patch 9.0.1664: divide by zero when scrolling with 'smoothscroll' set

Problem:    Divide by zero when scrolling with 'smoothscroll' set.
Solution:   Avoid using a negative width. (closes #12540, closes #12528)

diff --git a/src/move.c b/src/move.c
index ea7d38005672483ca1f0222922e969e7e3f0f85e..22c37ce28591ed9a6ac83c98d73b0c1910e6ef26 100644 (file)
--- a/src/move.c
+++ b/src/move.c
@@ -2591,17 +2591,20 @@ scroll_cursor_bot(int min_scroll, int set_topbot)
                                        (curwin, curwin->w_topline, FALSE);
            int skip_lines = 0;
            int width1 = curwin->w_width - curwin_col_off();
-           int width2 = width1 + curwin_col_off2();
-           // similar formula is used in curs_columns()
-           if (curwin->w_skipcol > width1)
-               skip_lines += (curwin->w_skipcol - width1) / width2 + 1;
-           else if (curwin->w_skipcol > 0)
-               skip_lines = 1;
-
-           top_plines -= skip_lines;
-           if (top_plines > curwin->w_height)
+           if (width1 > 0)
            {
-               scrolled += (top_plines - curwin->w_height);
+               int width2 = width1 + curwin_col_off2();
+               // similar formula is used in curs_columns()
+               if (curwin->w_skipcol > width1)
+                   skip_lines += (curwin->w_skipcol - width1) / width2 + 1;
+               else if (curwin->w_skipcol > 0)
+                   skip_lines = 1;
+
+               top_plines -= skip_lines;
+               if (top_plines > curwin->w_height)
+               {
+                   scrolled += (top_plines - curwin->w_height);
+               }
            }
        }
     }

diff --git a/src/testdir/dumps/Test_smoothscroll_zero_bot.dump b/src/testdir/dumps/Test_smoothscroll_zero_bot.dump
new file mode 100644 (file)
index 0000000..179b95c
--- /dev/null
+++ b/src/testdir/dumps/Test_smoothscroll_zero_bot.dump
@@ -0,0 +1,19 @@
+| +0#af5f00255#ffffff0||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+|@+0#4040ff13&||+1#0000000&| +0&&@9
+>@+0#4040ff13&||+1#0000000&| +0&&@9
+|<+3&&| |<+1&&|a|m|e|]| |[|+|]| 
+| +0&&@11

diff --git a/src/testdir/test_scroll_opt.vim b/src/testdir/test_scroll_opt.vim
index 460416665d7ff0b66f07d9397e8449d5d75cf0bc..279e547f860302113f69cf97aaac6cd971a2be90 100644 (file)
--- a/src/testdir/test_scroll_opt.vim
+++ b/src/testdir/test_scroll_opt.vim
@@ -833,4 +833,28 @@ func Test_smoothscroll_multi_skipcol()
   call StopVimInTerminal(buf)
 endfunc
 
+" this was dividing by zero bug in scroll_cursor_bot
+func Test_smoothscroll_zero_width_scroll_cursor_bot()
+  CheckScreendump
+
+  let lines =<< trim END
+      silent normal yy
+      silent normal 19p
+      winsize 0 19
+      vsplit
+      vertical resize 0
+      set foldcolumn=1
+      set number
+      set smoothscroll
+      silent normal 20G
+  END
+  call writefile(lines, 'XSmoothScrollZeroBot', 'D')
+  let buf = RunVimInTerminal('-u NONE -S XSmoothScrollZeroBot', #{rows: 19, wait_for_ruler: 0})
+  call TermWait(buf, 1000)
+
+  call VerifyScreenDump(buf, 'Test_smoothscroll_zero_bot', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

diff --git a/src/version.c b/src/version.c
index 53ac924fecb63413eb63e3fffdd3d31adb9b5c9c..894b47d419761a6fa4d6af9a2197fc4625d14aae 100644 (file)
--- a/src/version.c
+++ b/src/version.c
@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1664,
 /**/
     1663,
 /**/