introduce get_uidnext() driver callback

... and make 'uidnext' private to the imap driver.

src/driver.h

@@ -89,7 +89,6 @@ typedef struct store {
 
 	/* currently open mailbox */
 	int uidvalidity;
-	int uidnext; /* from SELECT responses */
 } store_t;
 
 typedef struct {
@@ -175,6 +174,9 @@ struct driver {
 	void (*open_box)( store_t *ctx,
 	                  void (*cb)( int sts, void *aux ), void *aux );
 
+	/* Return the minimal UID the next stored message will have. */
+	int (*get_uidnext)( store_t *ctx );
+
 	/* Confirm that the open mailbox is empty. */
 	int (*confirm_box_empty)( store_t *ctx );
 

src/drv_imap.c

@@ -112,6 +112,7 @@ struct imap_store {
 	// note that the message counts do _not_ reflect stats from msgs,
 	// but mailbox totals. also, don't trust them beyond the initial load.
 	int total_msgs, recent_msgs;
+	int uidnext;
 	message_t *msgs;
 	message_t **msgapp; /* FETCH results */
 	uint caps; /* CAPABILITY results */
@@ -1086,7 +1087,7 @@ parse_fetch_rsp( imap_store_t *ctx, list_t *list, char *s ATTR_UNUSED )
 	} else if ((cmdp = ctx->in_progress) && cmdp->param.lastuid) {
 		assert( !body && !tuid && !msgid );
 		// Workaround for server not sending UIDNEXT and/or APPENDUID.
-		ctx->gen.uidnext = uid + 1;
+		ctx->uidnext = uid + 1;
 	} else if (body) {
 		assert( !tuid && !msgid );
 		for (cmdp = ctx->in_progress; cmdp; cmdp = cmdp->next)
@@ -1171,7 +1172,7 @@ parse_response_code( imap_store_t *ctx, imap_cmd_t *cmd, char *s )
 			return RESP_CANCEL;
 		}
 	} else if (!strcmp( "UIDNEXT", arg )) {
-		if (!(arg = next_arg( &s )) || !(ctx->gen.uidnext = atoi( arg ))) {
+		if (!(arg = next_arg( &s )) || !(ctx->uidnext = atoi( arg ))) {
 			error( "IMAP error: malformed NEXTUID status\n" );
 			return RESP_CANCEL;
 		}
@@ -1520,7 +1521,7 @@ 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 {
-		ctx->gen.uidnext = 1;
+		ctx->uidnext = 1;
 		if (ocmd->param.to_trash)
 			ctx->trashnc = TrashKnown;
 		ocmd->param.create = 0;
@@ -2355,7 +2356,7 @@ imap_open_box( store_t *gctx,
 		return;
 	}
 
-	ctx->gen.uidnext = 0;
+	ctx->uidnext = 0;
 
 	INIT_IMAP_CMD(imap_cmd_simple_t, cmd, cb, aux)
 	cmd->gen.param.failok = 1;
@@ -2370,7 +2371,7 @@ imap_open_box_p2( imap_store_t *ctx, imap_cmd_t *gcmd, int response )
 	imap_cmd_simple_t *cmdp = (imap_cmd_simple_t *)gcmd;
 	imap_cmd_simple_t *cmd;
 
-	if (response != RESP_OK || ctx->gen.uidnext) {
+	if (response != RESP_OK || ctx->uidnext) {
 		imap_done_simple_box( ctx, &cmdp->gen, response );
 		return;
 	}
@@ -2385,12 +2386,20 @@ static void
 imap_open_box_p3( imap_store_t *ctx, imap_cmd_t *gcmd, int response )
 {
 	// This will happen if the box is empty.
-	if (!ctx->gen.uidnext)
-		ctx->gen.uidnext = 1;
+	if (!ctx->uidnext)
+		ctx->uidnext = 1;
 
 	imap_done_simple_box( ctx, gcmd, response );
 }
 
+static int
+imap_get_uidnext( store_t *gctx )
+{
+	imap_store_t *ctx = (imap_store_t *)gctx;
+
+	return ctx->uidnext;
+}
+
 /******************* imap_create_box *******************/
 
