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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- */
/* Sysprof -- Sampling, systemwide CPU profiler
* Copyright (C) 2005 Søren Sandmann (sandmann@daimi.au.dk)
*
* This library 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 library 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 library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <signal.h>
#include <unistd.h>
#include <string.h>
#include "libnul.h"
typedef struct signal_watch_t signal_watch_t;
struct signal_watch_t
{
int signo;
signal_func_t handler;
gpointer user_data;
struct sigaction old_action;
signal_watch_t * next;
};
static int read_end = -1;
static int write_end = -1;
static signal_watch_t *signal_watch_tes = NULL;
static signal_watch_t *
lookup_signal_watch_t (int signo)
{
signal_watch_t *w;
for (w = signal_watch_tes; w != NULL; w = w->next)
{
if (w->signo == signo)
return w;
}
return NULL;
}
static void
remove_signal_watch_t (signal_watch_t *watch)
{
signal_watch_t *prev, *w;
g_return_if_fail (watch != NULL);
prev = NULL;
for (w = signal_watch_tes; w != NULL; w = w->next)
{
if (w == watch)
{
if (prev)
prev->next = w->next;
else
signal_watch_tes = w->next;
break;
}
prev = w;
}
}
static void
signal_handler (int signo,
siginfo_t *info,
void *data)
{
/* FIXME: I suppose we should handle short
* and non-successful writes ...
*
* And also, there is a deadlock if so many signals arrive that
* write() blocks. Then we will be stuck right here, and the
* main loop will never run. Kinda hard to fix without dropping
* signals ...
*
*/
write (write_end, &signo, sizeof (int));
}
static void
on_read (gpointer data)
{
signal_watch_t *watch;
int signo;
/* FIXME: handle short read I suppose */
read (read_end, &signo, sizeof (int));
watch = lookup_signal_watch_t (signo);
if (watch)
watch->handler (signo, watch->user_data);
}
static gboolean
create_pipe (int *read_end,
int *write_end,
GError **err)
{
int p[2];
if (pipe (p) < 0)
{
/* FIXME - create an error */
return FALSE;
}
/* FIXME: We should probably make the fd's non-blocking */
if (read_end)
*read_end = p[0];
if (write_end)
*write_end = p[1];
return TRUE;
}
static gboolean
install_signal_handler (int signo,
struct sigaction *old_action,
GError **err)
{
struct sigaction action;
memset (&action, 0, sizeof (action));
action.sa_sigaction = signal_handler;
sigemptyset (&action.sa_mask);
action.sa_flags = SA_SIGINFO;
if (sigaction (signo, &action, old_action) < 0)
{
/* FIXME - create an error */
return TRUE;
}
return TRUE;
}
static void
signal_watch_free (signal_watch_t *watch)
{
remove_signal_watch_t (watch);
g_free (watch);
}
gboolean
nul_signal_set_handler (int signo,
signal_func_t handler,
gpointer data,
GError **err)
{
signal_watch_t *watch;
g_return_val_if_fail (handler == NULL ||
lookup_signal_watch_t (signo) == NULL, FALSE);
if (handler == NULL)
{
watch = lookup_signal_watch_t (signo);
if (watch)
{
/* FIXME: error */
sigaction (signo, &watch->old_action, NULL);
signal_watch_free (watch);
}
return TRUE;
}
else
{
if (read_end == -1)
{
if (!create_pipe (&read_end, &write_end, err))
return FALSE;
nul_fd_add_watch (read_end, NULL);
nul_fd_set_read_callback (read_end, on_read);
}
watch = g_new0 (signal_watch_t, 1);
watch->signo = signo;
watch->handler = handler;
watch->user_data = data;
watch->next = signal_watch_tes;
signal_watch_tes = watch;
if (!install_signal_handler (signo, &watch->old_action, err))
{
signal_watch_free (watch);
return FALSE;
}
return TRUE;
}
}
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