Reland "[LLVM][llvm-objcopy] Added basic plumbing to get things started"

As discussed on llvm-dev I've implemented the first basic steps towards
llvm-objcopy/llvm-objtool (name pending).

This change adds the ability to copy (without modification) 64-bit
little endian ELF executables that have SHT_PROGBITS, SHT_NOBITS,
SHT_NULL and SHT_STRTAB sections.

Patch by Jake Ehrlich

Differential Revision: https://reviews.llvm.org/D33964

llvm-svn: 308821

1 files changed, 99 insertions, 0 deletions

diff --git a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
new file mode 100644
index 00000000000..342ef36fc30
--- /dev/null
+++ b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
@@ -0,0 +1,99 @@
+//===- llvm-objcopy.cpp -----------------------------------------*- C++ -*-===//
+//
+//                      The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include "llvm-objcopy.h"
+#include "Object.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/FileOutputBuffer.h"
+#include "llvm/Support/PrettyStackTrace.h"
+#include "llvm/Support/Signals.h"
+#include "llvm/Support/ToolOutputFile.h"
+
+#include <memory>
+#include <string>
+#include <system_error>
+
+using namespace llvm;
+using namespace object;
+using namespace ELF;
+
+// The name this program was invoked as.
+static StringRef ToolName;
+
+namespace llvm {
+
+LLVM_ATTRIBUTE_NORETURN void error(Twine Message) {
+  errs() << ToolName << ": " << Message << ".\n";
+  errs().flush();
+  exit(1);
+}
+
+LLVM_ATTRIBUTE_NORETURN void reportError(StringRef File, std::error_code EC) {
+  assert(EC);
+  errs() << ToolName << ": '" << File << "': " << EC.message() << ".\n";
+  exit(1);
+}
+
+LLVM_ATTRIBUTE_NORETURN void reportError(StringRef File, llvm::Error E) {
+  assert(E);
+  std::string Buf;
+  raw_string_ostream OS(Buf);
+  logAllUnhandledErrors(std::move(E), OS, "");
+  OS.flush();
+  errs() << ToolName << ": '" << File << "': " << Buf;
+  exit(1);
+}
+}
+
+cl::opt<std::string> InputFilename(cl::Positional, cl::desc("<input>"));
+cl::opt<std::string> OutputFilename(cl::Positional, cl::desc("<output>"),
+                                    cl::init("-"));
+
+void CopyBinary(const ELFObjectFile<ELF64LE> &ObjFile) {
+  std::unique_ptr<FileOutputBuffer> Buffer;
+  Object<ELF64LE> Obj{ObjFile};
+  Obj.finalize();
+  ErrorOr<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
+      FileOutputBuffer::create(OutputFilename, Obj.totalSize(),
+                               FileOutputBuffer::F_executable);
+  if (BufferOrErr.getError())
+    error("failed to open " + OutputFilename);
+  else
+    Buffer = std::move(*BufferOrErr);
+  std::error_code EC;
+  std::unique_ptr<tool_output_file> Out =
+      make_unique<tool_output_file>(OutputFilename.data(), EC, sys::fs::F_None);
+  if (EC)
+    report_fatal_error(EC.message());
+  Obj.write(*Buffer);
+  if (auto EC = Buffer->commit())
+    reportError(OutputFilename, EC);
+  Out->keep();
+}
+
+int main(int argc, char **argv) {
+  // Print a stack trace if we signal out.
+  sys::PrintStackTraceOnErrorSignal(argv[0]);
+  PrettyStackTraceProgram X(argc, argv);
+  llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
+  cl::ParseCommandLineOptions(argc, argv, "llvm objcopy utility\n");
+  ToolName = argv[0];
+  if (InputFilename.empty()) {
+    cl::PrintHelpMessage();
+    return 2;
+  }
+  Expected<OwningBinary<Binary>> BinaryOrErr = createBinary(InputFilename);
+  if (!BinaryOrErr)
+    reportError(InputFilename, BinaryOrErr.takeError());
+  Binary &Binary = *BinaryOrErr.get().getBinary();
+  if (ELFObjectFile<ELF64LE> *o = dyn_cast<ELFObjectFile<ELF64LE>>(&Binary)) {
+    CopyBinary(*o);
+    return 0;
+  }
+  reportError(InputFilename, object_error::invalid_file_type);
+}