From 2a17be71ba0d6b09d0fafc0c198df528cc423b7f Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@anytun.org>
Date: Sun, 3 May 2009 14:01:41 +0000
Subject: added signal handling without races

---
 src/sig_handler.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 111 insertions(+), 17 deletions(-)

(limited to 'src/sig_handler.c')

diff --git a/src/sig_handler.c b/src/sig_handler.c
index 6fd4b85..7a1ad74 100644
--- a/src/sig_handler.c
+++ b/src/sig_handler.c
@@ -36,29 +36,123 @@
 
 #include "log.h"
 #include <signal.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/select.h>
+#include <errno.h>
+
 #include "sig_handler.h"
 
-volatile sig_atomic_t signal_exit = 0;
+#include <stdio.h>
+
+
+static int sig_pipe_fds[2];
+
 
-void signal_init()
+static void sig_handler(int sig)
 {
-  signal(SIGINT, handle_signal);
-  signal(SIGQUIT, handle_signal);
-  signal(SIGTERM, handle_signal);
-  signal(SIGHUP, handle_signal);
-  signal(SIGUSR1, handle_signal);
-  signal(SIGUSR2, handle_signal);
+  sigset_t set;
+  int ret = read(sig_pipe_fds[0], &set, sizeof(sigset_t));
+  if(ret != sizeof(sigset_t))
+    sigemptyset(&set);
+
+  sigaddset(&set, sig);
+  ret = write(sig_pipe_fds[1], &set, sizeof(sigset_t));
+}
+
+
+int signal_init()
+{
+  if(pipe(sig_pipe_fds)) {
+    log_printf(ERROR, "signal handling init failed (pipe error: %s)", strerror(errno));
+    return -1;
+  }
+
+  int i;
+  for(i=0; i<2; ++i) {
+    int fd_flags = fcntl(sig_pipe_fds[i], F_GETFL);
+    if(fd_flags == -1) {
+      log_printf(ERROR, "signal handling init failed (pipe fd[%d] read flags error: %s)", i, strerror(errno));
+      return -1;
+    }
+    if(fcntl(sig_pipe_fds[i], F_SETFL, fd_flags | O_NONBLOCK) == -1){
+      log_printf(ERROR, "signal handling init failed (pipe fd[%d] write flags error: %s)", i, strerror(errno));
+      return -1;
+    }
+  }
+
+  struct sigaction act;
+  act.sa_handler = sig_handler;
+  sigfillset(&act.sa_mask);
+  act.sa_flags = 0;
+
+  if((sigaction(SIGINT, &act, NULL) < 0) ||
+     (sigaction(SIGQUIT, &act, NULL) < 0) ||
+     (sigaction(SIGTERM, &act, NULL) < 0) ||
+     (sigaction(SIGHUP, &act, NULL) < 0) ||
+     (sigaction(SIGUSR1, &act, NULL) < 0) ||
+     (sigaction(SIGUSR2, &act, NULL) < 0)) {
+
+    log_printf(ERROR, "signal handling init failed (sigaction error: %s)", strerror(errno));
+    close(sig_pipe_fds[0]);
+    close(sig_pipe_fds[1]);
+  }
+
+  return sig_pipe_fds[0];
 }
 
-void handle_signal(int sig)
+int signal_handle()
 {
-  switch(sig) {
-  case SIGINT: log_printf(NOTICE, "SIG-Int caught, exitting"); signal_exit = 1; break;
-  case SIGQUIT: log_printf(NOTICE, "SIG-Quit caught, exitting"); signal_exit = 1; break;
-  case SIGTERM: log_printf(NOTICE, "SIG-Term caught, exitting"); signal_exit = 1; break;
-  case SIGHUP: log_printf(NOTICE, "SIG-Hup caught"); break;
-  case SIGUSR1: log_printf(NOTICE, "SIG-Usr1 caught"); break;
-  case SIGUSR2: log_printf(NOTICE, "SIG-Usr2 caught"); break;
-  default: log_printf(NOTICE, "Signal %d caught, ignoring", sig); break;
+  sigset_t set, oldset, tmpset;
+
+  sigemptyset(&tmpset);
+  sigaddset(&tmpset, SIGINT);
+  sigaddset(&tmpset, SIGQUIT);
+  sigaddset(&tmpset, SIGTERM);
+  sigaddset(&tmpset, SIGHUP);
+  sigaddset(&tmpset, SIGUSR1);
+  sigaddset(&tmpset, SIGUSR2);
+  sigprocmask(SIG_BLOCK, &tmpset, &oldset);
+
+  int ret = read(sig_pipe_fds[0], &set, sizeof(sigset_t));
+  if(ret != sizeof(sigset_t))
+    sigemptyset(&set);
+
+  int return_value = 0;
+  int sig;
+  for(sig=1; sig < _NSIG; ++sig) {
+    if(sigismember(&set, sig)) {
+      switch(sig) {
+      case SIGINT: log_printf(NOTICE, "SIG-Int caught, exitting"); return_value = 1; break;
+      case SIGQUIT: log_printf(NOTICE, "SIG-Quit caught, exitting"); return_value = 1; break;
+      case SIGTERM: log_printf(NOTICE, "SIG-Term caught, exitting"); return_value = 1; break;
+      case SIGHUP: log_printf(NOTICE, "SIG-Hup caught"); break;
+      case SIGUSR1: log_printf(NOTICE, "SIG-Usr1 caught"); break;
+      case SIGUSR2: log_printf(NOTICE, "SIG-Usr2 caught"); break;
+      default: log_printf(WARNING, "unknown signal %d caught, ignoring", sig); break;
+      }
+      sigdelset(&set, sig);
+    }
   }
+
+  sigprocmask(SIG_SETMASK, &oldset, NULL);
+  return return_value;
+}
+
+void signal_stop()
+{
+  struct sigaction act;
+  act.sa_handler = SIG_DFL;
+  sigemptyset(&act.sa_mask);
+  act.sa_flags = 0;
+
+  sigaction(SIGINT, &act, NULL);
+  sigaction(SIGQUIT, &act, NULL);
+  sigaction(SIGTERM, &act, NULL);
+  sigaction(SIGHUP, &act, NULL);
+  sigaction(SIGUSR1, &act, NULL);
+  sigaction(SIGUSR2, &act, NULL);
+
+  close(sig_pipe_fds[0]);
+  close(sig_pipe_fds[1]);
 }
-- 
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