Implement parsing and writing of a single xml manifest file.

[ecbeckmann]

Summary

Implement parsing and writing of a single xml manifest file.

[ecbeckmann]

llvm/lib/Support/WindowsManifestMerger.cpp

46 ↗

(On Diff #106670)

remove

llvm/test/CMakeLists.txt

141 ↗

(On Diff #106670)

remove

llvm/tools/llvm-mt/llvm-mt.cpp

147 ↗

(On Diff #106670)

remove

153 ↗

(On Diff #106670)

remove

156 ↗

(On Diff #106670)

remove

[ecbeckmann]

Removed logging.

[ecbeckmann]

Tests will not be run without libxml2.

[ecbeckmann]

Also ensure that the libary actually exists...

[ecbeckmann]

a couple test fixes.

[ecbeckmann]

Added newline

[ruiu]

llvm/cmake/config-ix.cmake

604 ↗

(On Diff #106733)

Does it make sense to not do this on Windows?

llvm/include/llvm/Support/WindowsManifestMerger.h

32 ↗

(On Diff #106733)

You can use #ifdef

51 ↗

(On Diff #106733)

const Twine &Msg?

llvm/lib/Support/WindowsManifestMerger.cpp

28 ↗

(On Diff #106733)

Use #ifdef throughout this patch.

41 ↗

(On Diff #106733)

This function returns something non-empty even if you dont' have libxml2, but I don't think that makes sense. Just like above function which just returns Error::success(), I think it is better to return {} from this function if libxml is not available.

41 ↗

(On Diff #106733)

Looks like it is more straightforward to return an std::vector<uint8_t> from this function instead of a MemoryBuffer. MemoryBuffer is usually used to represent something you've read from files. In this case, this function just construct an in-memory data structure which can easily be represented as std::vector.

llvm/test/CMakeLists.txt

61 ↗

(On Diff #106733)

Is this intentional?

llvm/tools/llvm-mt/llvm-mt.cpp

68 ↗

(On Diff #106733)

Remove a full stop.

77–79 ↗

(On Diff #106733)

nit: since the real function body is just one line, this is simpler

if (EC)
  reportError

83–87 ↗

(On Diff #106733)

Ditto

110 ↗

(On Diff #106733)

Remove a full stop and \n.

Error messages should start with lowercase letter.

122 ↗

(On Diff #106733)

Ditto

129 ↗

(On Diff #106733)

Ditto

133 ↗

(On Diff #106733)

Ditto

149 ↗

(On Diff #106733)

Ditto

[ecbeckmann]

Some syntax and return value changes.

[ruiu]

Is this ready for another round of review?

[ecbeckmann]

Rebase

llvm/cmake/config-ix.cmake

604 ↗

(On Diff #106733)

Yes, apparently the version of libxml2 on Windows uses different headers than what we expect and linking it in would cause a problem. Besides, if we are on windows we can just continue to shell out to the original mt.exe tool.

llvm/lib/Support/WindowsManifestMerger.cpp

41 ↗

(On Diff #106733)

In this case I feel it is more convenient to use MemoryBuffer because it directly takes ownership of the underlying data allocated by xmlDocDumpMemory(). For using a vector we would need an additional copy, and then explicitly delete the allocated memory. Though perhaps this is okay for clarity?

llvm/test/CMakeLists.txt

61 ↗

(On Diff #106733)

Yes down below I only add the test depends if libxml2 is found.

llvm/tools/llvm-mt/llvm-mt.cpp

68 ↗

(On Diff #106733)

When I rebase the previous patch these mistakes will go away.

[ruiu]

llvm/include/llvm/Support/WindowsManifestMerger.h

28 ↗

(On Diff #107188)

This include guard is not correct. #endif should be at end of the file.

