Licensing

PureDarwin has no single licence. It is Apple’s open source under the APSL, plus BSD-licensed code from FreeBSD, plus MIT-licensed work from Haiku and other projects, plus code written here. That is normal for a system of this shape. It means “what licence is PureDarwin” has no single answer, and anyone packaging or redistributing it needs the detail.

This page is an orientation. It is not legal advice. The authority is always the header on the file in front of you.

The Broad Shape

Foundation is worth a note. It contains MPL 2.0 code, and the project treats the whole component as MPL. That is a working convention. Handling it uniformly keeps merging simple, and contributors are encouraged to do the same. The licence itself does not require it.

XPC in Detail

src/Libraries/XPC is the clearest example of why a single answer does not work. It is one directory holding components under different terms:

There is no aggregate licence for the directory. Collecting differently licensed components in one place does not give them shared terms, so each of the above keeps its own, and the SPDX header on the file in front of you is what governs it.

PD 1.0 is the project’s own licence, a BSD-2-Clause derivative. The text is in PUREDARWIN_LICENSE.txt at the root of the repository.

corecrypto

The corecrypto kext, libSystem and the host linker build against Vali0004/corecrypto, an interim MPL-2.0 fork of NeoDarwin’s corecrypto. It sits in the tree as the external/corecrypto submodule. It is experimental and has not been reviewed for security.

The older GPLv3 corecrypto, which came from Darling, is still in src/Libraries/libSystem/corecrypto. Only Security.framework compiles it, because the fork does not have RSA key generation, EC or DH yet. If you redistribute PureDarwin, that copy inside Security.framework is the GPL code to know about.

Published Is Not the Same as Licensed

Some source Apple has published carries no usable licence grant. The pattern is a repository where only some files have a per-file licence header and there is no repository-wide LICENSE, which leaves everything unheaded with nothing attached to it.

CommonCrypto is one example. The tree uses Apple’s published CommonCrypto, and nearly all of it carries the APSL. Six files had no grant: the CommonKeyDerivationSPI, CommonRandomSPI and CommonCollabKeyGen sources and CommonBuffering.c. The project rewrote those from their public interfaces.

Apple’s libDER arrived with the same gap. That one had a better ending. The project wrote its own libDER, and it is PD 1.0 as a result.

Check licensing file by file before building a port around an Apple component. Finding out late is expensive, because by then somebody has read the code.

Code Kept Outside the Tree

The project avoids folding another independently licensed substantial component into the default distribution when keeping it external works just as well.

fbDOOM is the working example. It is GPL, so it lives in an external checkout, pointed at by PUREDARWIN_FBDOOM_SOURCE_ENV and built with --impure. This is no objection to the GPL. A GPL component in the tree brings obligations for everyone who packages or redistributes PureDarwin. Keeping it opt-in means the default build has one less licence to reason about, and people who want fbDOOM can still have it.

If you need to add something that must stay external, copy the fbDOOM shape. The principle applies beyond the GPL. ZFS, under the CDDL, is the other obvious candidate.

Contributing

What the project can accept, and the clean-room rules for writing drivers from datasheets, are in Contributing and in CONTRIBUTING.md. The short version is that every contribution has to be yours to give under a compatible licence, and code whose licensing is unknown cannot be accepted or even looked at.