[05/16] qemu-char: Allow a chardev to reconnect if disconnected

diff --git a/qemu-char.c b/qemu-char.c
index c9348fa..76d4deb 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -111,9 +111,15 @@  void qemu_chr_be_event(CharDriverState *s, int event)
     /* Keep track if the char device is open */
     switch (event) {
         case CHR_EVENT_OPENED:
+	    if (s->recon_timer)
+		qemu_del_timer(s->recon_timer);
             s->opened = 1;
             break;
         case CHR_EVENT_CLOSED:
+	    if (s->recon_timer)
+		qemu_mod_timer(s->recon_timer,
+			       (qemu_get_clock_ns(vm_clock) +
+				(s->recon_time * 1000000000ULL)));
             s->opened = 0;
             break;
     }
@@ -2726,6 +2732,19 @@  static const struct {
 #endif
 };
 
+static void recon_timeout(void *opaque)
+{
+    CharDriverState *chr = opaque;
+
+    if (chr->opened)
+	return;
+
+    qemu_mod_timer(chr->recon_timer,
+		   (qemu_get_clock_ns(vm_clock) +
+		    (chr->recon_time * 1000000000ULL)));
+    backend_table[chr->backend].open(chr, chr->opts);
+}
+
 CharDriverState *qemu_chr_new_from_opts(QemuOpts *opts,
                                     void (*init)(struct CharDriverState *s))
 {
@@ -2753,11 +2772,36 @@  CharDriverState *qemu_chr_new_from_opts(QemuOpts *opts,
     }
 
     chr = g_malloc0(sizeof(CharDriverState));
+
+    chr->backend = i;
+    if ((chr->recon_time = qemu_opt_get_number(opts, "reconnect", 0))) {
+	if (strcmp(qemu_opt_get(opts, "backend"), "socket") != 0) {
+	    g_free(chr);
+	    fprintf(stderr, "chardev: reconnect only supported on sockets\n");
+	    return NULL;
+	}
+	if (qemu_opt_get_bool(opts, "server", 0)) {
+	    g_free(chr);
+	    fprintf(stderr, "chardev: server device cannot reconnect\n");
+	    return NULL;
+	}
+	chr->opts = opts;
+	chr->recon_timer = qemu_new_timer_ns(vm_clock, recon_timeout, chr);
+
+	/* Make sure it connects in time. */
+	qemu_mod_timer(chr->recon_timer,
+		       (qemu_get_clock_ns(vm_clock) +
+			(chr->recon_time * 1000000000ULL)));
+    }
+
     if (!backend_table[i].open(chr, opts)) {
-	g_free(chr);
-        fprintf(stderr, "chardev: opening backend \"%s\" failed\n",
-                qemu_opt_get(opts, "backend"));
-        return NULL;
+	if (!chr->recon_time) {
+	    /* Reconnect is not enabled, give up */
+	    g_free(chr);
+	    fprintf(stderr, "chardev: opening backend \"%s\" failed\n",
+		    qemu_opt_get(opts, "backend"));
+	    return NULL;
+	}
     }
 
     if (!chr->filename)
@@ -2829,6 +2873,8 @@  void qemu_chr_delete(CharDriverState *chr)
     QTAILQ_REMOVE(&chardevs, chr, next);
     if (chr->chr_close)
         chr->chr_close(chr);
+    if (chr->recon_timer)
+	qemu_free_timer(chr->recon_timer);
     g_free(chr->filename);
     g_free(chr->label);
     g_free(chr);
diff --git a/qemu-char.h b/qemu-char.h
index 486644b..d21ae39 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -75,6 +75,10 @@  struct CharDriverState {
     int opened;
     int avail_connections;
     QTAILQ_ENTRY(CharDriverState) next;
+    int backend;
+    QemuOpts *opts;
+    QEMUTimer *recon_timer;
+    uint64_t recon_time;
 };
 
 /**
diff --git a/qemu-config.c b/qemu-config.c
index 54694cc..9ebe432 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -209,6 +209,9 @@  static QemuOptsList qemu_chardev_opts = {
             .name = "mux",
             .type = QEMU_OPT_BOOL,
         },{
+            .name = "reconnect",
+            .type = QEMU_OPT_NUMBER,
+        },{
             .name = "signal",
             .type = QEMU_OPT_BOOL,
         },{
diff --git a/qemu-options.hx b/qemu-options.hx
index 72aace6..c5f592c 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1620,8 +1620,9 @@  DEFHEADING(Character device options:)
 DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
     "-chardev null,id=id[,mux=on|off]\n"
     "-chardev socket,id=id[,host=host],port=host[,to=to][,ipv4][,ipv6][,nodelay]\n"
-    "         [,server][,nowait][,telnet][,mux=on|off] (tcp)\n"
-    "-chardev socket,id=id,path=path[,server][,nowait][,telnet],[mux=on|off] (unix)\n"
+    "         [,server][,nowait][,telnet][,mux=on|off][,reconnect=seconds] (tcp)\n"
+    "-chardev socket,id=id,path=path[,server][,nowait][,telnet][,mux=on|off]\n"
+    "         [,reconnect=seconds] (unix)\n"
     "-chardev udp,id=id[,host=host],port=port[,localaddr=localaddr]\n"
     "         [,localport=localport][,ipv4][,ipv6][,mux=on|off]\n"
     "-chardev msmouse,id=id[,mux=on|off]\n"
@@ -1690,7 +1691,7 @@  Options to each backend are described below.
 A void device. This device will not emit any data, and will drop any data it
 receives. The null backend does not take any options.
 
-@item -chardev socket ,id=@var{id} [@var{TCP options} or @var{unix options}] [,server] [,nowait] [,telnet]
+@item -chardev socket ,id=@var{id} [@var{TCP options} or @var{unix options}] [,server] [,nowait] [,telnet] [,reconnect=@var{seconds}]
 
 Create a two-way stream socket, which can be either a TCP or a unix socket. A
 unix socket will be created if @option{path} is specified. Behaviour is
@@ -1704,6 +1705,10 @@  connect to a listening socket.
 @option{telnet} specifies that traffic on the socket should interpret telnet
 escape sequences.
 
+@option{reconnect} specifies that if the socket does not come up at startup,
+or if the socket is closed for some reason (like the other end exited),
+wait the given number of seconds and attempt to reconnect.
+
 TCP and unix socket options are given below:
 
 @table @option