From 395bd1f6d3edc9f7edb5d1f2d7deaf5a9e3ab93c Mon Sep 17 00:00:00 2001
From: Bram Moolenaar <Bram@vim.org>
Date: Sat, 14 May 2022 21:29:44 +0100
Subject: [PATCH] patch 8.2.4956: reading past end of line with "gf" in Visual
 block mode

Problem:    Reading past end of line with "gf" in Visual block mode.
Solution:   Do not include the NUL in the length.
---
 src/normal.c            | 13 ++++++++++---
 src/testdir/test_gf.vim | 15 +++++++++++++++
 src/version.c           |  2 ++
 3 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/src/normal.c b/src/normal.c
index 1baf68a1453ae..bc3e29e1abaa1 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -3671,9 +3671,16 @@ get_visual_text(
 	}
 	if (**pp == NUL)
 	    *lenp = 0;
-	if (has_mbyte && *lenp > 0)
-	    // Correct the length to include all bytes of the last character.
-	    *lenp += (*mb_ptr2len)(*pp + (*lenp - 1)) - 1;
+	if (*lenp > 0)
+	{
+	    if (has_mbyte)
+		// Correct the length to include all bytes of the last
+		// character.
+		*lenp += (*mb_ptr2len)(*pp + (*lenp - 1)) - 1;
+	    else if ((*pp)[*lenp - 1] == NUL)
+		// Do not include a trailing NUL.
+		*lenp -= 1;
+	}
     }
     reset_VIsual_and_resel();
     return OK;
diff --git a/src/testdir/test_gf.vim b/src/testdir/test_gf.vim
index 3602ba010e8c4..1b3b139810eca 100644
--- a/src/testdir/test_gf.vim
+++ b/src/testdir/test_gf.vim
@@ -138,6 +138,21 @@ func Test_gf_visual()
   call assert_equal('Xtest_gf_visual', bufname('%'))
   call assert_equal(3, getcurpos()[1])
 
+  " do not include the NUL at the end 
+  call writefile(['x'], 'X')
+  let save_enc = &enc
+  for enc in ['latin1', 'utf-8']
+    exe "set enc=" .. enc
+    new
+    call setline(1, 'X')
+    set nomodified
+    exe "normal \<C-V>$gf"
+    call assert_equal('X', bufname())
+    bwipe!
+  endfor
+  let &enc = save_enc
+  call delete('X')
+
   " line number in visual area is used for file name
   if has('unix')
     bwipe!
diff --git a/src/version.c b/src/version.c
index 62e2b0af69411..821f3680e2fb5 100644
--- a/src/version.c
+++ b/src/version.c
@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4956,
 /**/
     4955,
 /**/