vim-patch:9.0.0816: CTRL-Z at end of file is always dropped

Problem:    CTRL-Z at end of file is always dropped.
Solution:   Add the 'endoffile' option, like the 'endofline' option.
            (closes vim/vim#11408, closes vim/vim#11397)

Cherry-pick test_fixeol.vim changes from patch 8.2.1432.
Cherry-pick 'endoffile' changes from latest Vim runtime update.

https://github.com/vim/vim/commit/fb0cf2357e0c85bbfd9f9178705ad8d77b6b3b4e

vim-patch:f0b567e32a46

Revert unintended Makefile change

https://github.com/vim/vim/commit/f0b567e32a462fe838170a202919d18b53eff987

vim-patch:72c8e3c070b3

Fix wrong struct access for member.

https://github.com/vim/vim/commit/72c8e3c070b30f82bc0d203a62c168e43a13e99b

vim-patch:3f68a4136eb9

Add missing entry for the 'endoffile' option.

https://github.com/vim/vim/commit/3f68a4136eb99840d739af5133ab31948f273f63

Co-authored-by: Bram Moolenaar <Bram@vim.org>

9 files changed, 48 insertions, 11 deletions

diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index a04d02946d..4718876b29 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -2135,6 +2135,15 @@ A jump table for the options with a short description can be found at |Q_op|.
 
 	See 'fileencoding' to control file-content encoding.
 
+			*'endoffile'* *'eof'* *'noendoffile'* *'noeof'*
+'endoffile' 'eof'	boolean	(default on)
+			local to buffer
+	Indicates that a CTRL-Z character was found at the end of the file
+	when reading it.  Normally only happens when 'fileformat' is "dos".
+	When writing a file and this option is off and the 'binary' option
+	is on, or 'fixeol' option is off, no CTRL-Z will be written at the
+	end of the file.
+
 			*'endofline'* *'eol'* *'noendofline'* *'noeol'*
 'endofline' 'eol'	boolean	(default on)
 			local to buffer
@@ -2490,7 +2499,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 'fixendofline' 'fixeol'	boolean	(default on)
 			local to buffer
 	When writing a file and this option is on, <EOL> at the end of file
-	will be restored if missing. Turn this option off if you want to
+	will be restored if missing.  Turn this option off if you want to
 	preserve the situation from the original file.
 	When the 'binary' option is set the value of this option doesn't
 	matter.
diff --git a/runtime/doc/quickref.txt b/runtime/doc/quickref.txt
index 2f91498857..e4a3dae08b 100644
--- a/runtime/doc/quickref.txt
+++ b/runtime/doc/quickref.txt
@@ -689,6 +689,7 @@ Short explanation of each option:		*option-list*
 'display'	  'dy'	    list of flags for how to display text
 'eadirection'	  'ead'     in which direction 'equalalways' works
 'encoding'	  'enc'     encoding used internally
+'endoffile'	  'eof'     write CTRL-Z at end of the file
 'endofline'	  'eol'     write <EOL> for last line in file
 'equalalways'	  'ea'	    windows are automatically made the same size
 'equalprg'	  'ep'	    external program to use for "=" command
diff --git a/runtime/optwin.vim b/runtime/optwin.vim
index 57e5392b98..db21066819 100644
--- a/runtime/optwin.vim
+++ b/runtime/optwin.vim
@@ -1,7 +1,7 @@
 " These commands create the option window.
 "
 " Maintainer:	Bram Moolenaar <Bram@vim.org>
-" Last Change:	2022 Oct 15
+" Last Change:	2022 Oct 28
 
