Use inline to vastly simplify the exposed API. This allows a
comptime-known endian parameter to be propogated, making extra functions
for a specific endianness completely unnecessary.
Most of this migration was performed automatically with `zig fmt`. There
were a few exceptions which I had to manually fix:
* `@alignCast` and `@addrSpaceCast` cannot be automatically rewritten
* `@truncate`'s fixup is incorrect for vectors
* Test cases are not formatted, and their error locations change
Anecdote 1: The generic version is way more popular than the non-generic
one in Zig codebase:
git grep -w alignForward | wc -l
56
git grep -w alignForwardGeneric | wc -l
149
git grep -w alignBackward | wc -l
6
git grep -w alignBackwardGeneric | wc -l
15
Anecdote 2: In my project (turbonss) that does much arithmetic and
alignment I exclusively use the Generic functions.
Anecdote 3: we used only the Generic versions in the Macho Man's linker
workshop.
By pulling out the parallel hashing setup from `CodeSignature.zig`,
we can now reuse it different places across MachO linker (for now;
I can totally see its usefulness beyond MachO, eg. in COFF or ELF too).
The parallel hasher is generic over actual hasher such as Sha256 or MD5.
The implementation is kept as it was.
For UUID calculation, depending on the linking mode:
* incremental - since it only supports debug mode, we don't bother with MD5
hashing of the contents, and populate it with random data but only once
per a sequence of in-place binary patches
* traditional - in debug, we use random string (for speed); in release,
we calculate the hash, however we use LLVM/LLD's trick in that we
calculate a series of MD5 hashes in parallel and then one an MD5 of MD5
final hash to generate digest.
This is a prelude to a more elaborate work which will implement
`-dead_strip` flag - garbage collection of unreachable atoms. Here,
when sorting sections, we also check that the section is actually
populated with some atoms, and if not, we exclude it from the final
linked image. This can happen when we do not import any symbols
from dynamic libraries in which case we will not be populating
the stubs sections or the GOT table, implying we can skip allocating
those sections. Furthermore, we also make a check that a segment
is actually occupied too, with the exception of `__TEXT` segment
which is non-optional given that it wraps the header and load commands
and thus is required by the `dyld` to perform dynamic linking, and
`__PAGEZERO` which is generally non-optional when the linked image
is an executable. For any other segment, if its section count is
zero, we mark it as dead and skip allocating it and generating
a load command for it.
This commit also includes some minor improvements to the linker such
as refactoring of the segment allocating codepaths, skipping
`__PAGEZERO` generation for dylibs, and skipping generation of zero-sized
atoms for special symbols such as `__mh_execute_header` and `___dso_handle`.
These special symbols are only allocated local and global symbol pair
and their VM addresses is set to the start of the `__TEXT` segment,
but no `Atom` is created, as it's not necessary given that they never
carry any machine code.
Finally, we now always force-link against `libSystem` which turns out
to be required for `dyld` to properly handle `LC_MAIN` load command
on older macOS versions such as 10.15.7.
This way, if the user wants to use `codesign` (or other tool) they
will not be forced to `-f` force signature update. This matches
the behavior promoted by Apple's `ld64` linker.
With this change, we can now bake in entitlements into the binary.
Additionally, I see this as the first step towards full code signature
support which includes baking in Apple issued certificates for
redistribution, etc.
These calls are all late-initialization of ArrayList's that were initialized outside the current scope. This allows us to still get the potential memory-saving benefits of the 'precision' of initCapacity.
It turns out I was wrong and we can set the page size to the actual
page size used by the target architecture when dividing the binary
into chunks and calculating a hash of each chunk for embedding within
the adhoc code signature. This shaves of a considerable amount of bytes
since we divide the code signature section by at least 2x.
I've also unified the `write` interface of `CodeSignature` struct to
follow that used in every other bit of `MachO`; namely, the functions
now accept a writer instead of a buffer, therefore, there is no need
to manually track where to write each struct field anymore.
