C++¶

Cache Processing¶

bool LIEF::dsc::enable_cache()¶

Enable globally cache/memoization. One can also leverage this function by setting the environment variable DYLDSC_ENABLE_CACHE to 1

By default, LIEF will use the directory specified by the environment variable DYLDSC_CACHE_DIR as its cache-root directory:

DYLDSC_ENABLE_CACHE=1 DYLDSC_CACHE_DIR=/tmp/my_dir ./my-program

Otherwise, if DYLDSC_CACHE_DIR is not set, LIEF will use the following directory (in this priority):

1. System or user cache directory

   • macOS: DARWIN_USER_TEMP_DIR / DARWIN_USER_CACHE_DIR + /dyld_shared_cache

   • Linux: ${XDG_CACHE_HOME}/dyld_shared_cache

   • Windows: LOCALAPPDATA%\dyld_shared_cache

2. Home directory

   • macOS/Linux: $HOME/.dyld_shared_cache

   • Windows: USERPROFILE%\.dyld_shared_cache

See also

LIEF::dsc::DyldSharedCache::enable_caching for a finer granularity

bool LIEF::dsc::enable_cache(const std::string &dir)¶

Same behavior as enable_cache() but with a user-provided cache directory.

DyldSharedCache¶

class DyldSharedCache¶

This class represents a dyld shared cache file.

Public Types

enum class VERSION : uint32_t¶

This enum wraps the dyld’s git tags for which the structure of dyld shared cache evolved.

Values:

enumerator UNKNOWN = 0¶

enumerator DYLD_95_3¶

dyld-95.3 (2007-10-30)

enumerator DYLD_195_5¶

dyld-195.5 (2011-07-13)

enumerator DYLD_239_3¶

dyld-239.3 (2013-10-29)

enumerator DYLD_360_14¶

dyld-360.14 (2015-09-04)

enumerator DYLD_421_1¶

dyld-421.1 (2016-09-22)

enumerator DYLD_832_7_1¶

dyld-832.7.1 (2020-11-19)

enumerator DYLD_940¶

dyld-940 (2021-02-09)

enumerator DYLD_1042_1¶

dyld-1042.1 (2022-10-19)

enumerator UNRELEASED¶

This value is used for versions of dyld not publicly released or not yet supported by LIEF.

enum class DYLD_TARGET_PLATFORM : uint32_t¶

Platforms supported by the dyld shared cache.

Values:

enumerator UNKNOWN = 0¶

enumerator MACOS = 1¶

enumerator IOS = 2¶

enumerator TVOS = 3¶

enumerator WATCHOS = 4¶

enumerator BRIDGEOS = 5¶

enumerator IOSMAC = 6¶

enumerator IOS_SIMULATOR = 7¶

enumerator TVOS_SIMULATOR = 8¶

enumerator WATCHOS_SIMULATOR = 9¶

enumerator DRIVERKIT = 10¶

enumerator VISIONOS = 11¶

enumerator VISIONOS_SIMULATOR = 12¶

enumerator FIRMWARE = 13¶

enumerator SEPOS = 14¶

enumerator ANY = 0xFFFFFFFF¶

enum class DYLD_TARGET_ARCH¶

Architecture supported by the dyld shared cache.

Values:

enumerator UNKNOWN = 0¶

enumerator I386¶

enumerator X86_64¶

enumerator X86_64H¶

enumerator ARMV5¶

enumerator ARMV6¶

enumerator ARMV7¶

enumerator ARM64¶

enumerator ARM64E¶

using dylib_iterator = iterator_range<Dylib::Iterator>¶

Iterator over the libraries in the shared cache.

using mapping_info_iterator = iterator_range<MappingInfo::Iterator>¶

Iterator over the mapping info in the shared cache.

using subcache_iterator = iterator_range<SubCache::Iterator>¶

Iterator over the split/sub-cache in this main shared cache.

using instructions_iterator = iterator_range<assembly::Instruction::Iterator>¶

Public Functions

DyldSharedCache(std::unique_ptr<details::DyldSharedCache> impl)¶

~DyldSharedCache()¶

std::string filename() const¶

Filename of the dyld shared file associated with this object.

