Revisione completa (e relativa razionalizzazione) dei sorgenti degli esempi.

[gapil.git] / sources / SigHand.c

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+/*****************************************************************************
+ *
+ * File SigHand.c: define a set of functions for signal manipulation 
+ *
+ * Author: S. Piccardi Dec. 2002
+ *
+ * $Id: SigHand.c,v 1.1 2002/12/03 11:06:05 piccardi Exp $
+ *
+ *****************************************************************************/
+#include <errno.h>                               /* error simbol definitions */
+#include <stdio.h>                                 /* standard I/O functions */
+#include <signal.h>                          /* signal handling declarations */
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "Gapil.h"
+#include "macros.h"
+
+/*
+ * Function Signal
+ * Initialize a signal handler.
+ * To enable the signal handling a process we need to tell it to
+ * kernel; this is done writing all needed info to a sigaction structure
+ * named sigact, and then callind sigaction() system call passing the
+ * information stored in the sigact structure variable.
+ *
+ * Input:  the signal to handle 
+ *         the signal handler function
+ * Return: the previous sigaction structure
+ */
+inline SigFunc * Signal(int signo, SigFunc *func) 
+{
+    struct sigaction new_handl, old_handl;
+    new_handl.sa_handler=func;
+    /* clear signal mask: no signal blocked during execution of func */
+    if (sigemptyset(&new_handl.sa_mask)!=0){        /* initialize signal set */
+        perror("cannot initializes the signal set to empty");   /* see mess. */
+        exit(1);
+    }
+    new_handl.sa_flags=0;                  /* init to 0 all flags */
+    /* change action for signo signal */
+    if (sigaction(signo,&new_handl,&old_handl)){ 
+        perror("sigaction failed on signal action setting");
+       exit(1);
+    }
+    return (old_handl.sa_handler);
+}
+/* 
+ * Functions: HandSigCHLD
+ * Generic handler for SIGCHLD signal
+ * 
+ * Simone Piccardi Dec. 2002
+ * $Id: SigHand.c,v 1.1 2002/12/03 11:06:05 piccardi Exp $
+ */
+void HandSigCHLD(int sig)
+{
+    int errno_save;
+    int status;
+    pid_t pid;
+    /* save errno current value */
+    errno_save = errno;
+    /* loop until no */
+    do {
+       errno = 0;
+       pid = waitpid(WAIT_ANY, &status, WNOHANG);
+       if (pid > 0) {
+           debug("child %d terminated with status %x\n", pid, status);
+       }
+    } while ((pid > 0) && (errno == EINTR));
+    /* restore errno value*/
+    errno = errno_save;
+    /* return */
+    return;
+}