elfwriter

Documentation

Overview

Package elfwriter is a package to write ELF files without having their entire contents in memory at any one time.

Original work started from https://github.com/go-delve/delve/blob/master/pkg/elfwriter/writer.go and additional functionality added on top.

This package does not provide completeness guarantees. Some of the missing features: - Consistency and soundness of relocations - Consistency and preservation of linked sections (when target removed (sh_link)) - partially supported - Consistency and existence of overlapping segments when a section removed (offset, range check)

Index

• func NewCompressionHeaderFromSource(fhdr *elf.FileHeader, src io.ReaderAt, offset int64) (*compressionHeader, error)
• type Extractor
  • func NewExtractor(logger log.Logger, tracer trace.Tracer, opts ...Option) *Extractor
  • func (e *Extractor) ExtractAll(ctx context.Context, srcDsts map[string]io.WriteSeeker) error
  • func (e *Extractor) OnlyKeepDebug(ctx context.Context, dst io.WriteSeeker, src io.ReaderAt) error
  • func (e *Extractor) StripDebug(ctx context.Context, dst io.WriteSeeker, src io.ReaderAt) error
• type FilteringWriter
  • func NewFilteringWriter(dst io.WriteSeeker, src io.ReaderAt, opts ...Option) (*FilteringWriter, error)
  • func (w *FilteringWriter) FilterHeaderOnlySections(predicates ...func(*elf.Section) bool)
  • func (w *FilteringWriter) FilterPrograms(predicates ...func(*elf.Prog) bool)
  • func (w *FilteringWriter) FilterSections(predicates ...func(*elf.Section) bool)
  • func (w *FilteringWriter) Flush() error
• type Note
• type NullifyingWriter
  • func NewNullifyingWriter(dst io.WriteSeeker, src io.ReaderAt, opts ...Option) (*NullifyingWriter, error)
  • func (w *NullifyingWriter) FilterPrograms(predicates ...func(*elf.Prog) bool)
  • func (w *NullifyingWriter) Flush() error
  • func (w *NullifyingWriter) KeepSections(predicates ...func(*elf.Section) bool)
• type Option
  • func WithCompressDWARFSections() Option
• type Writer
  • func (w *Writer) AddNotes(additionalNotes ...Note)
  • func (w *Writer) Flush() error
  • func (w *Writer) Reset(ws io.WriteSeeker)

Functions

func NewCompressionHeaderFromSource

func NewCompressionHeaderFromSource(fhdr *elf.FileHeader, src io.ReaderAt, offset int64) (*compressionHeader, error)

Types

type Extractor

type Extractor struct {
	// contains filtered or unexported fields
}

Extractor extracts debug information from a binary.

func NewExtractor

func NewExtractor(logger log.Logger, tracer trace.Tracer, opts ...Option) *Extractor

NewExtractor creates a new Extractor.

func (*Extractor) ExtractAll

func (e *Extractor) ExtractAll(ctx context.Context, srcDsts map[string]io.WriteSeeker) error

ExtractAll extracts debug information from the given executables. It consumes a map of file sources to extract and a destination io.Writer.

func (*Extractor) OnlyKeepDebug

func (e *Extractor) OnlyKeepDebug(ctx context.Context, dst io.WriteSeeker, src io.ReaderAt) error

OnlyKeepDebug nullifies all the sections except debug information from the given executable. Mimics `objcopy --only-keep-debug`.

func (*Extractor) StripDebug

func (e *Extractor) StripDebug(ctx context.Context, dst io.WriteSeeker, src io.ReaderAt) error

StripDebug extracts debug information from the given executable. Cleaning up the temporary directory and the interim file is the caller's responsibility. Mimics `objcopy --strip-debug`.

type FilteringWriter

type FilteringWriter struct {
	Writer
	// contains filtered or unexported fields
}

FilteringWriter is a wrapper around Writer that allows to filter out sections, and programs from the source. Then write them to underlying io.WriteSeeker.

func NewFilteringWriter

func NewFilteringWriter(dst io.WriteSeeker, src io.ReaderAt, opts ...Option) (*FilteringWriter, error)

NewFilteringWriter creates a new Writer using given source.

func (*FilteringWriter) FilterHeaderOnlySections

func (w *FilteringWriter) FilterHeaderOnlySections(predicates ...func(*elf.Section) bool)

FilterHeaderOnlySections filters out header only sections from the source.

func (*FilteringWriter) FilterPrograms

func (w *FilteringWriter) FilterPrograms(predicates ...func(*elf.Prog) bool)

FilterPrograms filters out programs from the source.

func (*FilteringWriter) FilterSections

func (w *FilteringWriter) FilterSections(predicates ...func(*elf.Section) bool)

FilterSections filters out sections from the source. If sections have links to other sections, the referred sections are also be carried over to the destination.

func (*FilteringWriter) Flush

func (w *FilteringWriter) Flush() error

type Note

type Note struct {
	Type elf.NType
	Name string
	Data []byte
}

type NullifyingWriter

type NullifyingWriter struct {
	Writer
	// contains filtered or unexported fields
}

NullifyingWriter is a wrapper around another Writer that nullifies all the sections except the whitelisted ones.

func NewNullifyingWriter

func NewNullifyingWriter(dst io.WriteSeeker, src io.ReaderAt, opts ...Option) (*NullifyingWriter, error)

NewNullifyingWriter creates a new NullifyingWriter.

func (*NullifyingWriter) FilterPrograms

func (w *NullifyingWriter) FilterPrograms(predicates ...func(*elf.Prog) bool)

FilterPrograms filters out programs from the source.

func (*NullifyingWriter) Flush

func (w *NullifyingWriter) Flush() error

func (*NullifyingWriter) KeepSections

func (w *NullifyingWriter) KeepSections(predicates ...func(*elf.Section) bool)

KeepSections keeps only the sections that match the predicates. If no predicates are given, all sections are nullified.

type Option

type Option func(w *Writer)

func WithCompressDWARFSections

func WithCompressDWARFSections() Option

WithCompressDWARFSections compresses DWARF sections.

type Writer

type Writer struct {
	// contains filtered or unexported fields
}

Writer writes ELF files.

func (*Writer) AddNotes

func (w *Writer) AddNotes(additionalNotes ...Note)

AddNotes adds additional notes to write to in the underlying io.WriterSeeker.

func (*Writer) Flush

func (w *Writer) Flush() error

Flush writes any buffered data to the underlying io.WriterSeeker.

func (*Writer) Reset

func (w *Writer) Reset(ws io.WriteSeeker)

Reset discards any unflushed buffered data, clears any error, and resets data to write its output to dst.