From ff06f283e3e4b3ec43012dd3b83f8454c98f6639 Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Tue, 21 Apr 2020 22:01:14 +0200
Subject: [PATCH] patch 8.2.0614: get ml_get error when deleting a line in
 'completefunc'

Problem:    Get ml_get error when deleting a line in 'completefunc'. (Yegappan
            Lakshmanan)
Solution:   Lock the text while evaluating 'completefunc'.
---
 runtime/doc/insert.txt       |  6 ++++--
 src/edit.c                   | 10 ++--------
 src/ex_getln.c               |  2 +-
 src/globals.h                |  5 +++--
 src/insexpand.c              | 22 ++++++++++++++--------
 src/testdir/test_edit.vim    | 21 +++++++++++++++++++--
 src/testdir/test_popup.vim   | 10 ++++------
 src/undo.c                   |  2 +-
 8 files changed, 48 insertions(+), 30 deletions(-)

diff --git a/runtime/doc/insert.txt b/runtime/doc/insert.txt
index 99c2d40..ff74d62 100644
--- a/runtime/doc/insert.txt
+++ b/runtime/doc/insert.txt
@@ -666,8 +666,10 @@ Note: The keys that are valid in CTRL-X mode are not mapped.  This allows for
 ends CTRL-X mode (any key that is not a valid CTRL-X mode command) is mapped.
 Also, when doing completion with 'complete' mappings apply as usual.
 
-Note: While completion is active Insert mode can't be used recursively.
-Mappings that somehow invoke ":normal i.." will generate an E523 error.
+							*E565*
+Note: While completion is active Insert mode can't be used recursively and
+buffer text cannot be changed.  Mappings that somehow invoke ":normal i.."
+will generate an E565 error.
 
 The following mappings are suggested to make typing the completion commands
 a bit easier (although they will hide other commands): >
diff --git a/src/edit.c b/src/edit.c
index 3f0803f..05518ce 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -175,16 +175,10 @@ edit(
 #endif
     // Don't allow changes in the buffer while editing the cmdline.  The
     // caller of getcmdline() may get confused.
-    if (textlock != 0)
-    {
-	emsg(_(e_secure));
-	return FALSE;
-    }
-
     // Don't allow recursive insert mode when busy with completion.
-    if (ins_compl_active() || compl_busy || pum_visible())
+    if (textlock != 0 || ins_compl_active() || compl_busy || pum_visible())
     {
-	emsg(_(e_secure));
+	emsg(_(e_textlock));
 	return FALSE;
     }
     ins_compl_clear();	    // clear stuff for CTRL-X mode
diff --git a/src/ex_getln.c b/src/ex_getln.c
index 9b959fb..18da926 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -2576,7 +2576,7 @@ get_text_locked_msg(void)
     if (cmdwin_type != 0)
 	return e_cmdwin;
 #endif
-    return e_secure;
+    return e_textlock;
 }
 
 /*
diff --git a/src/globals.h b/src/globals.h
index 4822bf3..f6c9d60 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -1678,9 +1678,10 @@ EXTERN char e_letunexp[]	INIT(= N_("E18: Unexpected characters in :let"));
 EXTERN char e_readerrf[]	INIT(= N_("E47: Error while reading errorfile"));
 #endif
 #ifdef HAVE_SANDBOX
-EXTERN char e_sandbox[]	INIT(= N_("E48: Not allowed in sandbox"));
+EXTERN char e_sandbox[]		INIT(= N_("E48: Not allowed in sandbox"));
 #endif
-EXTERN char e_secure[]	INIT(= N_("E523: Not allowed here"));
+EXTERN char e_secure[]		INIT(= N_("E523: Not allowed here"));
+EXTERN char e_textlock[]	INIT(= N_("E565: Not allowed to change text here"));
 #if defined(AMIGA) || defined(MACOS_X) || defined(MSWIN)  \
 	|| defined(UNIX) || defined(VMS)
 EXTERN char e_screenmode[]	INIT(= N_("E359: Screen mode setting not supported"));
diff --git a/src/insexpand.c b/src/insexpand.c
index 0278522..48ab260 100644
--- a/src/insexpand.c
+++ b/src/insexpand.c
@@ -2217,6 +2217,8 @@ expand_by_function(
     pos = curwin->w_cursor;
     curwin_save = curwin;
     curbuf_save = curbuf;
+    // Lock the text to avoid weird things from happening.
+    ++textlock;
 
