UNIX/Linux a.out binary file format. More...

#include <aout.h>

Inheritance diagram for AOut::AOutFormat:

Classes
class	Symbol

Public Types
enum	magic_type { OMAGIC = 0x0107 , NMAGIC = 0x0108 , ZMAGIC = 0x010B , QMAGIC = 0x00CC }

enum	cpu_type { UNKNOWN = 0x00 , M68010 = 0x01 , M68020 = 0x02 , SPARC = 0x03 , I80386 = 0x64 , ARM = 0x67 , MIPS1 = 0x97 , MIPS2 = 0x98 , PDP11 = 0xFF }

enum	system_type { UNIX , DJGPP1 , PDOS386 }

Public Member Functions
::EndianType	GetEndianType () const

unsigned	GetWordSize () const

void	ReadFile (Linker::Reader &rd) override
	Loads file into memory.

void	WriteFile (Linker::Writer &wr) override
	Stores data in memory to file.

void	ProduceModule (Linker::Module &module, Linker::Reader &rd) override
	Reads a file and loads the information into a module object.

void	SetOptions (std::map< std::string, std::string > &options) override
	Passes command line parameters as settings over to format object.

void	OnNewSegment (std::shared_ptr< Linker::Segment > segment) override
	Callback function when allocating a new segment When the linker script runs, it creates segments consecutively. Overriding this method permits the output format to handle the allocated segment.

void	CreateDefaultSegments ()

std::unique_ptr< Script::List >	GetScript (Linker::Module &module)

void	Link (Linker::Module &module)

std::shared_ptr< Linker::Segment >	GetCodeSegment ()

std::shared_ptr< Linker::Segment >	GetDataSegment ()

std::shared_ptr< Linker::Segment >	GetBssSegment ()

void	ProcessModule (Linker::Module &module) override
	Processes the module object and initializes format fields.

void	CalculateValues () override
	Intermediate step between processing module and generating output file to set up headers and management sections It is expected that after a module is processed, additional steps are required to evaluate the final values of the fields.

void	GenerateFile (std::string filename, Linker::Module &module) override
	The main function that handles processing, calculating and generating the final image.

std::string	GetDefaultExtension (Linker::Module &module, std::string filename) override
	Appends a default extension to the filename.

std::string	GetDefaultExtension (Linker::Module &module) override
	Provides a default filename for the output file.

Public Member Functions inherited from Linker::InputFormat
virtual void	SetupOptions (std::shared_ptr< OutputFormat > format)
	Initializes the reader for linking purposes.

virtual bool	FormatProvidesSegmentation () const
	Whether the format enables multiple x86 segments.

virtual bool	FormatRequiresDataStreamFix () const
	Whether the generated file might contain bugs that require fixing.

virtual bool	FormatProvidesResources () const
	Whether the format supports resources.

virtual bool	FormatProvidesLibraries () const
	Whether the format enables importing/exporting libraries.

Public Member Functions inherited from Linker::Format
	Format (offset_t file_offset=0)

virtual void	Clear ()
	Resets all fields to their default values, deallocate memory.

virtual void	Dump (Dumper::Dumper &dump)
	Display file contents in a nice manner.

Public Member Functions inherited from Linker::OutputFormat
virtual bool	AddSupplementaryOutputFormat (std::string subformat)
	If the output format actually drives multiple output formats (resource file, apple double, etc.), specify multiple types, return false if unknown.

std::optional< std::string >	FetchOption (std::map< std::string, std::string > &options, std::string name)
	Convenience method to look up option by name.

std::string	FetchOption (std::map< std::string, std::string > &options, std::string name, std::string default_value)
	Convenience method to look up option by name, returning default value if name is missing.

std::optional< offset_t >	FetchIntegerOption (std::map< std::string, std::string > &options, std::string name)
	Convenience method to look up option by name and convert it to integer.

virtual void	SetModel (std::string model)
	Sets the way memory is organized, typically modifying a built-in script.

virtual void	SetLinkScript (std::string script_file, std::map< std::string, std::string > &options)
	Selects a script file to use for linking.

virtual bool	FormatSupportsSegmentation () const
	Whether the format supports multiple segments.

virtual bool	FormatIs16bit () const
	Whether the format is 16-bit or not.

virtual bool	FormatIsLinear () const
	Whether the address space is linear or segmented.

virtual bool	FormatSupportsResources () const
	Whether the format supports resources.

