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[gapil.git] / sources / SigHand.c

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+/* SigHand.c
+ * 
+ * Copyright (C) 2002 Simone Piccardi
+ * 
+ * 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, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+/*****************************************************************************
+ *
+ * File SigHand.c: define a set of functions for signal manipulation 
+ *
+ * Author: S. Piccardi Dec. 2002
+ *
+ * $Id: SigHand.c,v 1.5 2003/05/02 09:55:14 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;                      /* set signal handler */
+    /* clear signal mask: no signal blocked during execution of func */
+    if (sigemptyset(&new_handl.sa_mask)!=0){       /* initialize signal set */
+        return SIG_ERR;
+    }
+    new_handl.sa_flags=0;                            /* init to 0 all flags */
+    /* change action for signo signal */
+    if (sigaction(signo,&new_handl,&old_handl)){ 
+        return SIG_ERR;
+    }
+    return (old_handl.sa_handler);
+}
+/* 
+ * Functions: HandSigCHLD
+ * Generic handler for SIGCHLD signal
+ * 
+ * Simone Piccardi Dec. 2002
+ * $Id: SigHand.c,v 1.5 2003/05/02 09:55:14 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;
+}