lib, ospfclient, vtysh: Allow for a minimum fd poll size

There exists cases where just honoring the FD_LIMIT size
as given to us by the operating system makes no sense.
Let's just make a switch to allow for this for things
like vtysh and ospfclient which will never have 1k files
open at any given time.

Fixes: #15315
Signed-off-by: Donald Sharp <[email protected]>

lib/event.c

@@ -544,7 +544,8 @@ static void initializer(void)
 }
 
 #define STUPIDLY_LARGE_FD_SIZE 100000
-struct event_loop *event_master_create(const char *name)
+#define FD_LIMIT_SIZE_FOR_VTYSH 1000
+struct event_loop *event_master_create(const char *name, bool limit_fds)
 {
 	struct event_loop *rv;
 	struct rlimit limit;
@@ -570,6 +571,9 @@ struct event_loop *event_master_create(const char *name)
 		rv->fd_limit = (int)limit.rlim_cur;
 	}
 
+	if (limit_fds)
+		rv->fd_limit = MIN(FD_LIMIT_SIZE_FOR_VTYSH, rv->fd_limit);
+
 	if (rv->fd_limit > STUPIDLY_LARGE_FD_SIZE)
 		zlog_warn("FD Limit set: %u is stupidly large.  Is this what you intended?  Consider using --limit-fds",
 			  rv->fd_limit);

lib/frr_pthread.c

@@ -78,7 +78,7 @@ struct frr_pthread *frr_pthread_new(const struct frr_pthread_attr *attr,
 	/* initialize mutex */
 	pthread_mutex_init(&fpt->mtx, NULL);
 	/* create new thread master */
-	fpt->master = event_master_create(name);
+	fpt->master = event_master_create(name, false);
 	/* set attributes */
 	fpt->attr = *attr;
 	name = (name ? name : "Anonymous thread");

lib/frrevent.h

@@ -223,7 +223,15 @@ static inline unsigned long timeval_elapsed(struct timeval a, struct timeval b)
 	}) /* end */
 
 /* Prototypes. */
-extern struct event_loop *event_master_create(const char *name);
+
+/*
+ * event_master_create
+ * inputs:
+ * name - The name of the event system that is being created
+ * limit_fds - Ignore the systems built in limit and use 1000 or
+ *             the actual value which ever is lesser
+ */
+extern struct event_loop *event_master_create(const char *name, bool limit_fds);
 void event_master_set_name(struct event_loop *master, const char *name);
 extern void event_master_free(struct event_loop *m);
 extern void event_master_free_unused(struct event_loop *m);

lib/grammar_sandbox_main.c

@@ -29,7 +29,7 @@ int main(int argc, char **argv)
 {
 	struct event event;
 
-	master = event_master_create(NULL);
+	master = event_master_create(NULL, true);
 
 	zlog_aux_init("NONE: ", LOG_DEBUG);
 

lib/libfrr.c

@@ -776,7 +776,7 @@ struct event_loop *frr_init(void)
 
 	zprivs_init(di->privs);
 
-	master = event_master_create(NULL);
+	master = event_master_create(NULL, false);
 	signal_init(master, di->n_signals, di->signals);
 	hook_call(frr_early_init, master);
 

ospfclient/ospfclient.c

@@ -293,7 +293,7 @@ int main(int argc, char *argv[])
 	/* Initialization */
 	zprivs_preinit(&ospfd_privs);
 	zprivs_init(&ospfd_privs);
-	master = event_master_create(NULL);
+	master = event_master_create(NULL, true);
 
 	/* Open connection to OSPF daemon */
 	oclient = ospf_apiclient_connect(args[1], ASYNCPORT);

vtysh/vtysh_main.c

@@ -236,7 +236,7 @@ static void vtysh_rl_run(void)
 	struct event thread;
 	bool suppress_warnings = true;
 
-	master = event_master_create(NULL);
+	master = event_master_create(NULL, true);
 
 	rl_callback_handler_install(vtysh_prompt(), vtysh_rl_callback);
 	event_add_read(master, vtysh_rl_read, &suppress_warnings, STDIN_FILENO,