Sean Dewar
bf21df1c7b
Problem: close_buffer() callers incorrectly handle b_nwindows,
especially after nasty autocmds, allowing it to go
out-of-sync. May lead to buffers that can't be unloaded, or
buffers that are prematurely freed whilst displayed.
Solution: Modify close_buffer() and review its callers; let them
decrement b_nwindows if it didn't unload the buffer. Remove
some now unneeded workarounds like 8.2.2354, 9.1.0143,
9.1.0764, which didn't always work (Sean Dewar)
close_buffer() now doesn't decrement b_nwindows when not unloading buf, or when
buf isn't w_buffer after autocmds (they would've already decremented it).
Callers are now expected to decrement b_nwindows if w_buffer is not NULL after
close_buffer(), and when still intending to switch buffers or close win, for two
reasons:
- close_buffer() autocmds may have switched buffers. The new w_buffer's
b_nwindows would also need decrementing.
- After close_buffer(), callers may opt to not switch w_buffer or close win.
b_nwindows would need to be incremented again. (unless w_buffer is NULL from
being unloaded; callers are already forced to find a new buffer then)
These were the main causes of b_nwindows bugs, as these cases could not be
reliably detected, and went largely unhandled.
NOTE: if close_buffer() autocmds switch buffers, close_buffer() is not called
for that new buffer before decrementing b_nwindows. This may skip side-effects
like from 'bufhidden', but I think it's mostly harmless, and was already
happening in other places.
Let's see how this goes... Other details: (I have lots to say!)
It's OK to pass a win to close_buffer() that isn't showing buf (used by
set_curbuf()). In that case, we skip some side-effects and don't decrement
b_nwindows, but may still unload buf if hidden.
buf_freeall() now returns whether it freed anything. Removes some repeated
checks in close_buffer().
Preserve close_buffer()'s behaviour when called by win_free_popup() after its
popup was already removed from the window list. This made win_valid_any_tab()
return FALSE, so we skip things that originally checked it in that case.
Add "set_context" to close_buffer() to preserve do_ecmd()'s behaviour of only
setting b_last_cursor and/or calling buflist_setfpos() when not splitting
(see 7.2.041: https://groups.google.com/g/vim_dev/c/ZGgNvaylNzI/m/WHxjhnuxqB0J)
Without this, Test_marks_cmd() fails from its ' mark differing. Don't use
oldwin though; it's not always the window with the closed buf, especially
after BufLeave autocmds in do_ecmd(). Also, only set context if win is really
displaying buf.
Don't bail in do_ecmd() if buf was deleted but curwin->w_buffer is NULL; that
leaves curwin open to a NULL buffer! Use lastbuf instead, like set_curbuf().
I don't think it's possible for buf to be deleted by close_buffer() anyway, as
b_locked was set (which I can't see a way to bypass, unlike b_locked_split).
Maybe such checks can be removed, but I'd rather not risk that here.
Don't set curwin to previouswin in set_curbuf(); shouldn't be needed, otherwise
may lead to curbuf != curwin->w_buffer if autocmds switch to a window showing
buf, as that skips enter_buffer()? Was introduced back in 7.3.557 to avoid
cases where autocmds switch windows, possibly leaving previouswin with a NULL
buffer. Since 7.4.2312 and 7.4.2328, close_buffer() and buf_freeall() already
handles this. I've added an assert() as a sanity check anyway.
In free_all_mem(), set b_nwindows to 0 before close_buffer() so buffers can be
wiped if still in a window before win_free_all(). Needed as close_buffer() now
skips unloading buffers that aren't hidden if win is NULL. If it's possible for
free_all_mem()'s :tabonly! and :only! to not close all windows before freeing,
then this issue was also previously possible if b_nwindows > 1.
related: #19728
Signed-off-by: Sean Dewar <6256228+seandewar@users.noreply.github.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
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This is README.md for version 9.2 of Vim: Vi IMproved.