X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=signal.c;h=0b7b47fa3d1401d57ae11ed107f487e9036a2870;hp=78e788d19021111b2f8ec712eb1ff8f0fd176375;hb=e5fbc490c2c16ecfa7bce58a18e11a0f7d382b91;hpb=ebb0565e946770c5b83c4d28c1f674dffdeaf551

diff --git a/signal.c b/signal.c
index 78e788d1..0b7b47fa 100644
--- a/signal.c
+++ b/signal.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2004-2008 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2004-2012 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
@@ -7,7 +7,6 @@
 
 #include <signal.h>
 #include <sys/types.h>
-#include <dirent.h>
 
 #include "para.h"
 #include "error.h"
@@ -57,8 +56,15 @@ err_out:
  */
 static void generic_signal_handler(int s)
 {
-	write(signal_pipe[1], &s, sizeof(int));
-	//fprintf(stderr, "got sig %i, write returned %d\n", s, ret);
+	ssize_t ret = write(signal_pipe[1], &s, sizeof(int));
+
+	if (ret == sizeof(int))
+		return;
+	if (ret < 0)
+		PARA_EMERG_LOG("%s\n", strerror(errno));
+	else
+		PARA_EMERG_LOG("short write to signal pipe\n");
+	exit(EXIT_FAILURE);
 }
 
 /**
@@ -73,7 +79,7 @@ static void generic_signal_handler(int s)
  * one otherwise. If and only if the function returns one, the content of \a
  * pid is meaningful.
  *
- * \sa waitpid(2)
+ * \sa waitpid(2).
  */
 int para_reap_child(pid_t *pid)
 {
@@ -96,57 +102,118 @@ int para_reap_child(pid_t *pid)
 }
 
 /**
- * Paraslash's zombie killer.
+ * Install the given handler for the given signal.
  *
- * It just calls \p para_reap_child() until there are no more children left to
- * reap.
+ * \param sig The number of the signal to catch.
+ * \param handler to be installed, \p SIG_IGN, or \p SIG_DFL.
+ *
+ * This either succeeds or calls exit(EXIT_FAILURE).
+ *
+ * \sa sigaction(2).
  */
-void para_reap_children(void)
+void para_sigaction(int sig, void (*handler)(int))
 {
-	pid_t pid;
+	struct sigaction act;
 
-	while (para_reap_child(&pid) > 0)
-		; /* nothing */
+	PARA_DEBUG_LOG("catching signal %d\n", sig);
+	act.sa_handler = handler;
+	sigemptyset(&act.sa_mask);
+	act.sa_flags = 0;
+	if (sig == SIGALRM) {
+		#ifdef SA_INTERRUPT /* SunOS */
+			act.sa_flags |= SA_INTERRUPT;
+		#endif
+	} else {
+		#ifdef SA_RESTART /* BSD */
+			act.sa_flags |= SA_RESTART;
+		#endif
+	}
+	if (sigaction(sig, &act, NULL) >= 0)
+		return;
+	PARA_EMERG_LOG("failed to install signal handler for signal %d\n",
+		sig);
+	exit(EXIT_FAILURE);
 }
 
 /**
- * wrapper around signal(2)
- * \param sig the number of the signal to catch
+ * Install the generic signal handler for the given signal number.
+ *
+ * \param sig The number of the signal to catch.
  *
- * This installs the generic signal handler for the given signal.
- * \return This function returns 1 on success and \p -E_SIGNAL_SIG_ERR on errors.
- * \sa signal(2)
+ * \sa signal(2), sigaction(2).
  */
-int para_install_sighandler(int sig)
+void para_install_sighandler(int sig)
 {
-	PARA_DEBUG_LOG("catching signal %d\n", sig);
-	return signal(sig, &generic_signal_handler) == SIG_ERR?  -E_SIGNAL_SIG_ERR : 1;
+	para_sigaction(sig, &generic_signal_handler);
+}
+
+/**
+ * Block a signal for the caller.
+ *
+ * \param sig The signal to block.
+ *
+ * This sets the given signal in the current signal mask of the calling process
+ * to prevent this signal from delivery.
+ *
+ * \sa \ref para_unblock_signal(), sigprocmask(2), sigaddset(3).
+ */
+void para_block_signal(int sig)
+{
+	sigset_t set;
+
+	PARA_DEBUG_LOG("blocking signal %d\n", sig);
+	sigemptyset(&set);
+	sigaddset(&set, sig);
+	sigprocmask(SIG_BLOCK, &set, NULL);
 }
 
 /**
- * return number of next pending signal
+ * Unblock a signal.
+ *
+ * \param sig The signal to unblock.
  *
- * This should be called if the fd for the signal pipe is ready for reading.
+ * This function removes the given signal from the current set of blocked
+ * signals.
  *
- * \return On success, the number of the received signal is returned. \p
- * -E_SIGNAL_READ is returned if a read error occurred while reading the signal
- * pipe.  If the read was interrupted by another signal the function returns 0.
+ * \sa \ref para_block_signal(), sigprocmask(2), sigaddset(3).
  */
-int para_next_signal(void)
+void para_unblock_signal(int sig)
 {
-	int s;
-	ssize_t r;
+	sigset_t set;
+
+	PARA_DEBUG_LOG("unblocking signal %d\n", sig);
+	sigemptyset(&set);
+	sigaddset(&set, sig);
+	sigprocmask(SIG_UNBLOCK, &set, NULL);
+}
 
-	r = read(signal_pipe[0], &s, sizeof(s));
-	if (r == sizeof(s)) {
-		PARA_DEBUG_LOG("next signal: %d\n", s);
-		return s;
+/**
+ * Return the number of the next pending signal.
+ *
+ * \param rfds The fd_set containing the signal pipe.
+ *
+ * \return On success, the number of the received signal is returned. If there
+ * is no signal currently pending, the function returns zero. On read errors
+ * from the signal pipe, the process is terminated.
+ */
+int para_next_signal(fd_set *rfds)
+{
+	size_t n;
+	int s, ret = read_nonblock(signal_pipe[0], &s, sizeof(s), rfds, &n);
+
+	if (ret < 0) {
+		PARA_EMERG_LOG("%s\n", para_strerror(-ret));
+		exit(EXIT_FAILURE);
 	}
-	return r < 0 && (errno != EAGAIN)? 0 : -E_SIGNAL_READ;
+	if (n == 0)
+		return 0;
+	assert(n == sizeof(s));
+	PARA_DEBUG_LOG("next signal: %d\n", s);
+	return s;
 }
 
 /**
- * Close the signal pipe.
+ * Close the write end of the signal pipe.
  */
 void para_signal_shutdown(void)
 {