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// 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.
// This package provides access to DWARF debugging information
// loaded from executable files, as defined in the DWARF 2.0 Standard
// at http://dwarfstd.org/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[uint32]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;
}
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