cmd/nm: minor cleanup from previous CL

I forgot to apply Ian's suggestions before submitting CL 40600043.

R=iant
CC=golang-dev
https://golang.org/cl/43560045

src/cmd/nm/doc.go

@@ -13,6 +13,8 @@
 //
 //	T	text (code) segment symbol
 //	t	static text segment symbol
+//	R	read-only data segment symbol
+//	r	static read-only data segment symbol
 //	D	data segment symbol
 //	d	static data segment symbol
 //	B	bss segment symbol

src/cmd/nm/elf.go

@@ -47,6 +47,9 @@ func elfSymbols(f *os.File) []Sym {
 				sym.Code = 'D'
 			}
 		}
+		if elf.ST_BIND(s.Info) == elf.STB_LOCAL {
+			sym.Code += 'a' - 'A'
+		}
 		syms = append(syms, sym)
 	}
 

src/cmd/nm/goobj.go

@@ -42,7 +42,7 @@ func goobjSymbols(f *os.File) []Sym {
 		case goobj.SBSS, goobj.SNOPTRBSS, goobj.STLSBSS:
 			sym.Code = 'B'
 		case goobj.SXREF, goobj.SMACHOSYMSTR, goobj.SMACHOSYMTAB, goobj.SMACHOINDIRECTPLT, goobj.SMACHOINDIRECTGOT, goobj.SFILE, goobj.SFILEPATH, goobj.SCONST, goobj.SDYNIMPORT, goobj.SHOSTOBJ:
-			sym.Code = 'X'
+			sym.Code = 'X' // should not see
 		}
 		if s.Version != 0 {
 			sym.Code += 'a' - 'A'

src/cmd/nm/nm.go

@@ -24,6 +24,8 @@ var (
 	sortOrder = flag.String("sort", "name", "")
 	printSize = flag.Bool("size", false, "")
 	printType = flag.Bool("type", false, "")
+
+	filePrefix = false
 )
 
 func init() {
@@ -64,6 +66,7 @@ func main() {
 	}
 
 	args := flag.Args()
+	filePrefix = len(args) > 1
 	if len(args) == 0 {
 		flag.Usage()
 	}
@@ -136,6 +139,9 @@ HaveSyms:
 
 	w := bufio.NewWriter(os.Stdout)
 	for _, sym := range syms {
+		if filePrefix {
+			fmt.Fprintf(w, "%s:\t", file)
+		}
 		if sym.Code == 'U' {
 			fmt.Fprintf(w, "%8s", "")
 		} else {
@@ -153,16 +159,6 @@ HaveSyms:
 	w.Flush()
 }
 
-func filter(syms []Sym, ok func(Sym) bool) []Sym {
-	out := syms[:0]
-	for _, sym := range syms {
-		if ok(sym) {
-			out = append(out, sym)
-		}
-	}
-	return out
-}
-
 type byAddr []Sym
 
 func (x byAddr) Len() int           { return len(x) }