[PATCH] D37044: Fix bug 34051 by handling empty .res files gracefully.

[Eric Beckmann via Phabricator via llvm-commits]

ecbeckmann created this revision.
Herald added a subscriber: hiraditya.

Previously, llvm-cvtres crashes on .res files which are empty except for
the null header.  This allows the library to simply pass over them.


https://reviews.llvm.org/D37044

Files:
  llvm/include/llvm/Object/WindowsResource.h
  llvm/lib/Object/WindowsResource.cpp


Index: llvm/lib/Object/WindowsResource.cpp
===================================================================
--- llvm/lib/Object/WindowsResource.cpp
+++ llvm/lib/Object/WindowsResource.cpp
@@ -57,6 +57,11 @@
 }
 
 Expected<ResourceEntryRef> WindowsResource::getHeadEntry() {
+  if (BBS.getLength() <
+      sizeof(WinResHeaderPrefix) + sizeof(WinResHeaderSuffix)) {
+    return make_error<EmptyResError>(".res contains no entries",
+                                     object_error::unexpected_eof);
+  }
   Error Err = Error::success();
   auto Ref = ResourceEntryRef(BinaryStreamRef(BBS), this, Err);
   if (Err)
@@ -67,9 +72,10 @@
 ResourceEntryRef::ResourceEntryRef(BinaryStreamRef Ref,
                                    const WindowsResource *Owner, Error &Err)
     : Reader(Ref), OwningRes(Owner) {
-  if (loadNext())
-    Err = make_error<GenericBinaryError>("Could not read first entry.\n",
-                                         object_error::unexpected_eof);
+  if (auto E = loadNext()) {
+    consumeError(std::move(Err));
+    Err = std::move(E);
+  }
 }
 
 Error ResourceEntryRef::moveNext(bool &End) {
@@ -127,8 +133,14 @@
 
 Error WindowsResourceParser::parse(WindowsResource *WR) {
   auto EntryOrErr = WR->getHeadEntry();
-  if (!EntryOrErr)
-    return EntryOrErr.takeError();
+  if (!EntryOrErr) {
+    auto E = EntryOrErr.takeError();
+    if (E.isA<EmptyResError>()) {
+      consumeError(std::move(E));
+      return Error::success();
+    }
+    return E;
+  }
 
   ResourceEntryRef Entry = EntryOrErr.get();
   bool End = false;
Index: llvm/include/llvm/Object/WindowsResource.h
===================================================================
--- llvm/include/llvm/Object/WindowsResource.h
+++ llvm/include/llvm/Object/WindowsResource.h
@@ -85,6 +85,13 @@
   support::ulittle32_t Characteristics;
 };
 
+class EmptyResError : public GenericBinaryError {
+public:
+  EmptyResError(Twine Msg, object_error ECOverride)
+      : GenericBinaryError(Msg, ECOverride) {}
+  static char ID;
+};
+
 class ResourceEntryRef {
 public:
   Error moveNext(bool &End);


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