From 44a331c36b5af25e51b072e8e77c478c2540ff43 Mon Sep 17 00:00:00 2001
From: Jan Edmund Lazo <jan.lazo@mail.utoronto.ca>
Date: Wed, 5 May 2021 22:08:18 -0400
Subject: vim-patch:8.2.2820: session file may divide by zero

Problem:    Session file may divide by zero.
Solution:   Avoid writing difide by zero. (closes vim/vim#8162)
https://github.com/vim/vim/commit/b6c2e9a010ebd7db586081957e634903d4972fa1

Avoid typecasts if possible.
Use PRIdLINENR, PRId64, to format line numbers.
---
 src/nvim/ex_session.c               | 23 +++++++++++++++--------
 src/nvim/testdir/test_mksession.vim | 15 +++++++++++++++
 2 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/src/nvim/ex_session.c b/src/nvim/ex_session.c
index b11ec4ad05..9e4e69e124 100644
--- a/src/nvim/ex_session.c
+++ b/src/nvim/ex_session.c
@@ -447,18 +447,25 @@ static int put_view(
   if (do_cursor) {
     // Restore the cursor line in the file and relatively in the
     // window.  Don't use "G", it changes the jumplist.
+    if (wp->w_height_inner <= 0) {
+      if (fprintf(fd, "let s:l = %" PRIdLINENR "\n", wp->w_cursor.lnum) < 0) {
+        return FAIL;
+      }
+    } else if (fprintf(fd,
+                       "let s:l = %" PRIdLINENR " - ((%" PRIdLINENR
+                       " * winheight(0) + %" PRId64 ") / %" PRId64 ")\n",
+                       wp->w_cursor.lnum,
+                       wp->w_cursor.lnum - wp->w_topline,
+                       (int64_t)(wp->w_height_inner / 2),
+                       (int64_t)wp->w_height_inner) < 0) {
+      return FAIL;
+    }
     if (fprintf(fd,
-                "let s:l = %" PRId64 " - ((%" PRId64
-                " * winheight(0) + %" PRId64 ") / %" PRId64 ")\n"
                 "if s:l < 1 | let s:l = 1 | endif\n"
                 "keepjumps exe s:l\n"
                 "normal! zt\n"
-                "keepjumps %" PRId64 "\n",
-                (int64_t)wp->w_cursor.lnum,
-                (int64_t)(wp->w_cursor.lnum - wp->w_topline),
-                (int64_t)(wp->w_height_inner / 2),
-                (int64_t)wp->w_height_inner,
-                (int64_t)wp->w_cursor.lnum) < 0) {
+                "keepjumps %" PRIdLINENR "\n",
+                wp->w_cursor.lnum) < 0) {
       return FAIL;
     }
     // Restore the cursor column and left offset when not wrapping.
diff --git a/src/nvim/testdir/test_mksession.vim b/src/nvim/testdir/test_mksession.vim
index 7bb76ad9eb..d7cb4e743c 100644
--- a/src/nvim/testdir/test_mksession.vim
+++ b/src/nvim/testdir/test_mksession.vim
@@ -149,6 +149,21 @@ func Test_mksession_large_winheight()
   call delete('Xtest_mks_winheight.out')
 endfunc
 
+func Test_mksession_zero_winheight()
+  set winminheight=0
+  edit SomeFile
+  split
+  wincmd _
+  mksession! Xtest_mks_zero
+  set winminheight&
+  " let text = readfile('Xtest_mks_zero')->join()
+  let text = join(readfile('Xtest_mks_zero'))
+  "call delete('Xtest_mks_zero')
+  close
+  " check there is no devide by zero
+  call assert_notmatch('/ 0[^0-9]', text)
+endfunc
+
 func Test_mksession_rtp()
   if has('win32')
     " TODO: fix problem with backslashes
-- 
cgit