If I attempt to use:

config_opts['files']['some/file'] = ...

to create a file in a directory that's not already created as part of the chroot "skeleton" in mock, it crashes out with a "No such file or directory" error like this:

$ mock -r city-fan-fedora-11-x86_64 libssh2-1.2.5-2.0.cf.fc12.src.rpm INFO: mock.py version 1.0.7 starting... State Changed: init plugins State Changed: start INFO: Start(libssh2-1.2.5-2.0.cf.fc12.src.rpm) Config(city-fan-fedora-11-x86_64) State Changed: lock buildroot State Changed: clean State Changed: init State Changed: lock buildroot Mock Version: 1.0.7 INFO: Mock Version: 1.0.7 INFO: mounting tmpfs. INFO: enabled root cache INFO: enabled yum cache State Changed: cleaning yum metadata INFO: enabled ccache INFO: unmounting tmpfs. ERROR: Exception(libssh2-1.2.5-2.0.cf.fc12.src.rpm) Config(city-fan-fedora-11-x86_64) 0 minutes 0 seconds INFO: Results and/or logs in: /var/lib/mock/city-fan-fedora-11-x86_64/result ERROR: [Errno 2] No such file or directory: '/var/lib/mock/city-fan-fedora-11-x86_64/root/selinux/enforce' Traceback (most recent call last): File "/usr/sbin/mock", line 693, in <module> main(retParams) File "/usr/sbin/mock", line 635, in main do_rebuild(config_opts, chroot, args) File "<peak.util.decorators.rewrap wrapping __main__.do_rebuild at 0x01655230>", line 3, in do_rebuild def do_rebuild(config_opts, chroot, srpms): return __decorated(config_opts, chroot, srpms) File "/usr/lib/python2.6/site-packages/mock/trace_decorator.py", line 70, in trace result = func(*args, **kw) File "/usr/sbin/mock", line 371, in do_rebuild chroot.init() File "<peak.util.decorators.rewrap wrapping mock.backend.init at 0x0164D9B0>", line 3, in init def init(self): return __decorated(self) File "/usr/lib/python2.6/site-packages/mock/trace_decorator.py", line 70, in trace result = func(*args, **kw) File "/usr/lib/python2.6/site-packages/mock/backend.py", line 163, in init self._init() File "<peak.util.decorators.rewrap wrapping mock.backend._init at 0x0164DDE8>", line 3, in _init def _init(self): return __decorated(self) File "/usr/lib/python2.6/site-packages/mock/trace_decorator.py", line 70, in trace result = func(*args, **kw) File "/usr/lib/python2.6/site-packages/mock/backend.py", line 270, in _init fo = open(p, 'w+') IOError: [Errno 2] No such file or directory: '/var/lib/mock/city-fan-fedora-11-x86_64/root/selinux/enforce'

This is because mock doesn't create any missing parent directories for the file. The attached patch addresses this.

Incidentally, what I was doing was:

config_opts['files']['selinux/enforce'] = "0"

This is sufficient to fool libselinux-using applications in the chroot into believing they're running in permissive mode, allowing for instance an OpenSSH server to run on localhost on a high port and accept connections as part of a package's test suite (libssh2 in this case). This might be a useful thing to have by default, but that's a different discussion.

Paul.