[llvm-objcopy] Add support for '--' for delimiting options from input/output files

This will allow to use llvm-objcopy with file names that begin with dashes.

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D102665

llvm/test/tools/llvm-objcopy/dash-dash.test

@@ -0,0 +1,25 @@
+## Create a clean temporary directory and cd to it to use relative paths.
+# RUN: rm -rf %t && mkdir %t && cd %t
+
+## Check that llvm-objcopy correctly treats paths after '--' as file paths,
+## even if they start with dashes.
+# RUN: yaml2obj %s -o test-obj
+# RUN: llvm-objcopy --only-section=.test test-obj -- --only-section
+# RUN: llvm-objcopy --only-section=.test test-obj out-obj1
+# RUN: cmp out-obj1 -- --only-section
+
+## Check the case when '--' is specified with input files but no options.
+# RUN: llvm-objcopy -- test-obj --add-section
+# RUN: llvm-objcopy test-obj out-obj2
+# RUN: cmp out-obj2 -- --add-section
+
+## Check the case when '--' is specified with options but no input files.
+# RUN: not llvm-objcopy --only-section=.test -- 2>&1 | FileCheck %s --check-prefixes=CHECK-NO-INPUT
+
+# CHECK-NO-INPUT: error: no input file specified
+
+--- !ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data:  ELFDATA2LSB
+  Type:  ET_REL

llvm/test/tools/llvm-objcopy/tool-help-message.test

@@ -1,6 +1,7 @@
 # RUN: llvm-objcopy -h | FileCheck --check-prefix=OBJCOPY-USAGE %s --match-full-lines
 # RUN: llvm-objcopy --help | FileCheck --check-prefix=OBJCOPY-USAGE %s --match-full-lines
 # RUN: not llvm-objcopy 2>&1 | FileCheck --check-prefix=OBJCOPY-USAGE %s --match-full-lines
+# RUN: not llvm-objcopy -- 2>&1 | FileCheck --check-prefix=OBJCOPY-USAGE %s --match-full-lines
 # RUN: not llvm-objcopy -abcabc 2>&1 | FileCheck --check-prefix=UNKNOWN-ARG %s
 # RUN: not llvm-objcopy --abcabc 2>&1 | FileCheck --check-prefix=UNKNOWN-ARG %s
 # RUN: not llvm-objcopy --strip-debug 2>&1 | FileCheck %s --check-prefix=NO-INPUT-FILES

llvm/tools/llvm-objcopy/CopyConfig.cpp

@@ -470,15 +470,23 @@ static void printHelp(const opt::OptTable &OptTable, raw_ostream &OS,
 // help flag is set then ParseObjcopyOptions will print the help messege and
 // exit.
 Expected<DriverConfig>
-parseObjcopyOptions(ArrayRef<const char *> ArgsArr,
+parseObjcopyOptions(ArrayRef<const char *> RawArgsArr,
                     llvm::function_ref<Error(Error)> ErrorCallback) {
   DriverConfig DC;
   ObjcopyOptTable T;
+
+  const char *const *DashDash =
+      std::find_if(RawArgsArr.begin(), RawArgsArr.end(),
+                   [](StringRef Str) { return Str == "--"; });
+  ArrayRef<const char *> ArgsArr = makeArrayRef(RawArgsArr.begin(), DashDash);
+  if (DashDash != RawArgsArr.end())
+    DashDash = std::next(DashDash);
+
   unsigned MissingArgumentIndex, MissingArgumentCount;
   llvm::opt::InputArgList InputArgs =
       T.ParseArgs(ArgsArr, MissingArgumentIndex, MissingArgumentCount);
 
-  if (InputArgs.size() == 0) {
+  if (InputArgs.size() == 0 && DashDash == RawArgsArr.end()) {
     printHelp(T, errs(), ToolType::Objcopy);
     exit(1);
   }
@@ -502,6 +510,7 @@ parseObjcopyOptions(ArrayRef<const char *> ArgsArr,
 
   for (auto Arg : InputArgs.filtered(OBJCOPY_INPUT))
     Positional.push_back(Arg->getValue());
+  std::copy(DashDash, RawArgsArr.end(), std::back_inserter(Positional));
 
   if (Positional.empty())
     return createStringError(errc::invalid_argument, "no input file specified");