[Xen-changelog] Test and fix acknowedge_watch from returning EINVAL.

[Xen patchbot -unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User cl349@xxxxxxxxxxxxxxxxxxxx
# Node ID 99366b44c42107b04238fbc183385ddae4bb10d5
# Parent  f9a3f32a129bdbfed70273d333cbac9dd8c99b83
Test and fix acknowedge_watch from returning EINVAL.
Also ensure that daemon re-xmits event if they ack wrong thing
(otherwise confused clients get stuck, as we will send no more
data while awaiting ack).
Signed-off-by: Rusty Russel <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Christian Limpach <Christian.Limpach@xxxxxxxxxxxx>

diff -r f9a3f32a129b -r 99366b44c421 tools/xenstore/xenstored_core.c
--- a/tools/xenstore/xenstored_core.c   Tue Jul 26 15:08:22 2005
+++ b/tools/xenstore/xenstored_core.c   Tue Jul 26 15:09:43 2005
@@ -1166,7 +1166,7 @@
        /* We might get a command while waiting for an ack: this means
         * the other end discarded it: we will re-transmit. */
        if (type != XS_WATCH_ACK)
-               conn->waiting_for_ack = false;
+               conn->waiting_for_ack = NULL;
 
        /* Careful: process_message may free connection.  We detach
         * "in" beforehand and allocate the new buffer to avoid
diff -r f9a3f32a129b -r 99366b44c421 tools/xenstore/xenstored_core.h
--- a/tools/xenstore/xenstored_core.h   Tue Jul 26 15:08:22 2005
+++ b/tools/xenstore/xenstored_core.h   Tue Jul 26 15:09:43 2005
@@ -64,7 +64,7 @@
        bool can_write;
 
        /* Are we waiting for a watch event ack? */
-       bool waiting_for_ack;
+       struct watch *waiting_for_ack;
 
        /* Buffered incoming data. */
        struct buffered_data *in;
diff -r f9a3f32a129b -r 99366b44c421 tools/xenstore/xenstored_watch.c
--- a/tools/xenstore/xenstored_watch.c  Tue Jul 26 15:08:22 2005
+++ b/tools/xenstore/xenstored_watch.c  Tue Jul 26 15:09:43 2005
@@ -102,7 +102,7 @@
        if (conn->waiting_reply) {
                conn->out = conn->waiting_reply;
                conn->waiting_reply = NULL;
-               conn->waiting_for_ack = false;
+               conn->waiting_for_ack = NULL;
                return;
        }
 
@@ -115,7 +115,7 @@
                return;
 
        /* If we decide to cancel, we will reset this. */
-       conn->waiting_for_ack = true;
+       conn->waiting_for_ack = event->watches[0];
 
        /* If we deleted /foo and they're watching /foo/bar, that's what we
         * tell them has changed. */
@@ -348,12 +348,17 @@
        if (!conn->waiting_for_ack)
                return send_error(conn, ENOENT);
 
-       event = get_first_event(conn);
-       if (!streq(event->watches[0]->token, token))
+       event = list_top(&conn->waiting_for_ack->events,
+                        struct watch_event, list);
+       assert(event->watches[0] == conn->waiting_for_ack);
+       if (!streq(conn->waiting_for_ack->token, token)) {
+               /* They're confused: this will cause us to send event again */
+               conn->waiting_for_ack = NULL;
                return send_error(conn, EINVAL);
+       }
 
        move_event_onwards(event);
-       conn->waiting_for_ack = false;
+       conn->waiting_for_ack = NULL;
        return send_ack(conn, XS_WATCH_ACK);
 }
 
diff -r f9a3f32a129b -r 99366b44c421 tools/xenstore/testsuite/13watch-ack.sh
--- /dev/null   Tue Jul 26 15:08:22 2005
+++ b/tools/xenstore/testsuite/13watch-ack.sh   Tue Jul 26 15:09:43 2005
@@ -0,0 +1,22 @@
+#! /bin/sh
+
+# This demonstrates a bug where an xs_acknowledge_watch returns
+# EINVAL, because the daemon doesn't track what watch event it sent
+# and relies on it being the "first" watch which has an event.
+# Watches firing after the first event is sent out will change this.
+
+# Create three things to watch.
+echo mkdir /test | ./xs_test
+echo mkdir /test/1 | ./xs_test
+echo mkdir /test/2 | ./xs_test
+echo mkdir /test/3 | ./xs_test
+
+# Watch all three, fire event on 2, read watch, fire event on 1 and 3, ack 2.
+[ "`echo '1 watch /test/1 token1 0
+1 watch /test/2 token2 0
+1 watch /test/3 token3 0
+2 write /test/2 create contents2
+1 waitwatch
+2 write /test/1 create contents1
+2 write /test/3 create contents3
+1 ackwatch token2' | ./xs_test 2>&1`" = "1:/test/2:token2" ]

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