commit b6befc7b0333ede9f44df3527f304729fdfe8426
parent 7d1ea699fb939fda4437f8ee507f33ec9ee03715
Author: zeertzjq <zeertzjq@outlook.com>
Date: Tue, 27 Jan 2026 11:46:54 +0800
fix(terminal): losing scrollback when TermOpen polls for events (#37573)
Problem: When TermOpen polls for enough events to use the scrollback
buffer, scrollback is lost until the next terminal refresh.
Solution: Allocate the scrollback buffer when it's needed.
Diffstat:
3 files changed, 78 insertions(+), 25 deletions(-)
diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
@@ -444,6 +444,34 @@ static void term_output_callback(const char *s, size_t len, void *user_data)
terminal_send((Terminal *)user_data, s, len);
}
+/// Allocates a terminal's scrollback buffer if it hasn't been allocated yet.
+/// Does nothing if it's already allocated, unlike adjust_scrollback().
+///
+/// @param term Terminal instance.
+/// @param buf The terminal's buffer, or NULL to get it from buf_handle.
+///
+/// @return whether the terminal now has a scrollback buffer.
+static bool term_may_alloc_scrollback(Terminal *term, buf_T *buf)
+{
+ if (term->sb_buffer != NULL) {
+ return true;
+ }
+ if (buf == NULL) {
+ buf = handle_get_buffer(term->buf_handle);
+ if (buf == NULL) { // No need to allocate scrollback if buffer is deleted.
+ return false;
+ }
+ }
+
+ if (buf->b_p_scbk < 1) {
+ buf->b_p_scbk = SB_MAX;
+ }
+ // Configure the scrollback buffer.
+ term->sb_size = (size_t)buf->b_p_scbk;
+ term->sb_buffer = xmalloc(sizeof(ScrollbackLine *) * term->sb_size);
+ return true;
+}
+
// public API {{{
/// Initializes terminal properties, and triggers TermOpen.
@@ -529,9 +557,11 @@ void terminal_open(Terminal **termpp, buf_T *buf, TerminalOptions opts)
RESET_BINDING(curwin);
// Reset cursor in current window.
curwin->w_cursor = (pos_T){ .lnum = 1, .col = 0, .coladd = 0 };
- // Initialize to check if the scrollback buffer has been allocated in a TermOpen autocmd.
- term->sb_buffer = NULL;
- // Apply TermOpen autocmds _before_ configuring the scrollback buffer.
+
+ // Apply TermOpen autocmds _before_ configuring the scrollback buffer, to avoid
+ // over-allocating in case TermOpen reduces 'scrollback'.
+ // In the rare case where TermOpen polls for events, the scrollback buffer will be
+ // allocated anyway if needed.
apply_autocmds(EVENT_TERMOPEN, NULL, NULL, false, buf);
aucmd_restbuf(&aco);
@@ -540,14 +570,9 @@ void terminal_open(Terminal **termpp, buf_T *buf, TerminalOptions opts)
return; // Terminal has already been destroyed.
}
- if (term->sb_buffer == NULL) {
- // Local 'scrollback' _after_ autocmds.
- if (buf->b_p_scbk < 1) {
- buf->b_p_scbk = SB_MAX;
- }
- // Configure the scrollback buffer.
- term->sb_size = (size_t)buf->b_p_scbk;
- term->sb_buffer = xmalloc(sizeof(ScrollbackLine *) * term->sb_size);
+ // Local 'scrollback' _after_ autocmds.
