3 Commits

Author	SHA1	Message	Date
Ralph Boehme	6c36ea0737	lib/util: only close the event_fd in tfork if the caller didn't call tfork_event_fd() ... Make closing of the event_fd the global responsibility of the parent process if it called tfork_event_fd(). Bug: https://bugzilla.samba.org/show_bug.cgi?id=13037 Signed-off-by: Ralph Boehme <slow@samba.org> Reviewed-by: Gary Lockyer <gary@catalyst.net.nz> Reviewed-by: Stefan Metzmacher <metze@samba.org>	2017-09-16 19:53:23 +02:00
Ralph Boehme	844db65498	lib/util: enhanced tfork() ... This function is a solution to the problem of fork() requiring special preperations in the caller to handle SIGCHLD signals and to reap the child by wait()ing for it. Instead, tfork provides a pollable file descriptor. The caller gets the file descriptor by calling tfork_event_fd() on the handle returned from tfork_create() and the caller can then get the status of the child with a call to tfork_status(). tfork avoids raising SIGCHLD signals in the caller by installing a temporary SIGCHLD handler from inside tfork_create() and tfork_status(). The termination signal of other child processes not created with tfork() is forwarded to the existing signal handler if any. There's one thing this thing can't protect us against and that is if a process installs a SIGCHLD handler from one thread while another thread is running inside tfork_create() or tfork_status() and the signal handler doesn't forward signals for exitted childs it didn't fork, ie our childs. Pair-Programmed-With: Stefan Metzmacher <metze@samba.org> Signed-off-by: Ralph Boehme <slow@samba.org> Signed-off-by: Stefan Metzmacher <metze@samba.org>	2017-07-03 19:59:07 +02:00
Stefan Metzmacher	6b950ae37e	lib/util: add tfork() ... triple-fork to avoid handling SIGCHLD in the parent. This function is a workaround for the problem of using fork() in library code. In that case the library should avoid setting a global signal handler for SIGCHLD, because the application may wants to use its own handler. status_fd can be used to wait for the child to exit and get its exit status. Signed-off-by: Ralph Boehme <slow@samba.org> Reviewed-by: Jeremy Allison <jra@samba.org>	2017-04-20 16:53:16 +02:00