Because of an objc quirk[1], calling curl_global_init for the first time
after fork() will always result in a crash.
Up until now the solution has been to set
OBJC_DISABLE_INITIALIZE_FORK_SAFETY for every nix process to ignore
that error.
This is less than ideal because we were setting it in package.nix,
which meant that running nix tests locally would fail because
that variable was not set.
Instead of working around that error we address it at the core -
by calling curl_global_init inside initLibStore, which should mean
curl will already have been initialized by the time we try to do so in
a forked process.
[1] 01edf1705f/runtime/objc-initialize.mm (L614-L636)
(cherry-picked and adapted from c7d97802e4)
Note: in general, we rely on the OS to tell us if a name is invalid or
if two names normalize in the same way. But for security, we do want
to make sure that we catch '.', '..', slashes and NUL characters. (NUL
characters aren't really a security issue, but since they would be
truncated when we pass them to the OS, it would be canonicity problem.)
Relative path flakes ("subflakes") are basically fundamentally
broken, since they produce lock file entries like
"locked": {
"lastModified": 1,
"narHash": "sha256-/2tW9SKjQbRLzfcJs5SHijli6l3+iPr1235zylGynK8=",
"path": "./flakeC",
"type": "path"
},
that don't specify what "./flakeC" is relative to. They *sometimes*
worked by accident because the `narHash` field allowed
`fetchToStore()` to get the store path of the subflake *if* it
happened to exist in the local store or in a substituter.
Subflakes are properly fixed in #10089 (which adds a "parent" field to
the lock file). Rather than come up with some crazy hack to make them
work in the interim, let's just disable the only test that depends on
the broken behaviour for now.
The impending release of macOS 15 Sequoia will break many existing nix
installs on macOS, which may lead to an increased number of people who
are looking to try to reinstall Nix without noticing the open/pinned
issue (#10892) that explains the problem and outlines how to migrate
existing installs.
These admonitions are a short-term measure until we are over the hump
and support volumes dwindle.
Was hoping to leave this enabled for a little while as core community
members test this script out, but Apple's aggressive release timeline
for macOS 15 Sequoia has caught us off-guard here.
It's probably not ideal for a general audience if the script spews all
of this output--and people can still force bash to run in trace mode
if we really need to debug a problem.
Caused by 1d3696f0fb
Without this fix the kept build directory is readable only by root
```
$ sudo ls -ld /comp-temp/nix-build-openssh-static-x86_64-unknown-linux-musl-9.8p1.drv-5
drwx------ root root 60 B Wed Sep 11 00:09:48 2024 /comp-temp/nix-build-openssh-static-x86_64-unknown-linux-musl-9.8p1.drv-5/
$ sudo ls -ld /comp-temp/nix-build-openssh-static-x86_64-unknown-linux-musl-9.8p1.drv-5/build
drwxr-xr-x nixbld1 nixbld 80 B Wed Sep 11 00:09:58 2024 /comp-temp/nix-build-openssh-static-x86_64-unknown-linux-musl-9.8p1.drv-5/build/
```
