bug#65060: 29.1.50; display_count_lines segv

[Kai Ma]

On Aug 12, 2023, at 16:41, Eli Zaretskii <eliz@gnu.org> wrote:

From: Kai Ma <justksqsf@gmail.com>
Date: Sat, 12 Aug 2023 15:28:16 +0800
Cc: 65060@debbugs.gnu.org

On Aug 12, 2023, at 14:50, Eli Zaretskii <eliz@gnu.org> wrote:

Ping!  Can you please help me finish investigating this bug by
providing the information I asked for?  Armed with that information, I
think I will be able to find a solution.

Sorry for the late reply!

cursor (before do) = 0x0
* GPT_BYTE = 3072
* GAP_SIZE = 2000
* BEG_ADDR = 0x0
* current_buffer->text->beg = 0x0

cursor (before memchr) = 0x0
* GPT_BYTE = 3072
* GAP_SIZE = 2000
* BEG_ADDR = 0x0
* current_buffer->text->beg = 0x0

Thanks.  My guess was correct: the buffer in question was killed.

Could you please try the patch below, and see if it avoids the
crashes?  The patch causes Emacs to signal an error when
format-mode-line is called for a dead buffer, so if I did this
correctly, you should see that Emacs no longer crashes, but there are
error messages about a dead buffer in *Messages*.  If this is what
happens, you should then take this up with the dirvish developers, and
ask them to avoid calling format-mode-line for a killed buffer.

Thanks!  The patch prevents the crash.  I will report this to dirvish developers.