// 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. # Security This package is not designed to be hardened against adversarial inputs, and is outside the scope of https://go.dev/security/policy. In particular, only basic validation is done when parsing object files. As such, care should be taken when parsing untrusted inputs, as parsing malformed files may consume significant resources, or cause panics. */ package dwarf import ( "encoding/binary" "errors" ) // 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 // New sections added in DWARF 5. addr []byte lineStr []byte strOffsets []byte rngLists []byte // parsed data abbrevCache map[uint64]abbrevTable bigEndian bool order binary.ByteOrder typeCache map[Offset]Type typeSigs map[uint64]*typeUnit unit []unit } var errSegmentSelector = errors.New("non-zero segment_selector size not supported") // 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[uint64]abbrevTable), typeCache: make(map[Offset]Type), typeSigs: make(map[uint64]*typeUnit), } // Sniff .debug_info to figure out byte order. // 32-bit DWARF: 4 byte length, 2 byte version. // 64-bit DWARf: 4 bytes of 0xff, 8 byte length, 2 byte version. if len(d.info) < 6 { return nil, DecodeError{"info", Offset(len(d.info)), "too short"} } offset := 4 if d.info[0] == 0xff && d.info[1] == 0xff && d.info[2] == 0xff && d.info[3] == 0xff { if len(d.info) < 14 { return nil, DecodeError{"info", Offset(len(d.info)), "too short"} } offset = 12 } // Fetch the version, a tiny 16-bit number (1, 2, 3, 4, 5). x, y := d.info[offset], d.info[offset+1] switch { case x == 0 && y == 0: return nil, DecodeError{"info", 4, "unsupported version 0"} case x == 0: d.bigEndian = true d.order = binary.BigEndian case y == 0: d.bigEndian = false 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 } // 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) } // AddSection adds another DWARF section by name. The name should be a // DWARF section name such as ".debug_addr", ".debug_str_offsets", and // so forth. This approach is used for new DWARF sections added in // DWARF 5 and later. func (d *Data) AddSection(name string, contents []byte) error { var err error switch name { case ".debug_addr": d.addr = contents case ".debug_line_str": d.lineStr = contents case ".debug_str_offsets": d.strOffsets = contents case ".debug_rnglists": d.rngLists = contents } // Just ignore names that we don't yet support. return err }