pkg/proc,pkg/dwarf: Introduce loclist package

Move the loclist code out of proc and into its own package in
`pkg/dwarf`.

pkg/dwarf/loclist/loclist.go

@@ -0,0 +1,81 @@
+package loclist
+
+import (
+	"encoding/binary"
+)
+
+// Reader parses and presents DWARF loclist information.
+type Reader struct {
+	data  []byte
+	cur   int
+	ptrSz int
+}
+
+// New returns an initialized loclist Reader.
+func New(data []byte, ptrSz int) *Reader {
+	return &Reader{data: data, ptrSz: ptrSz}
+}
+
+// Empty returns true if this reader has no data.
+func (rdr *Reader) Empty() bool {
+	return rdr.data == nil
+}
+
+// Seek moves the data pointer to the specified offset.
+func (rdr *Reader) Seek(off int) {
+	rdr.cur = off
+}
+
+// Next advances the reader to the next loclist entry, returning
+// the entry and true if successful, or nil, false if not.
+func (rdr *Reader) Next(e *Entry) bool {
+	e.LowPC = rdr.oneAddr()
+	e.HighPC = rdr.oneAddr()
+
+	if e.LowPC == 0 && e.HighPC == 0 {
+		return false
+	}
+
+	if e.BaseAddressSelection() {
+		e.Instr = nil
+		return true
+	}
+
+	instrlen := binary.LittleEndian.Uint16(rdr.read(2))
+	e.Instr = rdr.read(int(instrlen))
+	return true
+}
+
+func (rdr *Reader) read(sz int) []byte {
+	r := rdr.data[rdr.cur : rdr.cur+sz]
+	rdr.cur += sz
+	return r
+}
+
+func (rdr *Reader) oneAddr() uint64 {
+	switch rdr.ptrSz {
+	case 4:
+		addr := binary.LittleEndian.Uint32(rdr.read(rdr.ptrSz))
+		if addr == ^uint32(0) {
+			return ^uint64(0)
+		}
+		return uint64(addr)
+	case 8:
+		addr := uint64(binary.LittleEndian.Uint64(rdr.read(rdr.ptrSz)))
+		return addr
+	default:
+		panic("bad address size")
+	}
+}
+
+// Entry represents a single entry in the loclist section.
+type Entry struct {
+	LowPC, HighPC uint64
+	Instr         []byte
+}
+
+// BaseAddressSelection returns true if entry.highpc should
+// be used as the base address for subsequent entries.
+func (e *Entry) BaseAddressSelection() bool {
+	return e.LowPC == ^uint64(0)
+}

pkg/proc/bininfo.go

@@ -24,6 +24,7 @@ import (
 	"github.com/go-delve/delve/pkg/dwarf/frame"
 	"github.com/go-delve/delve/pkg/dwarf/godwarf"
 	"github.com/go-delve/delve/pkg/dwarf/line"
+	"github.com/go-delve/delve/pkg/dwarf/loclist"
 	"github.com/go-delve/delve/pkg/dwarf/op"
 	"github.com/go-delve/delve/pkg/dwarf/reader"
 	"github.com/go-delve/delve/pkg/goversion"
@@ -233,70 +234,6 @@ type packageVar struct {
 	addr   uint64
 }
 
-type loclistReader struct {
-	data  []byte
-	cur   int
-	ptrSz int
-}
-
-func (rdr *loclistReader) Seek(off int) {
-	rdr.cur = off
-}
-
-func (rdr *loclistReader) read(sz int) []byte {
-	r := rdr.data[rdr.cur : rdr.cur+sz]
-	rdr.cur += sz
-	return r
-}
-
-func (rdr *loclistReader) oneAddr() uint64 {
-	switch rdr.ptrSz {
-	case 4:
-		addr := binary.LittleEndian.Uint32(rdr.read(rdr.ptrSz))
-		if addr == ^uint32(0) {
-			return ^uint64(0)
-		}
-		return uint64(addr)
-	case 8:
-		addr := uint64(binary.LittleEndian.Uint64(rdr.read(rdr.ptrSz)))
-		return addr
-	default:
-		panic("bad address size")
-	}
-}
-
-func (rdr *loclistReader) Next(e *loclistEntry) bool {
-	e.lowpc = rdr.oneAddr()
-	e.highpc = rdr.oneAddr()
-
-	if e.lowpc == 0 && e.highpc == 0 {
-		return false
-	}
-
-	if e.BaseAddressSelection() {
-		e.instr = nil
-		return true
-	}
-
-	instrlen := binary.LittleEndian.Uint16(rdr.read(2))
-	e.instr = rdr.read(int(instrlen))
-	return true
-}
-
-type loclistEntry struct {
-	lowpc, highpc uint64
-	instr         []byte
-}
-
-type runtimeTypeDIE struct {
-	offset dwarf.Offset
-	kind   int64
-}
-
-func (e *loclistEntry) BaseAddressSelection() bool {
-	return e.lowpc == ^uint64(0)
-}
-
 type buildIDHeader struct {
 	Namesz uint32
 	Descsz uint32
@@ -529,7 +466,7 @@ type Image struct {
 
 	dwarf       *dwarf.Data
 	dwarfReader *dwarf.Reader
-	loclist     loclistReader
+	loclist     *loclist.Reader
 
 	typeCache map[dwarf.Offset]godwarf.Type
 
@@ -670,18 +607,13 @@ func (bi *BinaryInfo) LoadImageFromData(dwdata *dwarf.Data, debugFrameBytes, deb
 		bi.frameEntries = frame.Parse(debugFrameBytes, frame.DwarfEndian(debugFrameBytes), 0)
 	}
 
