vim-patch:8.0.0486

Problem:    Crash and endless loop when closing windows in a SessionLoadPost
            autocommand.
Solution:   Check for valid tabpage.  (partly neovim/neovim#6308)

https://github.com/vim/vim/commit/8c752bd6c4af54c0b7bac35a39acc2bf16015f85

Closes #6308

3 files changed, 121 insertions, 11 deletions

diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 873c15ff4a..d948e20b32 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -6464,6 +6464,12 @@ win_found:
     win_remove(curwin, NULL);
     aucmd_win_used = false;
     last_status(false);         // may need to remove last status line
+
+    if (!valid_tabpage_win(curtab)) {
+      // no valid window in current tabpage
+      close_tabpage(curtab);
+    }
+
     restore_snapshot(SNAP_AUCMD_IDX, false);
     (void)win_comp_pos();       // recompute window positions
     unblock_autocmds();
diff --git a/src/nvim/testdir/test_autocmd.vim b/src/nvim/testdir/test_autocmd.vim
index f05a55f1aa..fe9a3dd451 100644
--- a/src/nvim/testdir/test_autocmd.vim
+++ b/src/nvim/testdir/test_autocmd.vim
@@ -196,3 +196,71 @@ func Test_augroup_deleted()
   au! VimEnter
 endfunc
 
+" Closing a window might cause an endless loop
+" E814 for older Vims
+function Test_autocmd_bufwipe_in_SessLoadPost()
+  if has('win32')
+    throw 'Skipped: test hangs on MS-Windows'
+  endif
+  tabnew
+  set noswapfile
+  let g:bufnr=bufnr('%')
+  mksession!
+
+  let content=['set nocp noswapfile',
+        \ 'let v:swapchoice="e"',
+        \ 'augroup test_autocmd_sessionload',
+        \ 'autocmd!',
+        \ 'autocmd SessionLoadPost * 4bw!',
+        \ 'augroup END'
+        \ ]
+  call writefile(content, 'Xvimrc')
+  let a=system(v:progpath. ' --headless -u Xvimrc --noplugins -S Session.vim')
+  call assert_match('E814', a)
+
+  unlet! g:bufnr
+  set swapfile
+  for file in ['Session.vim', 'Xvimrc']
+    call delete(file)
+  endfor
+endfunc
+
+" SEGV occurs in older versions.
+function Test_autocmd_bufwipe_in_SessLoadPost2()
+  if has('win32')
+    throw 'Skipped: test hangs on MS-Windows'
+  endif
+  tabnew
+  set noswapfile
+  let g:bufnr=bufnr('%')
+  mksession!
+
+  let content = ['set nocp noswapfile',
+      \ 'function! DeleteInactiveBufs()',
+      \ '  tabfirst',
+      \ '  let tabblist = []',
+      \ '  for i in range(1, tabpagenr(''$''))',
+      \ '    call extend(tabblist, tabpagebuflist(i))',
+      \ '  endfor',
+      \ '  for b in range(1, bufnr(''$''))',
+      \ '    if bufexists(b) && buflisted(b) && (index(tabblist, b) == -1 || bufname(b) =~# ''^$'')',
+      \ '      exec ''bwipeout '' . b',
+      \ '    endif',
+      \ '  endfor',
+      \ 'call append("1", "SessionLoadPost DONE")',
+      \ 'endfunction',
+      \ 'au SessionLoadPost * call DeleteInactiveBufs()']
+  call writefile(content, 'Xvimrc')
+  let a=system(v:progpath. ' --headless -u Xvimrc --noplugins -S Session.vim')
+  " this probably only matches on unix
+  if has("unix")
+    call assert_notmatch('Caught deadly signal SEGV', a)
+  endif
+  call assert_match('SessionLoadPost DONE', a)
+
+  unlet! g:bufnr
+  set swapfile
+  for file in ['Session.vim', 'Xvimrc']
+    call delete(file)
+  endfor
+endfunc
diff --git a/src/nvim/window.c b/src/nvim/window.c
index 6c9d3554f1..eda3cd7810 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -1714,14 +1714,10 @@ static void win_equal_rec(
   }
 }
 
-/*
- * close all windows for buffer 'buf'
- */
-void 
-close_windows (
-    buf_T *buf,
-    int keep_curwin                    /* don't close "curwin" */
-)
+/// Closes all windows for buffer `buf`.
+///
+/// @param keep_curwin don't close `curwin`
+void close_windows(buf_T *buf, int keep_curwin)
 {
   tabpage_T   *tp, *nexttp;
   int h = tabline_height();
@@ -1731,9 +1727,11 @@ close_windows (
 
   for (win_T *wp = firstwin; wp != NULL && lastwin != firstwin; ) {
     if (wp->w_buffer == buf && (!keep_curwin || wp != curwin)
-        && !(wp->w_closing || wp->w_buffer->b_closing)
-        ) {
-      win_close(wp, FALSE);
+        && !(wp->w_closing || wp->w_buffer->b_closing)) {
+      if (win_close(wp, false) == FAIL) {
+        // If closing the window fails give up, to avoid looping forever.
+        break;
+      }
 
       /* Start all over, autocommands may change the window layout. */
       wp = firstwin;
@@ -3134,6 +3132,44 @@ bool valid_tabpage(tabpage_T *tpc) FUNC_ATTR_PURE FUNC_ATTR_WARN_UNUSED_RESULT
   return false;
 }
 
+/// Returns true when `tpc` is valid and at least one window is valid.
+int valid_tabpage_win(tabpage_T *tpc)
+{
+  FOR_ALL_TABS(tp) {
+    if (tp == tpc) {
+      FOR_ALL_WINDOWS_IN_TAB(wp, tp) {
+        if (win_valid_any_tab(wp)) {
+          return true;
+        }
+      }
+      return false;
+    }
+  }
+  // shouldn't happen
+  return false;
+}
+
+/// Close tabpage `tab`, assuming it has no windows in it.
+/// There must be another tabpage or this will crash.
+void close_tabpage(tabpage_T *tab)
+{
+  tabpage_T *ptp;
+
+  if (tab == first_tabpage) {
+    first_tabpage = tab->tp_next;
+    ptp = first_tabpage;
+  } else {
+    for (ptp = first_tabpage; ptp != NULL && ptp->tp_next != tab;
+         ptp = ptp->tp_next) {
+      // do nothing
+    }
+    ptp->tp_next = tab->tp_next;
+  }
+
+  goto_tabpage_tp(ptp, false, false);
+  free_tabpage(tab);
+}
+
 /*
  * Find tab page "n" (first one is 1).  Returns NULL when not found.
  */