60–61 ↗

(On Diff #107188)

Do you need this? Since you didn't define any other ctors, this is defined as a default ctor. Isn't it enough?

llvm/lib/Support/WindowsManifestMerger.cpp

42–45 ↗

(On Diff #107188)

I think you'll get a compiler warning if you compile it in an environment that doesn't have libxml, as BufferSize and XmlBuff will be unused.

A better way of doing it is to completely separate two conditions:

std::unique_ptr<MemoryBuffer> WindowsManifestMerger::getMergedManifest() {
#ifdef LIBXML2_ENABLED
  ...
  return OutputBuffer;
#else
  return nullptr;
#endif
}

68 ↗

(On Diff #107188)

Remove else after return.

llvm/tools/llvm-mt/llvm-mt.cpp

78 ↗

(On Diff #107188)

Indentation.

83 ↗

(On Diff #107188)

Indentation.

[ecbeckmann]

update

[ecbeckmann]

More elegant linking of the xml2 library in the build system.

[ruiu]

llvm/include/llvm/Support/WindowsManifestMerger.h

76 ↗

(On Diff #107351)

Fix this. (It doesn't say that you need a blank line at end of a file, but it says that your last line doesn't end with '\n'.)

llvm/lib/Support/WindowsManifestMerger.cpp

51–54 ↗

(On Diff #107351)

You can eliminate OutputBuffer by doing this:

if (BufferSize == 0)
  return nullptr;  
return MemoryBuffer::getMemBuffer(
      StringRef(reinterpret_cast<const char *>(XmlBuff), (size_t)BufferSize));

llvm/tools/llvm-mt/llvm-mt.cpp

146 ↗

(On Diff #107351)

Isn't this an error? Looks like this program exits with 0 in this case.

[ecbeckmann]

some reformats

[ruiu]

llvm/lib/Support/WindowsManifestMerger.cpp

43 ↗

(On Diff #107362)

This is dead now.

llvm/tools/llvm-mt/llvm-mt.cpp

146 ↗

(On Diff #107351)

How about this?

[ecbeckmann]

Remove vestigal variable.

[ecbeckmann]

llvm/tools/llvm-mt/llvm-mt.cpp

146 ↗

(On Diff #107351)

check most recent patch.

[ruiu]

llvm/tools/llvm-mt/llvm-mt.cpp

147 ↗

(On Diff #107383)

Since reportError is a noreturn function, remove else.

[ecbeckmann]

Remove else block after error.

[ruiu]

LGTM

Please make sure that this patch works with/without libxml2 before committing.

[ecbeckmann]

Final changes to the build system.

[orivej]

WindowsManifestMerger.h should not include llvm/Config/config.h: https://bugs.llvm.org/show_bug.cgi?id=34608

llvm/trunk/CMakeLists.txt

 set(FFI_LIBRARY_DIR "" CACHE PATH "Additional directory, where CMake should search for libffi.so")
 set(FFI_INCLUDE_DIR "" CACHE PATH "Additional directory, where CMake should search for ffi.h or ffi/ffi.h")
 
 set(LLVM_TARGET_ARCH "host"
   CACHE STRING "Set target to use for LLVM JIT or use \"host\" for automatic detection.")
 
 option(LLVM_ENABLE_TERMINFO "Use terminfo database if available." ON)
 
+option(LLVM_ENABLE_LIBXML2 "Use libxml2 if available." ON)
+
 option(LLVM_ENABLE_LIBEDIT "Use libedit if available." ON)
 
 option(LLVM_ENABLE_THREADS "Use threads if available." ON)
 
 option(LLVM_ENABLE_ZLIB "Use zlib for compression/decompression if available." ON)
 
 if( LLVM_TARGETS_TO_BUILD STREQUAL "all" )
   set( LLVM_TARGETS_TO_BUILD ${LLVM_ALL_TARGETS} )

