actually implement imap_commit_cmds()

delay reporting success of STORE FLAGS until a subsequent CHECK
succeeds.

this fixes (inverse flag change propagation) and (deletes not being
propagated) after an interruption due to prematurely logged flag
updates.

src/drv_imap.c

@@ -129,9 +129,10 @@ struct imap_store {
 	string_list_t *auth_mechs;
 	parse_list_state_t parse_list_sts;
 	/* command queue */
-	int nexttag, num_in_progress;
 	imap_cmd_t *pending, **pending_append;
 	imap_cmd_t *in_progress, **in_progress_append;
+	imap_cmd_t *wait_check, **wait_check_append;
+	int nexttag, num_in_progress, num_wait_check;
 	uint buffer_mem; /* memory currently occupied by buffers in the queue */
 
 	/* Used during sequential operations like connect */
@@ -169,6 +170,7 @@ struct imap_cmd {
 		uint data_len;
 		uint uid; /* to identify fetch responses */
 		char high_prio; /* if command is queued, put it at the front of the queue. */
+		char wait_check;  // Don't report success until subsequent CHECK success.
 		char to_trash; /* we are storing to trash, not current. */
 		char create; /* create the mailbox if we get an error which suggests so. */
 		char failok; /* Don't complain about NO response. */
@@ -286,6 +288,8 @@ new_imap_cmd( uint size )
 static void
 done_imap_cmd( imap_store_t *ctx, imap_cmd_t *cmd, int response )
 {
+	if (cmd->param.wait_check)
+		ctx->num_wait_check--;
 	cmd->param.done( ctx, cmd, response );
 	if (cmd->param.data) {
 		free( cmd->param.data );
@@ -405,6 +409,18 @@ flush_imap_cmds( imap_store_t *ctx )
 	}
 }
 
+static void
+finalize_checked_imap_cmds( imap_store_t *ctx, int resp )
+{
+	imap_cmd_t *cmd;
+
+	while ((cmd = ctx->wait_check)) {
+		if (!(ctx->wait_check = cmd->next))
+			ctx->wait_check_append = &ctx->wait_check;
+		done_imap_cmd( ctx, cmd, resp );
+	}
+}
+
 static void
 cancel_pending_imap_cmds( imap_store_t *ctx )
 {
@@ -438,6 +454,8 @@ submit_imap_cmd( imap_store_t *ctx, imap_cmd_t *cmd )
 	assert( cmd );
 	assert( cmd->param.done );
 
+	if (cmd->param.wait_check)
+		ctx->num_wait_check++;
 	if ((ctx->pending && !cmd->param.high_prio) || !cmd_sendable( ctx, cmd )) {
 		if (ctx->pending && cmd->param.high_prio) {
 			cmd->next = ctx->pending;
@@ -1600,7 +1618,13 @@ imap_socket_read( void *aux )
 			imap_ref( ctx );
 			if (resp == RESP_CANCEL)
 				imap_invoke_bad_callback( ctx );
-			done_imap_cmd( ctx, cmdp, resp );
+			if (resp == RESP_OK && cmdp->param.wait_check) {
+				cmdp->next = NULL;
+				*ctx->wait_check_append = cmdp;
+				ctx->wait_check_append = &cmdp->next;
+			} else {
+				done_imap_cmd( ctx, cmdp, resp );
+			}
 			if (imap_deref( ctx ))
 				return;
 			if (ctx->canceling && !ctx->in_progress) {
@@ -1623,6 +1647,7 @@ get_cmd_result_p2( imap_store_t *ctx, imap_cmd_t *cmd, int response )
 	if (response != RESP_OK) {
 		done_imap_cmd( ctx, ocmd, response );
 	} else {
+		assert( !ocmd->param.wait_check );
 		ctx->uidnext = 1;
 		if (ocmd->param.to_trash)
 			ctx->trashnc = TrashKnown;
@@ -1643,6 +1668,7 @@ imap_cancel_store( store_t *gctx )
 	sasl_dispose( &ctx->sasl );
 #endif
 	socket_close( &ctx->conn );
+	finalize_checked_imap_cmds( ctx, RESP_CANCEL );
 	cancel_sent_imap_cmds( ctx );
 	cancel_pending_imap_cmds( ctx );
 	free( ctx->ns_prefix );
@@ -1699,6 +1725,8 @@ imap_free_store( store_t *gctx )
 {
 	imap_store_t *ctx = (imap_store_t *)gctx;
 
