From 03ecfb9280ece68cce33c2f2002877d9a000ef1e Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Tue, 5 Apr 2016 10:52:01 +0200 Subject: [PATCH] Be truthful about reporting whether readahead is available In 7346568 (Make requested console reports work, 2016-03-16), code was introduced to report the current cursor position. It works by using a pointer that either points to the next byte in the readahead buffer, or to a NUL byte if the buffer is depleted, or the pointer is NULL. These conditions are heeded in the fhandler_console::read() method, but the condition that the pointer can point at the end of the readahead buffer was not handled properly in the get_cons_readahead_valid() method. This poses a problem e.g. in Git for Windows (which uses a slightly modified MSYS2 runtime which is in turn a slightly modified Cygwin runtime) when vim queries the cursor position and immediately goes on to read console input, erroneously thinking that the readahead buffer is valid when it is already depleted instead. This condition results in an apparent freeze that can be helped only by pressing keys repeatedly. The full Git for Windows bug report is here: https://github.com/git-for-windows/git/issues/711 Let's just teach the get_cons_readahead_valid() method to handle a depleted readahead buffer correctly. Signed-off-by: Johannes Schindelin --- winsup/cygwin/fhandler.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/winsup/cygwin/fhandler.h b/winsup/cygwin/fhandler.h index 461055766..bd1a92378 100644 --- a/winsup/cygwin/fhandler.h +++ b/winsup/cygwin/fhandler.h @@ -1453,7 +1453,8 @@ private: bool focus_aware () {return shared_console_info->con.use_focus;} bool get_cons_readahead_valid () { - return shared_console_info->con.cons_rapoi != NULL; + return shared_console_info->con.cons_rapoi != NULL && + *shared_console_info->con.cons_rapoi; } select_record *select_read (select_stuff *);