llvm/trunk/cmake/config-ix.cmake

foreach(library tinfo terminfo curses ncurses ncursesw)
         set(HAVE_TERMINFO 1)
         set(TERMINFO_LIBS "${library}")
         break()
       endif()
     endforeach()
   else()
     set(HAVE_TERMINFO 0)
   endif()
+
+  set(LLVM_LIBXML2_ENABLED 0)
+  set(LIBXML2_FOUND 0)
+  if(LLVM_ENABLE_LIBXML2)
+    find_package(LibXml2)
+    if (LIBXML2_FOUND)
+      set(LLVM_LIBXML2_ENABLED 1)
+      include_directories(${LIBXML2_INCLUDE_DIR})
+      set(LIBXML2_LIBS "xml2")
+    endif()
+  endif()
 endif()
 
 check_library_exists(xar xar_open "" HAVE_LIBXAR)
 if(HAVE_LIBXAR)
   set(XAR_LIB xar)
 endif()
 
 # function checks

llvm/trunk/include/llvm/Config/config.h.cmake

 #define LLVM_VERSION_MINOR ${LLVM_VERSION_MINOR}
 
 /* Patch version of the LLVM API */
 #define LLVM_VERSION_PATCH ${LLVM_VERSION_PATCH}
 
 /* LLVM version string */
 #define LLVM_VERSION_STRING "${PACKAGE_VERSION}"
 
+/* Define if libxml2 is supported on this platform. */
+#cmakedefine LLVM_LIBXML2_ENABLED ${LLVM_LIBXML2_ENABLED}
+
 /* Define to the extension used for shared libraries, say, ".so". */
 #cmakedefine LTDL_SHLIB_EXT "${LTDL_SHLIB_EXT}"
 
 /* Define to the address where bug reports for this package should be sent. */
 #cmakedefine PACKAGE_BUGREPORT "${PACKAGE_BUGREPORT}"
 
 /* Define to the full name of this package. */
 #cmakedefine PACKAGE_NAME "${PACKAGE_NAME}"

llvm/trunk/include/llvm/Support/WindowsManifestMerger.h

+//===-- WindowsManifestMerger.h ---------------------------------*- C++-*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===---------------------------------------------------------------------===//
+//
+// This file provides a utility for merging Microsoft .manifest files.  These
+// files are xml documents which contain meta-information about applications,
+// such as whether or not admin access is required, system compatibility,
+// versions, etc.  Part of the linking process of an executable may require
+// merging several of these .manifest files using a tree-merge following
+// specific rules.  Unfortunately, these rules are not documented well
+// anywhere.  However, a careful investigation of the behavior of the original
+// Microsoft Manifest Tool (mt.exe) revealed the rules of this merge.  As the
+// saying goes, code is the best documentation, so please look below if you are
+// interested in the exact merging requirements.
+//
+// Ref:
+// https://msdn.microsoft.com/en-us/library/windows/desktop/aa374191(v=vs.85).aspx
+//
+//===---------------------------------------------------------------------===//
+
+#ifndef LLVM_INCLUDE_LLVM_SUPPORT_WINDOWS_MANIFEST_MERGER_H
+#define LLVM_INCLUDE_LLVM_SUPPORT_WINDOWS_MANIFEST_MERGER_H
+
+#include "llvm/Config/config.h"
+#include "llvm/Support/Error.h"
+
+#if LLVM_LIBXML2_ENABLED
+#include <libxml/xmlreader.h>
+#endif
+
+namespace llvm {
+
+class MemoryBuffer;
+
+#if LLVM_LIBXML2_ENABLED
+typedef xmlDocPtr XMLDocumentImpl;
+typedef xmlNodePtr XMLNodeImpl;
+#else
+typedef void *XMLDocumentImpl;
+typedef void *XMLNodeImpl;
+#endif
+
+class WindowsManifestError : public ErrorInfo<WindowsManifestError, ECError> {
+public:
+  static char ID;
+  WindowsManifestError(const Twine &Msg);
+  void log(raw_ostream &OS) const override;
+
+private:
+  std::string Msg;
+};
+
+class WindowsManifestMerger {
+public:
+  Error merge(const MemoryBuffer &Manifest);
+
+  // Returns vector containing merged xml manifest, or uninitialized vector for
+  // empty manifest.
+  std::unique_ptr<MemoryBuffer> getMergedManifest();
+
+private:
+  static void errorCallback(void *Ctx, const char *Format, ...);
+  Error getParseError();
+
+  XMLNodeImpl CombinedRoot = nullptr;
+  bool ParseErrorOccurred = false;
+};
+
+} // namespace llvm
+#endif

