cmd/objdump: use cmd/internal/objfile

This removes a bunch of ugly duplicate code.
The end goal is to factor the disassembly code
into cmd/internal/objfile too, so that pprof can use it,
but one step at a time.

LGTM=r, iant
R=r, alex.brainman, iant
CC=golang-codereviews
https://codereview.appspot.com/149400043

6 files changed, 124 insertions, 0 deletions

diff --git a/src/cmd/internal/objfile/elf.go b/src/cmd/internal/objfile/elf.go
index 8495fa753..17755b84d 100644
--- a/src/cmd/internal/objfile/elf.go
+++ b/src/cmd/internal/objfile/elf.go
@@ -8,6 +8,7 @@ package objfile
 
 import (
 	"debug/elf"
+	"fmt"
 	"os"
 )
 
@@ -77,3 +78,27 @@ func (f *elfFile) pcln() (textStart uint64, symtab, pclntab []byte, err error) {
 	}
 	return textStart, symtab, pclntab, nil
 }
+
+func (f *elfFile) text() (textStart uint64, text []byte, err error) {
+	sect := f.elf.Section(".text")
+	if sect == nil {
+		return 0, nil, fmt.Errorf("text section not found")
+	}
+	textStart = sect.Addr
+	text, err = sect.Data()
+	return
+}
+
+func (f *elfFile) goarch() string {
+	switch f.elf.Machine {
+	case elf.EM_386:
+		return "386"
+	case elf.EM_X86_64:
+		return "amd64"
+	case elf.EM_ARM:
+		return "arm"
+	case elf.EM_PPC64:
+		return "power64"
+	}
+	return ""
+}
diff --git a/src/cmd/internal/objfile/goobj.go b/src/cmd/internal/objfile/goobj.go
index a4f49ebe4..a1d773023 100644
--- a/src/cmd/internal/objfile/goobj.go
+++ b/src/cmd/internal/objfile/goobj.go
@@ -79,3 +79,15 @@ func (f *goobjFile) symbols() ([]Sym, error) {
 func (f *goobjFile) pcln() (textStart uint64, symtab, pclntab []byte, err error) {
 	return 0, nil, nil, fmt.Errorf("pcln not available in go object file")
 }
+
+// text does not make sense for Go object files, because
+// each function has a separate section.
+func (f *goobjFile) text() (textStart uint64, text []byte, err error) {
+	return 0, nil, fmt.Errorf("text not available in go object file")
+}
+
+// goarch makes sense but is not exposed in debug/goobj's API,
+// and we don't need it yet for any users of internal/objfile.
+func (f *goobjFile) goarch() string {
+	return "GOARCH unimplemented for debug/goobj files"
+}
diff --git a/src/cmd/internal/objfile/macho.go b/src/cmd/internal/objfile/macho.go
index f845792ff..7dd84a339 100644
--- a/src/cmd/internal/objfile/macho.go
+++ b/src/cmd/internal/objfile/macho.go
@@ -85,6 +85,30 @@ func (f *machoFile) pcln() (textStart uint64, symtab, pclntab []byte, err error)
 	return textStart, symtab, pclntab, nil
 }
 
+func (f *machoFile) text() (textStart uint64, text []byte, err error) {
+	sect := f.macho.Section("__text")
+	if sect == nil {
+		return 0, nil, fmt.Errorf("text section not found")
+	}
+	textStart = sect.Addr
+	text, err = sect.Data()
+	return
+}
+
+func (f *machoFile) goarch() string {
+	switch f.macho.Cpu {
+	case macho.Cpu386:
+		return "386"
+	case macho.CpuAmd64:
+		return "amd64"
+	case macho.CpuArm:
+		return "arm"
+	case macho.CpuPpc64:
+		return "power64"
+	}
+	return ""
+}
+
 type uint64s []uint64
 
 func (x uint64s) Len() int           { return len(x) }
diff --git a/src/cmd/internal/objfile/objfile.go b/src/cmd/internal/objfile/objfile.go
index 09fa63e60..3d4a5d27c 100644
--- a/src/cmd/internal/objfile/objfile.go
+++ b/src/cmd/internal/objfile/objfile.go
@@ -14,6 +14,8 @@ import (
 type rawFile interface {
 	symbols() (syms []Sym, err error)
 	pcln() (textStart uint64, symtab, pclntab []byte, err error)
+	text() (textStart uint64, text []byte, err error)
+	goarch() string
 }
 