For instance: dyld_shared_cache_arm64e, dyld_shared_cache_arm64e.62.dyldlinkedit

VERSION version() const¶

Version of dyld used by this cache.

std::string filepath() const¶

Full path to the original dyld shared cache file associated with object (e.g. /home/lief/downloads/visionos/dyld_shared_cache_arm64e.42)

uint64_t load_address() const¶

Based address of this cache.

std::string arch_name() const¶

Name of the architecture targeted by this cache (x86_64h)

DYLD_TARGET_PLATFORM platform() const¶

Platform targeted by this cache (e.g. vision-os)

DYLD_TARGET_ARCH arch() const¶

Architecture targeted by this cache.

std::unique_ptr<Dylib> find_lib_from_va(uint64_t va) const¶

Find the Dylib that encompasses the given virtual address. It returns a nullptr if a Dylib can’t be found.

std::unique_ptr<Dylib> find_lib_from_path(const std::string &path) const¶

Find the Dylib whose Dylib::path matches the provided path.

std::unique_ptr<Dylib> find_lib_from_name(const std::string &name) const¶

Find the Dylib whose filename of Dylib::path matches the provided name.

If multiple libraries have the same name (but with a different path), the first one matching the provided name is returned.

bool has_subcaches() const¶

True if the subcaches are associated with this cache.

dylib_iterator libraries() const¶

Return an interator over the libraries embedded in this dyld shared cache.

This iterator implements the random access trait. Thus, one can use iterator_range::size, iterator_range::at, iterator_range::operator[] to a access Dylib at an arbitrary index:

auto libraries = cache.libaries();
for (size_t i = 0; i < libraries.size(); ++i) {
  std::string path = libaries[i]->path();
}

mapping_info_iterator mapping_info() const¶

Return an interator over the mapping information of this dyld shared cache.

This iterator implements the random access trait. Thus, one can use iterator_range::size, iterator_range::at, iterator_range::operator[] to access a MappingInfo at an arbitrary index:

auto mapping = cache.mapping_info();
for (size_t i = 0; i < mapping.size(); ++i) {
  const uint64_t addr = mapping[i]->address();
}

subcache_iterator subcaches() const¶

Return an interator over the subcaches associated with this (main) dyld shared cache.

This iterator implements the random access trait. Thus, one can use iterator_range::size, iterator_range::at, iterator_range::operator[] to access a SubCache at an arbitrary index:

auto subcaches = cache.subcaches();
for (size_t i = 0; i < subcaches.size(); ++i) {
  std::unique_ptr<DyldSharedCache> impl = subcaches[i]->cache();
}

instructions_iterator disassemble(uint64_t va) const¶

Disassemble instructions at the provided virtual address. This function returns an iterator over assembly::Instruction.

std::vector<uint8_t> get_content_from_va(uint64_t va, uint64_t size) const¶

Return the content at the specified virtual address.

std::unique_ptr<DyldSharedCache> cache_for_address(uint64_t va) const¶

Find the sub-DyldSharedCache that wraps the given virtual address.

std::unique_ptr<DyldSharedCache> main_cache() const¶

Return the principal dyld shared cache in the case of multiple subcaches.

std::unique_ptr<DyldSharedCache> find_subcache(const std::string &filename) const¶

Try to find the DyldSharedCache associated with the filename given in the first parameter.

result<uint64_t> va_to_offset(uint64_t va) const¶

Convert the given virtual address into an offset.

Warning

If the shared cache contains multiple subcaches, this function needs to be called on the targeted subcache. See cache_for_address() to find the associated subcache.

FileStream &stream() const¶

Return the stream associated with this dyld shared cache.

FileStream &stream()¶

Return the stream associated with this dyld shared cache.

void enable_caching(const std::string &target_cache_dir) const¶

When enabled, this function allows to record and to keep in cache, dyld shared cache information that are costly to access.

