1 files changed, 41 insertions, 10 deletions
diff --git a/src/pkg/debug/dwarf/unit.go b/src/pkg/debug/dwarf/unit.go
index c10d75dbd..270cd2e33 100644
--- a/src/pkg/debug/dwarf/unit.go
+++ b/src/pkg/debug/dwarf/unit.go
@@ -10,19 +10,44 @@ import "strconv"
 // Each unit has its own abbreviation table and address size.
 
 type unit struct {
-	base     Offset // byte offset of header within the aggregate info
-	off      Offset // byte offset of data within the aggregate info
-	data     []byte
-	atable   abbrevTable
-	addrsize int
+	base   Offset // byte offset of header within the aggregate info
+	off    Offset // byte offset of data within the aggregate info
+	data   []byte
+	atable abbrevTable
+	asize  int
+	vers   int
+	is64   bool // True for 64-bit DWARF format
+}
+
+// Implement the dataFormat interface.
+
+func (u *unit) version() int {
+	return u.vers
+}
+
+func (u *unit) dwarf64() (bool, bool) {
+	return u.is64, true
+}
+
+func (u *unit) addrsize() int {
+	return u.asize
 }
 
 func (d *Data) parseUnits() ([]unit, error) {
 	// Count units.
 	nunit := 0
-	b := makeBuf(d, "info", 0, d.info, 0)
+	b := makeBuf(d, unknownFormat{}, "info", 0, d.info)
 	for len(b.data) > 0 {
-		b.skip(int(b.uint32()))
+		len := b.uint32()
+		if len == 0xffffffff {
+			len64 := b.uint64()
+			if len64 != uint64(uint32(len64)) {
+				b.error("unit length overflow")
+				break
+			}
+			len = uint32(len64)
+		}
+		b.skip(int(len))
 		nunit++
 	}
 	if b.err != nil {
@@ -30,16 +55,22 @@ func (d *Data) parseUnits() ([]unit, error) {
 	}
 
 	// Again, this time writing them down.
-	b = makeBuf(d, "info", 0, d.info, 0)
+	b = makeBuf(d, unknownFormat{}, "info", 0, d.info)
 	units := make([]unit, nunit)
 	for i := range units {
 		u := &units[i]
 		u.base = b.off
 		n := b.uint32()
-		if vers := b.uint16(); vers != 2 {
+		if n == 0xffffffff {
+			u.is64 = true
+			n = uint32(b.uint64())
+		}
+		vers := b.uint16()
+		if vers != 2 && vers != 3 {
 			b.error("unsupported DWARF version " + strconv.Itoa(int(vers)))
 			break
 		}
+		u.vers = int(vers)
 		atable, err := d.parseAbbrev(b.uint32())
 		if err != nil {
 			if b.err == nil {
@@ -48,7 +79,7 @@ func (d *Data) parseUnits() ([]unit, error) {
 			break
 		}
 		u.atable = atable
-		u.addrsize = int(b.uint8())
+		u.asize = int(b.uint8())
 		u.off = b.off
 		u.data = b.bytes(int(n - (2 + 4 + 1)))
 	}