llvm/trunk/lib/Support/CMakeLists.txt

elseif( CMAKE_HOST_UNIX )
   endif()
   set(system_libs ${system_libs} ${LLVM_PTHREAD_LIB})
   if ( LLVM_ENABLE_ZLIB AND HAVE_LIBZ )
     set(system_libs ${system_libs} z)
   endif()
   if( UNIX AND NOT (BEOS OR HAIKU) )
     set(system_libs ${system_libs} m)
   endif()
+  if( LLVM_LIBXML2_ENABLED )
+    set(system_libs ${system_libs} ${LIBXML2_LIBS})
+  endif()
 endif( MSVC OR MINGW )
 
 add_llvm_library(LLVMSupport
   AMDGPUCodeObjectMetadata.cpp
   APFloat.cpp
   APInt.cpp
   APSInt.cpp
   ARMBuildAttrs.cpp
add_llvm_library(LLVMSupport
   TargetParser.cpp
   ThreadPool.cpp
   Timer.cpp
   ToolOutputFile.cpp
   TrigramIndex.cpp
   Triple.cpp
   Twine.cpp
   Unicode.cpp
+  WindowsManifestMerger.cpp
   YAMLParser.cpp
   YAMLTraits.cpp
   raw_os_ostream.cpp
   raw_ostream.cpp
   regcomp.c
   regerror.c
   regexec.c
   regfree.c

llvm/trunk/lib/Support/WindowsManifestMerger.cpp

+//===-- WindowsManifestMerger.cpp ------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===---------------------------------------------------------------------===//
+//
+// This file implements the .manifest merger class.
+//
+//===---------------------------------------------------------------------===//
+
+#include "llvm/Support/WindowsManifestMerger.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+#include <stdarg.h>
+
+namespace llvm {
+
+char WindowsManifestError::ID = 0;
+
+WindowsManifestError::WindowsManifestError(const Twine &Msg) : Msg(Msg.str()) {}
+
+void WindowsManifestError::log(raw_ostream &OS) const { OS << Msg; }
+
+Error WindowsManifestMerger::merge(const MemoryBuffer &Manifest) {
+#if LLVM_LIBXML2_ENABLED
+  xmlSetGenericErrorFunc((void *)this, WindowsManifestMerger::errorCallback);
+  XMLDocumentImpl ManifestXML =
+      xmlReadMemory(Manifest.getBufferStart(), Manifest.getBufferSize(),
+                    "manifest.xml", nullptr, 0);
+  xmlSetGenericErrorFunc(nullptr, nullptr);
+  if (auto E = getParseError())
+    return E;
+  CombinedRoot = xmlDocGetRootElement(ManifestXML);
+#endif
+  return Error::success();
+}
+
+std::unique_ptr<MemoryBuffer> WindowsManifestMerger::getMergedManifest() {
+#if LLVM_LIBXML2_ENABLED
+  unsigned char *XmlBuff;
+  int BufferSize = 0;
+  if (CombinedRoot) {
+    std::unique_ptr<xmlDoc> OutputDoc(xmlNewDoc((const unsigned char *)"1.0"));
+    xmlDocSetRootElement(OutputDoc.get(), CombinedRoot);
+    xmlDocDumpMemory(OutputDoc.get(), &XmlBuff, &BufferSize);
+  }
+  if (BufferSize == 0)
+    return nullptr;
+  return MemoryBuffer::getMemBuffer(
+      StringRef(reinterpret_cast<const char *>(XmlBuff), (size_t)BufferSize));
+#else
+  return nullptr;
+#endif
+}
+
+void WindowsManifestMerger::errorCallback(void *Ctx, const char *Format, ...) {
+  auto *Merger = (WindowsManifestMerger *)Ctx;
+  Merger->ParseErrorOccurred = true;
+}
+
+Error WindowsManifestMerger::getParseError() {
+  if (!ParseErrorOccurred)
+    return Error::success();
+  return make_error<WindowsManifestError>("invalid xml document");
+}
+
+} // namespace llvm

