectionReader))
89     return EC;
90 
91   std::tie(SectionReader, Reader) = Reader.split(Header->ByteSize);
92   if (auto EC = readStrings(SectionReader))
93     return EC;
94 
95   // We don't know how long the hash table is until we parse it, so let the
96   // function responsible for doing that figure it out.
97   if (auto EC = readHashTable(Reader))
98     return EC;
99 
100   std::tie(SectionReader, Reader) = Reader.split(sizeof(uint32_t));
101   if (auto EC = readEpilogue(SectionReader))
102     return EC;
103 
104   assert(Reader.bytesRemaining() == 0);
105   return Error::success();
106 }
107 
108 Expected<StringRef> PDBStringTable::getStringForID(uint32_t ID) const {
109   return Strings.getString(ID);
110 }
111 
112 Expected<uint32_t> PDBStringTable::getIDForString(StringRef Str) const {
113   uint32_t Hash =
114       (Header->HashVersion == 1) ? hashStringV1(Str) : hashStringV2(Str);
115   size_t Count = IDs.size();
116   uint32_t Start = Hash % Count;
117   for (size_t I = 0; I < Count; ++I) {
118     // The hash is just a starting point for the search, but if it
119     // doesn't work we should find the string no matter what, because
120     // we iterate the entire array.
121     uint32_t Index = (Start + I) % Count;
122 
123     // If we find 0, it means the item isn't in the hash table.
124     uint32_t ID = IDs[Index];
125     if (ID == 0)
126       return make_error<RawError>(raw_error_code::no_entry);
127     auto ExpectedStr = getStringForID(ID);
128     if (!ExpectedStr)
129       return ExpectedStr.takeError();
130 
131     if (*ExpectedStr == Str)
132       return ID;
133   }
134   return make_error<RawError>(raw_error_code::no_entry);
135 }
136 
137 FixedStreamArray<support::ulittle32_t> PDBStringTable::name_ids() const {
138   return IDs;
139 }
140