server: Avoid deadlock in daemon_log().

[paraslash.git] / signal.c

diff --git a/signal.c b/signal.c
index 5d6e6e45dcd8e728c1bfcc6e08899bf08d4fc512..9b328caf6550da385eb64c824217da7f3abd4588 100644 (file)
--- a/signal.c
+++ b/signal.c
@@ -1,8 +1,4 @@
-/*
- * Copyright (C) 2004 Andre Noll <maan@tuebingen.mpg.de>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* Copyright (C) 2004 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
 /** \file signal.c Signal handling functions. */
 
 #include <signal.h>
@@ -25,7 +21,7 @@ static int signal_pipe[2];
  * 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.
+ * to \ref para_install_sighandler() for each signal that should be caught.
  *
  * A generic signal handler is used for all signals simultaneously. When a
  * signal arrives, the signal handler writes the number of the signal received
@@ -33,7 +29,7 @@ static int signal_pipe[2];
  * by checking if the file descriptor of the other end of the signal pipe is
  * ready for reading, see select(2).
  *
- * \return This function either succeeds or calls exit(2) to terminate the
+ * \return This function either succeeds or calls exit(3) to terminate the
  * current process. On success, a signal task structure is returned.
  */
 struct signal_task *signal_init_or_die(void)
@@ -76,10 +72,13 @@ static void generic_signal_handler(int s)
                errno = save_errno;
                return;
        }
-       if (ret < 0)
-               PARA_EMERG_LOG("%s\n", strerror(errno));
-       else
-               PARA_EMERG_LOG("short write to signal pipe\n");
+       /*
+        * This is a fatal error which should never happen. We must not call
+        * PARA_XXX_LOG() here because this might acquire the log mutex which
+        * is already taken by the main program if the interrupt occurs while a
+        * log message is being printed. The mutex will not be released as long
+        * as this signal handler is running, so a deadlock ensues.
+        */
        exit(EXIT_FAILURE);
 }