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use alloc::vec::Vec;
use core::slice;
use crate::read::{Error, File, ReadError, ReadRef, Result};
use crate::{macho, Architecture, Endian, Endianness};
/// A parsed representation of the dyld shared cache.
#[derive(Debug)]
pub struct DyldCache<'data, E = Endianness, R = &'data [u8]>
where
E: Endian,
R: ReadRef<'data>,
{
endian: E,
data: R,
subcaches: Vec<DyldSubCache<'data, E, R>>,
mappings: &'data [macho::DyldCacheMappingInfo<E>],
images: &'data [macho::DyldCacheImageInfo<E>],
arch: Architecture,
}
/// Information about a subcache.
#[derive(Debug)]
pub struct DyldSubCache<'data, E = Endianness, R = &'data [u8]>
where
E: Endian,
R: ReadRef<'data>,
{
data: R,
mappings: &'data [macho::DyldCacheMappingInfo<E>],
}
// This is the offset of the images_across_all_subcaches_count field.
const MIN_HEADER_SIZE_SUBCACHES: u32 = 0x1c4;
impl<'data, E, R> DyldCache<'data, E, R>
where
E: Endian,
R: ReadRef<'data>,
{
/// Parse the raw dyld shared cache data.
/// For shared caches from macOS 12 / iOS 15 and above, the subcache files need to be
/// supplied as well, in the correct order, with the .symbols subcache last (if present).
/// For example, data would be the data for dyld_shared_cache_x86_64,
/// and subcache_data would be the data for [dyld_shared_cache_x86_64.1, dyld_shared_cache_x86_64.2, ...]
pub fn parse(data: R, subcache_data: &[R]) -> Result<Self> {
let header = macho::DyldCacheHeader::parse(data)?;
let (arch, endian) = header.parse_magic()?;
let mappings = header.mappings(endian, data)?;
let symbols_subcache_uuid = header.symbols_subcache_uuid(endian);
let subcaches_info = header.subcaches(endian, data)?.unwrap_or(&[]);
if subcache_data.len() != subcaches_info.len() + symbols_subcache_uuid.is_some() as usize {
return Err(Error("Incorrect number of SubCaches"));
}
// Split out the .symbols subcache data from the other subcaches.
let (symbols_subcache_data_and_uuid, subcache_data) =
if let Some(symbols_uuid) = symbols_subcache_uuid {
let (sym_data, rest_data) = subcache_data.split_last().unwrap();
(Some((*sym_data, symbols_uuid)), rest_data)
} else {
(None, subcache_data)
};
// Read the regular SubCaches (.1, .2, ...), if present.
let mut subcaches = Vec::new();
for (&data, info) in subcache_data.iter().zip(subcaches_info.iter()) {
let sc_header = macho::DyldCacheHeader::<E>::parse(data)?;
if sc_header.uuid != info.uuid {
return Err(Error("Unexpected SubCache UUID"));
}
let mappings = sc_header.mappings(endian, data)?;
subcaches.push(DyldSubCache { data, mappings });
}
// Read the .symbols SubCache, if present.
// Other than the UUID verification, the symbols SubCache is currently unused.
let _symbols_subcache = match symbols_subcache_data_and_uuid {
Some((data, uuid)) => {
let sc_header = macho::DyldCacheHeader::<E>::parse(data)?;
if sc_header.uuid != uuid {
return Err(Error("Unexpected .symbols SubCache UUID"));
}
let mappings = sc_header.mappings(endian, data)?;
Some(DyldSubCache { data, mappings })
}
None => None,
};
let images = header.images(endian, data)?;
Ok(DyldCache {
endian,
data,
subcaches,
mappings,
images,
arch,
})
}
/// Get the architecture type of the file.
pub fn architecture(&self) -> Architecture {
self.arch
}
/// Get the endianness of the file.