llvm/trunk/test/CMakeLists.txt

set(LLVM_TEST_DEPENDS
           llvm-dwp
           llvm-extract
           llvm-lib
           llvm-link
           llvm-lto2
           llvm-mc
           llvm-mcmarkup
           llvm-modextract
-          llvm-mt
           llvm-nm
           llvm-objdump
           llvm-opt-report
           llvm-pdbutil
           llvm-profdata
           llvm-ranlib
           llvm-readobj
           llvm-readelf
set(LLVM_TEST_DEPENDS ${LLVM_TEST_DEPENDS}
           ocaml_llvm_ipo
           ocaml_llvm_passmgr_builder
           ocaml_llvm_scalar_opts
           ocaml_llvm_transform_utils
           ocaml_llvm_vectorize
         )
 endif()
 
+if (LLVM_LIBXML2_ENABLED)
+  set(LLVM_TEST_DEPENDS ${LLVM_TEST_DEPENDS}
+          llvm-mt
+        )
+endif()
+
 add_custom_target(llvm-test-depends DEPENDS ${LLVM_TEST_DEPENDS})
 set_target_properties(llvm-test-depends PROPERTIES FOLDER "Tests")
 
 add_lit_testsuite(check-llvm "Running the LLVM regression tests"
   ${CMAKE_CURRENT_BINARY_DIR}
   PARAMS llvm_site_config=${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
          llvm_unit_site_config=${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg
   DEPENDS ${LLVM_TEST_DEPENDS}

llvm/trunk/test/lit.cfg

for pattern in [r"\bbugpoint\b(?!-)",
                 NOJUNK + r"\bllc\b",
                 r"\blli\b",
                 r"\bllvm-ar\b",
                 r"\bllvm-as\b",
                 r"\bllvm-bcanalyzer\b",
                 r"\bllvm-config\b",
                 r"\bllvm-cov\b",
                 r"\bllvm-cxxdump\b",
+                r"\bllvm-cvtres\b",
                 r"\bllvm-diff\b",
                 r"\bllvm-dis\b",
                 r"\bllvm-dsymutil\b",
                 r"\bllvm-dwarfdump\b",
                 r"\bllvm-extract\b",
                 r"\bllvm-lib\b",
                 r"\bllvm-link\b",
                 r"\bllvm-lto\b",
if not tool_path:
         # Warn, but still provide a substitution.
         lit_config.note('Did not find ' + tool_name + ' in ' + llvm_tools_dir)
         tool_path = llvm_tools_dir + '/' + tool_name
     config.substitutions.append((pattern, tool_pipe + tool_path))
 
 # For tools that are optional depending on the config, we won't warn
 # if they're missing.
 for pattern in [r"\bllvm-go\b",
+                r"\bllvm-mt\b",
                 r"\bKaleidoscope-Ch3\b",
                 r"\bKaleidoscope-Ch4\b",
                 r"\bKaleidoscope-Ch5\b",
                 r"\bKaleidoscope-Ch6\b",
                 r"\bKaleidoscope-Ch7\b",
                 r"\bKaleidoscope-Ch8\b"]:
     tool_name, tool_path, tool_pipe = find_tool_substitution(pattern)
     if not tool_path:
if re.search(r'ON', llvm_config_cmd.stdout.read().decode('ascii')):
     config.available_features.add('global-isel')
 llvm_config_cmd.wait()
 
 if config.have_libxar:
     config.available_features.add('xar')
 
 if config.enable_abi_breaking_checks == "1":
     config.available_features.add('abi-breaking-checks')
+
+if config.llvm_disable_libxml2 == "OFF" and config.have_libxml2 == "TRUE":
+    config.available_features.add('libxml2')
     
