1 files changed, 101 insertions, 0 deletions
diff --git a/llvm/lib/DebugInfo/PDB/Native/PublicsStream.cpp b/llvm/lib/DebugInfo/PDB/Native/PublicsStream.cpp
new file mode 100644
index 000000000000..a33bf03bf8fb
--- /dev/null
+++ b/llvm/lib/DebugInfo/PDB/Native/PublicsStream.cpp
@@ -0,0 +1,101 @@
+//===- PublicsStream.cpp - PDB Public Symbol Stream -----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// The data structures defined in this file are based on the reference
+// implementation which is available at
+// https://github.com/Microsoft/microsoft-pdb/blob/master/PDB/dbi/gsi.h
+//
+// When you are reading the reference source code, you'd find the
+// information below useful.
+//
+//  - ppdb1->m_fMinimalDbgInfo seems to be always true.
+//  - SMALLBUCKETS macro is defined.
+//
+// The reference doesn't compile, so I learned just by reading code.
+// It's not guaranteed to be correct.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/PDB/Native/PublicsStream.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/DebugInfo/CodeView/SymbolRecord.h"
+#include "llvm/DebugInfo/MSF/MappedBlockStream.h"
+#include "llvm/DebugInfo/PDB/Native/RawError.h"
+#include "llvm/Support/BinaryStreamReader.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Error.h"
+#include <algorithm>
+#include <cstdint>
+
+using namespace llvm;
+using namespace llvm::msf;
+using namespace llvm::support;
+using namespace llvm::pdb;
+
+PublicsStream::PublicsStream(std::unique_ptr<MappedBlockStream> Stream)
+    : Stream(std::move(Stream)) {}
+
+PublicsStream::~PublicsStream() = default;
+
+uint32_t PublicsStream::getSymHash() const { return Header->SymHash; }
+uint16_t PublicsStream::getThunkTableSection() const {
+  return Header->ISectThunkTable;
+}
+uint32_t PublicsStream::getThunkTableOffset() const {
+  return Header->OffThunkTable;
+}
+
+// Publics stream contains fixed-size headers and a serialized hash table.
+// This implementation is not complete yet. It reads till the end of the
+// stream so that we verify the stream is at least not corrupted. However,
+// we skip over the hash table which we believe contains information about
+// public symbols.
+Error PublicsStream::reload() {
+  BinaryStreamReader Reader(*Stream);
+
+  // Check stream size.
+  if (Reader.bytesRemaining() <
+      sizeof(PublicsStreamHeader) + sizeof(GSIHashHeader))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Publics Stream does not contain a header.");
+
+  // Read PSGSIHDR struct.
+  if (Reader.readObject(Header))
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Publics Stream does not contain a header.");
+
+  // Read the hash table.
+  if (auto E = PublicsTable.read(Reader))
+    return E;
+
+  // Something called "address map" follows.
+  uint32_t NumAddressMapEntries = Header->AddrMap / sizeof(uint32_t);
+  if (auto EC = Reader.readArray(AddressMap, NumAddressMapEntries))
+    return joinErrors(std::move(EC),
+                      make_error<RawError>(raw_error_code::corrupt_file,
+                                           "Could not read an address map."));
+
+  // Something called "thunk map" follows.
+  if (auto EC = Reader.readArray(ThunkMap, Header->NumThunks))
+    return joinErrors(std::move(EC),
+                      make_error<RawError>(raw_error_code::corrupt_file,
+                                           "Could not read a thunk map."));
+
+  // Something called "section map" follows.
+  if (Reader.bytesRemaining() > 0) {
+    if (auto EC = Reader.readArray(SectionOffsets, Header->NumSections))
+      return joinErrors(std::move(EC),
+                        make_error<RawError>(raw_error_code::corrupt_file,
+                                             "Could not read a section map."));
+  }
+
+  if (Reader.bytesRemaining() > 0)
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Corrupted publics stream.");
+  return Error::success();
+}