LIEF::MachO::DyldInfo Class Reference

Class that represents the LC_DYLD_INFO and LC_DYLD_INFO_ONLY commands. More...

#include <DyldInfo.hpp>

Inheritance diagram for LIEF::MachO::DyldInfo:

Collaboration diagram for LIEF::MachO::DyldInfo:

Public Types
enum class	BINDING_ENCODING_VERSION { UNKNOWN = 0 , V1 , V2 }
using	info_t = std::pair< uint32_t, uint32_t >
	Tuple of offset and size
using	binding_info_t = std::vector< std::unique_ptr< DyldBindingInfo > >
	Internal container for storing DyldBindingInfo.
using	it_binding_info = ref_iterator< binding_info_t &, DyldBindingInfo * >
	Iterator which outputs DyldBindingInfo&.
using	it_const_binding_info = const_ref_iterator< const binding_info_t &, DyldBindingInfo * >
	Iterator which outputs const DyldBindingInfo&.
using	export_info_t = std::vector< std::unique_ptr< ExportInfo > >
	Internal container for storing ExportInfo.
using	it_export_info = ref_iterator< export_info_t &, ExportInfo * >
	Iterator which outputs const ExportInfo&.
using	it_const_export_info = const_ref_iterator< const export_info_t &, ExportInfo * >
	Iterator which outputs const ExportInfo&.
Public Types inherited from LIEF::MachO::LoadCommand
using	raw_t = std::vector< uint8_t >
Public Types inherited from LIEF::Object
template<class T >
using	output_t = add_pointer_t< decay_t< T > >
template<class T >
using	output_const_t = add_pointer_t< add_const_t< decay_t< T > > >

Public Member Functions
	DyldInfo (const details::dyld_info_command &dyld_info_cmd)
DyldInfo &	operator= (DyldInfo other)
	DyldInfo (const DyldInfo &copy)
void	swap (DyldInfo &other)
DyldInfo *	clone () const override
const info_t &	rebase () const
	Rebase information
span< const uint8_t >	rebase_opcodes () const
	Return Rebase's opcodes as raw data.
span< uint8_t >	rebase_opcodes ()
void	rebase_opcodes (buffer_t raw)
	Set new opcodes.
std::string	show_rebases_opcodes () const
	Return the rebase opcodes in a humman-readable way.
const info_t &	bind () const
	Bind information
span< const uint8_t >	bind_opcodes () const
	Return Binding's opcodes as raw data.
span< uint8_t >	bind_opcodes ()
void	bind_opcodes (buffer_t raw)
	Set new opcodes.
std::string	show_bind_opcodes () const
	Return the bind opcodes in a humman-readable way.
const info_t &	weak_bind () const
	Weak Bind information
span< const uint8_t >	weak_bind_opcodes () const
	Return Weak Binding's opcodes as raw data.
span< uint8_t >	weak_bind_opcodes ()
void	weak_bind_opcodes (buffer_t raw)
	Set new opcodes.
std::string	show_weak_bind_opcodes () const
	Return the bind opcodes in a humman-readable way.
const info_t &	lazy_bind () const
	Lazy Bind information
span< const uint8_t >	lazy_bind_opcodes () const
	Return Lazy Binding's opcodes as raw data.
span< uint8_t >	lazy_bind_opcodes ()
void	lazy_bind_opcodes (buffer_t raw)
	Set new opcodes.
std::string	show_lazy_bind_opcodes () const
	Return the lazy opcodes in a humman-readable way.
it_binding_info	bindings ()
	Iterator over BindingInfo entries.
it_const_binding_info	bindings () const
const info_t &	export_info () const
	Export information
it_export_info	exports ()
	Iterator over ExportInfo entries.
it_const_export_info	exports () const
span< const uint8_t >	export_trie () const
	Return Export's trie as raw data.
span< uint8_t >	export_trie ()
void	export_trie (buffer_t raw)
	Set new trie.
std::string	show_export_trie () const
	Return the export trie in a humman-readable way.
void	rebase (const info_t &info)
void	bind (const info_t &info)
void	weak_bind (const info_t &info)
void	lazy_bind (const info_t &info)
void	export_info (const info_t &info)
void	set_rebase_offset (uint32_t offset)
void	set_rebase_size (uint32_t size)
void	set_bind_offset (uint32_t offset)
void	set_bind_size (uint32_t size)
void	set_weak_bind_offset (uint32_t offset)
void	set_weak_bind_size (uint32_t size)
void	set_lazy_bind_offset (uint32_t offset)
void	set_lazy_bind_size (uint32_t size)
void	set_export_offset (uint32_t offset)
void	set_export_size (uint32_t size)
void	add (std::unique_ptr< ExportInfo > info)
void	accept (Visitor &visitor) const override
std::ostream &	print (std::ostream &os) const override
Public Member Functions inherited from LIEF::MachO::LoadCommand
	LoadCommand (const details::load_command &command)
	LoadCommand (LOAD_COMMAND_TYPES type, uint32_t size)
LoadCommand &	operator= (LoadCommand copy)
	LoadCommand (const LoadCommand &copy)
void	swap (LoadCommand &other)
LOAD_COMMAND_TYPES	command () const
	Command type.
uint32_t	size () const
	Size of the command (should be greather than sizeof(load_command))
span< const uint8_t >	data () const
	Raw command.
uint64_t	command_offset () const
	Offset of the command within the Load Command Table
void	data (const raw_t &data)
void	command (LOAD_COMMAND_TYPES command)
void	size (uint32_t size)
void	command_offset (uint64_t offset)
void	accept (Visitor &visitor) const override
Public Member Functions inherited from LIEF::Object
	Object (const Object &other)
Object &	operator= (const Object &other)
template<class T >
output_t< T >	as ()
template<class T >
output_const_t< T >	as () const
virtual bool	operator== (const Object &other) const
virtual bool	operator!= (const Object &other) const