 // A File is an opened executable file.
@@ -70,3 +72,11 @@ func (f *File) PCLineTable() (*gosym.Table, error) {
 	}
 	return gosym.NewTable(symtab, gosym.NewLineTable(pclntab, textStart))
 }
+
+func (f *File) Text() (uint64, []byte, error) {
+	return f.raw.text()
+}
+
+func (f *File) GOARCH() string {
+	return f.raw.goarch()
+}
diff --git a/src/cmd/internal/objfile/pe.go b/src/cmd/internal/objfile/pe.go
index 868709eaf..67e59c226 100644
--- a/src/cmd/internal/objfile/pe.go
+++ b/src/cmd/internal/objfile/pe.go
@@ -133,6 +133,25 @@ func (f *peFile) pcln() (textStart uint64, symtab, pclntab []byte, err error) {
 	return textStart, symtab, pclntab, nil
 }
 
+func (f *peFile) text() (textStart uint64, text []byte, err error) {
+	var imageBase uint64
+	switch oh := f.pe.OptionalHeader.(type) {
+	case *pe.OptionalHeader32:
+		imageBase = uint64(oh.ImageBase)
+	case *pe.OptionalHeader64:
+		imageBase = oh.ImageBase
+	default:
+		return 0, nil, fmt.Errorf("pe file format not recognized")
+	}
+	sect := f.pe.Section(".text")
+	if sect == nil {
+		return 0, nil, fmt.Errorf("text section not found")
+	}
+	textStart = imageBase + uint64(sect.VirtualAddress)
+	text, err = sect.Data()
+	return
+}
+
 func findPESymbol(f *pe.File, name string) (*pe.Symbol, error) {
 	for _, s := range f.Symbols {
 		if s.Name != name {
@@ -168,3 +187,15 @@ func loadPETable(f *pe.File, sname, ename string) ([]byte, error) {
 	}
 	return data[ssym.Value:esym.Value], nil
 }
+
+func (f *peFile) goarch() string {
+	// Not sure how to get the info we want from PE header.
+	// Look in symbol table for telltale rt0 symbol.
+	if _, err := findPESymbol(f.pe, "_rt0_386_windows"); err == nil {
+		return "386"
+	}
+	if _, err := findPESymbol(f.pe, "_rt0_amd64_windows"); err == nil {
+		return "amd64"
+	}
+	return ""
+}
diff --git a/src/cmd/internal/objfile/plan9obj.go b/src/cmd/internal/objfile/plan9obj.go
index 80744f82a..eb6cba5eb 100644
--- a/src/cmd/internal/objfile/plan9obj.go
+++ b/src/cmd/internal/objfile/plan9obj.go
@@ -88,6 +88,16 @@ func (f *plan9File) pcln() (textStart uint64, symtab, pclntab []byte, err error)
 	return textStart, symtab, pclntab, nil
 }
 
+func (f *plan9File) text() (textStart uint64, text []byte, err error) {
+	sect := f.plan9.Section("text")
+	if sect == nil {
+		return 0, nil, fmt.Errorf("text section not found")
+	}
+	textStart = f.plan9.LoadAddress + f.plan9.HdrSize
+	text, err = sect.Data()
+	return
+}
+
 func findPlan9Symbol(f *plan9obj.File, name string) (*plan9obj.Sym, error) {
 	syms, err := f.Symbols()
 	if err != nil {
@@ -122,3 +132,15 @@ func loadPlan9Table(f *plan9obj.File, sname, ename string) ([]byte, error) {
 	textStart := f.LoadAddress + f.HdrSize
 	return data[ssym.Value-textStart : esym.Value-textStart], nil
 }
+
+func (f *plan9File) goarch() string {
+	switch f.plan9.Magic {
+	case plan9obj.Magic386:
+		return "386"
+	case plan9obj.MagicAMD64:
+		return "amd64"
+	case plan9obj.MagicARM:
+		return "arm"
+	}
+	return ""
+}