[PECOFF] Fix section header.

The PE/COFF spec says that SizeOfRawData field in the section
header must be a multiple of FileAlignment from the optional
header. LLD emits 512 as FileAlignment, so it must have been
a multiple of 512.

LLD did not follow that. It emitted the actual section size
without the last padding as the SizeOfRawData. Although it's
not correct as per the spec, the Windows loader doesn't seem
to actually bother to check that. Executables created by LLD
worked fine.

However, tools dealing with executalbe files may expect it
to be the correct value, and one instance of it is mt.exe
tool distributed as a part of Windows SDK.

If CMake is invoked with "-E vs_link_exe" option, it silently
run mt.exe to embed a resource file to the resulting file.
And mt.exe sometimes breaks an input file if it's section
header does not follow the standard. That caused a misterous
error that CMake with Ninja occasionally produces a broken
executable.

This patch fixes the section header to make mt.exe and
other tools happy.

llvm-svn: 214453

1 files changed, 13 insertions, 6 deletions

diff --git a/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp b/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
index 22dd2f01ca9..07642dbc510 100644
--- a/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
+++ b/lld/lib/ReaderWriter/PECOFF/WriterPECOFF.cpp
@@ -75,6 +75,7 @@ public:
   virtual ~Chunk() {}
   virtual void write(uint8_t *buffer) = 0;
   virtual uint64_t size() const { return _size; }
+  virtual uint64_t onDiskSize() const { return size(); }
   virtual uint64_t align() const { return 1; }
 
   uint64_t fileOffset() const { return _fileOffset; }
@@ -175,6 +176,12 @@ private:
 
 class SectionChunk : public Chunk {
 public:
+  uint64_t onDiskSize() const override {
+    if (_characteristics & llvm::COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA)
+      return 0;
+    return llvm::RoundUpToAlignment(size(), SECTOR_SIZE);
+  }
+
   uint64_t align() const override { return SECTOR_SIZE; }
   uint32_t getCharacteristics() const { return _characteristics; }
   StringRef getSectionName() const { return _sectionName; }
@@ -730,19 +737,18 @@ SectionHeaderTableChunk::createSectionHeader(SectionChunk *chunk) {
                std::min(sizeof(header.Name), sectionName.size()));
 
   uint32_t characteristics = chunk->getCharacteristics();
+  header.VirtualSize = chunk->size();
   header.VirtualAddress = chunk->getVirtualAddress();
+  header.SizeOfRawData = chunk->onDiskSize();
   header.PointerToRelocations = 0;
   header.PointerToLinenumbers = 0;
   header.NumberOfRelocations = 0;
   header.NumberOfLinenumbers = 0;
-  header.SizeOfRawData = chunk->size();
   header.Characteristics = characteristics;
 
   if (characteristics & llvm::COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA) {
-    header.VirtualSize = 0;
     header.PointerToRawData = 0;
   } else {
-    header.VirtualSize = chunk->size();
     header.PointerToRawData = chunk->fileOffset();
   }
   return header;
@@ -1018,7 +1024,8 @@ std::error_code PECOFFWriter::writeFile(const File &linkedFile,
     this->build<llvm::object::pe32_header>(linkedFile);
   }
 
-  uint64_t totalSize = _chunks.back()->fileOffset() + _chunks.back()->size();
+  uint64_t totalSize =
+      _chunks.back()->fileOffset() + _chunks.back()->onDiskSize();
   std::unique_ptr<llvm::FileOutputBuffer> buffer;
   std::error_code ec = llvm::FileOutputBuffer::create(
       path, totalSize, buffer, llvm::FileOutputBuffer::F_executable);
@@ -1144,7 +1151,7 @@ void PECOFFWriter::setImageSizeOnDisk() {
     _imageSizeOnDisk =
         llvm::RoundUpToAlignment(_imageSizeOnDisk, chunk->align());
     chunk->setFileOffset(_imageSizeOnDisk);
-    _imageSizeOnDisk += chunk->size();
+    _imageSizeOnDisk += chunk->onDiskSize();
   }
 }
 
@@ -1154,7 +1161,7 @@ uint64_t PECOFFWriter::calcSectionSize(
   for (auto &cp : _chunks)
     if (SectionChunk *chunk = dyn_cast<SectionChunk>(&*cp))
       if (chunk->getCharacteristics() & sectionType)
-        ret += chunk->size();
+        ret += chunk->onDiskSize();
   return ret;
 }