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//! A Mach-o fat binary is a multi-architecture binary container
use core::fmt;
if_std! {
use std::fs::File;
use std::io::{self, Read};
}
use crate::error;
use crate::mach::constants::cputype::{CpuSubType, CpuType, CPU_ARCH_ABI64, CPU_SUBTYPE_MASK};
use scroll::{Pread, Pwrite, SizeWith};
pub const FAT_MAGIC: u32 = 0xcafe_babe;
pub const FAT_CIGAM: u32 = 0xbeba_feca;
#[repr(C)]
#[derive(Clone, Copy, Default, Pread, Pwrite, SizeWith)]
/// The Mach-o `FatHeader` always has its data bigendian
pub struct FatHeader {
/// The magic number, `cafebabe`
pub magic: u32,
/// How many fat architecture headers there are
pub nfat_arch: u32,
}
pub const SIZEOF_FAT_HEADER: usize = 8;
impl fmt::Debug for FatHeader {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("FatHeader")
.field("magic", &format_args!("0x{:x}", self.magic))
.field("nfat_arch", &self.nfat_arch)
.finish()
}
}
impl FatHeader {
/// Reinterpret a `FatHeader` from `bytes`
pub fn from_bytes(bytes: [u8; SIZEOF_FAT_HEADER]) -> FatHeader {
let mut offset = 0;
let magic = bytes.gread_with(&mut offset, scroll::BE).unwrap();
let nfat_arch = bytes.gread_with(&mut offset, scroll::BE).unwrap();
FatHeader { magic, nfat_arch }
}
/// Reads a `FatHeader` from a `File` on disk
#[cfg(feature = "std")]
pub fn from_fd(fd: &mut File) -> io::Result<FatHeader> {
let mut header = [0; SIZEOF_FAT_HEADER];
fd.read_exact(&mut header)?;
Ok(FatHeader::from_bytes(header))
}
/// Parse a mach-o fat header from the `bytes`
pub fn parse(bytes: &[u8]) -> error::Result<FatHeader> {
Ok(bytes.pread_with::<FatHeader>(0, scroll::BE)?)
}
}
#[repr(C)]
#[derive(Clone, Copy, Default, Pread, Pwrite, SizeWith)]
/// The Mach-o `FatArch` always has its data bigendian
pub struct FatArch {
/// What kind of CPU this binary is
pub cputype: u32,
pub cpusubtype: u32,
/// Where in the fat binary it starts
pub offset: u32,
/// How big the binary is
pub size: u32,
pub align: u32,
}
pub const SIZEOF_FAT_ARCH: usize = 20;
impl fmt::Debug for FatArch {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
fmt.debug_struct("FatArch")
.field("cputype", &self.cputype())
.field("cmdsize", &self.cpusubtype())
.field("offset", &format_args!("{:#x}", &self.offset))
.field("size", &self.size)
.field("align", &self.align)
.finish()
}
}
impl FatArch {
/// Get the slice of bytes this header describes from `bytes`
pub fn slice<'a>(&self, bytes: &'a [u8]) -> &'a [u8] {
// FIXME: This function should ideally validate the inputs and return a `Result`.
// Best we can do for now without `panic`ing is return an empty slice.
let start = self.offset as usize;
match start
.checked_add(self.size as usize)
.and_then(|end| bytes.get(start..end))
{
Some(slice) => slice,
None => {
log::warn!("invalid `FatArch` offset");
&[]
}
}
}
/// Returns the cpu type
pub fn cputype(&self) -> CpuType {
self.cputype
}
/// Returns the cpu subtype with the capabilities removed
pub fn cpusubtype(&self) -> CpuSubType {
self.cpusubtype & !CPU_SUBTYPE_MASK
}
/// Returns the capabilities of the CPU
pub fn cpu_caps(&self) -> u32 {
(self.cpusubtype & CPU_SUBTYPE_MASK) >> 24
}
/// Whether this fat architecture header describes a 64-bit binary
pub fn is_64(&self) -> bool {
(self.cputype & CPU_ARCH_ABI64) == CPU_ARCH_ABI64
}
/// Parse a `FatArch` header from `bytes` at `offset`
pub fn parse(bytes: &[u8], offset: usize) -> error::Result<Self> {
let arch = bytes.pread_with::<FatArch>(offset, scroll::BE)?;
Ok(arch)
}
}