Implement progress messages in the daemon and library.

This implements progress notification messages in the daemon, and
adds a callback in the library to handle them.

No calls are changed so far, so in fact no progress messages can
be generated by this commit.

For more details, see:
https://www.redhat.com/archives/libguestfs/2010-July/msg00003.html
https://www.redhat.com/archives/libguestfs/2010-July/msg00024.html

6 files changed, 128 insertions, 5 deletions

diff --git a/src/generator.ml b/src/generator.ml
index c25c8712..bbf313a7 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -6327,11 +6327,12 @@ and generate_xdr () =
  */
 
 const GUESTFS_PROGRAM = 0x2000F5F5;
-const GUESTFS_PROTOCOL_VERSION = 1;
+const GUESTFS_PROTOCOL_VERSION = 2;
 
 /* These constants must be larger than any possible message length. */
 const GUESTFS_LAUNCH_FLAG = 0xf5f55ff5;
 const GUESTFS_CANCEL_FLAG = 0xffffeeee;
+const GUESTFS_PROGRESS_FLAG = 0xffff5555;
 
 enum guestfs_message_direction {
   GUESTFS_DIRECTION_CALL = 0,        /* client -> daemon */
@@ -6370,6 +6371,23 @@ struct guestfs_chunk {
   /* data size is 0 bytes if the transfer has finished successfully */
   opaque data<GUESTFS_MAX_CHUNK_SIZE>;
 };
+
+/* Progress notifications.  Daemon self-limits these messages to
+ * at most one per second.  The daemon can send these messages
+ * at any time, and the caller should discard unexpected messages.
+ * 'position' and 'total' have undefined units; however they may
+ * have meaning for some calls.
+ *
+ * NB. guestfs___recv_from_daemon assumes the XDR-encoded
+ * structure is 24 bytes long.
+ */
+struct guestfs_progress {
+  guestfs_procedure proc;            /* @0:  GUESTFS_PROC_x */
+  unsigned serial;                   /* @4:  message serial number */
+  unsigned hyper position;           /* @8:  0 <= position <= total */
+  unsigned hyper total;              /* @16: total size of operation */
+                                     /* @24: size of structure */
+};
 "
 
 (* Generate the guestfs-structs.h file. *)
@@ -6869,6 +6887,7 @@ and generate_linker_script () =
     "guestfs_set_launch_done_callback";
     "guestfs_set_log_message_callback";
     "guestfs_set_out_of_memory_handler";
+    "guestfs_set_progress_callback";
     "guestfs_set_subprocess_quit_callback";
 
     (* Unofficial parts of the API: the bindings code use these
diff --git a/src/guestfs-internal.h b/src/guestfs-internal.h
index e37c9c26..32a6c2a6 100644
--- a/src/guestfs-internal.h
+++ b/src/guestfs-internal.h
@@ -122,6 +122,8 @@ struct guestfs_h
   void *                     launch_done_cb_data;
   guestfs_close_cb           close_cb;
   void *                     close_cb_data;
+  guestfs_progress_cb        progress_cb;
+  void *                     progress_cb_data;
 
   int msg_next_serial;
 
diff --git a/src/guestfs.c b/src/guestfs.c
index eaacd395..206347e5 100644
--- a/src/guestfs.c
+++ b/src/guestfs.c
@@ -645,3 +645,11 @@ guestfs_set_close_callback (guestfs_h *g,
   g->close_cb = cb;
   g->close_cb_data = opaque;
 }
+
+void
+guestfs_set_progress_callback (guestfs_h *g,
+                               guestfs_progress_cb cb, void *opaque)
+{
+  g->progress_cb = cb;
+  g->progress_cb_data = opaque;
+}
diff --git a/src/guestfs.h b/src/guestfs.h
index 3cff4849..ec88f228 100644
--- a/src/guestfs.h
+++ b/src/guestfs.h
@@ -34,6 +34,8 @@
 extern "C" {
 #endif
 