 No newline at end of file

llvm/trunk/test/lit.site.cfg.in

 config.host_ldflags = "@HOST_LDFLAGS@"
 config.llvm_use_intel_jitevents = @LLVM_USE_INTEL_JITEVENTS@
 config.llvm_use_sanitizer = "@LLVM_USE_SANITIZER@"
 config.have_zlib = @HAVE_LIBZ@
 config.have_libxar = @HAVE_LIBXAR@
 config.have_dia_sdk = @LLVM_ENABLE_DIA_SDK@
 config.enable_ffi = @LLVM_ENABLE_FFI@
 config.build_shared_libs = @BUILD_SHARED_LIBS@
+config.llvm_disable_libxml2 = "@LLVM_DISABLE_LIBXML2@"
+config.have_libxml2 = "@LIBXML2_FOUND@"
 
 # Support substitution of the tools_dir with user parameters. This is
 # used when we can't determine the tool dir at configuration time.
 try:
     config.llvm_tools_dir = config.llvm_tools_dir % lit_config.params
     config.llvm_shlib_dir = config.llvm_shlib_dir % lit_config.params
 except KeyError:
     e = sys.exc_info()[1]
     key, = e.args
     lit_config.fatal("unable to find %r parameter, use '--param=%s=VALUE'" % (key,key))
 
 # Let the main config do the real work.
 lit_config.load_config(config, "@LLVM_SOURCE_DIR@/test/lit.cfg")

llvm/trunk/test/tools/llvm-mt/Inputs/test_manifest.manifest

+<?xml version="1.0"?>
+<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
+  <trustInfo>
+    <security>
+      <requestedPrivileges>
+         <requestedExecutionLevel level="3" uiAccess="1"/>
+      </requestedPrivileges>
+    </security>
+  </trustInfo>
+  <dependency>
+    <dependentAssembly>
+      <assemblyIdentity program="displayDriver"/>
+    </dependentAssembly>
+  </dependency>
+</assembly>

llvm/trunk/test/tools/llvm-mt/help.test

 RUN: llvm-mt /h | FileCheck %s -check-prefix=HELP
 
-RUN: llvm-mt /inputresource:foo.res /manifest foo.manifest | FileCheck %s -check-prefix=NOT_SUPPORTED
-
 HELP:      OVERVIEW: Manifest Tool
-
-NOT_SUPPORTED: llvm-mt: ignoring unsupported 'inputresource:' option

llvm/trunk/test/tools/llvm-mt/single_file.test

+REQUIRES: libxml2
+UNSUPPORTED: windows
+
+RUN: llvm-mt /manifest %p/Inputs/test_manifest.manifest /out:%t
+RUN: diff %p/Inputs/test_manifest.manifest %t

llvm/trunk/test/tools/llvm-mt/xml_error.test

+REQUIRES: libxml2
+UNSUPPORTED: windows
+
+RUN: not llvm-mt /manifest %p/Inputs/bad.manifest 2>&1 >/dev/null | FileCheck %s
+
+CHECK: llvm-mt error: invalid xml document
+
+RUN: llvm-mt /inputresource:foo.res /manifest \
+RUN:   %p/Inputs/test_manifest.manifest | FileCheck %s -check-prefix=NOT_SUPPORTED
+
+NOT_SUPPORTED: llvm-mt: ignoring unsupported 'inputresource:' option

llvm/trunk/tools/LLVMBuild.txt

  llvm-dwp
  llvm-extract
  llvm-jitlistener
  llvm-link
  llvm-lto
  llvm-mc
  llvm-mcmarkup
  llvm-modextract
+ llvm-mt
  llvm-nm
  llvm-objdump
  llvm-pdbutil
  llvm-profdata
  llvm-rtdyld
  llvm-size
  llvm-split
  opt
  verify-uselistorder
 