     // Call a function, which returns a list or dict.
     if (call_vim_function(funcname, 2, args, &rettv) == OK)
@@ -2239,6 +2241,7 @@ expand_by_function(
 		break;
 	}
     }
+    --textlock;
 
     if (curwin_save != curwin || curbuf_save != curbuf)
     {
@@ -2431,6 +2434,7 @@ set_completion(colnr_T startcol, list_T *list)
 f_complete(typval_T *argvars, typval_T *rettv UNUSED)
 {
     int	    startcol;
+    int	    save_textlock = textlock;
 
     if ((State & INSERT) == 0)
     {
@@ -2438,22 +2442,24 @@ f_complete(typval_T *argvars, typval_T *rettv UNUSED)
 	return;
     }
 
+    // "textlock" is set when evaluating 'completefunc' but we can change text
+    // here.
+    textlock = 0;
+
     // Check for undo allowed here, because if something was already inserted
     // the line was already saved for undo and this check isn't done.
     if (!undo_allowed())
 	return;
 
     if (argvars[1].v_type != VAR_LIST || argvars[1].vval.v_list == NULL)
-    {
 	emsg(_(e_invarg));
-	return;
+    else
+    {
+	startcol = (int)tv_get_number_chk(&argvars[0], NULL);
+	if (startcol > 0)
+	    set_completion(startcol - 1, argvars[1].vval.v_list);
     }
-
-    startcol = (int)tv_get_number_chk(&argvars[0], NULL);
-    if (startcol <= 0)
-	return;
-
-    set_completion(startcol - 1, argvars[1].vval.v_list);
+    textlock = save_textlock;
 }
 
 /*
diff --git a/src/testdir/test_edit.vim b/src/testdir/test_edit.vim
index 9096fcd..ce55f6b 100644
--- a/src/testdir/test_edit.vim
+++ b/src/testdir/test_edit.vim
@@ -915,6 +915,23 @@ func Test_edit_CTRL_U()
   bw!
 endfunc
 
+func Test_edit_completefunc_delete()
+  func CompleteFunc(findstart, base)
+    if a:findstart == 1
+      return col('.') - 1
+    endif
+    normal dd
+    return ['a', 'b']
+  endfunc
+  new
+  set completefunc=CompleteFunc
+  call setline(1, ['', 'abcd', ''])
+  2d
+  call assert_fails("normal 2G$a\<C-X>\<C-U>", 'E565:')
+  bwipe!
+endfunc
+
+
 func Test_edit_CTRL_Z()
   " Ctrl-Z when insertmode is not set inserts it literally
   new
@@ -1240,7 +1257,7 @@ func Test_edit_forbidden()
   try
     call feedkeys("ix\<esc>", 'tnix')
     call assert_fails(1, 'textlock')
-  catch /^Vim\%((\a\+)\)\=:E523/ " catch E523: not allowed here
+  catch /^Vim\%((\a\+)\)\=:E565/ " catch E565: not allowed here
   endtry
   " TODO: Might be a bug: should x really be inserted here
   call assert_equal(['xa'], getline(1, '$'))
@@ -1264,7 +1281,7 @@ func Test_edit_forbidden()
   try
     call feedkeys("i\<c-x>\<c-u>\<esc>", 'tnix')
     call assert_fails(1, 'change in complete function')
-  catch /^Vim\%((\a\+)\)\=:E523/ " catch E523
+  catch /^Vim\%((\a\+)\)\=:E565/ " catch E565
   endtry
   delfu Complete
   set completefunc=
diff --git a/src/testdir/test_popup.vim b/src/testdir/test_popup.vim
index e96d5fd..9890377 100644
--- a/src/testdir/test_popup.vim
+++ b/src/testdir/test_popup.vim
@@ -334,19 +334,17 @@ func DummyCompleteOne(findstart, base)
   endif
 endfunc
 
-" Test that nothing happens if the 'completefunc' opens
-" a new window (no completion, no crash)
+" Test that nothing happens if the 'completefunc' tries to open
+" a new window (fails to open window, continues)
 func Test_completefunc_opens_new_window_one()
   new
   let winid = win_getid()
   setlocal completefunc=DummyCompleteOne
   call setline(1, 'one')
   /^one
-  call assert_fails('call feedkeys("A\<C-X>\<C-U>\<C-N>\<Esc>", "x")', 'E839:')
-  call assert_notequal(winid, win_getid())
-  q!
+  call assert_fails('call feedkeys("A\<C-X>\<C-U>\<C-N>\<Esc>", "x")', 'E565:')
   call assert_equal(winid, win_getid())
-  call assert_equal('', getline(1))
+  call assert_equal('oneDEF', getline(1))
   q!
 endfunc
 
diff --git a/src/undo.c b/src/undo.c
index c5ce306..c11b048 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -333,7 +333,7 @@ undo_allowed(void)
     // caller of getcmdline() may get confused.
     if (textlock != 0)
     {
-	emsg(_(e_secure));
+	emsg(_(e_textlock));
 	return FALSE;
     }
 
-- 
1.8.3.1

