debug/macho: support LC_RPATH

Updates #21487

Change-Id: Ia549a87a8a305cc80da11ea9bd904402f1a14689
Reviewed-on: https://go-review.googlesource.com/56321
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

5 files changed, 94 insertions, 13 deletions

diff --git a/src/debug/macho/file.go b/src/debug/macho/file.go
index 306e9ae1da..cbf24787be 100644
--- a/src/debug/macho/file.go
+++ b/src/debug/macho/file.go
@@ -143,6 +143,12 @@ type Dysymtab struct {
 	IndirectSyms []uint32 // indices into Symtab.Syms
 }
 
+// A Rpath represents a Mach-O rpath command.
+type Rpath struct {
+	LoadBytes
+	Path string
+}
+
 // A Symbol is a Mach-O 32-bit or 64-bit symbol table entry.
 type Symbol struct {
 	Name  string
@@ -258,6 +264,19 @@ func NewFile(r io.ReaderAt) (*File, error) {
 		default:
 			f.Loads[i] = LoadBytes(cmddat)
 
+		case LoadCmdRpath:
+			var hdr RpathCmd
+			b := bytes.NewReader(cmddat)
+			if err := binary.Read(b, bo, &hdr); err != nil {
+				return nil, err
+			}
+			l := new(Rpath)
+			if hdr.Path >= uint32(len(cmddat)) {
+				return nil, &FormatError{offset, "invalid path in rpath command", hdr.Path}
+			}
+			l.Path = cstring(cmddat[hdr.Path:])
+			f.Loads[i] = l
+
 		case LoadCmdDylib:
 			var hdr DylibCmd
 			b := bytes.NewReader(cmddat)
diff --git a/src/debug/macho/file_test.go b/src/debug/macho/file_test.go
index 01a8e70121..30705b1bc7 100644
--- a/src/debug/macho/file_test.go
+++ b/src/debug/macho/file_test.go
@@ -96,6 +96,52 @@ var fileTests = []fileTest{
 			{"__debug_str", "__DWARF", 0x10000215c, 0x60, 0x115c, 0x0, 0x0, 0x0, 0x0},
 		},
 	},
+	{
+		"testdata/clang-386-darwin-exec-with-rpath",
+		FileHeader{0xfeedface, Cpu386, 0x3, 0x2, 0x10, 0x42c, 0x1200085},
+		[]interface{}{
+			nil, // LC_SEGMENT
+			nil, // LC_SEGMENT
+			nil, // LC_SEGMENT
+			nil, // LC_SEGMENT
+			nil, // LC_DYLD_INFO_ONLY
+			nil, // LC_SYMTAB
+			nil, // LC_DYSYMTAB
+			nil, // LC_LOAD_DYLINKER
+			nil, // LC_UUID
+			nil, // LC_VERSION_MIN_MACOSX
+			nil, // LC_SOURCE_VERSION
+			nil, // LC_MAIN
+			nil, // LC_LOAD_DYLIB
+			&Rpath{nil, "/my/rpath"},
+			nil, // LC_FUNCTION_STARTS
+			nil, // LC_DATA_IN_CODE
+		},
+		nil,
+	},
+	{
+		"testdata/clang-amd64-darwin-exec-with-rpath",
+		FileHeader{0xfeedfacf, CpuAmd64, 0x80000003, 0x2, 0x10, 0x4c8, 0x200085},
+		[]interface{}{
+			nil, // LC_SEGMENT
+			nil, // LC_SEGMENT
+			nil, // LC_SEGMENT
+			nil, // LC_SEGMENT
+			nil, // LC_DYLD_INFO_ONLY
+			nil, // LC_SYMTAB
+			nil, // LC_DYSYMTAB
+			nil, // LC_LOAD_DYLINKER
+			nil, // LC_UUID
+			nil, // LC_VERSION_MIN_MACOSX
+			nil, // LC_SOURCE_VERSION
+			nil, // LC_MAIN
+			nil, // LC_LOAD_DYLIB
+			&Rpath{nil, "/my/rpath"},
+			nil, // LC_FUNCTION_STARTS
+			nil, // LC_DATA_IN_CODE
+		},
+		nil,
+	},
 }
 
 func TestOpen(t *testing.T) {
@@ -133,6 +179,12 @@ func TestOpen(t *testing.T) {
 				if !reflect.DeepEqual(have, want) {
 					t.Errorf("open %s, segment %d:\n\thave %#v\n\twant %#v\n", tt.file, i, have, want)
 				}
+			case *Rpath:
+				have := l
+				have.LoadBytes = nil
+				if !reflect.DeepEqual(have, want) {
+					t.Errorf("open %s, segment %d:\n\thave %#v\n\twant %#v\n", tt.file, i, have, want)
+				}
 			default:
 				t.Errorf("open %s, section %d: unknown load command\n\thave %#v\n\twant %#v\n", tt.file, i, l, want)
 			}
@@ -143,22 +195,23 @@ func TestOpen(t *testing.T) {
 			t.Errorf("open %s: len(Loads) = %d, want %d", tt.file, fn, tn)
 		}
 
-		for i, sh := range f.Sections {
-			if i >= len(tt.sections) {
-				break
+		if tt.sections != nil {
+			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)
+				}
 			}
-			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)
 			}
 		}
-		tn = len(tt.sections)
-		fn = len(f.Sections)
-		if tn != fn {
-			t.Errorf("open %s: len(Sections) = %d, want %d", tt.file, fn, tn)
-		}
-
 	}
 }
 
diff --git a/src/debug/macho/macho.go b/src/debug/macho/macho.go
index 045adb090a..907be31341 100644
--- a/src/debug/macho/macho.go
+++ b/src/debug/macho/macho.go
@@ -87,6 +87,7 @@ const (
 	LoadCmdDylib      LoadCmd = 0xc // load dylib command
 	LoadCmdDylinker   LoadCmd = 0xf // id dylinker command (not load dylinker command)
 	LoadCmdSegment64  LoadCmd = 0x19
+	LoadCmdRpath      LoadCmd = 0x8000001c
 )
 
 var cmdStrings = []intName{
@@ -95,6 +96,7 @@ var cmdStrings = []intName{
 	{uint32(LoadCmdUnixThread), "LoadCmdUnixThread"},
 	{uint32(LoadCmdDylib), "LoadCmdDylib"},
 	{uint32(LoadCmdSegment64), "LoadCmdSegment64"},
+	{uint32(LoadCmdRpath), "LoadCmdRpath"},
 }
 
 func (i LoadCmd) String() string   { return stringName(uint32(i), cmdStrings, false) }
@@ -175,6 +177,13 @@ type (
 		CompatVersion  uint32
 	}
 
+	// A RpathCmd is a Mach-O rpath command.
+	RpathCmd struct {
+		Cmd  LoadCmd
+		Len  uint32
+		Path uint32
+	}
+
 	// A Thread is a Mach-O thread state command.
 	Thread struct {
 		Cmd  LoadCmd
diff --git a/src/debug/macho/testdata/clang-386-darwin-exec-with-rpath b/src/debug/macho/testdata/clang-386-darwin-exec-with-rpath
new file mode 100644
index 0000000000..a8720feb92
--- /dev/null
+++ b/src/debug/macho/testdata/clang-386-darwin-exec-with-rpath
diff --git a/src/debug/macho/testdata/clang-amd64-darwin-exec-with-rpath b/src/debug/macho/testdata/clang-amd64-darwin-exec-with-rpath
new file mode 100644
index 0000000000..191c7688cb
--- /dev/null
+++ b/src/debug/macho/testdata/clang-amd64-darwin-exec-with-rpath