[llvm-objcopy] Return Error from Buffer::allocate(), [ELF]Writer::fin…

…alize(), and [ELF]Writer::commit()

Summary:
This patch changes a few methods to return Error instead of manually calling error/reportError to abort. This will make it easier to extract into a library.

Note that error() takes just a string (this patch also adds an overload that takes an Error), while reportError() takes string + [error/code]. To help unify things, use FileError to associate a given filename with an error. Note that this takes some special care (for now), e.g. calling reportError(FileName, <something that could be FileError>) will duplicate the filename. The goal is to eventually remove reportError() and have every error associated with a file to be a FileError, and just one error handling block at the tool level.

This change was suggested in D56806. I took it a little further than suggested, but completely fixing llvm-objcopy will take a couple more patches. If this approach looks good, I'll commit this and apply similar patche(s) for the rest.

This change is NFC in terms of non-error related code, although the error message changes in one context.

Reviewers: alexshap, jhenderson, jakehehrlich, mstorsjo, espindola

Reviewed By: alexshap, jhenderson

Subscribers: llvm-commits, emaste, arichardson

Differential Revision: https://reviews.llvm.org/D56930

llvm-svn: 351896

llvm/test/tools/llvm-objcopy/ELF/fail-no-output-directory.test

@@ -1,6 +1,6 @@
 # RUN: yaml2obj %s > %t
 # RUN: not llvm-objcopy %t no/such/dir 2>&1 | FileCheck %s
-# CHECK: failed to open no/such/dir:
+# CHECK: error: 'no/such/dir': No such file or directory
 
 !ELF
 FileHeader:

llvm/tools/llvm-objcopy/Buffer.cpp

@@ -17,23 +17,31 @@ namespace objcopy {
 
 Buffer::~Buffer() {}
 
-void FileBuffer::allocate(size_t Size) {
+Error FileBuffer::allocate(size_t Size) {
   Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
       FileOutputBuffer::create(getName(), Size, FileOutputBuffer::F_executable);
-  handleAllErrors(BufferOrErr.takeError(), [this](const ErrorInfoBase &E) {
-    error("failed to open " + getName() + ": " + E.message());
-  });
+  // FileOutputBuffer::create() returns an Error that is just a wrapper around
+  // std::error_code. Wrap it in FileError to include the actual filename.
+  if (!BufferOrErr)
+    return createFileError(getName(), BufferOrErr.takeError());
   Buf = std::move(*BufferOrErr);
+  return Error::success();
 }
 
-Error FileBuffer::commit() { return Buf->commit(); }
+Error FileBuffer::commit() {
+  Error Err = Buf->commit();
+  // FileOutputBuffer::commit() returns an Error that is just a wrapper around
+  // std::error_code. Wrap it in FileError to include the actual filename.
+  return Err ? createFileError(getName(), std::move(Err)) : std::move(Err);
+}
 
 uint8_t *FileBuffer::getBufferStart() {
   return reinterpret_cast<uint8_t *>(Buf->getBufferStart());
 }
 
-void MemBuffer::allocate(size_t Size) {
+Error MemBuffer::allocate(size_t Size) {
   Buf = WritableMemoryBuffer::getNewMemBuffer(Size, getName());
+  return Error::success();
 }
 
 Error MemBuffer::commit() { return Error::success(); }

llvm/tools/llvm-objcopy/Buffer.h

@@ -27,7 +27,7 @@ class Buffer {
 
 public:
   virtual ~Buffer();
-  virtual void allocate(size_t Size) = 0;
+  virtual Error allocate(size_t Size) = 0;
   virtual uint8_t *getBufferStart() = 0;
   virtual Error commit() = 0;
 
@@ -39,7 +39,7 @@ class FileBuffer : public Buffer {
   std::unique_ptr<FileOutputBuffer> Buf;
 
 public:
-  void allocate(size_t Size) override;
+  Error allocate(size_t Size) override;
   uint8_t *getBufferStart() override;
   Error commit() override;
 
