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79 lines
1.9 KiB
C
79 lines
1.9 KiB
C
/* Using kill for Communication
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Copyright (C) 1991-2016 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, if not, see <http://www.gnu.org/licenses/>.
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*/
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/*@group*/
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#include <signal.h>
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#include <stdio.h>
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#include <sys/types.h>
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#include <unistd.h>
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/*@end group*/
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/* When a @code{SIGUSR1} signal arrives, set this variable. */
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volatile sig_atomic_t usr_interrupt = 0;
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void
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synch_signal (int sig)
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{
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usr_interrupt = 1;
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}
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/* The child process executes this function. */
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void
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child_function (void)
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{
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/* Perform initialization. */
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printf ("I'm here!!! My pid is %d.\n", (int) getpid ());
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/* Let parent know you're done. */
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kill (getppid (), SIGUSR1);
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/* Continue with execution. */
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puts ("Bye, now....");
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exit (0);
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}
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int
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main (void)
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{
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struct sigaction usr_action;
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sigset_t block_mask;
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pid_t child_id;
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/* Establish the signal handler. */
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sigfillset (&block_mask);
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usr_action.sa_handler = synch_signal;
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usr_action.sa_mask = block_mask;
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usr_action.sa_flags = 0;
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sigaction (SIGUSR1, &usr_action, NULL);
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/* Create the child process. */
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child_id = fork ();
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if (child_id == 0)
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child_function (); /* Does not return. */
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/*@group*/
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/* Busy wait for the child to send a signal. */
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while (!usr_interrupt)
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;
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/*@end group*/
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/* Now continue execution. */
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puts ("That's all, folks!");
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return 0;
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}
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