GSoC: Separation of Ports Build Process from Local Installation

[Theron Tarigo]

Hello all,

This project aims to decouple the build process of the ports framework 
from the local installation.  To work around the assumptions made by 
ports about dependency file locations, a userspace tool to remap 
processes' filesystem namespaces is under development.

This past week, I have made the following progress:
- Ldconfig hints file is maintained at each dependency port 
installation, allowing build tools to run as expected.
- Fixed several more problems with running programs under the namespace 
tool:
     - Some ports contain /bin/sh scripts with no shebang.  FreeBSD 
allows this; Namespace tool's execve implementation is changed accordingly.
     - Fixed a bug in execve implementation concerning argv[0]
     - Debugging output, when requested, now does not get written to 
wrong file after (v)fork and/or exec.
- Have ports use devel/bmake instead of /usr/bin/make, where possible, 
as the latter is statically linked and cannot handle ports Makefiles' 
dependencies on installed files.
- Confirmed that devel/llvm60 and all its dependencies build 
successfully.  This selection of ports represents many build tools 
commonly used in building of other ports.  To see for yourself: make -C 
/usr/ports/devel/llvm60 all-depends-list

What I am working on next:
- Create a port of freebsd-user-namespace to be used by ports framework, 
similarly to how ports-mgmt/pkg is used.
- Build larger set of ports to discover remaining incompatibilities.
- Set up automated testing of ports to assess progress and catch 
regressions.

Project goals and status are kept at 
https://wiki.freebsd.org/SummerOfCode2019Projects/PortsSeparatedBuild .

Source of the userspace filesystem namespace tool is shared at 
https://github.com/therontarigo/freebsd-user-namespace .
Changes to ports framework are shared at 
https://github.com/freebsd/freebsd-ports/compare/master...therontarigo:separated.

Theron Tarigo