From: Johannes Sixt Date: Sat, 30 Jul 2016 09:50:12 GMT Subject: Re: [PATCH v3 06/10] run-command: add clean_on_exit_handler Message-ID: In-Reply-To: <20160729233801.82844-7-larsxschneider@gmail.com> Am 30.07.2016 um 01:37 schrieb larsxschneider@gmail.com: > Some commands might need to perform cleanup tasks on exit. Let's give > them an interface for doing this. > > Signed-off-by: Lars Schneider > --- > run-command.c | 12 ++++++++---- > run-command.h | 1 + > 2 files changed, 9 insertions(+), 4 deletions(-) > > diff --git a/run-command.c b/run-command.c > index 33bc63a..197b534 100644 > --- a/run-command.c > +++ b/run-command.c > @@ -21,6 +21,7 @@ void child_process_clear(struct child_process *child) > > struct child_to_clean { > pid_t pid; > + void (*clean_on_exit_handler)(pid_t); > struct child_to_clean *next; > }; > static struct child_to_clean *children_to_clean; > @@ -30,6 +31,8 @@ static void cleanup_children(int sig, int in_signal) > { > while (children_to_clean) { > struct child_to_clean *p = children_to_clean; > + if (p->clean_on_exit_handler) > + p->clean_on_exit_handler(p->pid); This summons demons. cleanup_children() is invoked from a signal handler. In this case, it can call only async-signal-safe functions. It does not look like the handler that you are going to install later will take note of this caveat! > children_to_clean = p->next; > kill(p->pid, sig); > if (!in_signal) The condition that we see here in the context protects free(p) (which is not async-signal-safe). Perhaps the invocation of the new callback should be skipped in the same manner when this is called from a signal handler? 507d7804 (pager: don't use unsafe functions in signal handlers) may be worth a look. -- Hannes