 " If there already is an option window, jump to that one.
 let buf = bufnr('option-window')
@@ -956,6 +956,9 @@ call <SID>BinOptionL("bin")
 call <SID>AddOption("endofline", gettext("last line in the file has an end-of-line"))
 call append("$", "\t" .. s:local_to_buffer)
 call <SID>BinOptionL("eol")
+call <SID>AddOption("endoffile", gettext("last line in the file followed by CTRL-Z"))
+call append("$", "\t" .. s:local_to_buffer)
+call <SID>BinOptionL("eof")
 call <SID>AddOption("fixendofline", gettext("fixes missing end-of-line at end of text file"))
 call append("$", "\t" .. s:local_to_buffer)
 call <SID>BinOptionL("fixeol")
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index 043a31bf16..8e29edc0f5 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -675,6 +675,7 @@ struct file_buffer {
   char *b_p_cfu;                ///< 'completefunc'
   char *b_p_ofu;                ///< 'omnifunc'
   char *b_p_tfu;                ///< 'tagfunc'
+  int b_p_eof;                  ///< 'endoffile'
   int b_p_eol;                  ///< 'endofline'
   int b_p_fixeol;               ///< 'fixendofline'
   int b_p_et;                   ///< 'expandtab'
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index cfdd6fe697..ae0340cdc6 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -525,6 +525,7 @@ int readfile(char *fname, char *sfname, linenr_T from, linenr_T lines_to_skip,
     // correctly set when reading stdin.
     if (!read_buffer) {
       curbuf->b_p_eol = true;
+      curbuf->b_p_eof = false;
       curbuf->b_start_eol = true;
     }
     curbuf->b_p_bomb = false;
@@ -1629,12 +1630,13 @@ failed:
       && !got_int
       && linerest != 0
       && !(!curbuf->b_p_bin
-           && fileformat == EOL_DOS
-           && *line_start == Ctrl_Z
-           && ptr == line_start + 1)) {
+           && fileformat == EOL_DOS)) {
     // remember for when writing
     if (set_options) {
       curbuf->b_p_eol = false;
+      if (*line_start == Ctrl_Z && ptr == line_start + 1) {
+        curbuf->b_p_eof = false;
+      }
     }
     *ptr = NUL;
     len = (colnr_T)(ptr - line_start + 1);
@@ -3191,6 +3193,11 @@ restore_backup:
         len = 0;
         write_info.bw_start_lnum = lnum;
       }
+      if (!buf->b_p_fixeol && buf->b_p_eof) {
+        // write trailing CTRL-Z
+        (void)write_eintr(write_info.bw_fd, "\x1a", 1);
+      }
+
       // write failed or last line has no EOL: stop here
       if (end == 0
           || (lnum == end
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 06662afd08..8de86ce76e 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -3978,6 +3978,8 @@ static char_u *get_varp(vimoption_T *p)
     return (char_u *)&(curbuf->b_p_cfu);
   case PV_OFU:
     return (char_u *)&(curbuf->b_p_ofu);
+  case PV_EOF:
+    return (char_u *)&(curbuf->b_p_eof);
   case PV_EOL:
     return (char_u *)&(curbuf->b_p_eol);
   case PV_FIXEOL:
diff --git a/src/nvim/option_defs.h b/src/nvim/option_defs.h
index 19e4780e0a..7c33773e41 100644
--- a/src/nvim/option_defs.h
+++ b/src/nvim/option_defs.h
@@ -497,6 +497,7 @@ EXTERN char_u *p_ef;            // 'errorfile'
 EXTERN char *p_efm;             // 'errorformat'
 EXTERN char *p_gefm;            // 'grepformat'
 EXTERN char *p_gp;              // 'grepprg'
+EXTERN int p_eof;               ///< 'endoffile'
 EXTERN int p_eol;               ///< 'endofline'
 EXTERN char *p_ei;              // 'eventignore'
 EXTERN int p_et;                ///< 'expandtab'
@@ -858,6 +859,7 @@ enum {
   BV_CFU,
   BV_DEF,
   BV_INC,
+  BV_EOF,
   BV_EOL,
   BV_FIXEOL,
   BV_EP,
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index ba483d3714..088aa40fda 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -641,6 +641,15 @@ return {
       defaults={if_true=macros('ENC_DFLT')}
     },
     {
+      full_name='endoffile', abbreviation='eof',
+      short_desc=N_("write CTRL-Z for last line in file"),
+      type='bool', scope={'buffer'},
+      no_mkrc=true,
+      redraw={'statuslines'},
+      varname='p_eof',
+      defaults={if_true=true}
+    },
+    {
       full_name='endofline', abbreviation='eol',
       short_desc=N_("write <EOL> for last line in file"),
       type='bool', scope={'buffer'},
diff --git a/src/nvim/testdir/test_fixeol.vim b/src/nvim/testdir/test_fixeol.vim
index 32cb059e26..3ede84f49e 100644
--- a/src/nvim/testdir/test_fixeol.vim
+++ b/src/nvim/testdir/test_fixeol.vim
@@ -1,16 +1,17 @@
-" Tests for 'fixeol' and 'eol'
+" Tests for 'fixeol', 'eof' and 'eol'
+
 func Test_fixeol()
   " first write two test files – with and without trailing EOL
   " use Unix fileformat for consistency
   set ff=unix
   enew!
-  call setline('.', 'with eol')
+  call setline('.', 'with eol or eof')
   w! XXEol
   enew!
-  set noeol nofixeol
-  call setline('.', 'without eol')
+  set noeof noeol nofixeol
+  call setline('.', 'without eol or eof')
   w! XXNoEol
-  set eol fixeol
+  set eol eof fixeol
   bwipe XXEol XXNoEol
 
   " try editing files with 'fixeol' disabled
@@ -43,6 +44,8 @@ func Test_fixeol()
   call delete('XXNoEol')
   call delete('XXTestEol')
   call delete('XXTestNoEol')
-  set ff& fixeol& eol&
+  set ff& fixeol& eof& eol&
   enew!
 endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab