From 3426cb2d4a8214aad997f376a6ffc33edb598ce3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20Bohusl=C3=A1vek?= <mbohuslavek@gmail.com>
Date: Fri, 11 Aug 2023 12:03:24 +0200
Subject: [PATCH 1/2] add support for body where last line does not end with \n

---
 acme.go  | 19 ++++++++++++++-----
 apply.go | 12 ++++++++----
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/acme.go b/acme.go
index fdc48a7..c224cda 100644
--- a/acme.go
+++ b/acme.go
@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"os"
@@ -11,10 +12,12 @@ import (
 	"9fans.net/go/acme"
 )
 
+var nl = []byte("\n")
+
 // We would use io.Copy except for a bug in acme
 // where it crashes when reading trying to read more
 // than the negotiated 9P message size.
-func copyBody(w io.Writer, win *acme.Win) error {
+func copyBody(w io.Writer, win *acme.Win) (endsWithNL bool, err error) {
 	buf := make([]byte, 8000)
 	for {
 		n, err := win.Read("body", buf)
@@ -22,13 +25,19 @@ func copyBody(w io.Writer, win *acme.Win) error {
 			break
 		}
 		if err != nil {
-			return err
+			return false, err
 		}
-		if _, err := w.Write(buf[0:n]); err != nil {
-			return fmt.Errorf("write error: %v", err)
+		if _, err := w.Write(buf[:n]); err != nil {
+			return false, fmt.Errorf("write error: %v", err)
 		}
+		endsWithNL = bytes.HasSuffix(buf[:n], nl)
 	}
-	return nil
+	if !endsWithNL {
+		if _, err := w.Write(nl); err != nil {
+			return false, fmt.Errorf("write error: %v", err)
+		}
+	}
+	return endsWithNL, nil
 }
 
 func acmeCurrentWin() (*acme.Win, error) {
diff --git a/apply.go b/apply.go
index d5ada7a..7d0e29d 100644
--- a/apply.go
+++ b/apply.go
@@ -46,7 +46,8 @@ func Main() error {
 	if err != nil {
 		return err
 	}
-	if err := copyBody(bodyFile, win); err != nil {
+	endsWithNL, err := copyBody(bodyFile, win)
+	if err != nil {
 		return err
 	}
 	bodyFile.Seek(0, 0)
@@ -76,7 +77,7 @@ func Main() error {
 	//		return err
 	//	}
 	//	defer win.Write("ctl", []byte("mark"))
-	err = apply(diffOut, func(addr string, data []byte) error {
+	edit := func(addr string, data []byte) error {
 		if _, err := win.Write("addr", []byte(addr)); err != nil {
 			return fmt.Errorf("cannot set address %q: %v", addr, err)
 		}
@@ -84,10 +85,13 @@ func Main() error {
 			return fmt.Errorf("cannot write data: %v", err)
 		}
 		return nil
-	})
-	if err != nil {
+	}
+	if err := apply(diffOut, edit); err != nil {
 		return err
 	}
+	if !endsWithNL {
+		return edit(`$-/\n/`, nil)
+	}
 	return nil
 }
 

From d8256cb9f1278f87d68f487a4042a623cef301ec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20Bohusl=C3=A1vek?= <mbohuslavek@gmail.com>
Date: Fri, 11 Aug 2023 12:21:48 +0200
Subject: [PATCH 2/2] mark before nomark

Still not perfect. It seems one has to Undo twice to have an effect.
But it does undo it all at once.
---
 apply.go | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/apply.go b/apply.go
index 7d0e29d..580fc22 100644
--- a/apply.go
+++ b/apply.go
@@ -71,12 +71,13 @@ func Main() error {
 	if err := pcmd.Start(); err != nil {
 		return fmt.Errorf("cannot start %q: %v", cmdArgs[0], err)
 	}
-	// TODO this doesn't appear to have the desired effect -
-	// changes made after "nomark" don't seem to be undoable.
-	//	if _, err := win.Write("ctl", []byte("nomark")); err != nil {
-	//		return err
-	//	}
-	//	defer win.Write("ctl", []byte("mark"))
+	if _, err := win.Write("ctl", []byte("mark")); err != nil {
+		return err
+	}
+	if _, err := win.Write("ctl", []byte("nomark")); err != nil {
+		return err
+	}
+	defer win.Write("ctl", []byte("mark"))
 	edit := func(addr string, data []byte) error {
 		if _, err := win.Write("addr", []byte(addr)); err != nil {
 			return fmt.Errorf("cannot set address %q: %v", addr, err)