From 6e0b1ce48e3cf95f447b932b03d8294903aa56e0 Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel@labath.sk>
Date: Tue, 8 Oct 2019 14:15:32 +0000
Subject: Object/minidump: Add support for the MemoryInfoList stream

Summary:
This patch adds the definitions of the constants and structures
necessary to interpret the MemoryInfoList minidump stream, as well as
the object::MinidumpFile interface to access the stream.

While the code is fairly simple, there is one important deviation from
the other minidump streams, which is worth calling out explicitly.
Unlike other "List" streams, the size of the records inside
MemoryInfoList stream is not known statically. Instead it is described
in the stream header. This makes it impossible to return
ArrayRef<MemoryInfo> from the accessor method, as it is done with other
streams. Instead, I create an iterator class, which can be parameterized
by the runtime size of the structure, and return
iterator_range<iterator> instead.

Reviewers: amccarth, jhenderson, clayborg

Subscribers: JosephTremoulet, zturner, markmentovai, lldb-commits, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68210

llvm-svn: 374051
---
 llvm/lib/Object/Minidump.cpp | 46 ++++++++++++++++++++++++++++++--------------
 1 file changed, 32 insertions(+), 14 deletions(-)

(limited to 'llvm/lib/Object')

diff --git a/llvm/lib/Object/Minidump.cpp b/llvm/lib/Object/Minidump.cpp
index 7b5b2155869..3e932fe7be2 100644
--- a/llvm/lib/Object/Minidump.cpp
+++ b/llvm/lib/Object/Minidump.cpp
@@ -53,13 +53,30 @@ Expected<std::string> MinidumpFile::getString(size_t Offset) const {
   return Result;
 }
 
+Expected<iterator_range<MinidumpFile::MemoryInfoIterator>>
+MinidumpFile::getMemoryInfoList() const {
+  Optional<ArrayRef<uint8_t>> Stream = getRawStream(StreamType::MemoryInfoList);
+  if (!Stream)
+    return createError("No such stream");
+  auto ExpectedHeader =
+      getDataSliceAs<minidump::MemoryInfoListHeader>(*Stream, 0, 1);
+  if (!ExpectedHeader)
+    return ExpectedHeader.takeError();
+  const minidump::MemoryInfoListHeader &H = ExpectedHeader.get()[0];
+  Expected<ArrayRef<uint8_t>> Data =
+      getDataSlice(*Stream, H.SizeOfHeader, H.SizeOfEntry * H.NumberOfEntries);
+  if (!Data)
+    return Data.takeError();
+  return make_range(MemoryInfoIterator(*Data, H.SizeOfEntry),
+                    MemoryInfoIterator({}, H.SizeOfEntry));
+}
+
 template <typename T>
-Expected<ArrayRef<T>> MinidumpFile::getListStream(StreamType Stream) const {
-  auto OptionalStream = getRawStream(Stream);
-  if (!OptionalStream)
+Expected<ArrayRef<T>> MinidumpFile::getListStream(StreamType Type) const {
+  Optional<ArrayRef<uint8_t>> Stream = getRawStream(Type);
+  if (!Stream)
     return createError("No such stream");
-  auto ExpectedSize =
-      getDataSliceAs<support::ulittle32_t>(*OptionalStream, 0, 1);
+  auto ExpectedSize = getDataSliceAs<support::ulittle32_t>(*Stream, 0, 1);
   if (!ExpectedSize)
     return ExpectedSize.takeError();
 
@@ -69,10 +86,10 @@ Expected<ArrayRef<T>> MinidumpFile::getListStream(StreamType Stream) const {
   // Some producers insert additional padding bytes to align the list to an
   // 8-byte boundary. Check for that by comparing the list size with the overall
   // stream size.
-  if (ListOffset + sizeof(T) * ListSize < OptionalStream->size())
+  if (ListOffset + sizeof(T) * ListSize < Stream->size())
     ListOffset = 8;
 
-  return getDataSliceAs<T>(*OptionalStream, ListOffset, ListSize);
+  return getDataSliceAs<T>(*Stream, ListOffset, ListSize);
 }
 template Expected<ArrayRef<Module>>
     MinidumpFile::getListStream(StreamType) const;
@@ -109,13 +126,14 @@ MinidumpFile::create(MemoryBufferRef Source) {
     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;
+  for (const auto &StreamDescriptor : llvm::enumerate(*ExpectedStreams)) {
+    StreamType Type = StreamDescriptor.value().Type;
+    const LocationDescriptor &Loc = StreamDescriptor.value().Location;
 
-    auto ExpectedStream = getDataSlice(Data, Loc.RVA, Loc.DataSize);
-    if (!ExpectedStream)
-      return ExpectedStream.takeError();
+    Expected<ArrayRef<uint8_t>> Stream =
+        getDataSlice(Data, Loc.RVA, Loc.DataSize);
+    if (!Stream)
+      return Stream.takeError();
 
     if (Type == StreamType::Unused && Loc.DataSize == 0) {
       // Ignore dummy streams. This is technically ill-formed, but a number of
@@ -128,7 +146,7 @@ MinidumpFile::create(MemoryBufferRef Source) {
       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)
+    if (!StreamMap.try_emplace(Type, StreamDescriptor.index()).second)
       return createError("Duplicate stream type");
   }
 
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