cmd/addr2line, cmd/nm: factor object reading into cmd/internal/objfile

To do in another CL: make cmd/objdump use cmd/internal/objfile too.

There is a package placement decision in this CL:
cmd/internal/objfile instead of internal/objfile.
I chose to put internal under cmd to make clear (and enforce)
that no standard library packages should use this
(it's a bit dependency-heavy).

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/123910043

1 files changed, 4 insertions, 155 deletions

diff --git a/src/cmd/addr2line/main.go b/src/cmd/addr2line/main.go
index 3802f764f9..267f4170a8 100644
--- a/src/cmd/addr2line/main.go
+++ b/src/cmd/addr2line/main.go
@@ -19,17 +19,14 @@ package main
 
 import (
 	"bufio"
-	"debug/elf"
-	"debug/gosym"
-	"debug/macho"
-	"debug/pe"
-	"debug/plan9obj"
 	"flag"
 	"fmt"
 	"log"
 	"os"
 	"strconv"
 	"strings"
+
+	"cmd/internal/objfile"
 )
 
 func printUsage(w *os.File) {
@@ -60,18 +57,12 @@ func main() {
 		usage()
 	}
 
-	f, err := os.Open(flag.Arg(0))
+	f, err := objfile.Open(flag.Arg(0))
 	if err != nil {
 		log.Fatal(err)
 	}
 
-	textStart, symtab, pclntab, err := loadTables(f)
-	if err != nil {
-		log.Fatalf("reading %s: %v", flag.Arg(0), err)
-	}
-
-	pcln := gosym.NewLineTable(pclntab, textStart)
-	tab, err := gosym.NewTable(symtab, pcln)
+	tab, err := f.PCLineTable()
 	if err != nil {
 		log.Fatalf("reading %s: %v", flag.Arg(0), err)
 	}
@@ -102,145 +93,3 @@ func main() {
 	}
 	stdout.Flush()
 }
-
-func loadTables(f *os.File) (textStart uint64, symtab, pclntab []byte, err error) {
-	if obj, err := elf.NewFile(f); err == nil {
-		if sect := obj.Section(".text"); sect != nil {
-			textStart = sect.Addr
-		}
-		if sect := obj.Section(".gosymtab"); sect != nil {
-			if symtab, err = sect.Data(); err != nil {
-				return 0, nil, nil, err
-			}
-		}
-		if sect := obj.Section(".gopclntab"); sect != nil {
-			if pclntab, err = sect.Data(); err != nil {
-				return 0, nil, nil, err
-			}
-		}
-		return textStart, symtab, pclntab, nil
-	}
-
-	if obj, err := macho.NewFile(f); err == nil {
-		if sect := obj.Section("__text"); sect != nil {
-			textStart = sect.Addr
-		}
-		if sect := obj.Section("__gosymtab"); sect != nil {
-			if symtab, err = sect.Data(); err != nil {
-				return 0, nil, nil, err
-			}
-		}
-		if sect := obj.Section("__gopclntab"); sect != nil {
-			if pclntab, err = sect.Data(); err != nil {
-				return 0, nil, nil, err
-			}
-		}
-		return textStart, symtab, pclntab, nil
-	}
-
-	if obj, err := pe.NewFile(f); err == nil {
-		var imageBase uint64
-		switch oh := obj.OptionalHeader.(type) {
-		case *pe.OptionalHeader32:
-			imageBase = uint64(oh.ImageBase)
-		case *pe.OptionalHeader64:
-			imageBase = oh.ImageBase
-		default:
-			return 0, nil, nil, fmt.Errorf("pe file format not recognized")
-		}
-		if sect := obj.Section(".text"); sect != nil {
-			textStart = imageBase + uint64(sect.VirtualAddress)
-		}
-		if pclntab, err = loadPETable(obj, "pclntab", "epclntab"); err != nil {
-			return 0, nil, nil, err
-		}
-		if symtab, err = loadPETable(obj, "symtab", "esymtab"); err != nil {
-			return 0, nil, nil, err
-		}
-		return textStart, symtab, pclntab, nil
-	}
-
-	if obj, err := plan9obj.NewFile(f); err == nil {
-		textStart = obj.LoadAddress + obj.HdrSize
-		if pclntab, err = loadPlan9Table(obj, "pclntab", "epclntab"); err != nil {
-			return 0, nil, nil, err
-		}
-		if symtab, err = loadPlan9Table(obj, "symtab", "esymtab"); err != nil {
-			return 0, nil, nil, err
-		}
-		return textStart, symtab, pclntab, nil
-	}
-
-	return 0, nil, nil, fmt.Errorf("unrecognized binary format")
-}
-
-func findPESymbol(f *pe.File, name string) (*pe.Symbol, error) {
-	for _, s := range f.Symbols {
-		if s.Name != name {
-			continue
-		}
-		if s.SectionNumber <= 0 {
-			return nil, fmt.Errorf("symbol %s: invalid section number %d", name, s.SectionNumber)
-		}
-		if len(f.Sections) < int(s.SectionNumber) {
-			return nil, fmt.Errorf("symbol %s: section number %d is larger than max %d", name, s.SectionNumber, len(f.Sections))
-		}
-		return s, nil
-	}
-	return nil, fmt.Errorf("no %s symbol found", name)
-}
-
-func loadPETable(f *pe.File, sname, ename string) ([]byte, error) {
-	ssym, err := findPESymbol(f, sname)
-	if err != nil {
-		return nil, err
-	}
-	esym, err := findPESymbol(f, ename)
-	if err != nil {
-		return nil, err
-	}
-	if ssym.SectionNumber != esym.SectionNumber {
-		return nil, fmt.Errorf("%s and %s symbols must be in the same section", sname, ename)
-	}
-	sect := f.Sections[ssym.SectionNumber-1]
-	data, err := sect.Data()
-	if err != nil {
-		return nil, err
-	}
-	return data[ssym.Value:esym.Value], nil
-}
-
-func findPlan9Symbol(f *plan9obj.File, name string) (*plan9obj.Sym, error) {
-	syms, err := f.Symbols()
-	if err != nil {
-		return nil, err
-	}
-	for _, s := range syms {
-		if s.Name != name {
-			continue
-		}
-		return &s, nil
-	}
-	return nil, fmt.Errorf("no %s symbol found", name)
-}
-
-func loadPlan9Table(f *plan9obj.File, sname, ename string) ([]byte, error) {
-	ssym, err := findPlan9Symbol(f, sname)
-	if err != nil {
-		return nil, err
-	}
-	esym, err := findPlan9Symbol(f, ename)
-	if err != nil {
-		return nil, err
-	}
-	sect := f.Section("text")
-	if sect == nil {
-		return nil, err
-	}
-	data, err := sect.Data()
-	if err != nil {
-		return nil, err
-	}
-	textStart := f.LoadAddress + f.HdrSize
-	return data[ssym.Value-textStart : esym.Value-textStart], nil
-}