1 files changed, 90 insertions, 0 deletions
diff --git a/src/debug/dwarf/unit.go b/src/debug/dwarf/unit.go
new file mode 100644
index 000000000..0fbc8e082
--- /dev/null
+++ b/src/debug/dwarf/unit.go
@@ -0,0 +1,90 @@
+// Copyright 2009 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 dwarf
+
+import "strconv"
+
+// DWARF debug info is split into a sequence of compilation units.
+// 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
+	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, unknownFormat{}, "info", 0, d.info)
+	for len(b.data) > 0 {
+		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 {
+		return nil, b.err
+	}
+
+	// Again, this time writing them down.
+	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 n == 0xffffffff {
+			u.is64 = true
+			n = uint32(b.uint64())
+		}
+		vers := b.uint16()
+		if vers != 2 && vers != 3 && vers != 4 {
+			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 {
+				b.err = err
+			}
+			break
+		}
+		u.atable = atable
+		u.asize = int(b.uint8())
+		u.off = b.off
+		u.data = b.bytes(int(n - (2 + 4 + 1)))
+	}
+	if b.err != nil {
+		return nil, b.err
+	}
+	return units, nil
+}