cmd/internal/xcoff: add new debug package for cmd

This commit adds a new package in cmd/internal which aims
to debug and load XCOFF files.

Updates: #25893, #28037

Change-Id: I47db495bedfa43e9129a831b9b8bbc35b703567b
Reviewed-on: https://go-review.googlesource.com/c/138727
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

misc/nacl/testzip.proto

@@ -37,6 +37,9 @@ go	src=..
 				buildid
 					testdata
 						+
+				xcoff
+					testdata
+						+
 			gofmt
 				gofmt.go
 				gofmt_test.go

src/cmd/internal/xcoff/file_test.go

+// Copyright 2018 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.
+
+package xcoff
+
+import (
+	"reflect"
+	"testing"
+)
+
+type fileTest struct {
+	file     string
+	hdr      FileHeader
+	sections []*SectionHeader
+	needed   []string
+}
+
+var fileTests = []fileTest{
+	{
+		"testdata/gcc-ppc32-aix-dwarf2-exec",
+		FileHeader{U802TOCMAGIC},
+		[]*SectionHeader{
+			{".text", 0x10000290, 0x00000bbd, STYP_TEXT, 0x7ae6, 0x36},
+			{".data", 0x20000e4d, 0x00000437, STYP_DATA, 0x7d02, 0x2b},
+			{".bss", 0x20001284, 0x0000021c, STYP_BSS, 0, 0},
+			{".loader", 0x00000000, 0x000004b3, STYP_LOADER, 0, 0},
+			{".dwline", 0x00000000, 0x000000df, STYP_DWARF | SSUBTYP_DWLINE, 0x7eb0, 0x7},
+			{".dwinfo", 0x00000000, 0x00000314, STYP_DWARF | SSUBTYP_DWINFO, 0x7ef6, 0xa},
+			{".dwabrev", 0x00000000, 0x000000d6, STYP_DWARF | SSUBTYP_DWABREV, 0, 0},
+			{".dwarnge", 0x00000000, 0x00000020, STYP_DWARF | SSUBTYP_DWARNGE, 0x7f5a, 0x2},
+			{".dwloc", 0x00000000, 0x00000074, STYP_DWARF | SSUBTYP_DWLOC, 0, 0},
+			{".debug", 0x00000000, 0x00005e4f, STYP_DEBUG, 0, 0},
+		},
+		[]string{"libc.a/shr.o"},
+	},
+	{
+		"testdata/gcc-ppc64-aix-dwarf2-exec",
+		FileHeader{U64_TOCMAGIC},
+		[]*SectionHeader{
+			{".text", 0x10000480, 0x00000afd, STYP_TEXT, 0x8322, 0x34},
+			{".data", 0x20000f7d, 0x000002f3, STYP_DATA, 0x85fa, 0x25},
+			{".bss", 0x20001270, 0x00000428, STYP_BSS, 0, 0},
+			{".loader", 0x00000000, 0x00000535, STYP_LOADER, 0, 0},
+			{".dwline", 0x00000000, 0x000000b4, STYP_DWARF | SSUBTYP_DWLINE, 0x8800, 0x4},
+			{".dwinfo", 0x00000000, 0x0000036a, STYP_DWARF | SSUBTYP_DWINFO, 0x8838, 0x7},
+			{".dwabrev", 0x00000000, 0x000000b5, STYP_DWARF | SSUBTYP_DWABREV, 0, 0},
+			{".dwarnge", 0x00000000, 0x00000040, STYP_DWARF | SSUBTYP_DWARNGE, 0x889a, 0x2},
+			{".dwloc", 0x00000000, 0x00000062, STYP_DWARF | SSUBTYP_DWLOC, 0, 0},
+			{".debug", 0x00000000, 0x00006605, STYP_DEBUG, 0, 0},
+		},
+		[]string{"libc.a/shr_64.o"},
+	},
+}
+
+func TestOpen(t *testing.T) {
+	for i := range fileTests {
+		tt := &fileTests[i]
+
+		f, err := Open(tt.file)
+		if err != nil {
+			t.Error(err)
+			continue
+		}
+		if !reflect.DeepEqual(f.FileHeader, tt.hdr) {
+			t.Errorf("open %s:\n\thave %#v\n\twant %#v\n", tt.file, f.FileHeader, tt.hdr)
+			continue
+		}
+
+		for i, sh := range f.Sections {
+			if i >= len(tt.sections) {
+				break
+			}
+			have := &sh.SectionHeader
+			want := tt.sections[i]
+			if !reflect.DeepEqual(have, want) {
+				t.Errorf("open %s, section %d:\n\thave %#v\n\twant %#v\n", tt.file, i, have, want)
+			}
+		}
+		tn := len(tt.sections)
+		fn := len(f.Sections)
+		if tn != fn {
+			t.Errorf("open %s: len(Sections) = %d, want %d", tt.file, fn, tn)
+		}
+		tl := tt.needed
+		fl, err := f.ImportedLibraries()
+		if err != nil {
+			t.Error(err)
+		}
+		if !reflect.DeepEqual(tl, fl) {
+			t.Errorf("open %s: loader import = %v, want %v", tt.file, tl, fl)
+		}
+	}
+}
+
+func TestOpenFailure(t *testing.T) {
+	filename := "file.go"    // not an XCOFF object file
+	_, err := Open(filename) // don't crash
+	if err == nil {
+		t.Errorf("open %s: succeeded unexpectedly", filename)
+	}
+}

src/cmd/internal/xcoff/testdata/hello.c

+#include <stdio.h>
+
+void
+main(int argc, char *argv[])
+{
+	printf("hello, world\n");
+}