Check for writes outside of the build directory

[powerboat9]

I noticed that libgrust/libformat_parser/target was seemingly generated outside the build directory on my machine. This should detect similar issues, and confirm/deny the aforementioned issue.

[P-E-P]

@powerboat9 The MacOS CI broke, we repaired it but you need to rebase your branch now.

[tschwinge]

That specific issue was addressed by #2947 "Move 'libformat_parser' build into the GCC build directory, and into libgrust" -- but yes, good idea to actually make sure we're not introducing similar things again! :+1:

[tschwinge]

Eh, the build now actually is failing due to a similar issue:

cargo build --manifest-path ../../gcc/rust/checks/errors/borrowck/ffi-polonius/Cargo.toml --release --target-dir rust/ffi-polonius
    Updating crates.io index
error: failed to write /home/runner/work/gccrs/gccrs/gcc/rust/checks/errors/borrowck/ffi-polonius/Cargo.lock

...., so that'll need to be addressed first (in a similar way as #2947 "Move 'libformat_parser' build into the GCC build directory, and into libgrust", I suppose).

[powerboat9]

From what I see from man documentation the chmod command doesn't accept flags after the mode(s) are given, but I'll change it just in case. Good catch though

[tschwinge]

It's easy enough to try:

$ ls -l
total 0
-rw-r--r-- 1 thomas thomas 0 May  8 10:50 --verbose
-rw-r--r-- 1 thomas thomas 0 May  8 10:50 foo
$ chmod -R a-w *
mode of 'foo' changed from 0644 (rw-r--r--) to 0444 (r--r--r--)
$ ls -l
total 0
-rw-r--r-- 1 thomas thomas 0 May  8 10:50 --verbose
-r--r--r-- 1 thomas thomas 0 May  8 10:50 foo

[P-E-P]

Looks like cargo is trying to update the lock file and fail. I've noticed ffi-polonius does not use the same cargo config as libformat parser. Maybe we should update the cargo invocation with a --config argument ?

[thesamesam]

I think it's worth passing some arguments to be safe. Even better would be to never call cargo directly and always through a variable to make sure we don't drop args.

In Gentoo, in cargo.eclass, we do:

cat > "${ECARGO_HOME}/config.toml" <<- _EOF_ || die "Failed to create cargo config"
[source.gentoo]
directory = "${ECARGO_VENDOR}"

[source.crates-io]
replace-with = "gentoo"
local-registry = "/nonexistent"

[net]
offline = true

[build]
jobs = $(makeopts_jobs)
incremental = false

[term]
verbose = true
$([[ "${NOCOLOR}" = true || "${NOCOLOR}" = yes ]] && echo "color = 'never'")
$(_cargo_gen_git_config)
_EOF_

export CARGO_HOME="${ECARGO_HOME}"

You don't need the local registry bit (although it doesn't do any harm), but you get the idea wrt offline. We also always invoke cargo with --offline. We could also set CARGO_HOME to be a temporary directory within the builddir.

[powerboat9]

It looks like the issues preventing this PR from passing checks have since been fixed