[CodeView] Healthy paranoia around strings

Make sure strings don't get too big for a record, truncate them if
need-be.

llvm-svn: 273710

2 files changed, 5 insertions, 8 deletions

diff --git a/llvm/lib/DebugInfo/CodeView/ListRecordBuilder.cpp b/llvm/lib/DebugInfo/CodeView/ListRecordBuilder.cpp
index dc72f500c87..eb79e8ac9a3 100644
--- a/llvm/lib/DebugInfo/CodeView/ListRecordBuilder.cpp
+++ b/llvm/lib/DebugInfo/CodeView/ListRecordBuilder.cpp
@@ -49,8 +49,10 @@ void ListRecordBuilder::finishSubRecord() {
   // back up and insert a continuation record, sliding the current subrecord
   // down.
   if (getLastContinuationSize() > 65535 - 8) {
+    assert(SubrecordStart != 0 && "can't slide from the start!");
     SmallString<128> SubrecordCopy(
         Builder.str().slice(SubrecordStart, Builder.size()));
+    assert(SubrecordCopy.size() < 65530 && "subrecord is too large to slide!");
     Builder.truncate(SubrecordStart);
 
     // Write a placeholder continuation record.
diff --git a/llvm/lib/DebugInfo/CodeView/TypeRecordBuilder.cpp b/llvm/lib/DebugInfo/CodeView/TypeRecordBuilder.cpp
index f1c293e39fd..112612cc85e 100644
--- a/llvm/lib/DebugInfo/CodeView/TypeRecordBuilder.cpp
+++ b/llvm/lib/DebugInfo/CodeView/TypeRecordBuilder.cpp
@@ -91,15 +91,10 @@ void TypeRecordBuilder::writeEncodedUnsignedInteger(uint64_t Value) {
   }
 }
 
-void TypeRecordBuilder::writeNullTerminatedString(const char *Value) {
-  assert(Value != nullptr);
-
-  size_t Length = strlen(Value);
-  Stream.write(Value, Length);
-  writeUInt8(0);
-}
-
 void TypeRecordBuilder::writeNullTerminatedString(StringRef Value) {
+  // Microsoft's linker seems to have trouble with symbol names longer than
+  // 0xffd8 bytes.
+  Value = Value.substr(0, 0xffd8);
   Stream.write(Value.data(), Value.size());
   writeUInt8(0);
 }