+ if (!term_may_alloc_scrollback(term, buf)) {
+ abort();
}
// Configure the color palette. Try to get the color from:
@@ -1494,9 +1519,10 @@ static int term_sb_push(int cols, const VTermScreenCell *cells, void *data)
{
Terminal *term = data;
- if (!term->sb_size) {
+ if (!term_may_alloc_scrollback(term, NULL)) {
return 0;
}
+ assert(term->sb_size > 0);
// copy vterm cells into sb_buffer
size_t c = (size_t)cols;
diff --git a/test/functional/terminal/buffer_spec.lua b/test/functional/terminal/buffer_spec.lua
@@ -772,10 +772,12 @@ describe(':terminal buffer', function()
]])
end)
- it('does not drop data when job exits immediately after output #3030', function()
+ --- @param subcmd 'REP'|'REPFAST'
+ local function check_term_rep_20000(subcmd)
local screen = Screen.new(50, 7)
+ api.nvim_set_option_value('scrollback', 30000, {})
api.nvim_create_autocmd('TermClose', { command = 'let g:did_termclose = 1' })
- fn.jobstart({ testprg('shell-test'), 'REPFAST', '20000', 'TEST' }, { term = true })
+ fn.jobstart({ testprg('shell-test'), subcmd, '20000', 'TEST' }, { term = true })
retry(nil, nil, function()
eq(1, api.nvim_get_var('did_termclose'))
end)
@@ -789,6 +791,23 @@ describe(':terminal buffer', function()
[Process exited 0]^ |
{5:-- TERMINAL --} |
]])
+ local lines = api.nvim_buf_get_lines(0, 0, -1, true)
+ for i = 0, 19999 do
+ eq(('%d: TEST'):format(i), lines[i + 1])
+ end
+ end
+
+ it('does not drop data when job exits immediately after output #3030', function()
+ check_term_rep_20000('REPFAST')
+ end)
+
+ -- it('does not drop data when autocommands poll for events #37559', function()
+ it('does not drop data when TermOpen polls for events', function()
+ -- api.nvim_create_autocmd('BufFilePre', { command = 'sleep 50m', nested = true })
+ -- api.nvim_create_autocmd('BufFilePost', { command = 'sleep 50m', nested = true })
+ api.nvim_create_autocmd('TermOpen', { command = 'sleep 50m', nested = true })
+ -- REP pauses 1 ms every 100 lines, so each autocommand processes some output.
+ check_term_rep_20000('REP')
end)
it('handles unprintable chars', function()
diff --git a/test/functional/terminal/channel_spec.lua b/test/functional/terminal/channel_spec.lua
@@ -140,17 +140,18 @@ end)
describe('no crash when TermOpen autocommand', function()
local screen
+ -- Use REPFAST for immediately output after start.
+ local term_args = { testprg('shell-test'), 'REPFAST', '50', 'TEST' }
before_each(function()
clear()
- api.nvim_set_option_value('shell', testprg('shell-test'), {})
- command('set shellcmdflag=EXE shellredir= shellpipe= shellquote= shellxquote=')
screen = Screen.new(60, 4)
+ command([[call setline(1, 'OLDBUF') | enew]])
end)
- it('processes job exit event on jobstart(…,{term=true})', function()
+ it('processes job exit event when using jobstart(…,{term=true})', function()
command([[autocmd TermOpen * call input('')]])
- async_meths.nvim_command('terminal foobar')
+ async_meths.nvim_call_function('jobstart', { term_args, { term = true } })
screen:expect([[
|
{1:~ }|*2
@@ -158,14 +159,21 @@ describe('no crash when TermOpen autocommand', function()
]])
feed('<CR>')
screen:expect([[
- ^ready $ foobar |
+ ^0: TEST |
+ 1: TEST |
+ 2: TEST |
|
- [Process exited 0] |
+ ]])
+ feed('i')
+ screen:expect([[
+ 49: TEST |
|
+ [Process exited 0]^ |
+ {5:-- TERMINAL --} |
]])
- feed('i<CR>')
+ feed('<CR>')
screen:expect([[
- ^ |
+ ^OLDBUF |
{1:~ }|*2
|
]])
@@ -174,7 +182,7 @@ describe('no crash when TermOpen autocommand', function()
it('wipes buffer and processes events when using jobstart(…,{term=true})', function()
command([[autocmd TermOpen * bwipe! | call input('')]])
- async_meths.nvim_command('terminal foobar')
+ async_meths.nvim_call_function('jobstart', { term_args, { term = true } })
screen:expect([[
|
{1:~ }|*2
@@ -182,7 +190,7 @@ describe('no crash when TermOpen autocommand', function()
]])
feed('<CR>')
screen:expect([[
- ^ |
+ ^OLDBUF |
{1:~ }|*2
|
]])
@@ -199,7 +207,7 @@ describe('no crash when TermOpen autocommand', function()
]])
feed('<CR>')
screen:expect([[
- ^ |
+ ^OLDBUF |
{1:~ }|*2
|
]])
