Fix StreamingMemoryObject to respect known object size.

The existing code for method StreamingMemoryObject.fetchToPos does not respect
the corresonding call to setKnownObjectSize(). As a result, it allows the
StreamingMemoryObject to read bytes past the object size.

This patch provides a test case, and code to fix the problem.

Patch by Karl Schimpf
Differential Revision: http://reviews.llvm.org/D8931

llvm-svn: 237939

1 files changed, 12 insertions, 5 deletions

diff --git a/llvm/lib/Support/StreamingMemoryObject.cpp b/llvm/lib/Support/StreamingMemoryObject.cpp
index 90f3ed80d12..6c5652af04c 100644
--- a/llvm/lib/Support/StreamingMemoryObject.cpp
+++ b/llvm/lib/Support/StreamingMemoryObject.cpp
@@ -73,7 +73,7 @@ namespace llvm {
 // block until we actually want to read it.
 bool StreamingMemoryObject::isValidAddress(uint64_t address) const {
   if (ObjectSize && address < ObjectSize) return true;
-    return fetchToPos(address);
+  return fetchToPos(address);
 }
 
 uint64_t StreamingMemoryObject::getExtent() const {
@@ -87,13 +87,18 @@ uint64_t StreamingMemoryObject::getExtent() const {
 uint64_t StreamingMemoryObject::readBytes(uint8_t *Buf, uint64_t Size,
                                           uint64_t Address) const {
   fetchToPos(Address + Size - 1);
-  if (Address >= BytesRead)
+  // Note: For wrapped bitcode files will set ObjectSize after the
+  // first call to fetchToPos. In such cases, ObjectSize can be
+  // smaller than BytesRead.
+  size_t MaxAddress =
+      (ObjectSize && ObjectSize < BytesRead) ? ObjectSize : BytesRead;
+  if (Address >= MaxAddress)
     return 0;
 
   uint64_t End = Address + Size;
-  if (End > BytesRead)
-    End = BytesRead;
-  assert(static_cast<int64_t>(End - Address) >= 0);
+  if (End > MaxAddress)
+    End = MaxAddress;
+  assert(End >= Address);
   Size = End - Address;
   memcpy(Buf, &Bytes[Address + BytesSkipped], Size);
   return Size;
@@ -109,6 +114,8 @@ bool StreamingMemoryObject::dropLeadingBytes(size_t s) {
 void StreamingMemoryObject::setKnownObjectSize(size_t size) {
   ObjectSize = size;
   Bytes.reserve(size);
+  if (ObjectSize <= BytesRead)
+    EOFReached = true;
 }
 
 MemoryObject *getNonStreamedMemoryObject(const unsigned char *Start,