cmd/addr2line: reimplement in Go

We never updated libmach for the new object file format,
so it the existing 'go tool addr2line' is broken.
Reimplement in Go to fix.

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews
https://golang.org/cl/66020043

src/cmd/addr2line/main.c

-// Copyright 2012 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-/*
- * addr2line simulation - only enough to make pprof work on Macs
- */
-
-#include <u.h>
-#include <libc.h>
-#include <bio.h>
-#include <mach.h>
-
-void
-printusage(int fd)
-{
-	fprint(fd, "usage: addr2line binary\n");
-	fprint(fd, "reads addresses from standard input and writes two lines for each:\n");
-	fprint(fd, "\tfunction name\n");
-	fprint(fd, "\tfile:line\n");
-}
-
-void
-usage(void)
-{
-	printusage(2);
-	exits("usage");
-}
-
-void
-main(int argc, char **argv)
-{
-	int fd;
-	char *p, *q;
-	uvlong pc;
-	Symbol s;
-	Fhdr fhdr;
-	Biobuf bin, bout;
-	char file[1024];
-
-	if(argc > 1 && strcmp(argv[1], "--help") == 0) {
-		printusage(1);
-		exits(0);
-	}
-
-	ARGBEGIN{
-	default:
-		usage();
-	}ARGEND
-
-	if(argc != 1)
-		usage();
-
-	fd = open(argv[0], OREAD);
-	if(fd < 0)
-		sysfatal("open %s: %r", argv[0]);
-	if(crackhdr(fd, &fhdr) <= 0)
-		sysfatal("crackhdr: %r");
-	machbytype(fhdr.type);
-	if(syminit(fd, &fhdr) <= 0)
-		sysfatal("syminit: %r");
-
-	Binit(&bin, 0, OREAD);
-	Binit(&bout, 1, OWRITE);
-	for(;;) {
-		p = Brdline(&bin, '\n');
-		if(p == nil)
-			break;
-		p[Blinelen(&bin)-1] = '\0';
-		q = strchr(p, ':');
-		if(q != nil) {
-			// reverse: translate file:line to pc
-			*q++ = '\0';
-			pc = file2pc(p, atoi(q));
-			if(pc == ~(uvlong)0)
-				Bprint(&bout, "!%r\n");
-			else
-				Bprint(&bout, "0x%llux\n", pc);
-			continue;
-		}			
-		pc = strtoull(p, 0, 16);
-		if(!findsym(pc, CTEXT, &s))
-			s.name = "??";
-		if(!fileline(file, sizeof file, pc))
-			strcpy(file, "??:0");
-		Bprint(&bout, "%s\n%s\n", s.name, file);
-	}
-	Bflush(&bout);
-	exits(0);
-}

src/cmd/addr2line/main.go

+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// addr2line simulation - only enough to make pprof work on Macs
+
+package main
+
+import (
+	"bufio"
+	"debug/elf"
+	"debug/gosym"
+	"debug/macho"
+	"debug/pe"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func printUsage(w *os.File) {
+	fmt.Fprintf(w, "usage: addr2line binary\n")
+	fmt.Fprintf(w, "reads addresses from standard input and writes two lines for each:\n")
+	fmt.Fprintf(w, "\tfunction name\n")
+	fmt.Fprintf(w, "\tfile:line\n")
+}
+
+func usage() {
+	printUsage(os.Stderr)
+	os.Exit(2)
+}
+
+func main() {
+	log.SetFlags(0)
+	log.SetPrefix("addr2line: ")
+
+	// pprof expects this behavior when checking for addr2line
+	if len(os.Args) > 1 && os.Args[1] == "--help" {
+		printUsage(os.Stdout)
+		os.Exit(0)
+	}
+
+	flag.Usage = usage
+	flag.Parse()
+	if flag.NArg() != 1 {
+		usage()
+	}
+
+	f, err := os.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)
+	if err != nil {
+		log.Fatalf("reading %s: %v", flag.Arg(0), err)
+	}
+
+	stdin := bufio.NewScanner(os.Stdin)
+	stdout := bufio.NewWriter(os.Stdout)
+
+	for stdin.Scan() {
+		p := stdin.Text()
+		if strings.Contains(p, ":") {
+			// Reverse translate file:line to pc.
+			// This was an extension in the old C version of 'go tool addr2line'
+			// and is probably not used by anyone, but recognize the syntax.
+			// We don't have an implementation.
+			fmt.Fprintf(stdout, "!reverse translation not implemented\n")
+			continue
+		}
+		pc, _ := strconv.ParseUint(p, 16, 64)
+		file, line, fn := tab.PCToLine(pc)
+		name := "?"
+		if fn != nil {
+			name = fn.Name
+		} else {
+			file = "?"
+			line = 0
+		}
+		fmt.Fprintf(stdout, "%s\n%s:%d\n", name, file, line)
+	}
+	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 {
+		if sect := obj.Section(".text"); sect != nil {
+			textStart = uint64(sect.VirtualAddress)
+		}
+		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
+	}
+
+	return 0, nil, nil, fmt.Errorf("unrecognized binary format")
+}

src/cmd/dist/build.c

@@ -1297,7 +1297,6 @@ static char *buildorder[] = {
 
 	"misc/pprof",
 
-	"cmd/addr2line",
 	"cmd/objdump",
 	"cmd/prof",
 
@@ -1372,7 +1371,6 @@ static char *cleantab[] = {
 	"cmd/8c",
 	"cmd/8g",
 	"cmd/8l",
-	"cmd/addr2line",
 	"cmd/cc",
 	"cmd/gc",
 	"cmd/go",	

src/cmd/go/pkg.go

@@ -307,6 +307,7 @@ const (
 
 // goTools is a map of Go program import path to install target directory.
 var goTools = map[string]targetDir{
+	"cmd/addr2line": toTool,
 	"cmd/api":       toTool,
 	"cmd/cgo":       toTool,
 	"cmd/fix":       toTool,