1 files changed, 93 insertions, 0 deletions
diff --git a/tools/virtiofsd/fuse_signals.c b/tools/virtiofsd/fuse_signals.c
new file mode 100644
index 000000000..1de46de1c
--- /dev/null
+++ b/tools/virtiofsd/fuse_signals.c
@@ -0,0 +1,93 @@
+/*
+ * FUSE: Filesystem in Userspace
+ * Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>
+ *
+ * Utility functions for setting signal handlers.
+ *
+ * This program can be distributed under the terms of the GNU LGPLv2.
+ * See the file COPYING.LIB
+ */
+
+#include "qemu/osdep.h"
+#include "fuse_i.h"
+#include "fuse_lowlevel.h"
+
+
+static struct fuse_session *fuse_instance;
+
+static void exit_handler(int sig)
+{
+    if (fuse_instance) {
+        fuse_session_exit(fuse_instance);
+        if (sig <= 0) {
+            fuse_log(FUSE_LOG_ERR, "assertion error: signal value <= 0\n");
+            abort();
+        }
+        fuse_instance->error = sig;
+    }
+}
+
+static void do_nothing(int sig)
+{
+    (void)sig;
+}
+
+static int set_one_signal_handler(int sig, void (*handler)(int), int remove)
+{
+    struct sigaction sa;
+    struct sigaction old_sa;
+
+    memset(&sa, 0, sizeof(struct sigaction));
+    sa.sa_handler = remove ? SIG_DFL : handler;
+    sigemptyset(&(sa.sa_mask));
+    sa.sa_flags = 0;
+
+    if (sigaction(sig, NULL, &old_sa) == -1) {
+        fuse_log(FUSE_LOG_ERR, "fuse: cannot get old signal handler: %s\n",
+                 strerror(errno));
+        return -1;
+    }
+
+    if (old_sa.sa_handler == (remove ? handler : SIG_DFL) &&
+        sigaction(sig, &sa, NULL) == -1) {
+        fuse_log(FUSE_LOG_ERR, "fuse: cannot set signal handler: %s\n",
+                 strerror(errno));
+        return -1;
+    }
+    return 0;
+}
+
+int fuse_set_signal_handlers(struct fuse_session *se)
+{
+    /*
+     * If we used SIG_IGN instead of the do_nothing function,
+     * then we would be unable to tell if we set SIG_IGN (and
+     * thus should reset to SIG_DFL in fuse_remove_signal_handlers)
+     * or if it was already set to SIG_IGN (and should be left
+     * untouched.
+     */
+    if (set_one_signal_handler(SIGHUP, exit_handler, 0) == -1 ||
+        set_one_signal_handler(SIGINT, exit_handler, 0) == -1 ||
+        set_one_signal_handler(SIGTERM, exit_handler, 0) == -1 ||
+        set_one_signal_handler(SIGPIPE, do_nothing, 0) == -1) {
+        return -1;
+    }
+
+    fuse_instance = se;
+    return 0;
+}
+
+void fuse_remove_signal_handlers(struct fuse_session *se)
+{
+    if (fuse_instance != se) {
+        fuse_log(FUSE_LOG_ERR,
+                 "fuse: fuse_remove_signal_handlers: unknown session\n");
+    } else {
+        fuse_instance = NULL;
+    }
+
+    set_one_signal_handler(SIGHUP, exit_handler, 1);
+    set_one_signal_handler(SIGINT, exit_handler, 1);
+    set_one_signal_handler(SIGTERM, exit_handler, 1);
+    set_one_signal_handler(SIGPIPE, do_nothing, 1);
+}