Libguestfs - Dec 2010 - [PATCH] Protocol changes to support upload progress messages and optional arguments.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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>From 4c7ca014212acfbe7800f5988cf9054b011f4273 Mon Sep 17 00:00:00 2001
From: Richard W.M. Jones <rjones at redhat.com>
Date: Wed, 1 Dec 2010 10:30:44 +0000
Subject: [PATCH] Protocol changes to support upload progress messages and
optional arguments.

---
 daemon/proto.c             |   28 ++++++++++++++++++++++++++++
 generator/generator_xdr.ml |    4 +++-
 src/guestfs.pod            |    8 ++++++++
 src/proto.c                |    2 ++
 4 files changed, 41 insertions(+), 1 deletions(-)

diff --git a/daemon/proto.c b/daemon/proto.c
index 63d1cc9..f3a3b26 100644
--- a/daemon/proto.c
+++ b/daemon/proto.c
@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include <stdarg.h>
 #include <string.h>
+#include <inttypes.h>
 #include <unistd.h>
 #include <errno.h>
 #include <sys/param.h>		/* defines MIN */
@@ -45,6 +46,23 @@
 int proc_nr;
 int serial;
 
+/* Hint for implementing progress messages for uploaded/incoming data.
+ * The caller sets this to a value > 0 if it knows or can estimate how
+ * much data will be sent (this is not always known, eg. for uploads
+ * coming from a pipe).  If this is known then we can emit progress
+ * messages as we write the data.
+ */
+uint64_t progress_hint;
+
+/* Optional arguments bitmask.  Caller sets this to indicate which
+ * optional arguments in the guestfs_<foo>_args structure are
+ * meaningful.  Optional arguments not covered by the bitmask are set
+ * to arbitrary values and the daemon should ignore them.  If the
+ * bitmask has bits set that the daemon doesn't understand, then the
+ * whole call is rejected early in processing.
+ */
+uint64_t optargs_bitmask;
+
 /* Time at which we received the current request. */
 static struct timeval start_t;
 
@@ -149,9 +167,19 @@ main_loop (int _sock)
       reply_with_error ("unexpected message status (%d)",
hdr.status);
       goto cont;
     }
+    /* This version of the daemon does not understand optional arguments
+     * at all.  When we fix this, we will remove the next conditional.
+     */
+    if (hdr.optargs_bitmask != 0) {
+      reply_with_error ("optargs_bitmask != 0 (%" PRIu64
")",
+                        hdr.optargs_bitmask);
+      goto cont;
+    }
 
     proc_nr = hdr.proc;
     serial = hdr.serial;
+    progress_hint = hdr.progress_hint;
+    optargs_bitmask = hdr.optargs_bitmask;
 
     /* Clear errors before we call the stub functions.  This is just
      * to ensure that we can accurately report errors in cases where
diff --git a/generator/generator_xdr.ml b/generator/generator_xdr.ml
index c6d8a4d..ca114c5 100644
--- a/generator/generator_xdr.ml
+++ b/generator/generator_xdr.ml
@@ -158,7 +158,7 @@ let generate_xdr ()   */
 
 const GUESTFS_PROGRAM = 0x2000F5F5;
-const GUESTFS_PROTOCOL_VERSION = 3;
+const GUESTFS_PROTOCOL_VERSION = 4;
 
 /* These constants must be larger than any possible message length. */
 const GUESTFS_LAUNCH_FLAG = 0xf5f55ff5;
@@ -193,6 +193,8 @@ struct guestfs_message_header {
   guestfs_procedure proc;            /* GUESTFS_PROC_x */
   guestfs_message_direction direction;
   unsigned serial;                   /* message serial number */
+  unsigned hyper progress_hint;      /* upload hint for progress bar */
+  unsigned hyper optargs_bitmask;    /* bitmask for optional args */
   guestfs_message_status status;
 };
 
diff --git a/src/guestfs.pod b/src/guestfs.pod
index 677d944..7cb05a6 100644
--- a/src/guestfs.pod
+++ b/src/guestfs.pod
@@ -1855,6 +1855,14 @@ The header contains the procedure number
(C<guestfs_proc>) which is
 how the receiver knows what type of args structure to expect, or none
 at all.
 
+For functions that take optional arguments, the optional arguments are
+encoded in the C<guestfs_I<foo>_args> structure in the same way as
+ordinary arguments.  A bitmask in the header indicates which optional
+arguments are meaningful.  The bitmask is also checked to see if it
+contains bits set which the daemon does not know about (eg. if more
+optional arguments were added in a later version of the library), and
+this causes the call to be rejected.
+
 The reply message for ordinary functions is:
 
  total length (header + ret,
diff --git a/src/proto.c b/src/proto.c
index 5d924e8..5c22e3d 100644
--- a/src/proto.c
+++ b/src/proto.c
@@ -658,6 +658,8 @@ guestfs___send (guestfs_h *g, int proc_nr, xdrproc_t xdrp,
char *args)
   hdr.direction = GUESTFS_DIRECTION_CALL;
   hdr.serial = serial;
   hdr.status = GUESTFS_STATUS_OK;
+  hdr.progress_hint = 0;
+  hdr.optargs_bitmask = 0;
 
   if (!xdr_guestfs_message_header (&xdr, &hdr)) {
     error (g, _("xdr_guestfs_message_header failed"));
-- 
1.7.3.2