virtual bool	FormatSupportsLibraries () const
	Whether the format supports libraries.

virtual unsigned	FormatAdditionalSectionFlags (std::string section_name) const

Public Member Functions inherited from Linker::LinkerManager
void	ClearLinkerManager ()

void	SetLinkScript (std::string script_file, std::map< std::string, std::string > &options)
	Sets up the linker script and linker parameters.

bool	SetLinkerParameter (std::map< std::string, std::string > &options, std::string key)
	Sets a single linker parameter, if inside options.

bool	SetLinkerParameter (std::map< std::string, std::string > &options, std::string key, std::string variable)
	Sets a single linker parameter, if inside options.

std::unique_ptr< Script::List >	GetScript (Linker::Module &module)
	Compiles the linker script into an internal format.

offset_t	GetCurrentAddress () const
	Retrieves current address pointer.

void	SetCurrentAddress (offset_t address)
	Moves the current address pointer further, and if the current segment already contains data, fill it up to the point.

void	AlignCurrentAddress (offset_t align)
	Aligns current address to alignment, using SetCurrentAddress.

void	SetLatestBase (offset_t address)
	Sets the base of the current section (the value from which offsets are counted from)

void	FinishCurrentSegment ()
	Closes the current segment, sets current_segment to null.

std::shared_ptr< Segment >	AppendSegment (std::string name)
	Terminates the current segment (if there is one), creates a new segment and attaches it to the image.

std::shared_ptr< Segment >	FetchSegment (std::string name)
	Attempts to fetch a segment, returns null if not found.

void	AppendSection (std::shared_ptr< Section > section)
	Adds a new section to the current segment, sets the base to the same as the segment.

void	ProcessScript (std::unique_ptr< Script::List > &directives, Module &module)
	Executes a parsed linker script on a module and collects segments The function OnNewSegment can be defined to handle each newly allocated segment.

void	ProcessAction (std::unique_ptr< Script::Node > &action, Module &module)

void	PostProcessAction (std::unique_ptr< Script::Node > &action, Module &module)

void	ProcessCommand (std::unique_ptr< Script::Node > &command, Module &module)

bool	CheckPredicate (std::unique_ptr< Script::Node > &predicate, std::shared_ptr< Section > section, Module &module)

offset_t	EvaluateExpression (std::unique_ptr< Script::Node > &expression, Module &module)

Static Public Member Functions
static std::shared_ptr< AOutFormat >	CreateWriter (system_type system, magic_type magic)

static std::shared_ptr< AOutFormat >	CreateWriter (system_type system)

static magic_type	GetDefaultMagic (system_type system)
	Default magic number associated with the system.

Public Attributes
::EndianType	endiantype

unsigned	word_size

magic_type	magic = magic_type(0)

cpu_type	cpu = UNKNOWN

uint32_t	code_size = 0

uint32_t	data_size = 0

uint32_t	bss_size = 0

uint32_t	symbol_table_size = 0

uint32_t	entry_address = 0

uint32_t	code_relocation_size = 0

uint32_t	data_relocation_size = 0

std::map< uint32_t, uint32_t >	code_relocations

std::map< uint32_t, uint32_t >	data_relocations

std::shared_ptr< Linker::Writable >	code

std::shared_ptr< Linker::Writable >	data

std::shared_ptr< Linker::Writable >	bss

std::vector< Symbol >	symbols

system_type	system = system_type(0)

Public Attributes inherited from Linker::Format
offset_t	file_offset

Public Attributes inherited from Linker::LinkerManager
offset_t	current_base = 0
	The base address of the current section.

std::vector< std::shared_ptr< Segment > >	segment_vector
	Ordered sequence of segments.

std::map< std::string, std::shared_ptr< Segment > >	segment_map
	Map of segments from their names.

std::shared_ptr< Segment >	current_segment
	Currently processed segment.

std::map< std::string, Location >	linker_parameters
	Parameters that permit customizing the linker script.

std::string	linker_script
	Contents of the linker script.

Additional Inherited Members
Protected Member Functions inherited from Microsoft::MZSimpleStubWriter
	MZSimpleStubWriter (std::string stub_file="")

bool	OpenAndCheckValidFile ()

offset_t	GetStubImageSize ()

void	WriteStubImage (std::ostream &out)

void	WriteStubImage (Linker::Writer &wr)

Protected Attributes inherited from Linker::LinkerManager
offset_t	current_address = 0
	Holds the current address value when there is no current_segment.

bool	current_is_template = false

bool	current_is_template_head = false

offset_t	template_counter = 0

std::string	current_template_name

Protected Attributes inherited from Microsoft::MZSimpleStubWriter
std::string	stub_file

bool	stub_file_valid = true

std::ifstream	stub

offset_t	stub_size = -1

Detailed Description

UNIX/Linux a.out binary file format.

