patch 9.1.0116: win_split_ins may not check available room Commit: https://github.com/vim/vim/commit/0fd44a5ad81ade342cb54d8984965bdedd2272c8 Author: Sean Dewar <6256228+seandewar@users.noreply.github.com> Date: Tue Feb 20 20:28:15 2024 +0100 patch 9.1.0116: win_split_ins may not check available room Problem: win_split_ins has no check for E36 when moving an existing window Solution: check for room and fix the issues in f_win_splitmove() (Sean Dewar) win_split_ins has no check for E36 when moving an existing window, allowing for layouts with many overlapping zero-sized windows to be created (which may also cause drawing issues with tablines and such). f_win_splitmove also has some bugs. So check for room and fix the issues in f_win_splitmove. Handle failure in the two relevant win_split_ins callers by restoring the original layout, and factor the common logic into win_splitmove. Don't check for room when opening an autocommand window, as it's a temporary window that's rarely interacted with or drawn anyhow, and is rather important for some autocommands. Issues fixed in f_win_splitmove: - Error if splitting is disallowed. - Fix heap-use-after-frees if autocommands fired from switching to "targetwin" close "wp" or "oldwin". - Fix splitting the wrong window if autocommands fired from switching to "targetwin" switch to a different window. - Ensure -1 is returned for all errors. Also handle allocation failure a bit earlier in make_snapshot (callers, except win_splitmove, don't really care if a snapshot can't be made, so just ignore the return value). Note: Test_smoothscroll_in_zero_width_window failed after these changes with E36, as it was using the previous behaviour to create a zero-width window. I've fixed the test such that it fails with UBSAN as expected when v9.0.1367 is reverted (and simplified it too). related: #14042 Signed-off-by: Sean Dewar <6256228+seandewar@users.noreply.github.com> Signed-off-by: Christian Brabandt <cb@256bit.org>

--- a/src/proto/window.pro
+++ b/src/proto/window.pro
@@ -4,7 +4,9 @@ win_T *prevwin_curwin(void);
 win_T *swbuf_goto_win_with_buf(buf_T *buf);
 void do_window(int nchar, long Prenum, int xchar);
 void get_wincmd_addr_type(char_u *arg, exarg_T *eap);
+int check_split_disallowed(win_T *wp);
 int win_split(int size, int flags);
+int win_splitmove(win_T *wp, int size, int flags);
 int win_split_ins(int size, int flags, win_T *new_wp, int dir);
 int win_valid_popup(win_T *win);
 int win_valid(win_T *win);
@@ -88,7 +90,7 @@ int only_one_window(void);
 void check_lnums(int do_curwin);
 void check_lnums_nested(int do_curwin);
 void reset_lnums(void);
-void make_snapshot(int idx);
+int make_snapshot(int idx);
 void restore_snapshot(int idx, int close_curwin);
 int win_hasvertsplit(void);
 int get_win_number(win_T *wp, win_T *first_win);