-	image.loclistInit(debugLocBytes, bi.Arch.PtrSize())
+	image.loclist = loclist.New(debugLocBytes, bi.Arch.PtrSize())
 
 	bi.loadDebugInfoMaps(image, debugLineBytes, nil, nil)
 
 	bi.Images = append(bi.Images, image)
 }
 
-func (image *Image) loclistInit(data []byte, ptrSz int) {
-	image.loclist.data = data
-	image.loclist.ptrSz = ptrSz
-}
-
 func (bi *BinaryInfo) locationExpr(entry reader.Entry, attr dwarf.Attr, pc uint64) ([]byte, string, error) {
 	a := entry.Val(attr)
 	if a == nil {
@@ -729,19 +661,19 @@ func (bi *BinaryInfo) LocationCovers(entry *dwarf.Entry, attr dwarf.Attr) ([][2]
 
 	image := cu.image
 	base := cu.lowPC
-	if image == nil || image.loclist.data == nil {
+	if image == nil || image.loclist.Empty() {
 		return nil, errors.New("malformed executable")
 	}
 
 	r := [][2]uint64{}
+	var e loclist.Entry
 	image.loclist.Seek(int(off))
-	var e loclistEntry
 	for image.loclist.Next(&e) {
 		if e.BaseAddressSelection() {
-			base = e.highpc
+			base = e.HighPC
 			continue
 		}
-		r = append(r, [2]uint64{e.lowpc + base, e.highpc + base})
+		r = append(r, [2]uint64{e.LowPC + base, e.HighPC + base})
 	}
 	return r, nil
 }
@@ -768,19 +700,19 @@ func (bi *BinaryInfo) loclistEntry(off int64, pc uint64) []byte {
 		base = cu.lowPC
 		image = cu.image
 	}
-	if image == nil || image.loclist.data == nil {
+	if image == nil || image.loclist.Empty() {
 		return nil
 	}
 
 	image.loclist.Seek(int(off))
-	var e loclistEntry
+	var e loclist.Entry
 	for image.loclist.Next(&e) {
 		if e.BaseAddressSelection() {
-			base = e.highpc
+			base = e.HighPC
 			continue
 		}
-		if pc >= e.lowpc+base && pc < e.highpc+base {
-			return e.instr
+		if pc >= e.LowPC+base && pc < e.HighPC+base {
+			return e.Instr
 		}
 	}
 
@@ -980,7 +912,7 @@ func loadBinaryInfoElf(bi *BinaryInfo, image *Image, path string, addr uint64, w
 		return err
 	}
 	debugLocBytes, _ := godwarf.GetDebugSectionElf(dwarfFile, "loc")
-	image.loclistInit(debugLocBytes, bi.Arch.PtrSize())
+	image.loclist = loclist.New(debugLocBytes, bi.Arch.PtrSize())
 
 	wg.Add(2)
 	go bi.parseDebugFrameElf(image, dwarfFile, wg)
@@ -1095,7 +1027,7 @@ func loadBinaryInfoPE(bi *BinaryInfo, image *Image, path string, entryPoint uint
 		return err
 	}
 	debugLocBytes, _ := godwarf.GetDebugSectionPE(peFile, "loc")
-	image.loclistInit(debugLocBytes, bi.Arch.PtrSize())
+	image.loclist = loclist.New(debugLocBytes, bi.Arch.PtrSize())
 
 	wg.Add(2)
 	go bi.parseDebugFramePE(image, peFile, wg)
@@ -1180,7 +1112,7 @@ func loadBinaryInfoMacho(bi *BinaryInfo, image *Image, path string, entryPoint u
 		return err
 	}
 	debugLocBytes, _ := godwarf.GetDebugSectionMacho(exe, "loc")
-	image.loclistInit(debugLocBytes, bi.Arch.PtrSize())
+	image.loclist = loclist.New(debugLocBytes, bi.Arch.PtrSize())
 
 	wg.Add(2)
 	go bi.parseDebugFrameMacho(image, exe, wg)

pkg/proc/types.go

@@ -42,6 +42,11 @@ const (
 	interfacetypeFieldMhdr = "mhdr"
 )
 
+type runtimeTypeDIE struct {
+	offset dwarf.Offset
+	kind   int64
+}
+
 func pointerTo(typ godwarf.Type, arch Arch) godwarf.Type {
 	return &godwarf.PtrType{
 		CommonType: godwarf.CommonType{