[pdb] handle missing pdb streams more gracefully

Summary: The code we use to read PDBs assumed that streams we ask it to read exist, and would read memory outside a vector and crash if this wasn't the case. This would, for example, cause llvm-pdbdump to crash on PDBs generated by lld. This patch handles such cases more gracefully: the PDB reading code in LLVM now reports errors when asked to get a stream that is not present, and llvm-pdbdump will report missing streams and continue processing streams that are present.

Reviewers: ruiu, zturner

Subscribers: thakis, amccarth

Differential Revision: https://reviews.llvm.org/D27325

llvm-svn: 288722

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp b/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
index 403c02b4268..e52c88a5bfb 100644
--- a/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
+++ b/llvm/lib/DebugInfo/MSF/MappedBlockStream.cpp
@@ -63,6 +63,7 @@ std::unique_ptr<MappedBlockStream>
 MappedBlockStream::createIndexedStream(const MSFLayout &Layout,
                                        const ReadableStream &MsfData,
                                        uint32_t StreamIndex) {
+  assert(StreamIndex < Layout.StreamMap.size() && "Invalid stream index");
   MSFStreamLayout SL;
   SL.Blocks = Layout.StreamMap[StreamIndex];
   SL.Length = Layout.StreamSizes[StreamIndex];
@@ -334,6 +335,7 @@ std::unique_ptr<WritableMappedBlockStream>
 WritableMappedBlockStream::createIndexedStream(const MSFLayout &Layout,
                                                const WritableStream &MsfData,
                                                uint32_t StreamIndex) {
+  assert(StreamIndex < Layout.StreamMap.size() && "Invalid stream index");
   MSFStreamLayout SL;
   SL.Blocks = Layout.StreamMap[StreamIndex];
   SL.Length = Layout.StreamSizes[StreamIndex];