X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=signal.c;h=f8be2f4612002214f669fa74ce92390866b0dc90;hp=bf0cd5ccff28286852858e1b4f22bf00f9436f7b;hb=8694f85b70488f2cdb48a1e853bdfae68dabc99f;hpb=3689799ede7bba230ca544ac953392b428c3d662

diff --git a/signal.c b/signal.c
index bf0cd5cc..f8be2f46 100644
--- a/signal.c
+++ b/signal.c
@@ -1,9 +1,9 @@
 /*
- * Copyright (C) 2004-2006 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2004-2008 Andre Noll <maan@systemlinux.org>
  *
  * Licensed under the GPL v2. For licencing details see COPYING.
  */
-/** \file signal.c signal handling functions */
+/** \file signal.c Signal handling functions. */
 
 #include <signal.h>
 #include <sys/types.h>
@@ -16,7 +16,7 @@
 static int signal_pipe[2];
 
 /**
- * initialize the paraslash signal subsystem
+ * Initialize the paraslash signal subsystem.
  *
  * This function creates a pipe, the signal pipe, to deliver pending
  * signals to the application (Bernstein's trick). It should be called
@@ -35,18 +35,20 @@ static int signal_pipe[2];
  */
 int para_signal_init(void)
 {
-	int ret = -E_SIGNAL_PIPE;
-	if (pipe(signal_pipe))
+	int ret;
+	if (pipe(signal_pipe) < 0) {
+		ret = -ERRNO_TO_PARA_ERROR(errno);
 		goto err_out;
-	ret = mark_fd_nonblock(signal_pipe[0]);
+	}
+	ret = mark_fd_nonblocking(signal_pipe[0]);
 	if (ret < 0)
 		goto err_out;
-	ret = mark_fd_nonblock(signal_pipe[1]);
+	ret = mark_fd_nonblocking(signal_pipe[1]);
 	if (ret < 0)
 		goto err_out;
 	return signal_pipe[0];
 err_out:
-	PARA_EMERG_LOG("%s\n", PARA_STRERROR(-ret));
+	PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 	exit(EXIT_FAILURE);
 }
 
@@ -60,55 +62,63 @@ static void generic_signal_handler(int s)
 }
 
 /**
- * reap one child
+ * Reap one child.
+ *
+ * \param pid In case a child died, its pid is returned here.
  *
- * call waitpid() and print a log message containing the pid
- * and the cause of the child's death.
+ * Call waitpid() and print a log message containing the pid and the cause of
+ * the child's death.
  *
- * \return Like \p waitpid(), this function returns the process ID of the
- * terminated child; on error, \p -E_WAITPID is returned.
- * \sa waitpid(2)
+ * \return A (negative) paraslash error code on errors, zero, if no child died,
+ * one otherwise. If and only if the function returns one, the content of \a
+ * pid is meaningful.
+ *
+ * \sa waitpid(2).
  */
-pid_t para_reap_child(void)
+int para_reap_child(pid_t *pid)
 {
 	int status;
-	pid_t pid = waitpid(-1, &status, WNOHANG);
+	*pid = waitpid(-1, &status, WNOHANG);
 
-	if (pid <= 0) {
-		if (pid < 0)
-			pid = -E_WAITPID;
-		return pid;
-	}
+	if (!*pid)
+		return 0;
+	if (*pid < 0)
+		return -ERRNO_TO_PARA_ERROR(errno);
 	if (WIFEXITED(status))
-		PARA_DEBUG_LOG("child %i exited. Exit status: %i\n", pid,
+		PARA_DEBUG_LOG("child %i exited. Exit status: %i\n", (int)*pid,
 			WEXITSTATUS(status));
 	else if (WIFSIGNALED(status))
-		PARA_DEBUG_LOG("child %i was killed by signal %i\n", pid,
+		PARA_DEBUG_LOG("child %i was killed by signal %i\n", (int)*pid,
 			WTERMSIG(status));
 	else
-		PARA_WARNING_LOG("child %i terminated abormally\n", pid);
-	return pid;
+		PARA_WARNING_LOG("child %i terminated abormally\n", (int)*pid);
+	return 1;
 }
 
 /**
- * paraslash's zombie killer
+ * Paraslash's zombie killer.
  *
  * It just calls \p para_reap_child() until there are no more children left to
  * reap.
  */
 void para_reap_children(void)
 {
-	while (para_reap_child() > 0)
+	pid_t pid;
+
+	while (para_reap_child(&pid) > 0)
 		; /* nothing */
 }
 
 /**
- * wrapper around signal(2)
- * \param sig the number of the signal to catch
+ * Wrapper around signal(2).
+ *
+ * \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).
  */
 int para_install_sighandler(int sig)
 {
@@ -117,22 +127,37 @@ int para_install_sighandler(int sig)
 }
 
 /**
- * return number of next pending signal
+ * Return the number of next pending signal.
  *
  * This should be called if the fd for the signal pipe is ready for reading.
  *
- * \return On success, the number of the received signal is returned. \p
- * -E_SIGNAL_READ is returned if a read error occured while reading the signal
- * pipe.  If the read was interrupted by another signal the function returns 0.
+ * \return On success, the number of the received signal is returned.  If the
+ * read returned zero or was interrupted by another signal the function returns
+ * 0.  Otherwise, a negative error value is returned.
  */
 int para_next_signal(void)
 {
 	int s;
-	ssize_t r;
+	ssize_t r = read(signal_pipe[0], &s, sizeof(s));
 
-	if ((r = read(signal_pipe[0], &s, sizeof(s)) == sizeof(s)) > 0) {
-		PARA_DEBUG_LOG("next signal: %d\n", s);
-		return s;
+	if (!r) {
+		PARA_CRIT_LOG("read from signal pipe returned zero\n");
+		return 0;
+	}
+	if (r < 0) {
+		if (errno == EAGAIN || errno == EINTR)
+			return 0;
+		return -ERRNO_TO_PARA_ERROR(errno);
 	}
-	return r < 0 && (errno != EAGAIN)? 0 : -E_SIGNAL_READ;
+	assert(r == sizeof(s));
+	PARA_DEBUG_LOG("next signal: %d\n", s);
+	return s;
+}
+
+/**
+ * Close the write end of the signal pipe.
+ */
+void para_signal_shutdown(void)
+{
+	close(signal_pipe[1]);
 }