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fix(inccommand): restrict cmdpreview undo calls (#24289)
Problem: The cmdpreview saved undo nodes on cmdpreview_prepare() from ex_getln.c may become invalid (free) if the preview function makes undo operations, causing heap-use-after-free errors. Solution: Save the buffer undo list on cmdpreview_prepare)_ and start a new empty one. On cmdpreview_restore_state(), undo all the entries in the new undo list and restore the original one. With this approach, the preview function will be allowed to undo only its own changes. Fix #20036 Fix #20248
This commit is contained in:
Alexandre Teoi
GitHub
parent
74bd4aba57
commit
643bea31b8
@ -130,6 +130,30 @@ typedef struct command_line_state {
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buf_T *b_im_ptr_buf; ///< buffer where b_im_ptr is valid
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} CommandLineState;
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typedef struct cmdpreview_undo_info {
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u_header_T *save_b_u_oldhead;
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u_header_T *save_b_u_newhead;
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u_header_T *save_b_u_curhead;
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int save_b_u_numhead;
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bool save_b_u_synced;
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long save_b_u_seq_last;
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long save_b_u_save_nr_last;
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long save_b_u_seq_cur;
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time_t save_b_u_time_cur;
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long save_b_u_save_nr_cur;
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char *save_b_u_line_ptr;
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linenr_T save_b_u_line_lnum;
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colnr_T save_b_u_line_colnr;
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} CpUndoInfo;
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typedef struct cmdpreview_buf_info {
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buf_T *buf;
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long save_b_p_ul;
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int save_b_changed;
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varnumber_T save_changedtick;
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CpUndoInfo undo_info;
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} CpBufInfo;
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typedef struct cmdpreview_win_info {
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win_T *win;
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pos_T save_w_cursor;
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@ -138,17 +162,6 @@ typedef struct cmdpreview_win_info {
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int save_w_p_cuc;
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} CpWinInfo;
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typedef struct cmdpreview_buf_info {
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buf_T *buf;
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bool save_b_u_synced;
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time_t save_b_u_time_cur;
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long save_b_u_seq_cur;
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u_header_T *save_b_u_newhead;
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long save_b_p_ul;
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int save_b_changed;
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varnumber_T save_changedtick;
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} CpBufInfo;
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typedef struct cmdpreview_info {
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kvec_t(CpWinInfo) win_info;
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kvec_t(CpBufInfo) buf_info;
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@ -2277,8 +2290,48 @@ static void cmdpreview_close_win(void)
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}
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}
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/// Save the undo state of a buffer for command preview.
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static void cmdpreview_save_undo(CpUndoInfo *cp_undoinfo, buf_T *buf)
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FUNC_ATTR_NONNULL_ALL
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{
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cp_undoinfo->save_b_u_synced = buf->b_u_synced;
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cp_undoinfo->save_b_u_oldhead = buf->b_u_oldhead;
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cp_undoinfo->save_b_u_newhead = buf->b_u_newhead;
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cp_undoinfo->save_b_u_curhead = buf->b_u_curhead;
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cp_undoinfo->save_b_u_numhead = buf->b_u_numhead;
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cp_undoinfo->save_b_u_seq_last = buf->b_u_seq_last;
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cp_undoinfo->save_b_u_save_nr_last = buf->b_u_save_nr_last;
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cp_undoinfo->save_b_u_seq_cur = buf->b_u_seq_cur;
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cp_undoinfo->save_b_u_time_cur = buf->b_u_time_cur;
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cp_undoinfo->save_b_u_save_nr_cur = buf->b_u_save_nr_cur;
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cp_undoinfo->save_b_u_line_ptr = buf->b_u_line_ptr;
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cp_undoinfo->save_b_u_line_lnum = buf->b_u_line_lnum;
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cp_undoinfo->save_b_u_line_colnr = buf->b_u_line_colnr;
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}
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/// Restore the undo state of a buffer for command preview.
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static void cmdpreview_restore_undo(const CpUndoInfo *cp_undoinfo, buf_T *buf)
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{
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buf->b_u_oldhead = cp_undoinfo->save_b_u_oldhead;
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buf->b_u_newhead = cp_undoinfo->save_b_u_newhead;
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buf->b_u_curhead = cp_undoinfo->save_b_u_curhead;
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buf->b_u_numhead = cp_undoinfo->save_b_u_numhead;
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buf->b_u_seq_last = cp_undoinfo->save_b_u_seq_last;
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buf->b_u_save_nr_last = cp_undoinfo->save_b_u_save_nr_last;
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buf->b_u_seq_cur = cp_undoinfo->save_b_u_seq_cur;
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buf->b_u_time_cur = cp_undoinfo->save_b_u_time_cur;
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buf->b_u_save_nr_cur = cp_undoinfo->save_b_u_save_nr_cur;
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buf->b_u_line_ptr = cp_undoinfo->save_b_u_line_ptr;
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buf->b_u_line_lnum = cp_undoinfo->save_b_u_line_lnum;
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buf->b_u_line_colnr = cp_undoinfo->save_b_u_line_colnr;
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if (buf->b_u_curhead == NULL) {
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buf->b_u_synced = cp_undoinfo->save_b_u_synced;
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}
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}
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/// Save current state and prepare windows and buffers for command preview.