+#include <stdint.h>
+
 typedef struct guestfs_h guestfs_h;
 
 /*--- Connection management ---*/
@@ -57,14 +59,15 @@ typedef void (*guestfs_log_message_cb) (guestfs_h *g, void *data, char *buf, int
 typedef void (*guestfs_subprocess_quit_cb) (guestfs_h *g, void *data);
 typedef void (*guestfs_launch_done_cb) (guestfs_h *g, void *data);
 typedef void (*guestfs_close_cb) (guestfs_h *g, void *data);
+typedef void (*guestfs_progress_cb) (guestfs_h *g, void *data, int proc_nr, int serial, uint64_t position, uint64_t total);
 
 extern void guestfs_set_log_message_callback (guestfs_h *g, guestfs_log_message_cb cb, void *opaque);
 extern void guestfs_set_subprocess_quit_callback (guestfs_h *g, guestfs_subprocess_quit_cb cb, void *opaque);
 extern void guestfs_set_launch_done_callback (guestfs_h *g, guestfs_launch_done_cb cb, void *opaque);
 extern void guestfs_set_close_callback (guestfs_h *g, guestfs_close_cb cb, void *opaque);
+extern void guestfs_set_progress_callback (guestfs_h *g, guestfs_progress_cb cb, void *opaque);
 
 /*--- Structures and actions ---*/
-#include <stdint.h>
 #include <rpc/types.h>
 #include <rpc/xdr.h>
 #include <guestfs-structs.h>
diff --git a/src/guestfs.pod b/src/guestfs.pod
index 590c768d..6a956edb 100644
--- a/src/guestfs.pod
+++ b/src/guestfs.pod
@@ -1186,6 +1186,56 @@ languages (eg. if your HLL interpreter has already been cleaned
 up by the time this is called, and if your callback then jumps
 into some HLL function).
 
+=head2 guestfs_set_progress_callback
+
+ typedef void (*guestfs_progress_cb) (guestfs_h *g, void *opaque,
+                                      int proc_nr, int serial,
+                                      uint64_t position, uint64_t total);
+ void guestfs_set_progress_callback (guestfs_h *g,
+                                     guestfs_progress_cb cb,
+                                     void *opaque);
+
+Some long-running operations can generate progress messages.  If
+this callback is registered, then it will be called each time a
+progress message is generated (usually two seconds after the
+operation started, and three times per second thereafter until
+it completes, although the frequency may change in future versions).
+
+The callback receives two numbers: C<position> and C<total>.
+The units of C<total> are not defined, although for some
+operations C<total> may relate in some way to the amount of
+data to be transferred (eg. in bytes or megabytes), and
+C<position> may be the portion which has been transferred.
+
+The only defined and stable parts of the API are:
+
+=over 4
+
+=item *
+
+The callback can display to the user some type of progress bar or
+indicator which shows the ratio of C<position>:C<total>.
+
+=item *
+
+0 E<lt>= C<position> E<lt>= C<total>
+
+=item *
+
+If any progress notification is sent during a call, then a final
+progress notification is always sent when C<position> = C<total>.
+
+This is to simplify caller code, so callers can easily set the
+progress indicator to "100%" at the end of the operation, without
+requiring special code to detect this case.
+
+=back
+
+The callback also receives the procedure number and serial number of
+the call.  These are only useful for debugging protocol issues, and
+the callback can normally ignore them.  The callback may want to
+print these numbers in error messages or debugging messages.
+
 =head1 BLOCK DEVICE NAMING
 