For instance, GOT symbols, rebases information, stub symbols, …

It is highly recommended to enable this function when processing a dyld shared cache several times or when extracting a large number of LIEF::dsc::Dylib with enhanced extraction options (e.g. Dylib::extract_opt_t::fix_branches)

One can enable caching by calling this function:

auto dyld_cache = LIEF::dsc::load("macos-15.0.1/");
dyld_cache->enable_caching("/home/user/.cache/lief-dsc");

One can also enable this cache optimization globally using the function: LIEF::dsc::enable_cache or by setting the environment variable DYLDSC_ENABLE_CACHE to 1.

void flush_cache() const¶

Flush internal information into the on-disk cache (see: enable_caching)

Public Static Functions

static std::unique_ptr<DyldSharedCache> from_path(const std::string &path, const std::string &arch = "")¶

See the load functions for the details.

static std::unique_ptr<DyldSharedCache> from_files(const std::vector<std::string> &path)¶

See the load functions for the details.

Dylib¶

class Dylib¶

This class represents a library embedded in a dyld shared cache. It mirrors the original dyld_cache_image_info structure.

Public Functions

Dylib(std::unique_ptr<details::Dylib> impl)¶

~Dylib()¶

std::string path() const¶

Original path of the library (e.g. /usr/lib/libcryptex.dylib)

uint64_t address() const¶

In-memory address of the library.

uint64_t modtime() const¶

Modification time of the library matching stat.st_mtime, or 0.

uint64_t inode() const¶

File serial number matching stat.st_ino or 0.

Note that for shared cache targeting iOS, this value can hold a hash of the path (if modtime is set to 0)

uint64_t padding() const¶

Padding alignment value (should be 0)

std::unique_ptr<LIEF::MachO::Binary> get(const extract_opt_t &opt = extract_opt_t()) const¶

Get a MachO::Binary representation for this Dylib.

One can use this function to write back the Mach-O binary on the disk:

dyld_cache->libraries()[12]->get()->write("liblockdown.dylib");

struct extract_opt_t¶

This structure is used to tweak the extraction process while calling Dylib::get. These options allow to deoptimize the dylib and get an accurate representation of the origin Mach-O binary.

Public Functions

extract_opt_t()¶

Public Members

bool pack = true¶

Whether the segment’s offsets should be packed to avoid an in-memory size while writing back the binary.

Note

This option does not have an impact on the performances

bool fix_branches = false¶

Fix call instructions that target addresses outside the current dylib virtual space.

Warning

Enabling this option can have a significant impact on the performances. Make sure to enable the internal cache mechanism: LIEF::dsc::enable_cache or LIEF::dsc::DyldSharedCache::enable_caching

bool fix_memory = false¶

Fix memory accesses performed outside the dylib’s virtual space.

Warning

Enabling this option can have a significant impact on the performances. Make sure to enable the internal cache mechanism: LIEF::dsc::enable_cache or LIEF::dsc::DyldSharedCache::enable_caching

bool fix_relocations = false¶

Recover and fix relocations.

Warning

Enabling this option can have a significant impact on the performances. Make sure to enable the internal cache mechanism: LIEF::dsc::enable_cache or LIEF::dsc::DyldSharedCache::enable_caching

bool fix_objc = false¶

Fix Objective-C information.

LIEF::result<bool> create_dyld_chained_fixup_cmd¶

Whether the LC_DYLD_CHAINED_FIXUPS command should be (re)created.

If this value is not set, LIEF will add the command only if it’s meaningful regarding the other options

class Iterator : public LIEF::iterator_facade_base<Iterator, std::random_access_iterator_tag, std::unique_ptr<Dylib>, std::ptrdiff_t, Dylib*, std::unique_ptr<Dylib>>¶

Dylib Iterator.

