Back in February 2021, we changed the obfuscation logic so that the
entire `garble build` process would use one shared temporary directory
across all package builds, reducing the amount of files we created in
the top-level system temporary directory.
However, we made one mistake: we didn't swap os.Remove for os.RemoveAll.
Ever since then, we've been leaving temporary files behind.
Add regression tests, which failed before the fix, and fix the bug.
Note that we need to test `garble reverse` as well, as it calls
toolexecCmd separately, so it needs its own cleanup as well.
The cleanup happens via the env var, which doesn't feel worse than
having toolexecCmd return an extra string or cleanup func.
While here, also test that we support TMPDIRs with special characters.
If we don't quote it, paths containing spaces or quote characters will
fail. For instance, the added test without the fix fails:
> env NAME='with spaces'
> mkdir $NAME
> cp $EXEC_PATH $NAME/garble$exe
> exec $NAME/garble$exe build main.go
[stderr]
go tool compile: fork/exec $WORK/with: no such file or directory
exit status 1
Luckily, the fix is easy: we bundle Go's cmd/internal/quoted package,
which implements a QuotedJoin API for this very purpose.
Fixes#544.
Daniel Martí