+	assert( !ctx->pending && !ctx->in_progress && !ctx->wait_check );
+
 	free_generic_messages( ctx->msgs );
 	ctx->msgs = NULL;
 	imap_set_bad_callback( gctx, imap_cancel_unowned, gctx );
@@ -1801,6 +1829,7 @@ imap_alloc_store( store_conf_t *conf, const char *label )
 	             imap_socket_read, (void (*)(void *))flush_imap_cmds, ctx );
 	ctx->in_progress_append = &ctx->in_progress;
 	ctx->pending_append = &ctx->pending;
+	ctx->wait_check_append = &ctx->wait_check;
 
   gotsrv:
 	ctx->gen.driver = &imap_driver;
@@ -2457,6 +2486,8 @@ imap_select_box( store_t *gctx, const char *name )
 {
 	imap_store_t *ctx = (imap_store_t *)gctx;
 
+	assert( !ctx->pending && !ctx->in_progress && !ctx->wait_check );
+
 	free_generic_messages( ctx->msgs );
 	ctx->msgs = NULL;
 	ctx->msgapp = &ctx->msgs;
@@ -2873,7 +2904,9 @@ imap_flags_helper( imap_store_t *ctx, uint uid, char what, int flags,
 	char buf[256];
 
 	buf[imap_make_flags( flags, buf )] = 0;
-	imap_exec( ctx, imap_refcounted_new_cmd( &sts->gen ), imap_set_flags_p2,
+	imap_cmd_t *cmd = imap_refcounted_new_cmd( &sts->gen );
+	cmd->param.wait_check = 1;
+	imap_exec( ctx, cmd, imap_set_flags_p2,
 	           "UID STORE %u %cFLAGS.SILENT %s", uid, what, buf );
 }
 
@@ -2934,6 +2967,8 @@ imap_close_box( store_t *gctx,
 {
 	imap_store_t *ctx = (imap_store_t *)gctx;
 
+	assert( !ctx->num_wait_check );
+
 	if (ctx->gen.conf->trash && CAP(UIDPLUS)) {
 		INIT_REFCOUNTED_STATE(imap_expunge_state_t, sts, cb, aux)
 		message_t *msg, *fmsg, *nmsg;
@@ -3216,6 +3251,7 @@ imap_cancel_cmds( store_t *gctx,
 {
 	imap_store_t *ctx = (imap_store_t *)gctx;
 
+	finalize_checked_imap_cmds( ctx, RESP_CANCEL );
 	cancel_pending_imap_cmds( ctx );
 	if (ctx->in_progress) {
 		ctx->canceling = 1;
@@ -3228,10 +3264,21 @@ imap_cancel_cmds( store_t *gctx,
 
 /******************* imap_commit_cmds *******************/
 
+static void imap_commit_cmds_p2( imap_store_t *, imap_cmd_t *, int );
+
 static void
 imap_commit_cmds( store_t *gctx )
 {
-	(void)gctx;
+	imap_store_t *ctx = (imap_store_t *)gctx;
+
+	if (ctx->num_wait_check)
+		imap_exec( ctx, NULL, imap_commit_cmds_p2, "CHECK" );
+}
+
+static void
+imap_commit_cmds_p2( imap_store_t *ctx, imap_cmd_t *cmd ATTR_UNUSED, int response )
+{
+	finalize_checked_imap_cmds( ctx, response );
 }
 
 /******************* imap_get_memory_usage *******************/

src/drv_proxy.c

@@ -288,14 +288,6 @@ proxy_@name@( store_t *gctx@decl_args@, void (*cb)( @decl_cb_args@void *aux ), v
 //# END
 #endif
 
-//# SPECIAL commit_cmds
-static void
-proxy_commit_cmds( store_t *gctx )
-{
-	// Currently a dummy in all real drivers.
-	(void) gctx;
-}
-
 //# SPECIAL set_bad_callback
 static void
 proxy_set_bad_callback( store_t *gctx, void (*cb)( void *aux ), void *aux )