github.com/decomp/exp@v0.0.0-20210624183419-6d058f5e1da6/cmd/bin2c/main.go (about)

     1  // bin2c is a tool which converts binary executables to equivalent C source
     2  // code.
     3  package main
     4  
     5  import (
     6  	"debug/pe"
     7  	"flag"
     8  	"fmt"
     9  	"go/printer"
    10  	"go/token"
    11  	"log"
    12  	"os"
    13  	"strconv"
    14  	"strings"
    15  
    16  	"github.com/mewkiz/pkg/errutil"
    17  )
    18  
    19  func usage() {
    20  	const use = `
    21  Usage: bin2c -addr ADDRESS [OPTION]... FILE
    22  Convert binary executables to equivalent C source code.
    23  
    24  Flags:
    25  `
    26  	fmt.Fprint(os.Stderr, use[1:])
    27  	flag.PrintDefaults()
    28  }
    29  
    30  // Command line flags.
    31  var (
    32  	// flagVerbose specifies whether verbose output is enabled.
    33  	flagVerbose bool
    34  )
    35  
    36  // Base address of the ".text" section.
    37  const baseAddr = 0x00401000
    38  
    39  func main() {
    40  	// Parse command line arguments.
    41  	var (
    42  		// addr specifies the address to decompile.
    43  		addr address
    44  	)
    45  	flag.BoolVar(&flagVerbose, "v", false, "Enable verbose output.")
    46  	flag.Var(&addr, "addr", "Address of function to decompile.")
    47  	flag.Usage = usage
    48  	flag.Parse()
    49  	if flag.NArg() != 1 {
    50  		flag.Usage()
    51  		os.Exit(1)
    52  	}
    53  	path := flag.Arg(0)
    54  	if addr == 0 {
    55  		flag.Usage()
    56  		os.Exit(1)
    57  	}
    58  
    59  	// Parse ".text" section.
    60  	text, err := parseText(path)
    61  	if err != nil {
    62  		log.Fatal(err)
    63  	}
    64  
    65  	// Sanity check.
    66  	offset := int(addr - baseAddr)
    67  	if offset < 0 || offset >= len(text) {
    68  		log.Fatalf("invalid address; expected >= 0x%X and < 0x%X, got 0x%X", baseAddr, baseAddr+len(text), addr)
    69  	}
    70  
    71  	// Parse basic blocks.
    72  	//blocks, err := parseBlocks(text, offset)
    73  	//if err != nil {
    74  	//	log.Fatal(err)
    75  	//}
    76  
    77  	// Convert the given function to C source code.
    78  	fn, err := parseFunc(text, offset)
    79  	if err != nil {
    80  		log.Fatal(err)
    81  	}
    82  	printer.Fprint(os.Stdout, token.NewFileSet(), fn)
    83  }
    84  
    85  // parseText parses and returns the ".text" section of the given binary
    86  // executable.
    87  func parseText(path string) (text []byte, err error) {
    88  	f, err := pe.Open(path)
    89  	if err != nil {
    90  		return nil, errutil.Err(err)
    91  	}
    92  	defer f.Close()
    93  
    94  	sect := f.Section(".text")
    95  	if sect == nil {
    96  		return nil, errutil.Newf(`unable to locate ".text" section in %q`, path)
    97  	}
    98  	return sect.Data()
    99  }
   100  
   101  // address implements the flag.Value interface and allows addresses to be
   102  // specified in hexadecimal format.
   103  type address uint64
   104  
   105  // String returns the hexadecimal string representation of v.
   106  func (v *address) String() string {
   107  	return fmt.Sprintf("0x%X", uint64(*v))
   108  }
   109  
   110  // Set sets v to the numberic value represented by s.
   111  func (v *address) Set(s string) error {
   112  	base := 10
   113  	if strings.HasPrefix(s, "0x") || strings.HasPrefix(s, "0X") {
   114  		s = s[2:]
   115  		base = 16
   116  	}
   117  	x, err := strconv.ParseUint(s, base, 64)
   118  	if err != nil {
   119  		return errutil.Err(err)
   120  	}
   121  	*v = address(x)
   122  	return nil
   123  }