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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /manual/examples/sigusr.c
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initial import
Diffstat (limited to 'manual/examples/sigusr.c')
-rw-r--r--manual/examples/sigusr.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/manual/examples/sigusr.c b/manual/examples/sigusr.c
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--- /dev/null
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@@ -0,0 +1,61 @@
+/*@group*/
+#include <signal.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <unistd.h>
+/*@end group*/
+
+/* When a @code{SIGUSR1} signal arrives, set this variable. */
+volatile sig_atomic_t usr_interrupt = 0;
+
+void
+synch_signal (int sig)
+{
+ usr_interrupt = 1;
+}
+
+/* The child process executes this function. */
+void
+child_function (void)
+{
+ /* Perform initialization. */
+ printf ("I'm here!!! My pid is %d.\n", (int) getpid ());
+
+ /* Let parent know you're done. */
+ kill (getppid (), SIGUSR1);
+
+ /* Continue with execution. */
+ puts ("Bye, now....");
+ exit (0);
+}
+
+int
+main (void)
+{
+ struct sigaction usr_action;
+ sigset_t block_mask;
+ pid_t child_id;
+
+ /* Establish the signal handler. */
+ sigfillset (&block_mask);
+ usr_action.sa_handler = synch_signal;
+ usr_action.sa_mask = block_mask;
+ usr_action.sa_flags = 0;
+ sigaction (SIGUSR1, &usr_action, NULL);
+
+ /* Create the child process. */
+ child_id = fork ();
+ if (child_id == 0)
+ child_function (); /* Does not return. */
+
+/*@group*/
+ /* Busy wait for the child to send a signal. */
+ while (!usr_interrupt)
+ ;
+/*@end group*/
+
+ /* Now continue execution. */
+ puts ("That's all, folks!");
+
+ return 0;
+}