Add a helper to walk all CPR fd's and run a callback for each.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
 include/migration/cpr.h |  3 +++
 migration/cpr.c         | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/include/migration/cpr.h b/include/migration/cpr.h
index 3fc19a7..2b074d7 100644
--- a/include/migration/cpr.h
+++ b/include/migration/cpr.h
@@ -34,6 +34,9 @@ void cpr_resave_fd(const char *name, int id, int fd);
 int cpr_open_fd(const char *path, int flags, const char *name, int id,
                 Error **errp);
 
+typedef bool (*cpr_walk_fd_cb)(int fd);
+bool cpr_walk_fd(cpr_walk_fd_cb cb);
+
 MigMode cpr_get_incoming_mode(void);
 void cpr_set_incoming_mode(MigMode mode);
 bool cpr_is_incoming(void);
diff --git a/migration/cpr.c b/migration/cpr.c
index 42ad0b0..d3e370e 100644
--- a/migration/cpr.c
+++ b/migration/cpr.c
@@ -121,6 +121,19 @@ int cpr_open_fd(const char *path, int flags, const char *name, int id,
     return fd;
 }
 
+bool cpr_walk_fd(cpr_walk_fd_cb cb)
+{
+    CprFd *elem;
+
+    QLIST_FOREACH(elem, &cpr_state.fds, next) {
+        g_assert(elem->fd >= 0);
+        if (!cb(elem->fd)) {
+            return false;
+        }
+    }
+    return true;
+}
+
 /*************************************************************************/
 static const VMStateDescription vmstate_cpr_state = {
     .name = CPR_STATE,
-- 
1.8.3.1