@@ -50,7 +50,7 @@ class MemBuffer : public Buffer {
   std::unique_ptr<WritableMemoryBuffer> Buf;
 
 public:
-  void allocate(size_t Size) override;
+  Error allocate(size_t Size) override;
   uint8_t *getBufferStart() override;
   Error commit() override;
 

llvm/tools/llvm-objcopy/COFF/Writer.cpp

@@ -324,7 +324,8 @@ Error COFFWriter::write(bool IsBigObj) {
   if (Error E = finalize(IsBigObj))
     return E;
 
-  Buf.allocate(FileSize);
+  if (Error E = Buf.allocate(FileSize))
+    return E;
 
   writeHeaders(IsBigObj);
   writeSections();

llvm/tools/llvm-objcopy/ELF/ELFObjcopy.cpp

@@ -176,8 +176,10 @@ static void splitDWOToFile(const CopyConfig &Config, const Reader &Reader,
     DWOFile->Machine = Config.OutputArch.getValue().EMachine;
   FileBuffer FB(File);
   auto Writer = createWriter(Config, *DWOFile, FB, OutputElfType);
-  Writer->finalize();
-  Writer->write();
+  if (Error E = Writer->finalize())
+    error(std::move(E));
+  if (Error E = Writer->write())
+    error(std::move(E));
 }
 
 static Error dumpSectionToFile(StringRef SecName, StringRef Filename,
@@ -542,8 +544,10 @@ void executeObjcopyOnRawBinary(const CopyConfig &Config, MemoryBuffer &In,
   handleArgs(Config, *Obj, Reader, OutputElfType);
   std::unique_ptr<Writer> Writer =
       createWriter(Config, *Obj, Out, OutputElfType);
-  Writer->finalize();
-  Writer->write();
+  if (Error E = Writer->finalize())
+    error(std::move(E));
+  if (Error E = Writer->write())
+    error(std::move(E));
 }
 
 void executeObjcopyOnBinary(const CopyConfig &Config,
@@ -570,8 +574,10 @@ void executeObjcopyOnBinary(const CopyConfig &Config,
   handleArgs(Config, *Obj, Reader, OutputElfType);
   std::unique_ptr<Writer> Writer =
       createWriter(Config, *Obj, Out, OutputElfType);
-  Writer->finalize();
-  Writer->write();
+  if (Error E = Writer->finalize())
+    error(std::move(E));
+  if (Error E = Writer->write())
+    error(std::move(E));
   if (!Config.BuildIdLinkDir.empty() && Config.BuildIdLinkOutput) {
     linkToBuildIdDir(Config, Config.OutputFilename,
                      Config.BuildIdLinkOutput.getValue(), BuildIdBytes);

llvm/tools/llvm-objcopy/ELF/Object.cpp

@@ -1488,17 +1488,16 @@ template <class ELFT> size_t ELFWriter<ELFT>::totalSize() const {
          NullSectionSize;
 }
 
-template <class ELFT> void ELFWriter<ELFT>::write() {
+template <class ELFT> Error ELFWriter<ELFT>::write() {
   writeEhdr();
   writePhdrs();
   writeSectionData();
   if (WriteSectionHeaders)
     writeShdrs();
-  if (auto E = Buf.commit())
-    reportError(Buf.getName(), errorToErrorCode(std::move(E)));
+  return Buf.commit();
 }
 
-template <class ELFT> void ELFWriter<ELFT>::finalize() {
+template <class ELFT> Error ELFWriter<ELFT>::finalize() {
   // It could happen that SectionNames has been removed and yet the user wants
   // a section header table output. We need to throw an error if a user tries
   // to do that.
@@ -1582,21 +1581,22 @@ template <class ELFT> void ELFWriter<ELFT>::finalize() {
     Section.finalize();
   }
 
-  Buf.allocate(totalSize());
+  if (Error E = Buf.allocate(totalSize()))
+    return E;
   SecWriter = llvm::make_unique<ELFSectionWriter<ELFT>>(Buf);
+  return Error::success();
 }
 
