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samba-mirror/lib/tevent/tevent_signal.c
Stefan Metzmacher 504f8816e3 s4:lib/events: move to toplevel directory as lib/tevent/
This commit will not compile on its own.

metze
2008-12-17 13:31:28 +01:00

292 lines
7.5 KiB
C

/*
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 3 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, see <http://www.gnu.org/licenses/>.
*/
#include <signal.h>
#include "replace.h"
#include "system/filesys.h"
#include "system/select.h"
#include "events.h"
#include "events_internal.h"
#include "events_util.h"
#define NUM_SIGNALS 64
/* maximum number of SA_SIGINFO signals to hold in the queue */
#define SA_INFO_QUEUE_COUNT 10
struct sigcounter {
uint32_t count;
uint32_t seen;
};
#define SIG_INCREMENT(s) (s).count++
#define SIG_SEEN(s, n) (s).seen += (n)
#define SIG_PENDING(s) ((s).seen != (s).count)
/*
the poor design of signals means that this table must be static global
*/
static struct sig_state {
struct signal_event *sig_handlers[NUM_SIGNALS+1];
struct sigaction *oldact[NUM_SIGNALS+1];
struct sigcounter signal_count[NUM_SIGNALS+1];
struct sigcounter got_signal;
int pipe_hack[2];
#ifdef SA_SIGINFO
/* with SA_SIGINFO we get quite a lot of info per signal */
siginfo_t *sig_info[NUM_SIGNALS+1];
struct sigcounter sig_blocked[NUM_SIGNALS+1];
#endif
} *sig_state;
/*
return number of sigcounter events not processed yet
*/
static uint32_t sig_count(struct sigcounter s)
{
if (s.count >= s.seen) {
return s.count - s.seen;
}
return 1 + (0xFFFFFFFF & ~(s.seen - s.count));
}
/*
signal handler - redirects to registered signals
*/
static void signal_handler(int signum)
{
char c = 0;
SIG_INCREMENT(sig_state->signal_count[signum]);
SIG_INCREMENT(sig_state->got_signal);
/* doesn't matter if this pipe overflows */
write(sig_state->pipe_hack[1], &c, 1);
}
#ifdef SA_SIGINFO
/*
signal handler with SA_SIGINFO - redirects to registered signals
*/
static void signal_handler_info(int signum, siginfo_t *info, void *uctx)
{
uint32_t count = sig_count(sig_state->signal_count[signum]);
sig_state->sig_info[signum][count] = *info;
signal_handler(signum);
/* handle SA_SIGINFO */
if (count+1 == SA_INFO_QUEUE_COUNT) {
/* we've filled the info array - block this signal until
these ones are delivered */
sigset_t set;
sigemptyset(&set);
sigaddset(&set, signum);
sigprocmask(SIG_BLOCK, &set, NULL);
SIG_INCREMENT(sig_state->sig_blocked[signum]);
}
}
#endif
/*
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) {
/* restore old handler, if any */
sigaction(se->signum, sig_state->oldact[se->signum], NULL);
sig_state->oldact[se->signum] = NULL;
#ifdef SA_SIGINFO
if (se->sa_flags & SA_SIGINFO) {
talloc_free(sig_state->sig_info[se->signum]);
sig_state->sig_info[se->signum] = NULL;
}
#endif
}
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,
int sa_flags,
event_signal_handler_t handler,
void *private_data)
{
struct signal_event *se;
if (signum >= NUM_SIGNALS) {
return NULL;
}
/* the sig_state needs to be on a global context as it can last across
multiple event contexts */
if (sig_state == NULL) {
sig_state = talloc_zero(talloc_autofree_context(), struct sig_state);
if (sig_state == NULL) {
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;
se->sa_flags = sa_flags;
/* Ensure, no matter the destruction order, that we always have a handle on the global sig_state */
if (!talloc_reference(se, sig_state)) {
return NULL;
}
/* only install a signal handler if not already installed */
if (sig_state->sig_handlers[signum] == NULL) {
struct sigaction act;
ZERO_STRUCT(act);
act.sa_handler = signal_handler;
act.sa_flags = sa_flags;
#ifdef SA_SIGINFO
if (sa_flags & SA_SIGINFO) {
act.sa_handler = NULL;
act.sa_sigaction = signal_handler_info;
if (sig_state->sig_info[signum] == NULL) {
sig_state->sig_info[signum] = talloc_array(sig_state, siginfo_t, SA_INFO_QUEUE_COUNT);
if (sig_state->sig_info[signum] == NULL) {
talloc_free(se);
return NULL;
}
}
}
#endif
sig_state->oldact[signum] = talloc(sig_state, struct sigaction);
if (sig_state->oldact[signum] == NULL) {
talloc_free(se);
return NULL;
}
if (sigaction(signum, &act, sig_state->oldact[signum]) == -1) {
talloc_free(se);
return NULL;
}
}
DLIST_ADD(sig_state->sig_handlers[signum], se);
talloc_set_destructor(se, signal_event_destructor);
/* we need to setup the pipe hack handler if not already
setup */
if (ev->pipe_fde == NULL) {
if (sig_state->pipe_hack[0] == 0 &&
sig_state->pipe_hack[1] == 0) {
pipe(sig_state->pipe_hack);
ev_set_blocking(sig_state->pipe_hack[0], false);
ev_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 || !SIG_PENDING(sig_state->got_signal)) {
return 0;
}
for (i=0;i<NUM_SIGNALS+1;i++) {
struct signal_event *se, *next;
struct sigcounter counter = sig_state->signal_count[i];
uint32_t count = sig_count(counter);
if (count == 0) {
continue;
}
for (se=sig_state->sig_handlers[i];se;se=next) {
next = se->next;
#ifdef SA_SIGINFO
if (se->sa_flags & SA_SIGINFO) {
int j;
for (j=0;j<count;j++) {
/* note the use of the sig_info array as a
ring buffer */
int ofs = ((count-1) + j) % SA_INFO_QUEUE_COUNT;
se->handler(ev, se, i, 1,
(void*)&sig_state->sig_info[i][ofs],
se->private_data);
}
if (SIG_PENDING(sig_state->sig_blocked[i])) {
/* we'd filled the queue, unblock the
signal now */
sigset_t set;
sigemptyset(&set);
sigaddset(&set, i);
SIG_SEEN(sig_state->sig_blocked[i],
sig_count(sig_state->sig_blocked[i]));
sigprocmask(SIG_UNBLOCK, &set, NULL);
}
if (se->sa_flags & SA_RESETHAND) {
talloc_free(se);
}
continue;
}
#endif
se->handler(ev, se, i, count, NULL, se->private_data);
if (se->sa_flags & SA_RESETHAND) {
talloc_free(se);
}
}
SIG_SEEN(sig_state->signal_count[i], count);
SIG_SEEN(sig_state->got_signal, count);
}
return 1;
}