Public Types

using implementation = details::DylibIt¶

Public Functions

Iterator(std::unique_ptr<details::DylibIt> impl)¶

Iterator(const Iterator&)¶

Iterator &operator=(const Iterator&)¶

Iterator(Iterator&&) noexcept¶

Iterator &operator=(Iterator&&) noexcept¶

~Iterator()¶

bool operator<(const Iterator &rhs) const¶

std::ptrdiff_t operator-(const Iterator &R) const¶

Iterator &operator+=(std::ptrdiff_t n)¶

Iterator &operator-=(std::ptrdiff_t n)¶

std::unique_ptr<Dylib> operator*() const¶

Friends

friend bool operator==(const Iterator &LHS, const Iterator &RHS)¶

inline friend bool operator!=(const Iterator &LHS, const Iterator &RHS)¶

MappingInfo¶

class MappingInfo¶

This class represents a dyld_cache_mapping_info entry.

It provides information about the relationshiop between on-disk shared cache and in-memory shared cache.

Public Functions

MappingInfo(std::unique_ptr<details::MappingInfo> impl)¶

~MappingInfo()¶

uint64_t address() const¶

The in-memory address where this dyld shared cache region is mapped.

uint64_t size() const¶

Size of the region being mapped.

inline uint64_t end_address() const¶

End virtual address of the region.

uint64_t file_offset() const¶

On-disk file offset.

uint32_t max_prot() const¶

Max memory protection.

uint32_t init_prot() const¶

Initial memory protection.

class Iterator : public LIEF::iterator_facade_base<Iterator, std::random_access_iterator_tag, std::unique_ptr<MappingInfo>, std::ptrdiff_t, MappingInfo*, std::unique_ptr<MappingInfo>>¶

MappingInfo Iterator.

Public Types

using implementation = details::MappingInfoIt¶

Public Functions

Iterator(std::unique_ptr<details::MappingInfoIt> impl)¶

Iterator(const Iterator&)¶

Iterator &operator=(const Iterator&)¶

Iterator(Iterator&&) noexcept¶

Iterator &operator=(Iterator&&) noexcept¶

~Iterator()¶

bool operator<(const Iterator &rhs) const¶

std::ptrdiff_t operator-(const Iterator &R) const¶

Iterator &operator+=(std::ptrdiff_t n)¶

Iterator &operator-=(std::ptrdiff_t n)¶

std::unique_ptr<MappingInfo> operator*() const¶

Friends

friend bool operator==(const Iterator &LHS, const Iterator &RHS)¶

inline friend bool operator!=(const Iterator &LHS, const Iterator &RHS)¶

SubCache¶

class SubCache¶

This class represents a subcache in the case of large/split dyld shared cache.

It mirror (and abstracts) the original dyld_subcache_entry / dyld_subcache_entry_v1

Public Functions

SubCache(std::unique_ptr<details::SubCache> impl)¶

~SubCache()¶

sc_uuid_t uuid() const¶

The uuid of the subcache file.

uint64_t vm_offset() const¶

The offset of this subcache from the main cache base address.

std::string suffix() const¶

The file name suffix of the subCache file (e.g. .25.data, .03.development)

std::unique_ptr<const DyldSharedCache> cache() const¶

The associated DyldSharedCache object for this subcache.

Friends

friend std::ostream &operator<<(std::ostream &os, const SubCache &subcache)¶

class Iterator : public LIEF::iterator_facade_base<Iterator, std::random_access_iterator_tag, std::unique_ptr<SubCache>, std::ptrdiff_t, SubCache*, std::unique_ptr<SubCache>>¶

SubCache Iterator.

Public Types

using implementation = details::SubCacheIt¶

Public Functions

Iterator(std::unique_ptr<details::SubCacheIt> impl)¶

Iterator(const Iterator&)¶

Iterator &operator=(const Iterator&)¶

Iterator(Iterator&&) noexcept¶

Iterator &operator=(Iterator&&) noexcept¶

~Iterator()¶

bool operator<(const Iterator &rhs) const¶

std::ptrdiff_t operator-(const Iterator &R) const¶

Iterator &operator+=(std::ptrdiff_t n)¶

Iterator &operator-=(std::ptrdiff_t n)¶

std::unique_ptr<SubCache> operator*() const¶

Friends

friend bool operator==(const Iterator &LHS, const Iterator &RHS)¶

inline friend bool operator!=(const Iterator &LHS, const Iterator &RHS)¶