client_common.c: Trivial cosmetic cleanups.

[paraslash.git] / signal.c

diff --git a/signal.c b/signal.c
index 82444cc81b9c1ffa7248e701ad36cd606b8fc877..cc49da11f2b647c83cb068b0cecab439419eb571 100644 (file)
--- a/signal.c
+++ b/signal.c
@@ -1,33 +1,27 @@
 /*
  * Copyright (C) 2004-2006 Andre Noll <maan@systemlinux.org>
  *
- *     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., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
+ * Licensed under the GPL v2. For licencing details see COPYING.
  */
 /** \file signal.c signal handling functions */
 
+#include <signal.h>
+#include <sys/types.h>
+#include <dirent.h>
+
 #include "para.h"
 #include "error.h"
+#include "fd.h"
+
 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. It should be called during the application's startup part,
- * followed by subsequent calls to para_install_sighandler() for each signal
- * that should be caught.
+ * This function creates a pipe, the signal pipe, to deliver pending
+ * signals to the application (Bernstein's trick). It should be called
+ * during the application's startup part, followed by subsequent calls
+ * to para_install_sighandler() for each signal that should be caught.
  *
  * para_signal_init() installs a generic signal handler which is used for all
  * signals simultaneously. When a signal arrives, this generic signal handler
@@ -41,9 +35,20 @@ static int signal_pipe[2];
  */
 int para_signal_init(void)
 {
-       if (!pipe(signal_pipe))
-               return signal_pipe[0];
-       PARA_EMERG_LOG("%s", "pipe error: Can not setup signal pipe");
+       int ret;
+       if (pipe(signal_pipe) < 0) {
+               ret = -ERRNO_TO_PARA_ERROR(errno);
+               goto err_out;
+       }
+       ret = mark_fd_nonblocking(signal_pipe[0]);
+       if (ret < 0)
+               goto err_out;
+       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));
        exit(EXIT_FAILURE);
 }
 
@@ -57,45 +62,50 @@ 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 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.
  *
- * \return Like \p waitpid(), this function returns the process ID of the
- * terminated child; on error, \p -E_WAITPID is returned.
  * \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;
+       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 */
 }
 
@@ -119,7 +129,7 @@ int para_install_sighandler(int sig)
  * 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
+ * -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.
  */
 int para_next_signal(void)
@@ -127,9 +137,18 @@ int para_next_signal(void)
        int s;
        ssize_t r;
 
-       if ((r = read(signal_pipe[0], &s, sizeof(s)) == sizeof(s)) > 0) {
+       r = read(signal_pipe[0], &s, sizeof(s));
+       if (r == sizeof(s)) {
                PARA_DEBUG_LOG("next signal: %d\n", s);
                return s;
        }
        return r < 0 && (errno != EAGAIN)? 0 : -E_SIGNAL_READ;
 }
+
+/**
+ * Close the signal pipe.
+ */
+void para_signal_shutdown(void)
+{
+       close(signal_pipe[1]);
+}