Class: ELFTools::Sections::Section

Inherits:
Object
  • Object
show all
Defined in:
lib/elftools/sections/section.rb

Overview

Base class of sections.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(header, stream, offset_from_vma: nil, section_name_table: nil, **_kwargs) ⇒ Section

Instantiate a ELFTools::Sections::Section object.

Parameters:

  • header (ELFTools::Structs::ELF_Shdr) —

    The section header object.

  • stream (#pos=, #read) —

    The streaming object for further dump.

  • section_name_table (ELFTools::Sections::StrTabSection, Proc) (defaults to: nil) —

    The string table object. For fetching section names. If Proc if given, it will call at the first time access #name.

  • offset_from_vma (Method) (defaults to: nil) —

    The method to get offset of file, given virtual memory address.



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# File 'lib/elftools/sections/section.rb', line 22

def initialize(header, stream, offset_from_vma: nil, section_name_table: nil, **_kwargs)
  @header = header
  @stream = stream
  @section_name_table = section_name_table
  @offset_from_vma = offset_from_vma
end

Instance Attribute Details

#header ⇒ ELFTools::Structs::ELF_Shdr (readonly)

Returns Section header.

Returns:



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# File 'lib/elftools/sections/section.rb', line 8

def header
  @header
end

#stream ⇒ #pos=, #read (readonly)

Returns Streaming object.

Returns:

  • (#pos=, #read) —

    Streaming object.



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# File 'lib/elftools/sections/section.rb', line 9

def stream
  @stream
end

Class Method Details

.create(header, stream, *args, **kwargs) ⇒ ELFTools::Sections::Section

Use different class according to header.sh_type.

Parameters:

Returns:



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# File 'lib/elftools/sections/sections.rb', line 28

def create(header, stream, *args, **kwargs)
  klass = case header.sh_type
          when Constants::SHT_DYNAMIC then DynamicSection
          when Constants::SHT_NULL then NullSection
          when Constants::SHT_NOTE then NoteSection
          when Constants::SHT_RELA, Constants::SHT_REL then RelocationSection
          when Constants::SHT_RELR then RelativeRelocationSection
          when Constants::SHT_GNU_versym then VersionSection
          when Constants::SHT_GNU_verneed then VersionNeedSection
          when Constants::SHT_GNU_verdef then VersionDefinitionSection
          when Constants::SHT_STRTAB then StrTabSection
          when Constants::SHT_SYMTAB, Constants::SHT_DYNSYM then SymTabSection
          else Section
          end
  klass.new(header, stream, *args, **kwargs)
end

Instance Method Details

#allocated? ⇒ Boolean

Does this section take memory while the file runs?

The ones that do are what a file is loaded by, the rest being what is recorded about it, its symbol names and its debugging information among them.

Examples:

elf.section_by_name('.symtab').allocated?
#=> false

Returns:

  • (Boolean) —

    True or false.



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# File 'lib/elftools/sections/section.rb', line 76

def allocated?
  header.sh_flags.allbits?(Constants::SHF_ALLOC)
end

#data ⇒ String

Fetch data of this section.

Returns:

  • (String) —

    Data.



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# File 'lib/elftools/sections/section.rb', line 44

def data
  stream.pos = header.sh_offset
  stream.read(header.sh_size)
end

#executable? ⇒ Boolean

Is this section executed?

Examples:

elf.section_by_name('.text').executable?
#=> true

Returns:

  • (Boolean) —

    True or false.



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# File 'lib/elftools/sections/section.rb', line 63

def executable?
  header.sh_flags.allbits?(Constants::SHF_EXECINSTR)
end

#name ⇒ String

Get name of this section.

Returns:

  • (String) —

    The name.



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# File 'lib/elftools/sections/section.rb', line 38

def name
  @name ||= @section_name_table.call.name_at(header.sh_name)
end

#null? ⇒ Boolean

Is this a null section?

Returns:

  • (Boolean) —

    No it's not.



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# File 'lib/elftools/sections/section.rb', line 82

def null?
  false
end

#type ⇒ Integer

Return header.sh_type in a simpler way.

Returns:

  • (Integer) —

    The type, meaning of types are defined in Constants::SHT.



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# File 'lib/elftools/sections/section.rb', line 32

def type
  header.sh_type.to_i
end

#writable? ⇒ Boolean

Is this section written to while the file runs?

Examples:

elf.section_by_name('.data').writable?
#=> true

Returns:

  • (Boolean) —

    True or false.



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# File 'lib/elftools/sections/section.rb', line 54

def writable?
  header.sh_flags.allbits?(Constants::SHF_WRITE)
end