Re-integrate FEAT_FILTERPIPE code

This feature was accidentally removed when doing the initial import from vim. It
makes vim use pipes instead of temporary files for filtering buffers through
shell commands.

I found that this was missing when looking for references of
SHELL_READ/SHELL_WRITE outside mch_call_shell`.

When `mch_call_shell` is reimplemented on top of libuv process management
facilities, pipes will always be used for communication with child processes so
it makes sense to enable the feature permanently.

1 files changed, 17 insertions, 1 deletions

diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index b0919f3b30..d0e4c9eccd 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -1024,7 +1024,23 @@ do_filter (
   if (do_out)
     shell_flags |= SHELL_DOOUT;
 
-  if ((do_in && (itmp = vim_tempname('i')) == NULL)
+  if (!do_in && do_out && !p_stmp) {
+    // Use a pipe to fetch stdout of the command, do not use a temp file.
+    shell_flags |= SHELL_READ;
+    curwin->w_cursor.lnum = line2;
+  } else if (do_in && !do_out && !p_stmp) {
+    // Use a pipe to write stdin of the command, do not use a temp file.
+    shell_flags |= SHELL_WRITE;
+    curbuf->b_op_start.lnum = line1;
+    curbuf->b_op_end.lnum = line2;
+  } else if (do_in && do_out && !p_stmp) {
+    // Use a pipe to write stdin and fetch stdout of the command, do not
+    // use a temp file.
+    shell_flags |= SHELL_READ|SHELL_WRITE;
+    curbuf->b_op_start.lnum = line1;
+    curbuf->b_op_end.lnum = line2;
+    curwin->w_cursor.lnum = line2;
+  } else if ((do_in && (itmp = vim_tempname('i')) == NULL)
       || (do_out && (otmp = vim_tempname('o')) == NULL)) {
     EMSG(_(e_notmp));
     goto filterend;