uxc: take provision entries from settings

2026-10-18T11:25:50Z

Files can be bound into a container only through the provision list of its registration, which the package or the stack writes, so an operator cannot hand a container a configuration file or a key of its own. Add a provision key to the settings file and uxc set --provision :[:secret]. uxc copies the file into the provision directory next to the registration, /etc/uxc/provision// for a container registered there and /tmp/run/uvol/.meta/provision// for one on the uvol metadata volume, the handover directory between uxc and ujail, under a name derived from the destination, and the entry names that copy as its source, so no host path from outside ever reaches ujail. The copy is staged before the settings are written and moved into place once they are, and it is dropped if they are not. Destinations must be normalised absolute paths, and the registration stays authoritative: a destination it provisions, or /etc/hosts when it sets a hosts file, is refused with EEXIST, and an entry shadowed by a later registration is skipped at create and marked in uxc state. Unsetting an entry removes its copy, and uxc delete and uxc reconcile remove the directory of an unregistered container. Signed-off-by: Daniel Golle

jail, uxc: share the atomic file writer

2026-10-18T10:25:00Z

jail_write_exit_status() writes the payload status to a fixed exit_status.tmp sibling of the pid file and renames it into place, and the uxc settings store is about to need the same write-then-rename sequence for files of its own. A fixed temporary name lets two writers of one path truncate each other's work, and a second copy of the sequence in uxc.c would drift from the first. Add state-file.h with file_write_atomic(), which creates a unique temporary file beside the target with mkstemp(), applies the requested mode with fchmod(), writes the whole buffer, closes it and renames it over the target, unlinking the temporary file and returning -errno on any failure. jail_write_exit_status() keeps its path and status formatting and hands the write to the helper; uxc.c includes the header for the settings writers that follow. Signed-off-by: Daniel Golle

procd/state-file.h, branch master

uxc: take provision entries from settings

jail, uxc: share the atomic file writer