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      1 //===- yaml2obj - Convert YAML to a binary object file --------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 // This program takes a YAML description of an object file and outputs the
     11 // binary equivalent.
     12 //
     13 // This is used for writing tests that require binary files.
     14 //
     15 //===----------------------------------------------------------------------===//
     16 
     17 #include "yaml2obj.h"
     18 #include "llvm/ADT/StringExtras.h"
     19 #include "llvm/Support/CommandLine.h"
     20 #include "llvm/Support/FileSystem.h"
     21 #include "llvm/Support/ManagedStatic.h"
     22 #include "llvm/Support/MemoryBuffer.h"
     23 #include "llvm/Support/PrettyStackTrace.h"
     24 #include "llvm/Support/Signals.h"
     25 #include "llvm/Support/ToolOutputFile.h"
     26 #include "llvm/Support/YAMLTraits.h"
     27 #include "llvm/Support/raw_ostream.h"
     28 #include <system_error>
     29 
     30 using namespace llvm;
     31 
     32 static cl::opt<std::string>
     33   Input(cl::Positional, cl::desc("<input>"), cl::init("-"));
     34 
     35 // TODO: The "right" way to tell what kind of object file a given YAML file
     36 // corresponds to is to look at YAML "tags" (e.g. `!Foo`). Then, different
     37 // tags (`!ELF`, `!COFF`, etc.) would be used to discriminate between them.
     38 // Interpreting the tags is needed eventually for when writing test cases,
     39 // so that we can e.g. have `!Archive` contain a sequence of `!ELF`, and
     40 // just Do The Right Thing. However, interpreting these tags and acting on
     41 // them appropriately requires some work in the YAML parser and the YAMLIO
     42 // library.
     43 enum YAMLObjectFormat {
     44   YOF_COFF,
     45   YOF_ELF
     46 };
     47 
     48 cl::opt<YAMLObjectFormat> Format(
     49   "format",
     50   cl::desc("Interpret input as this type of object file"),
     51   cl::values(
     52     clEnumValN(YOF_COFF, "coff", "COFF object file format"),
     53     clEnumValN(YOF_ELF, "elf", "ELF object file format"),
     54   clEnumValEnd));
     55 
     56 cl::opt<unsigned>
     57 DocNum("docnum", cl::init(1),
     58        cl::desc("Read specified document from input (default = 1)"));
     59 
     60 static cl::opt<std::string> OutputFilename("o", cl::desc("Output filename"),
     61                                            cl::value_desc("filename"));
     62 
     63 typedef int (*ConvertFuncPtr)(yaml::Input & YIn, raw_ostream &Out);
     64 
     65 static int convertYAML(yaml::Input &YIn, raw_ostream &Out,
     66                        ConvertFuncPtr Convert) {
     67   unsigned CurDocNum = 0;
     68   do {
     69     if (++CurDocNum == DocNum)
     70       return Convert(YIn, Out);
     71   } while (YIn.nextDocument());
     72 
     73   errs() << "yaml2obj: Cannot find the " << DocNum
     74          << llvm::getOrdinalSuffix(DocNum) << " document\n";
     75   return 1;
     76 }
     77 
     78 int main(int argc, char **argv) {
     79   cl::ParseCommandLineOptions(argc, argv);
     80   sys::PrintStackTraceOnErrorSignal();
     81   PrettyStackTraceProgram X(argc, argv);
     82   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
     83 
     84   if (OutputFilename.empty())
     85     OutputFilename = "-";
     86 
     87   std::error_code EC;
     88   std::unique_ptr<tool_output_file> Out(
     89       new tool_output_file(OutputFilename, EC, sys::fs::F_None));
     90   if (EC) {
     91     errs() << EC.message() << '\n';
     92     return 1;
     93   }
     94 
     95   ErrorOr<std::unique_ptr<MemoryBuffer>> Buf =
     96       MemoryBuffer::getFileOrSTDIN(Input);
     97   if (!Buf)
     98     return 1;
     99 
    100   ConvertFuncPtr Convert = nullptr;
    101   if (Format == YOF_COFF)
    102     Convert = yaml2coff;
    103   else if (Format == YOF_ELF)
    104     Convert = yaml2elf;
    105   else {
    106     errs() << "Not yet implemented\n";
    107     return 1;
    108   }
    109 
    110   yaml::Input YIn(Buf.get()->getBuffer());
    111 
    112   int Res = convertYAML(YIn, Out->os(), Convert);
    113   if (Res == 0)
    114     Out->keep();
    115 
    116   return Res;
    117 }
    118