#[inline]
pub fn endianness(&self) -> Endianness {
if self.is_little_endian() {
Endianness::Little
} else {
Endianness::Big
}
}
/// Return true if the file is little endian, false if it is big endian.
pub fn is_little_endian(&self) -> bool {
self.endian.is_little_endian()
}
/// Iterate over the images in this cache.
pub fn images<'cache>(&'cache self) -> DyldCacheImageIterator<'data, 'cache, E, R> {
DyldCacheImageIterator {
cache: self,
iter: self.images.iter(),
}
}
/// Find the address in a mapping and return the cache or subcache data it was found in,
/// together with the translated file offset.
pub fn data_and_offset_for_address(&self, address: u64) -> Option<(R, u64)> {
if let Some(file_offset) = address_to_file_offset(address, self.endian, self.mappings) {
return Some((self.data, file_offset));
}
for subcache in &self.subcaches {
if let Some(file_offset) =
address_to_file_offset(address, self.endian, subcache.mappings)
{
return Some((subcache.data, file_offset));
}
}
None
}
}
/// An iterator over all the images (dylibs) in the dyld shared cache.
#[derive(Debug)]
pub struct DyldCacheImageIterator<'data, 'cache, E = Endianness, R = &'data [u8]>
where
E: Endian,
R: ReadRef<'data>,
{
cache: &'cache DyldCache<'data, E, R>,
iter: slice::Iter<'data, macho::DyldCacheImageInfo<E>>,
}
impl<'data, 'cache, E, R> Iterator for DyldCacheImageIterator<'data, 'cache, E, R>
where
E: Endian,
R: ReadRef<'data>,
{
type Item = DyldCacheImage<'data, 'cache, E, R>;
fn next(&mut self) -> Option<DyldCacheImage<'data, 'cache, E, R>> {
let image_info = self.iter.next()?;
Some(DyldCacheImage {
cache: self.cache,
image_info,
})
}
}
/// One image (dylib) from inside the dyld shared cache.
#[derive(Debug)]
pub struct DyldCacheImage<'data, 'cache, E = Endianness, R = &'data [u8]>
where
E: Endian,
R: ReadRef<'data>,
{
pub(crate) cache: &'cache DyldCache<'data, E, R>,
image_info: &'data macho::DyldCacheImageInfo<E>,
}
impl<'data, 'cache, E, R> DyldCacheImage<'data, 'cache, E, R>
where
E: Endian,
R: ReadRef<'data>,
{
/// The file system path of this image.
pub fn path(&self) -> Result<&'data str> {
let path = self.image_info.path(self.cache.endian, self.cache.data)?;
// The path should always be ascii, so from_utf8 should always succeed.
let path = core::str::from_utf8(path).map_err(|_| Error("Path string not valid utf-8"))?;
Ok(path)
}
/// The subcache data which contains the Mach-O header for this image,
/// together with the file offset at which this image starts.
pub fn image_data_and_offset(&self) -> Result<(R, u64)> {
let address = self.image_info.address.get(self.cache.endian);
self.cache
.data_and_offset_for_address(address)
.ok_or(Error("Address not found in any mapping"))
}
/// Parse this image into an Object.
pub fn parse_object(&self) -> Result<File<'data, R>> {
File::parse_dyld_cache_image(self)
}
}
impl<E: Endian> macho::DyldCacheHeader<E> {
/// Read the dyld cache header.
pub fn parse<'data, R: ReadRef<'data>>(data: R) -> Result<&'data Self> {
data.read_at::<macho::DyldCacheHeader<E>>(0)
.read_error("Invalid dyld cache header size or alignment")
}
/// Returns (arch, endian) based on the magic string.
pub fn parse_magic(&self) -> Result<(Architecture, E)> {
let (arch, is_big_endian) = match &self.magic {
b"dyld_v1 i386\0" => (Architecture::I386, false),
b"dyld_v1 x86_64\0" => (Architecture::X86_64, false),
b"dyld_v1 x86_64h\0" => (Architecture::X86_64, false),
b"dyld_v1 ppc\0" => (Architecture::PowerPc, true),
b"dyld_v1 armv6\0" => (Architecture::Arm, false),
b"dyld_v1 armv7\0" => (Architecture::Arm, false),
b"dyld_v1 armv7f\0" => (Architecture::Arm, false),
b"dyld_v1 armv7s\0" => (Architecture::Arm, false),
b"dyld_v1 armv7k\0" => (Architecture::Arm, false),
b"dyld_v1 arm64\0" => (Architecture::Aarch64, false),
b"dyld_v1 arm64e\0" => (Architecture::Aarch64, false),
_ => return Err(Error("Unrecognized dyld cache magic")),
};
let endian =
E::from_big_endian(is_big_endian).read_error("Unsupported dyld cache endian")?;
Ok((arch, endian))
}
/// Return the mapping information table.
