varlink,qemu: Use CmdFds API for fd passing #248
Merged
gursewak1997 merged 2 commits intobootc-dev:mainfrom Apr 15, 2026
Merged
varlink,qemu: Use CmdFds API for fd passing #248gursewak1997 merged 2 commits intobootc-dev:mainfrom
gursewak1997 merged 2 commits intobootc-dev:mainfrom
Conversation
The new release adds the CmdFds API for atomic fd passing and systemd socket-activation environment setup. Prep for migrating to that API. Assisted-by: OpenCode (Claude Opus 4) Signed-off-by: Colin Walters <walters@verbum.org>
Replace the deprecated per-fd `take_fd_n()` calls with the new `CmdFds` + `take_fds()` API from cap-std-ext 5.1.2. The new API handles all fd shuffling atomically in a single `pre_exec` hook, avoiding the race where separate hooks can clobber each other when a source fd number equals another mapping's target. For varlink socket activation in integration tests, this is a significant simplification: the entire unsafe `pre_exec` block with manual `libc::setenv` calls for LISTEN_PID/LISTEN_FDS/LISTEN_FDNAMES is replaced by `CmdFds::new_systemd_fds()`, which handles both the fd placement at fd 3 and the environment variable setup. This also drops the `libc` and `rustix` direct dependencies from the integration-tests crate. Assisted-by: OpenCode (Claude Opus 4) Signed-off-by: Colin Walters <walters@verbum.org>
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Code Review
This pull request updates the cap-std-ext dependency to version 5.1.2 and refactors file descriptor handling to utilize the CmdFds API. In bcvk-qemu, manual FD passing is replaced with a CmdFds collection, and in the integration tests, the manual pre_exec logic for systemd socket activation is replaced with CmdFds::new_systemd_fds. A review comment suggests wrapping the take_fds call in a conditional check to prevent the unintended closing of inherited file descriptors when the CmdFds collection is empty.
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