[Object] Add basic minidump support

Summary:
This patch adds basic support for reading minidump files. It contains
the definitions of various important minidump data structures (header,
stream directory), and of one minidump stream (SystemInfo). The ability
to read other streams will be added in follow-up patches. However, all
streams can be read even now as raw data, which means lldb's minidump
support (where this code is taken from) can be immediately rebased on
top of this patch as soon as it lands.

As we don't have any support for generating minidump files (yet), this
tests the code via unit tests with some small handcrafted binaries in
the form of c char arrays.

Reviewers: Bigcheese, jhenderson, zturner

Subscribers: srhines, dschuff, mgorny, fedor.sergeev, lemo, clayborg, JDevlieghere, aprantl, lldb-commits, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59291

llvm-svn: 356652

1 files changed, 77 insertions, 0 deletions

diff --git a/llvm/lib/Object/Minidump.cpp b/llvm/lib/Object/Minidump.cpp
new file mode 100644
index 00000000000..d0d49b4e8d3
--- /dev/null
+++ b/llvm/lib/Object/Minidump.cpp
@@ -0,0 +1,77 @@
+//===- Minidump.cpp - Minidump object file implementation -----------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Object/Minidump.h"
+#include "llvm/Object/Error.h"
+
+using namespace llvm;
+using namespace llvm::object;
+using namespace llvm::minidump;
+
+Optional<ArrayRef<uint8_t>>
+MinidumpFile::getRawStream(minidump::StreamType Type) const {
+  auto It = StreamMap.find(Type);
+  if (It != StreamMap.end())
+    return getRawStream(Streams[It->second]);
+  return None;
+}
+
+Expected<ArrayRef<uint8_t>>
+MinidumpFile::getDataSlice(ArrayRef<uint8_t> Data, size_t Offset, size_t Size) {
+  // Check for overflow.
+  if (Offset + Size < Offset || Offset + Size < Size ||
+      Offset + Size > Data.size())
+    return createEOFError();
+  return Data.slice(Offset, Size);
+}
+
+Expected<std::unique_ptr<MinidumpFile>>
+MinidumpFile::create(MemoryBufferRef Source) {
+  ArrayRef<uint8_t> Data = arrayRefFromStringRef(Source.getBuffer());
+  auto ExpectedHeader = getDataSliceAs<minidump::Header>(Data, 0, 1);
+  if (!ExpectedHeader)
+    return ExpectedHeader.takeError();
+
+  const minidump::Header &Hdr = (*ExpectedHeader)[0];
+  if (Hdr.Signature != Header::MagicSignature)
+    return createError("Invalid signature");
+  if ((Hdr.Version & 0xffff) != Header::MagicVersion)
+    return createError("Invalid version");
+
+  auto ExpectedStreams = getDataSliceAs<Directory>(Data, Hdr.StreamDirectoryRVA,
+                                                   Hdr.NumberOfStreams);
+  if (!ExpectedStreams)
+    return ExpectedStreams.takeError();
+
+  DenseMap<StreamType, std::size_t> StreamMap;
+  for (const auto &Stream : llvm::enumerate(*ExpectedStreams)) {
+    StreamType Type = Stream.value().Type;
+    const LocationDescriptor &Loc = Stream.value().Location;
+
+    auto ExpectedStream = getDataSlice(Data, Loc.RVA, Loc.DataSize);
+    if (!ExpectedStream)
+      return ExpectedStream.takeError();
+
+    if (Type == StreamType::Unused && Loc.DataSize == 0) {
+      // Ignore dummy streams. This is technically ill-formed, but a number of
+      // existing minidumps seem to contain such streams.
+      continue;
+    }
+
+    if (Type == DenseMapInfo<StreamType>::getEmptyKey() ||
+        Type == DenseMapInfo<StreamType>::getTombstoneKey())
+      return createError("Cannot handle one of the minidump streams");
+
+    // Update the directory map, checking for duplicate stream types.
+    if (!StreamMap.try_emplace(Type, Stream.index()).second)
+      return createError("Duplicate stream type");
+  }
+
+  return std::unique_ptr<MinidumpFile>(
+      new MinidumpFile(Source, Hdr, *ExpectedStreams, std::move(StreamMap)));
+}