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const std = @import("std");
const builtin = @import("builtin");
const log = std.log.scoped(.archive);
const macho = std.macho;
const mem = std.mem;
const native_endian = builtin.target.cpu.arch.endian();
pub fn decodeArch(cputype: macho.cpu_type_t, comptime logError: bool) !std.Target.Cpu.Arch {
const cpu_arch: std.Target.Cpu.Arch = switch (cputype) {
macho.CPU_TYPE_ARM64 => .aarch64,
macho.CPU_TYPE_X86_64 => .x86_64,
else => {
if (logError) {
log.err("unsupported cpu architecture 0x{x}", .{cputype});
}
return error.UnsupportedCpuArchitecture;
},
};
return cpu_arch;
}
fn readFatStruct(reader: anytype, comptime T: type) !T {
// Fat structures (fat_header & fat_arch) are always written and read to/from
// disk in big endian order.
var res = try reader.readStruct(T);
if (native_endian != std.builtin.Endian.Big) {
mem.byteSwapAllFields(T, &res);
}
return res;
}
pub fn getLibraryOffset(reader: anytype, cpu_arch: std.Target.Cpu.Arch) !u64 {
const fat_header = try readFatStruct(reader, macho.fat_header);
if (fat_header.magic != macho.FAT_MAGIC) return 0;
var fat_arch_index: u32 = 0;
while (fat_arch_index < fat_header.nfat_arch) : (fat_arch_index += 1) {
const fat_arch = try readFatStruct(reader, macho.fat_arch);
// If we come across an architecture that we do not know how to handle, that's
// fine because we can keep looking for one that might match.
const lib_arch = decodeArch(fat_arch.cputype, false) catch |err| switch (err) {
error.UnsupportedCpuArchitecture => continue,
};
if (lib_arch == cpu_arch) {
// We have found a matching architecture!
return fat_arch.offset;
}
} else {
log.err("Could not find matching cpu architecture in fat library: expected {s}", .{
@tagName(cpu_arch),
});
return error.MismatchedCpuArchitecture;
}
}
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