mirror of
https://sourceware.org/git/glibc.git
synced 2025-10-30 10:45:40 +03:00
688903eb3e
* All files with FSF copyright notices: Update copyright dates using scripts/update-copyrights. * locale/programs/charmap-kw.h: Regenerated. * locale/programs/locfile-kw.h: Likewise.
117 lines
3.1 KiB
C
117 lines
3.1 KiB
C
/* Complete Context Control
|
|
Copyright (C) 1991-2018 Free Software Foundation, Inc.
|
|
|
|
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, if not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <signal.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <ucontext.h>
|
|
#include <sys/time.h>
|
|
|
|
/* Set by the signal handler. */
|
|
static volatile int expired;
|
|
|
|
/* The contexts. */
|
|
static ucontext_t uc[3];
|
|
|
|
/* We do only a certain number of switches. */
|
|
static int switches;
|
|
|
|
|
|
/* This is the function doing the work. It is just a
|
|
skeleton, real code has to be filled in. */
|
|
static void
|
|
f (int n)
|
|
{
|
|
int m = 0;
|
|
while (1)
|
|
{
|
|
/* This is where the work would be done. */
|
|
if (++m % 100 == 0)
|
|
{
|
|
putchar ('.');
|
|
fflush (stdout);
|
|
}
|
|
|
|
/* Regularly the @var{expire} variable must be checked. */
|
|
if (expired)
|
|
{
|
|
/* We do not want the program to run forever. */
|
|
if (++switches == 20)
|
|
return;
|
|
|
|
printf ("\nswitching from %d to %d\n", n, 3 - n);
|
|
expired = 0;
|
|
/* Switch to the other context, saving the current one. */
|
|
swapcontext (&uc[n], &uc[3 - n]);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* This is the signal handler which simply set the variable. */
|
|
void
|
|
handler (int signal)
|
|
{
|
|
expired = 1;
|
|
}
|
|
|
|
|
|
int
|
|
main (void)
|
|
{
|
|
struct sigaction sa;
|
|
struct itimerval it;
|
|
char st1[8192];
|
|
char st2[8192];
|
|
|
|
/* Initialize the data structures for the interval timer. */
|
|
sa.sa_flags = SA_RESTART;
|
|
sigfillset (&sa.sa_mask);
|
|
sa.sa_handler = handler;
|
|
it.it_interval.tv_sec = 0;
|
|
it.it_interval.tv_usec = 1;
|
|
it.it_value = it.it_interval;
|
|
|
|
/* Install the timer and get the context we can manipulate. */
|
|
if (sigaction (SIGPROF, &sa, NULL) < 0
|
|
|| setitimer (ITIMER_PROF, &it, NULL) < 0
|
|
|| getcontext (&uc[1]) == -1
|
|
|| getcontext (&uc[2]) == -1)
|
|
abort ();
|
|
|
|
/* Create a context with a separate stack which causes the
|
|
function @code{f} to be call with the parameter @code{1}.
|
|
Note that the @code{uc_link} points to the main context
|
|
which will cause the program to terminate once the function
|
|
return. */
|
|
uc[1].uc_link = &uc[0];
|
|
uc[1].uc_stack.ss_sp = st1;
|
|
uc[1].uc_stack.ss_size = sizeof st1;
|
|
makecontext (&uc[1], (void (*) (void)) f, 1, 1);
|
|
|
|
/* Similarly, but @code{2} is passed as the parameter to @code{f}. */
|
|
uc[2].uc_link = &uc[0];
|
|
uc[2].uc_stack.ss_sp = st2;
|
|
uc[2].uc_stack.ss_size = sizeof st2;
|
|
makecontext (&uc[2], (void (*) (void)) f, 1, 2);
|
|
|
|
/* Start running. */
|
|
swapcontext (&uc[0], &uc[1]);
|
|
putchar ('\n');
|
|
|
|
return 0;
|
|
}
|