Static Public Member Functions
static bool	classof (const LoadCommand *cmd)
Static Public Member Functions inherited from LIEF::MachO::LoadCommand
static bool	is_linkedit_data (const LoadCommand &cmd)

Detailed Description

Class that represents the LC_DYLD_INFO and LC_DYLD_INFO_ONLY commands.

Member Function Documentation

accept()

void LIEF::MachO::DyldInfo::accept ( Visitor &  visitor ) const

overridevirtual

Implements LIEF::Object.

bind()

const info_t & LIEF::MachO::DyldInfo::bind

(

)

const

Bind information

Dyld binds an image during the loading process, if the image requires any pointers to be initialized to symbols in other images. The rebase information is a stream of byte sized opcodes for which symbolic names start with BIND_OPCODE_. Conceptually the bind information is a table of tuples: <seg-index, seg-offset, type, symbol-library-ordinal, symbol-name, addend> The opcodes are a compressed way to encode the table by only encoding when a column changes. In addition simple patterns like for runs of pointers initialzed to the same value can be encoded in a few bytes.

See also

/usr/include/mach-o/loader.h

clone()

DyldInfo * LIEF::MachO::DyldInfo::clone ( ) const

overridevirtual

Reimplemented from LIEF::MachO::LoadCommand.

export_info()

const info_t & LIEF::MachO::DyldInfo::export_info

(

)

const

Export information

The symbols exported by a dylib are encoded in a trie. This is a compact representation that factors out common prefixes. It also reduces LINKEDIT pages in RAM because it encodes all information (name, address, flags) in one small, contiguous range. The export area is a stream of nodes. The first node sequentially is the start node for the trie.

Nodes for a symbol start with a byte that is the length of the exported symbol information for the string so far. If there is no exported symbol, the byte is zero. If there is exported info, it follows the length byte. The exported info normally consists of a flags and offset both encoded in uleb128. The offset is location of the content named by the symbol. It is the offset from the mach_header for the image.

After the initial byte and optional exported symbol information is a byte of how many edges (0-255) that this node has leaving it, followed by each edge. Each edge is a zero terminated cstring of the addition chars in the symbol, followed by a uleb128 offset for the node that edge points to.

See also

/usr/include/mach-o/loader.h

lazy_bind()

const info_t & LIEF::MachO::DyldInfo::lazy_bind

(

)

const

Lazy Bind information

Some uses of external symbols do not need to be bound immediately. Instead they can be lazily bound on first use. The lazy_bind are contains a stream of BIND opcodes to bind all lazy symbols. Normal use is that dyld ignores the lazy_bind section when loading an image. Instead the static linker arranged for the lazy pointer to initially point to a helper function which pushes the offset into the lazy_bind area for the symbol needing to be bound, then jumps to dyld which simply adds the offset to lazy_bind_off to get the information on what to bind.

See also

/usr/include/mach-o/loader.h

print()

std::ostream & LIEF::MachO::DyldInfo::print ( std::ostream &  os ) const

overridevirtual

Reimplemented from LIEF::MachO::LoadCommand.

rebase()

const info_t & LIEF::MachO::DyldInfo::rebase

(

)

const

Rebase information

Dyld rebases an image whenever dyld loads it at an address different from its preferred address. The rebase information is a stream of byte sized opcodes for which symbolic names start with REBASE_OPCODE_. Conceptually the rebase information is a table of tuples: <seg-index, seg-offset, type> The opcodes are a compressed way to encode the table by only encoding when a column changes. In addition simple patterns like "every n'th offset for m times" can be encoded in a few bytes.

See also

/usr/include/mach-o/loader.h

weak_bind()

const info_t & LIEF::MachO::DyldInfo::weak_bind

(

)

const

Weak Bind information

Some C++ programs require dyld to unique symbols so that all images in the process use the same copy of some code/data. This step is done after binding. The content of the weak_bind info is an opcode stream like the bind_info. But it is sorted alphabetically by symbol name. This enables dyld to walk all images with weak binding information in order and look for collisions. If there are no collisions, dyld does no updating. That means that some fixups are also encoded in the bind_info. For instance, all calls to "operator new" are first bound to libstdc++.dylib using the information in bind_info. Then if some image overrides operator new that is detected when the weak_bind information is processed and the call to operator new is then rebound.

See also

/usr/include/mach-o/loader.h

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

• DyldInfo.hpp