pub fn mappings<'data, R: ReadRef<'data>>(
&self,
endian: E,
data: R,
) -> Result<&'data [macho::DyldCacheMappingInfo<E>]> {
data.read_slice_at::<macho::DyldCacheMappingInfo<E>>(
self.mapping_offset.get(endian).into(),
self.mapping_count.get(endian) as usize,
)
.read_error("Invalid dyld cache mapping size or alignment")
}
/// Return the information about subcaches, if present.
pub fn subcaches<'data, R: ReadRef<'data>>(
&self,
endian: E,
data: R,
) -> Result<Option<&'data [macho::DyldSubCacheInfo<E>]>> {
if self.mapping_offset.get(endian) >= MIN_HEADER_SIZE_SUBCACHES {
let subcaches = data
.read_slice_at::<macho::DyldSubCacheInfo<E>>(
self.subcaches_offset.get(endian).into(),
self.subcaches_count.get(endian) as usize,
)
.read_error("Invalid dyld subcaches size or alignment")?;
Ok(Some(subcaches))
} else {
Ok(None)
}
}
/// Return the UUID for the .symbols subcache, if present.
pub fn symbols_subcache_uuid(&self, endian: E) -> Option<[u8; 16]> {
if self.mapping_offset.get(endian) >= MIN_HEADER_SIZE_SUBCACHES {
let uuid = self.symbols_subcache_uuid;
if uuid != [0; 16] {
return Some(uuid);
}
}
None
}
/// Return the image information table.
pub fn images<'data, R: ReadRef<'data>>(
&self,
endian: E,
data: R,
) -> Result<&'data [macho::DyldCacheImageInfo<E>]> {
if self.mapping_offset.get(endian) >= MIN_HEADER_SIZE_SUBCACHES {
data.read_slice_at::<macho::DyldCacheImageInfo<E>>(
self.images_across_all_subcaches_offset.get(endian).into(),
self.images_across_all_subcaches_count.get(endian) as usize,
)
.read_error("Invalid dyld cache image size or alignment")
} else {
data.read_slice_at::<macho::DyldCacheImageInfo<E>>(
self.images_offset.get(endian).into(),
self.images_count.get(endian) as usize,
)
.read_error("Invalid dyld cache image size or alignment")
}
}
}
impl<E: Endian> macho::DyldCacheImageInfo<E> {
/// The file system path of this image.
pub fn path<'data, R: ReadRef<'data>>(&self, endian: E, data: R) -> Result<&'data [u8]> {
let r_start = self.path_file_offset.get(endian).into();
let r_end = data.len().read_error("Couldn't get data len()")?;
data.read_bytes_at_until(r_start..r_end, 0)
.read_error("Couldn't read dyld cache image path")
}
/// Find the file offset of the image by looking up its address in the mappings.
pub fn file_offset(
&self,
endian: E,
mappings: &[macho::DyldCacheMappingInfo<E>],
) -> Result<u64> {
let address = self.address.get(endian);
address_to_file_offset(address, endian, mappings)
.read_error("Invalid dyld cache image address")
}
}
/// Find the file offset of the image by looking up its address in the mappings.
pub fn address_to_file_offset<E: Endian>(
address: u64,
endian: E,
mappings: &[macho::DyldCacheMappingInfo<E>],
) -> Option<u64> {
for mapping in mappings {
let mapping_address = mapping.address.get(endian);
if address >= mapping_address
&& address < mapping_address.wrapping_add(mapping.size.get(endian))
{
return Some(address - mapping_address + mapping.file_offset.get(endian));
}
}
None
}