Add fat/universal dylib support to zig ld

With this change zig ld can link with dynamic libraries
contained within a fat/universal file that had multiple
seperate binaries embedded within it for multi-arch
support (in macOS).

Whilst zig can still only create single-architecture
executables - the ability to link with fat libraries is
useful for cases where they are the easiest (or only)
option to link against.

1 files changed, 27 insertions, 0 deletions

diff --git a/lib/std/macho.zig b/lib/std/macho.zig
index 20620b1fbf..cb030e941e 100644
--- a/lib/std/macho.zig
+++ b/lib/std/macho.zig
@@ -24,6 +24,19 @@ pub const mach_header_64 = extern struct {
     reserved: u32,
 };
 
+pub const fat_header = extern struct {
+    magic: u32,
+    nfat_arch: u32,
+};
+
+pub const fat_arch = extern struct {
+    cputype: cpu_type_t,
+    cpusubtype: cpu_subtype_t,
+    offset: u32,
+    size: u32,
+    @"align": u32,
+};
+
 pub const load_command = extern struct {
     cmd: u32,
     cmdsize: u32,
@@ -1040,6 +1053,20 @@ pub const MH_APP_EXTENSION_SAFE = 0x02000000;
 /// The external symbols listed in the nlist symbol table do not include all the symbols listed in the dyld info.
 pub const MH_NLIST_OUTOFSYNC_WITH_DYLDINFO = 0x04000000;
 
+// Constants for the flags field of the fat_header
+
+/// the fat magic number
+pub const FAT_MAGIC = 0xcafebabe;
+
+/// NXSwapLong(FAT_MAGIC)
+pub const FAT_CIGAM = 0xbebafeca;
+
+/// the 64-bit fat magic number
+pub const FAT_MAGIC_64 = 0xcafebabf;
+
+/// NXSwapLong(FAT_MAGIC_64)
+pub const FAT_CIGAM_64 = 0xbfbafeca;
+
 /// The flags field of a section structure is separated into two parts a section
 /// type and section attributes.  The section types are mutually exclusive (it
 /// can only have one type) but the section attributes are not (it may have more