main.go

Documentation: cmd/objdump

     1  // Copyright 2012 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Objdump disassembles executable files.
     6  //
     7  // Usage:
     8  //
     9  //	go tool objdump [-s symregexp] binary
    10  //
    11  // Objdump prints a disassembly of all text symbols (code) in the binary.
    12  // If the -s option is present, objdump only disassembles
    13  // symbols with names matching the regular expression.
    14  //
    15  // Alternate usage:
    16  //
    17  //	go tool objdump binary start end
    18  //
    19  // In this mode, objdump disassembles the binary starting at the start address and
    20  // stopping at the end address. The start and end addresses are program
    21  // counters written in hexadecimal with optional leading 0x prefix.
    22  // In this mode, objdump prints a sequence of stanzas of the form:
    23  //
    24  //	file:line
    25  //	 address: assembly
    26  //	 address: assembly
    27  //	 ...
    28  //
    29  // Each stanza gives the disassembly for a contiguous range of addresses
    30  // all mapped to the same original source file and line number.
    31  // This mode is intended for use by pprof.
    32  package main
    33  
    34  import (
    35  	"flag"
    36  	"fmt"
    37  	"log"
    38  	"os"
    39  	"regexp"
    40  	"strconv"
    41  	"strings"
    42  
    43  	"cmd/internal/objfile"
    44  	"cmd/internal/telemetry/counter"
    45  )
    46  
    47  var printCode = flag.Bool("S", false, "print Go code alongside assembly")
    48  var symregexp = flag.String("s", "", "only dump symbols matching this regexp")
    49  var gnuAsm = flag.Bool("gnu", false, "print GNU assembly next to Go assembly (where supported)")
    50  var symRE *regexp.Regexp
    51  
    52  func usage() {
    53  	fmt.Fprintf(os.Stderr, "usage: go tool objdump [-S] [-gnu] [-s symregexp] binary [start end]\n\n")
    54  	flag.PrintDefaults()
    55  	os.Exit(2)
    56  }
    57  
    58  func main() {
    59  	log.SetFlags(0)
    60  	log.SetPrefix("objdump: ")
    61  	counter.Open()
    62  
    63  	flag.Usage = usage
    64  	flag.Parse()
    65  	counter.Inc("objdump/invocations")
    66  	counter.CountFlags("objdump/flag:", *flag.CommandLine)
    67  	if flag.NArg() != 1 && flag.NArg() != 3 {
    68  		usage()
    69  	}
    70  
    71  	if *symregexp != "" {
    72  		re, err := regexp.Compile(*symregexp)
    73  		if err != nil {
    74  			log.Fatalf("invalid -s regexp: %v", err)
    75  		}
    76  		symRE = re
    77  	}
    78  
    79  	f, err := objfile.Open(flag.Arg(0))
    80  	if err != nil {
    81  		log.Fatal(err)
    82  	}
    83  	defer f.Close()
    84  
    85  	dis, err := f.Disasm()
    86  	if err != nil {
    87  		log.Fatalf("disassemble %s: %v", flag.Arg(0), err)
    88  	}
    89  
    90  	switch flag.NArg() {
    91  	default:
    92  		usage()
    93  	case 1:
    94  		// disassembly of entire object
    95  		dis.Print(os.Stdout, symRE, 0, ^uint64(0), *printCode, *gnuAsm)
    96  
    97  	case 3:
    98  		// disassembly of PC range
    99  		start, err := strconv.ParseUint(strings.TrimPrefix(flag.Arg(1), "0x"), 16, 64)
   100  		if err != nil {
   101  			log.Fatalf("invalid start PC: %v", err)
   102  		}
   103  		end, err := strconv.ParseUint(strings.TrimPrefix(flag.Arg(2), "0x"), 16, 64)
   104  		if err != nil {
   105  			log.Fatalf("invalid end PC: %v", err)
   106  		}
   107  		dis.Print(os.Stdout, symRE, start, end, *printCode, *gnuAsm)
   108  	}
   109  }
   110
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