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2023-01-20start-stop-daemon, supervise-daemon: use closefrom()/close_range()Matt Whitlock
On systems with a very large RLIMIT_NOFILE, calling close() in a loop from 3 to getdtablesize() effects an enormous number of system calls. There are better alternatives. Both BSD and Linux have the closefrom() system call that closes all file descriptors with indices not less than a specified minimum. Have start-stop-daemon call closefrom() on systems where it's implemented, falling back to the old loop elsewhere. Likewise, calling fcntl(i, F_SETFD, FD_CLOEXEC) in a loop from 3 to getdtablesize() raises a similar performance concern. Linux 5.11 and onward has a close_range() system call with a CLOSE_RANGE_CLOEXEC flag that sets the FD_CLOEXEC flag on all file descriptors in a specified range. Have supervise-daemon utilize this feature on systems where it's implemented, falling back to the old loop elsewhere.
2022-09-06start-stop-daemon, supervise-daemon: set autogroup nicelevelMatt Whitlock
As described in "Why nice levels are a placebo and have been for a very long time, and no one seems to have noticed"[1], the Linux kernel in its default configuration on many Linux distributions autogroups tasks by session ID and "fairly" allocates CPU time among such autogroups. The nice levels of tasks within each autogroup are only relative to other tasks within the same autogroup. Effectively, this means that the traditional nice level is rendered moot for tools like start-stop-daemon and supervise-daemon, which start each daemon in its own session and thus in its own autogroup. Linux does provide a means to change the niceness of autogroups relative to each other, so let's have start-stop- daemon and supervise-daemon make use of this feature where available so that -N,--nicelevel/SSD_NICELEVEL will actually do what the user intends. On systems where autogroups are not supported or are disabled, this commit introduces no change in behavior. Note that the setsid() call in the child process of start-stop-daemon is moved to much earlier. This is necessary so that the new process will be assigned to a new autogroup before the autogroup nicelevel is set. To avoid inadvertently acquiring /dev/tty as the controlling terminal of the new session after setsid() has given up the controlling terminal inherited from the parent process, tty_fd is opened before the call to setsid(). [1] https://www.reddit.com/r/linux/comments/d7hx2c/why_nice_levels_are_a_placebo_and_have_been_for_a/ This fixes #542.
2022-05-08supervise-daemon: fix -WshadowSam James
Signed-off-by: Sam James <sam@gentoo.org>
2022-04-30multiple spelling and typo fixesJosh Soref
This fixes #516.
2022-04-06migrate fully to meson build systemWilliam Hubbs
- drop old build system - move shared include and source files to common directory - drop "rc-" prefix from shared include and source files - move executable-specific code to individual directories under src - adjust top-level .gitignore file for new build system This closes #489.