Introduced in the earliest versions of UNIX, it underwent several incompatible updates, including being extended to 32 bits. At the time of writing, almost all current UNIX platforms use the COFF or ELF format.

Versions:

PDP-7 version (unimplemented)
UNIX v1 version (unimplemented)
16-bit UNIX version (unimplemented)
32-bit UNIX version (first introduced on the VAX)

Variants:

OMAGIC (old magic), the code segment is writable
NMAGIC (new magic), the code segment is pure and can be shared (read-only)
ZMAGIC, demand paged
QMAGIC (TODO)

Platforms:

early Linux (unimplemented) (obsolete)
early DJGPP before version 1.11
early PDOS/386 and PD-Windows (http://pdos.sourceforge.net/) (obsolete)

Member Function Documentation

◆ CalculateValues()

void AOutFormat::CalculateValues ( )

overridevirtual

Intermediate step between processing module and generating output file to set up headers and management sections It is expected that after a module is processed, additional steps are required to evaluate the final values of the fields.

Reimplemented from Linker::OutputFormat.

◆ GenerateFile()

void AOutFormat::GenerateFile	(	std::string	filename,
		Linker::Module &	module )

overridevirtual

The main function that handles processing, calculating and generating the final image.

Reimplemented from Linker::OutputFormat.

◆ GetDefaultExtension() [1/2]

std::string AOutFormat::GetDefaultExtension ( Linker::Module & module )

overridevirtual

Provides a default filename for the output file.

Typically a.out or some other extension, such as a.exe.

Reimplemented from Linker::OutputFormat.

◆ GetDefaultExtension() [2/2]

std::string AOutFormat::GetDefaultExtension	(	Linker::Module &	module,
		std::string	filename )

overridevirtual

Appends a default extension to the filename.

A typical behavior would be to append .exe at the end of the filename. The default action is to leave it intact.

Reimplemented from Linker::OutputFormat.

◆ GetDefaultMagic()

AOutFormat::magic_type AOutFormat::GetDefaultMagic ( system_type system )

static

Default magic number associated with the system.

This information is based on studying the executables included with that software. PDOS/386 uses OMAGIC, whereas DJGPP uses ZMAGIC.

◆ OnNewSegment()

void AOutFormat::OnNewSegment ( std::shared_ptr< Linker::Segment > segment )

overridevirtual

Callback function when allocating a new segment When the linker script runs, it creates segments consecutively. Overriding this method permits the output format to handle the allocated segment.

Reimplemented from Linker::LinkerManager.

◆ ProcessModule()

void AOutFormat::ProcessModule ( Linker::Module & object )

overridevirtual

Processes the module object and initializes format fields.

Reimplemented from Linker::OutputFormat.

◆ ProduceModule()

void AOutFormat::ProduceModule	(	Linker::Module &	module,
		Linker::Reader &	rd )

overridevirtual

Reads a file and loads the information into a module object.

Implements Linker::InputFormat.

◆ ReadFile()

void AOutFormat::ReadFile ( Linker::Reader & in )

overridevirtual

Loads file into memory.

Implements Linker::Format.

◆ SetOptions()

void AOutFormat::SetOptions ( std::map< std::string, std::string > & options )

overridevirtual

Passes command line parameters as settings over to format object.

Reimplemented from Linker::OutputFormat.

◆ WriteFile()

void AOutFormat::WriteFile ( Linker::Writer & out )

overridevirtual

Stores data in memory to file.

Implements Linker::Format.

The documentation for this class was generated from the following files:

src/format/aout.h
src/format/aout.cc

Classes

Public Types

Public Member Functions

Static Public Member Functions

Public Attributes

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ CalculateValues()

◆ GenerateFile()

◆ GetDefaultExtension() [1/2]

◆ GetDefaultExtension() [2/2]

◆ GetDefaultMagic()

◆ OnNewSegment()

◆ ProcessModule()

◆ ProduceModule()

◆ ReadFile()

◆ SetOptions()

◆ WriteFile()