-void BinaryWriter::write() {
+Error BinaryWriter::write() {
   for (auto &Section : Obj.sections()) {
     if ((Section.Flags & SHF_ALLOC) == 0)
       continue;
     Section.accept(*SecWriter);
   }
-  if (auto E = Buf.commit())
-    reportError(Buf.getName(), errorToErrorCode(std::move(E)));
+  return Buf.commit();
 }
 
-void BinaryWriter::finalize() {
+Error BinaryWriter::finalize() {
   // TODO: Create a filter range to construct OrderedSegments from so that this
   // code can be deduped with assignOffsets above. This should also solve the
   // todo below for LayoutSections.
@@ -1675,8 +1675,10 @@ void BinaryWriter::finalize() {
       TotalSize = std::max(TotalSize, Section->Offset + Section->Size);
   }
 
-  Buf.allocate(TotalSize);
+  if (Error E = Buf.allocate(TotalSize))
+    return E;
   SecWriter = llvm::make_unique<BinarySectionWriter>(Buf);
+  return Error::success();
 }
 
 template class ELFBuilder<ELF64LE>;

llvm/tools/llvm-objcopy/ELF/Object.h

@@ -193,8 +193,8 @@ class Writer {
 
 public:
   virtual ~Writer();
-  virtual void finalize() = 0;
-  virtual void write() = 0;
+  virtual Error finalize() = 0;
+  virtual Error write() = 0;
 
   Writer(Object &O, Buffer &B) : Obj(O), Buf(B) {}
 };
@@ -226,8 +226,8 @@ template <class ELFT> class ELFWriter : public Writer {
   virtual ~ELFWriter() {}
   bool WriteSectionHeaders = true;
 
-  void finalize() override;
-  void write() override;
+  Error finalize() override;
+  Error write() override;
   ELFWriter(Object &Obj, Buffer &Buf, bool WSH)
       : Writer(Obj, Buf), WriteSectionHeaders(WSH) {}
 };
@@ -240,8 +240,8 @@ class BinaryWriter : public Writer {
 
 public:
   ~BinaryWriter() {}
-  void finalize() override;
-  void write() override;
+  Error finalize() override;
+  Error write() override;
   BinaryWriter(Object &Obj, Buffer &Buf) : Writer(Obj, Buf) {}
 };
 

llvm/tools/llvm-objcopy/llvm-objcopy.cpp

@@ -56,6 +56,16 @@ LLVM_ATTRIBUTE_NORETURN void error(Twine Message) {
   exit(1);
 }
 
+LLVM_ATTRIBUTE_NORETURN void error(Error E) {
+  assert(E);
+  std::string Buf;
+  raw_string_ostream OS(Buf);
+  logAllUnhandledErrors(std::move(E), OS);
+  OS.flush();
+  WithColor::error(errs(), ToolName) << Buf;
+  exit(1);
+}
+
 LLVM_ATTRIBUTE_NORETURN void reportError(StringRef File, std::error_code EC) {
   assert(EC);
   WithColor::error(errs(), ToolName)
@@ -100,10 +110,11 @@ static Error deepWriteArchive(StringRef ArcName,
     // NewArchiveMember still requires them even though writeArchive does not
     // write them on disk.
     FileBuffer FB(Member.MemberName);
-    FB.allocate(Member.Buf->getBufferSize());
+    if (Error E = FB.allocate(Member.Buf->getBufferSize()))
+      return E;
     std::copy(Member.Buf->getBufferStart(), Member.Buf->getBufferEnd(),
               FB.getBufferStart());
-    if (auto E = FB.commit())
+    if (Error E = FB.commit())
       return E;
   }
   return Error::success();

llvm/tools/llvm-objcopy/llvm-objcopy.h

@@ -19,6 +19,7 @@ namespace llvm {
 namespace objcopy {
 
 LLVM_ATTRIBUTE_NORETURN extern void error(Twine Message);
+LLVM_ATTRIBUTE_NORETURN extern void error(Error E);
 LLVM_ATTRIBUTE_NORETURN extern void reportError(StringRef File, Error E);
 LLVM_ATTRIBUTE_NORETURN extern void reportError(StringRef File,
                                                 std::error_code EC);