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static void cmdpreview_prepare(CpInfo *cpinfo)
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FUNC_ATTR_NONNULL_ALL
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{
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kv_init(cpinfo->buf_info);
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kv_init(cpinfo->win_info);
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@ -2294,14 +2347,13 @@ static void cmdpreview_prepare(CpInfo *cpinfo)
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CpBufInfo cp_bufinfo;
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cp_bufinfo.buf = buf;
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cp_bufinfo.save_b_u_synced = buf->b_u_synced;
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cp_bufinfo.save_b_u_time_cur = buf->b_u_time_cur;
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cp_bufinfo.save_b_u_seq_cur = buf->b_u_seq_cur;
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cp_bufinfo.save_b_u_newhead = buf->b_u_newhead;
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cp_bufinfo.save_b_p_ul = buf->b_p_ul;
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cp_bufinfo.save_b_changed = buf->b_changed;
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cp_bufinfo.save_changedtick = buf_get_changedtick(buf);
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cmdpreview_save_undo(&cp_bufinfo.undo_info, buf);
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u_clearall(buf);
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kv_push(cpinfo->buf_info, cp_bufinfo);
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buf->b_p_ul = LONG_MAX; // Make sure we can undo all changes
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@ -2336,8 +2388,9 @@ static void cmdpreview_prepare(CpInfo *cpinfo)
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u_sync(true);
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}
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// Restore the state of buffers and windows before command preview.
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/// Restore the state of buffers and windows for command preview.
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static void cmdpreview_restore_state(CpInfo *cpinfo)
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FUNC_ATTR_NONNULL_ALL
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{
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for (size_t i = 0; i < cpinfo->buf_info.size; i++) {
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CpBufInfo cp_bufinfo = cpinfo->buf_info.items[i];
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@ -2345,31 +2398,29 @@ static void cmdpreview_restore_state(CpInfo *cpinfo)
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buf->b_changed = cp_bufinfo.save_b_changed;
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if (buf->b_u_seq_cur != cp_bufinfo.save_b_u_seq_cur) {
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if (buf->b_u_seq_cur != cp_bufinfo.undo_info.save_b_u_seq_cur) {
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int count = 0;
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// Calculate how many undo steps are necessary to restore earlier state.
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for (u_header_T *uhp = buf->b_u_curhead ? buf->b_u_curhead : buf->b_u_newhead;
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uhp != NULL && uhp->uh_seq > cp_bufinfo.save_b_u_seq_cur;
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uhp != NULL;
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uhp = uhp->uh_next.ptr, ++count) {}
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aco_save_T aco;
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aucmd_prepbuf(&aco, buf);
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// Ensure all the entries will be undone
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if (curbuf->b_u_synced == false) {
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u_sync(true);
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}
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// Undo invisibly. This also moves the cursor!
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if (!u_undo_and_forget(count, false)) {
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abort();
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}
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aucmd_restbuf(&aco);
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// Restore newhead. It is meaningless when curhead is valid, but we must
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// restore it so that undotree() is identical before/after the preview.
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buf->b_u_newhead = cp_bufinfo.save_b_u_newhead;
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buf->b_u_time_cur = cp_bufinfo.save_b_u_time_cur;
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}
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if (buf->b_u_curhead == NULL) {
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buf->b_u_synced = cp_bufinfo.save_b_u_synced;
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}
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u_blockfree(buf);
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cmdpreview_restore_undo(&cp_bufinfo.undo_info, buf);
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if (cp_bufinfo.save_changedtick != buf_get_changedtick(buf)) {
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buf_set_changedtick(buf, cp_bufinfo.save_changedtick);
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@ -435,6 +435,28 @@ describe("'inccommand' for user commands", function()
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]])
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assert_alive()
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end)
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it("no crash if preview callback executes undo", function()
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command('set inccommand=nosplit')
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exec_lua([[
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vim.api.nvim_create_user_command('Foo', function() end, {
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nargs = '?',
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preview = function(_, _, _)
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vim.cmd.undo()
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end,
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})
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]])
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-- Clear undo history
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command('set undolevels=-1')
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feed('ggyyp')
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command('set undolevels=1000')
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feed('yypp:Fo')
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assert_alive()
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feed('<Esc>:Fo')
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assert_alive()
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end)
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end)
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describe("'inccommand' with multiple buffers", function()
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