 static void
@@ -2536,7 +2545,7 @@ imap_load_box( store_t *gctx, int minuid, int maxuid, int newuid, int seenuid, i
 			imap_submit_load( ctx, buf, shifted_bit( ctx->opts, OPEN_OLD_IDS, WantMsgids ), sts );
 		}
 		if (maxuid == INT_MAX)
-			maxuid = ctx->gen.uidnext - 1;
+			maxuid = ctx->uidnext - 1;
 		if (maxuid >= minuid) {
 			imap_range_t ranges[3];
 			ranges[0].first = minuid;
@@ -2888,7 +2897,7 @@ imap_find_new_msgs_p2( imap_store_t *ctx, imap_cmd_t *gcmd, int response )
 		return;
 	}
 
-	ctx->gen.uidnext = 0;
+	ctx->uidnext = 0;
 
 	INIT_IMAP_CMD(imap_cmd_find_new_t, cmd, cmdp->callback, cmdp->callback_aux)
 	cmd->out_msgs = cmdp->out_msgs;
@@ -2904,14 +2913,14 @@ imap_find_new_msgs_p3( imap_store_t *ctx, imap_cmd_t *gcmd, int response )
 	imap_cmd_find_new_t *cmdp = (imap_cmd_find_new_t *)gcmd;
 	imap_cmd_find_new_t *cmd;
 
-	if (response != RESP_OK || ctx->gen.uidnext <= cmdp->uid) {
+	if (response != RESP_OK || ctx->uidnext <= cmdp->uid) {
 		imap_find_new_msgs_p4( ctx, gcmd, response );
 		return;
 	}
 	INIT_IMAP_CMD(imap_cmd_find_new_t, cmd, cmdp->callback, cmdp->callback_aux)
 	cmd->out_msgs = cmdp->out_msgs;
 	imap_exec( (imap_store_t *)ctx, &cmd->gen, imap_find_new_msgs_p4,
-	           "UID FETCH %d:%d (UID BODY.PEEK[HEADER.FIELDS (X-TUID)])", cmdp->uid, ctx->gen.uidnext - 1 );
+	           "UID FETCH %d:%d (UID BODY.PEEK[HEADER.FIELDS (X-TUID)])", cmdp->uid, ctx->uidnext - 1 );
 }
 
 static void
@@ -3343,6 +3352,7 @@ struct driver imap_driver = {
 	imap_get_box_path,
 	imap_create_box,
 	imap_open_box,
+	imap_get_uidnext,
 	imap_confirm_box_empty,
 	imap_delete_box,
 	imap_finish_delete_box,

src/drv_maildir.c

@@ -1311,6 +1311,12 @@ maildir_open_box( store_t *gctx,
 	cb( ret, aux );
 }
 
+static int
+maildir_get_uidnext( store_t *gctx ATTR_UNUSED )
+{
+	return 0;
+}
+
 static void
 maildir_create_box( store_t *gctx,
                     void (*cb)( int sts, void *aux ), void *aux )
@@ -1920,6 +1926,7 @@ struct driver maildir_driver = {
 	maildir_get_box_path,
 	maildir_create_box,
 	maildir_open_box,
+	maildir_get_uidnext,
 	maildir_confirm_box_empty,
 	maildir_delete_box,
 	maildir_finish_delete_box,

src/sync.c

@@ -1807,7 +1807,7 @@ box_loaded( int sts, message_t *msgs, int total_msgs, int recent_msgs, void *aux
 	if (UseFSync)
 		fdatasync( fileno( svars->jfp ) );
 	for (t = 0; t < 2; t++) {
-		svars->newuid[t] = svars->ctx[t]->uidnext;
+		svars->newuid[t] = svars->drv[t]->get_uidnext( svars->ctx[t] );
 		jFprintf( svars, "F %d %d\n", t, svars->newuid[t] );
 		svars->new_msgs[t] = svars->msgs[1-t];
 		msgs_copied( svars, t );