Imported Upstream version 60upstream/60

1 files changed, 80 insertions, 0 deletions

diff --git a/src/pkg/debug/dwarf/open.go b/src/pkg/debug/dwarf/open.go
new file mode 100644
index 000000000..d9525f788
--- /dev/null
+++ b/src/pkg/debug/dwarf/open.go
@@ -0,0 +1,80 @@
+// 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 provides access to DWARF debugging information loaded from
+// executable files, as defined in the DWARF 2.0 Standard at
+// http://dwarfstd.org/doc/dwarf-2.0.0.pdf
+package dwarf
+
+import (
+	"encoding/binary"
+	"os"
+)
+
+// Data represents the DWARF debugging information
+// loaded from an executable file (for example, an ELF or Mach-O executable).
+type Data struct {
+	// raw data
+	abbrev   []byte
+	aranges  []byte
+	frame    []byte
+	info     []byte
+	line     []byte
+	pubnames []byte
+	ranges   []byte
+	str      []byte
+
+	// parsed data
+	abbrevCache map[uint32]abbrevTable
+	addrsize    int
+	order       binary.ByteOrder
+	typeCache   map[Offset]Type
+	unit        []unit
+}
+
+// New returns a new Data object initialized from the given parameters.
+// Clients should typically use [TODO(rsc): method to be named later] instead of calling
+// New directly.
+//
+// The []byte arguments are the data from the corresponding debug section
+// in the object file; for example, for an ELF object, abbrev is the contents of
+// the ".debug_abbrev" section.
+func New(abbrev, aranges, frame, info, line, pubnames, ranges, str []byte) (*Data, os.Error) {
+	d := &Data{
+		abbrev:      abbrev,
+		aranges:     aranges,
+		frame:       frame,
+		info:        info,
+		line:        line,
+		pubnames:    pubnames,
+		ranges:      ranges,
+		str:         str,
+		abbrevCache: make(map[uint32]abbrevTable),
+		typeCache:   make(map[Offset]Type),
+	}
+
+	// Sniff .debug_info to figure out byte order.
+	// bytes 4:6 are the version, a tiny 16-bit number (1, 2, 3).
+	if len(d.info) < 6 {
+		return nil, DecodeError{"info", Offset(len(d.info)), "too short"}
+	}
+	x, y := d.info[4], d.info[5]
+	switch {
+	case x == 0 && y == 0:
+		return nil, DecodeError{"info", 4, "unsupported version 0"}
+	case x == 0:
+		d.order = binary.BigEndian
+	case y == 0:
+		d.order = binary.LittleEndian
+	default:
+		return nil, DecodeError{"info", 4, "cannot determine byte order"}
+	}
+
+	u, err := d.parseUnits()
+	if err != nil {
+		return nil, err
+	}
+	d.unit = u
+	return d, nil
+}