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

1 files changed, 13 insertions, 2 deletions

diff --git a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
index d27395f..75d5135 100644
--- a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
+++ b/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();