Add monitor_get_fd() command for fetching named fds

Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

monitor.c

@@ -1774,6 +1774,30 @@ static void do_closefd(Monitor *mon, const char *fdname)
                    fdname);
 }
 
+int monitor_get_fd(Monitor *mon, const char *fdname)
+{
+    mon_fd_t *monfd;
+
+    LIST_FOREACH(monfd, &mon->fds, next) {
+        int fd;
+
+        if (strcmp(monfd->name, fdname) != 0) {
+            continue;
+        }
+
+        fd = monfd->fd;
+
+        /* caller takes ownership of fd */
+        LIST_REMOVE(monfd, next);
+        qemu_free(monfd->name);
+        qemu_free(monfd);
+
+        return fd;
+    }
+
+    return -1;
+}
+
 static const mon_cmd_t mon_cmds[] = {
 #include "qemu-monitor.h"
     { NULL, NULL, },

monitor.h

@@ -20,6 +20,8 @@ void monitor_read_bdrv_key_start(Monitor *mon, BlockDriverState *bs,
                                  BlockDriverCompletionFunc *completion_cb,
                                  void *opaque);
 
+int monitor_get_fd(Monitor *mon, const char *fdname);
+
 void monitor_vprintf(Monitor *mon, const char *fmt, va_list ap);
 void monitor_printf(Monitor *mon, const char *fmt, ...)
     __attribute__ ((__format__ (__printf__, 2, 3)));