 [component_0]
 type = Group
 name = Tools
 parent = $ROOT

llvm/trunk/tools/llvm-mt/llvm-mt.cpp

 // of Microsoft's mt.exe.
 //
 //===---------------------------------------------------------------------===//
 
 #include "llvm/Option/Arg.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Option/Option.h"
 #include "llvm/Support/Error.h"
+#include "llvm/Support/FileOutputBuffer.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/PrettyStackTrace.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Signals.h"
+#include "llvm/Support/WindowsManifestMerger.h"
 #include "llvm/Support/raw_ostream.h"
 
 #include <system_error>
 
 using namespace llvm;
 
 namespace {
 

 static ExitOnError ExitOnErr;
 } // namespace
 
 LLVM_ATTRIBUTE_NORETURN void reportError(Twine Msg) {
   errs() << "llvm-mt error: " << Msg << "\n";
   exit(1);
 }
 
+static void reportError(StringRef Input, std::error_code EC) {
+  reportError(Twine(Input) + ": " + EC.message());
+}
+
+void error(std::error_code EC) {
+  if (EC)
+    reportError(EC.message());
+}
+
+void error(Error EC) {
+  if (EC)
+    handleAllErrors(std::move(EC), [&](const ErrorInfoBase &EI) {
+      reportError(EI.message());
+    });
+}
+
 int main(int argc, const char **argv) {
   sys::PrintStackTraceOnErrorSignal(argv[0]);
   PrettyStackTraceProgram X(argc, argv);
 
   ExitOnErr.setBanner("llvm-mt: ");
 
   SmallVector<const char *, 256> argv_buf;
   SpecificBumpPtrAllocator<char> ArgAllocator;
int main(int argc, const char **argv) {
 
   std::vector<std::string> InputFiles = InputArgs.getAllArgValues(OPT_manifest);
 
   if (InputFiles.size() == 0) {
     reportError("no input file specified");
   }
 
   StringRef OutputFile;
-
   if (InputArgs.hasArg(OPT_out)) {
     OutputFile = InputArgs.getLastArgValue(OPT_out);
   } else if (InputFiles.size() == 1) {
     OutputFile = InputFiles[0];
   } else {
     reportError("no output file specified");
   }
 
+  WindowsManifestMerger Merger;
+
+  for (const auto &File : InputFiles) {
+    ErrorOr<std::unique_ptr<MemoryBuffer>> ManifestOrErr =
+        MemoryBuffer::getFile(File);
+    if (!ManifestOrErr)
+      reportError(File, ManifestOrErr.getError());
+    MemoryBuffer &Manifest = *ManifestOrErr.get();
+    error(Merger.merge(Manifest));
+  }
+
+  std::unique_ptr<MemoryBuffer> OutputBuffer = Merger.getMergedManifest();
+  if (!OutputBuffer)
+    reportError("empty manifest not written");
+  ErrorOr<std::unique_ptr<FileOutputBuffer>> FileOrErr =
+      FileOutputBuffer::create(OutputFile, OutputBuffer->getBufferSize());
+  if (!FileOrErr)
+    reportError(OutputFile, FileOrErr.getError());
+  std::unique_ptr<FileOutputBuffer> FileBuffer = std::move(*FileOrErr);
+  std::copy(OutputBuffer->getBufferStart(), OutputBuffer->getBufferEnd(),
+            FileBuffer->getBufferStart());
+  error(FileBuffer->commit());
   return 0;
 }