 In the kernel there is now quite a profusion of schemata for naming
diff --git a/src/proto.c b/src/proto.c
index ad173c6b..5d924e86 100644
--- a/src/proto.c
+++ b/src/proto.c
@@ -373,7 +373,15 @@ guestfs___send_to_daemon (guestfs_h *g, const void *v_buf, size_t n)
  *
  * It also checks for EOF (qemu died) and passes that up through the
  * child_cleanup function above.
+ *
+ * Progress notifications are handled transparently by this function.
+ * If the callback exists, it is called.  The caller of this function
+ * will not see GUESTFS_PROGRESS_FLAG.
  */
+
+/* Size of guestfs_progress message on the wire. */
+#define PROGRESS_MESSAGE_SIZE 24
+
 int
 guestfs___recv_from_daemon (guestfs_h *g, uint32_t *size_rtn, void **buf_rtn)
 {
@@ -400,7 +408,13 @@ guestfs___recv_from_daemon (guestfs_h *g, uint32_t *size_rtn, void **buf_rtn)
    */
   ssize_t nr = -4;
 
-  while (nr < (ssize_t) *size_rtn) {
+  for (;;) {
+    ssize_t message_size =
+      *size_rtn != GUESTFS_PROGRESS_FLAG ?
+      *size_rtn : PROGRESS_MESSAGE_SIZE;
+    if (nr >= message_size)
+      break;
+
     rset2 = rset;
     int r = select (max_fd+1, &rset2, NULL, NULL, NULL);
     if (r == -1) {
@@ -450,6 +464,11 @@ guestfs___recv_from_daemon (guestfs_h *g, uint32_t *size_rtn, void **buf_rtn)
         xdr_uint32_t (&xdr, size_rtn);
         xdr_destroy (&xdr);
 
+        /* *size_rtn changed, recalculate message_size */
+        message_size =
+          *size_rtn != GUESTFS_PROGRESS_FLAG ?
+          *size_rtn : PROGRESS_MESSAGE_SIZE;
+
         if (*size_rtn == GUESTFS_LAUNCH_FLAG) {
           if (g->state != LAUNCHING)
             error (g, _("received magic signature from guestfsd, but in state %d"),
@@ -463,6 +482,8 @@ guestfs___recv_from_daemon (guestfs_h *g, uint32_t *size_rtn, void **buf_rtn)
         }
         else if (*size_rtn == GUESTFS_CANCEL_FLAG)
           return 0;
+        else if (*size_rtn == GUESTFS_PROGRESS_FLAG)
+          /*FALLTHROUGH*/;
         /* If this happens, it's pretty bad and we've probably lost
          * synchronization.
          */
@@ -473,11 +494,11 @@ guestfs___recv_from_daemon (guestfs_h *g, uint32_t *size_rtn, void **buf_rtn)
         }
 
         /* Allocate the complete buffer, size now known. */
-        *buf_rtn = safe_malloc (g, *size_rtn);
+        *buf_rtn = safe_malloc (g, message_size);
         /*FALLTHROUGH*/
       }
 
-      size_t sizetoread = *size_rtn - nr;
+      size_t sizetoread = message_size - nr;
       if (sizetoread > BUFSIZ) sizetoread = BUFSIZ;
 
       r = read (g->sock, (char *) (*buf_rtn) + nr, sizetoread);
@@ -524,6 +545,26 @@ guestfs___recv_from_daemon (guestfs_h *g, uint32_t *size_rtn, void **buf_rtn)
   }
 #endif
 
+  if (*size_rtn == GUESTFS_PROGRESS_FLAG) {
+    if (g->state == BUSY && g->progress_cb) {
+      guestfs_progress message;
+      XDR xdr;
+      xdrmem_create (&xdr, *buf_rtn, PROGRESS_MESSAGE_SIZE, XDR_DECODE);
+      xdr_guestfs_progress (&xdr, &message);
+      xdr_destroy (&xdr);
+
+      g->progress_cb (g, g->progress_cb_data,
+                      message.proc, message.serial,
+                      message.position, message.total);
+    }
+
+    free (*buf_rtn);
+    *buf_rtn = NULL;
+
+    /* Process next message. */
+    return guestfs___recv_from_daemon (g, size_rtn, buf_rtn);
+  }
+
   return 0;
 }