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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.
// 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 "golang.org/x/debug/dwarf"
import "encoding/binary"
// 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
order binary.ByteOrder
typeCache map[Offset]Type
typeSigs map[uint64]*typeUnit
unit []unit
sourceFiles []string // source files listed in .debug_line.
nameCache // map from name to top-level entries in .debug_info.
pcToFuncEntries // cache of .debug_info data for function bounds.
pcToLineEntries // cache of .debug_line data, used for efficient PC-to-line mapping.
lineToPCEntries // cache of .debug_line data, used for efficient line-to-[]PC mapping.
}
// New returns a new Data object initialized from the given parameters.
// Rather than calling this function directly, clients should typically use
// the DWARF method of the File type of the appropriate package debug/elf,
// debug/macho, or debug/pe.
//
// 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, 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),
typeSigs: make(map[uint64]*typeUnit),
}
// 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
d.buildInfoCaches()
d.buildLineCaches()
return d, nil
}
// AddTypes will add one .debug_types section to the DWARF data. A
// typical object with DWARF version 4 debug info will have multiple
// .debug_types sections. The name is used for error reporting only,
// and serves to distinguish one .debug_types section from another.
func (d *Data) AddTypes(name string, types []byte) error {
return d.parseTypes(name, types)
}
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