From 96d73c08a2786806f3def1fda66641b81e0af988 Mon Sep 17 00:00:00 2001
From: SHIMIZU Akifumi <shimizu.akifumi@fujitsu.com>
Date: Mon, 7 Apr 2025 19:47:16 +0900
Subject: [PATCH] Fix long multibyte characters paste issue via ssh (#840)
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When I paste long multibyte characters(over 80 byte) to ksh via
SSH, the characters are not displayed correctly. For example, the
following input demonstrates the issue. ja_JP.UTF-8 encoding is
used.

Expected command line display:
$ echo "長い文字列を入れるとkshで文字列が乱れる場合があるようです"

Actual command line display:
$ です"echo "長い文字列を入れるとkshで文字列が乱れる場合がある
...with the cursor over the 'e' in 'echo'.

This issue appears to be caused by the ed_read() function splitting
a multibyte character sequence when reading into an 80-byte buffer.
This leads to incorrect character interpretation and display.

Therefore, we edited the code to handle the case where the buffer
size is full in the middle of a multi-byte character.

src/cmd/ksh93/sh/edit.c:
- putstack():
  - Before retrying to interpret a multibyte character in case of a
    split due to end of buffer, restore the start position 'p'.
  - Fix zeroing out errno = EILSEQ.
- ed_getchar(): Avoid a potential buffer overflow in 'readin';
  allow for an extra multibyte character, not merely an extra byte.

Co-authored-by: Martijn Dekker <martijn@inlv.org>
---
 src/cmd/ksh93/edit/edit.c       | 13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/cmd/ksh93/edit/edit.c b/src/cmd/ksh93/edit/edit.c
index 0ac54ba..1dcef1b 100644
--- a/src/cmd/ksh93/edit/edit.c
+++ b/src/cmd/ksh93/edit/edit.c
@@ -15,6 +15,7 @@
 *            Johnothan King <johnothanking@protonmail.com>             *
 *               Anuradha Weeraman <anuradha@debian.org>                *
 *               K. Eugene Carlson <kvngncrlsn@gmail.com>               *
+*            SHIMIZU Akifumi <shimizu.akifumi@fujitsu.com>             *
 *                                                                      *
 ***********************************************************************/
 /*
@@ -861,6 +862,7 @@ static int putstack(Edit_t *ep,char string[], int nbyte, int type)
 		}
 		else
 		{
+			char *prevp = p;
 		again:
 			if((c=mbchar(p)) >=0)
 			{
@@ -868,19 +870,20 @@ static int putstack(Edit_t *ep,char string[], int nbyte, int type)
 				if(type)
 					c = -c;
 			}
-#ifdef EILSEQ
-			else if(errno == EILSEQ)
-				errno = 0;
-#endif
 			else if((endp-p) < mbmax())
 			{
+				if(errno == EILSEQ)
+					errno = 0;
 				if ((c=ed_read(ep,ep->e_fd,endp, 1,0)) == 1)
 				{
+					p = prevp;
 					*++endp = 0;
 					goto again;
 				}
 				return c;
 			}
+			else if(errno == EILSEQ)
+				errno = 0;
 			else
 			{
 				ed_ringbell();
@@ -930,7 +933,7 @@ static int putstack(Edit_t *ep,char string[], int nbyte, int type)
 int ed_getchar(Edit_t *ep,int mode)
 {
 	int n, c;
-	char readin[LOOKAHEAD+1];
+	char *readin = fmtbuf(LOOKAHEAD + mbmax());
 	if(!ep->e_lookahead)
 	{
 		ed_flush(ep);