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/*
Unix SMB/CIFS implementation.
common events code for signal events
Copyright (C) Andrew Tridgell 2007
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
#include "system/filesys.h"
#include "system/select.h"
#include "lib/util/dlinklist.h"
#include "lib/events/events.h"
#include "lib/events/events_internal.h"
#define NUM_SIGNALS 64
/*
the poor design of signals means that this table must be static global
*/
static struct {
struct signal_event *sig_handlers[NUM_SIGNALS];
uint32_t signal_count[NUM_SIGNALS];
uint32_t got_signal;
int pipe_hack[2];
} sig_state;
/*
signal handler - redirects to registered signals
*/
static void signal_handler(int signum)
{
char c = 0;
sig_state.signal_count[signum]++;
sig_state.got_signal++;
/* doesn't matter if this pipe overflows */
write(sig_state.pipe_hack[1], &c, 1);
}
/*
destroy a signal event
*/
static int signal_event_destructor(struct signal_event *se)
{
se->event_ctx->num_signal_handlers--;
DLIST_REMOVE(sig_state.sig_handlers[se->signum], se);
if (sig_state.sig_handlers[se->signum] == NULL) {
signal(se->signum, SIG_DFL);
}
return 0;
}
/*
this is part of the pipe hack needed to avoid the signal race condition
*/
static void signal_pipe_handler(struct event_context *ev, struct fd_event *fde,
uint16_t flags, void *private)
{
char c[16];
/* its non-blocking, doesn't matter if we read too much */
read(sig_state.pipe_hack[0], c, sizeof(c));
}
/*
add a signal event
return NULL on failure (memory allocation error)
*/
struct signal_event *common_event_add_signal(struct event_context *ev,
TALLOC_CTX *mem_ctx,
int signum,
event_signal_handler_t handler,
void *private_data)
{
struct signal_event *se;
if (signum >= NUM_SIGNALS) {
return NULL;
}
se = talloc(mem_ctx?mem_ctx:ev, struct signal_event);
if (se == NULL) return NULL;
se->event_ctx = ev;
se->handler = handler;
se->private_data = private_data;
se->signum = signum;
if (sig_state.sig_handlers[signum] == NULL) {
signal(signum, signal_handler);
}
DLIST_ADD(sig_state.sig_handlers[signum], se);
talloc_set_destructor(se, signal_event_destructor);
if (ev->pipe_fde == NULL) {
if (sig_state.pipe_hack[0] == 0 &&
sig_state.pipe_hack[1] == 0) {
pipe(sig_state.pipe_hack);
set_blocking(sig_state.pipe_hack[0], False);
set_blocking(sig_state.pipe_hack[1], False);
}
ev->pipe_fde = event_add_fd(ev, ev, sig_state.pipe_hack[0],
EVENT_FD_READ, signal_pipe_handler, NULL);
}
ev->num_signal_handlers++;
return se;
}
/*
check if a signal is pending
return != 0 if a signal was pending
*/
int common_event_check_signal(struct event_context *ev)
{
int i;
if (sig_state.got_signal == 0) {
return 0;
}
for (i=0;i<NUM_SIGNALS+1;i++) {
uint32_t count = sig_state.signal_count[i];
if (count != 0) {
struct signal_event *se, *next;
for (se=sig_state.sig_handlers[i];se;se=next) {
next = se->next;
se->handler(ev, se, i, count, se->private_data);
}
sig_state.signal_count[i] -= count;
sig_state.got_signal -= count;
}
}
return 1;
}
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