From 28d52b2b181aba1d201caf12de7a6ce67181d273 Mon Sep 17 00:00:00 2001 From: Oswald Buddenhagen Date: Sat, 4 Mar 2017 12:47:33 +0100 Subject: [PATCH] de-obfuscate cmd_sendable() split the monster conditional and add comments. --- src/drv_imap.c | 36 +++++++++++++++++++++++++++--------- 1 file changed, 27 insertions(+), 9 deletions(-) diff --git a/src/drv_imap.c b/src/drv_imap.c index 80c97c9..e12c7cc 100644 --- a/src/drv_imap.c +++ b/src/drv_imap.c @@ -333,15 +333,33 @@ send_imap_cmd( imap_store_t *ctx, imap_cmd_t *cmd ) static int cmd_sendable( imap_store_t *ctx, imap_cmd_t *cmd ) { - imap_cmd_t *cmdp; - - return !ctx->conn.write_buf && - !(ctx->in_progress && - (cmdp = (imap_cmd_t *)((char *)ctx->in_progress_append - - offsetof(imap_cmd_t, next)), 1) && - (cmdp->param.cont || cmdp->param.data)) && - !(cmd->param.to_trash && ctx->trashnc == TrashChecking) && - ctx->num_in_progress < ((imap_store_conf_t *)ctx->gen.conf)->server->max_in_progress; + if (ctx->conn.write_buf) { + /* Don't build up a long queue in the socket, so we can + * control when the commands are actually sent. + * This allows reliable cancelation of pending commands, + * injecting commands in front of other pending commands, + * and keeping num_in_progress accurate. */ + return 0; + } + if (ctx->in_progress) { + /* If the last command in flight ... */ + imap_cmd_t *cmdp = (imap_cmd_t *)((char *)ctx->in_progress_append - + offsetof(imap_cmd_t, next)); + if (cmdp->param.cont || cmdp->param.data) { + /* ... is expected to trigger a continuation request, we need to + * wait for that round-trip before sending the next command. */ + return 0; + } + } + if (cmd->param.to_trash && ctx->trashnc == TrashChecking) { + /* Don't build a queue of MOVE/COPY/APPEND commands that may all fail. */ + return 0; + } + if (ctx->num_in_progress >= ((imap_store_conf_t *)ctx->gen.conf)->server->max_in_progress) { + /* Too many commands in flight. */ + return 0; + } + return 1; } static void