Re: nano hangs when pasting just a few characters

Benno Schulenberg <[email protected]> Wed, 26 Feb 2025 11:55:53 +0100

Newsgroups	gmane.editors.nano.devel
Message-ID	<[email protected]>

Op 26-02-2025 om 04:52 schreef Doug Smythies:
>> Thank you for the patch. It made no difference. I even tried a much bigger
>> delay and several in between delays.

Okay.  Then please try this other patch, attached.


> I found some other paste buffer sizes that FAIL, in addition to the 5
> characters already talked about. 85, 197, and 293 (there will be more, but
> that is as far as I got).

No need to try all kinds of different sizes.  But what I'm curious
about: it fails when pasting 5 bytes, but not when pasting 6 or 7?
If  not, what does the "Sequence of hex codes" look like for those
pastes?  (Because I would expect the end-of-paste escape sequence
to be broken there too.)


> If I use PuTTY instead of OpenSSH_for_Windows these buffer lengths work
> fine, suggesting that the root issue is with the OpenSSH_for_Windows code.

Yes, the root issue is the OpenSSH_for_Windows splitting an escape
sequence.  But... if PuTTY works fine, I would strongly suggest to
just use that.


> [...]
> Sequence of hex codes:  33  34  35  36  37  38  39  30  31  32  33  34  35
> 36  37  38  39  30  31  32  33  34  35  36  37  38  39  30  31  32  33  34
> 35  36  37  38  39  30  31  32  33  34  35  36  37  38  39  30  31  32  33
> 34  35  36  37  38  39  30  31  32  33  34  35  36  37  38  39  30  31  32
> 33  34  35  36  37  38  39  30  31  32  33  34  35  36  37  38  39  30  31
> 32  33  1b  5b  32  30  31
> 
> Sequence of hex codes:  7e

This seems to suggest that OpenSSH_for_Windows does notice the escape
sequence, but thinks that something that starts with "[2" (5b 32) has
two more bytes, where in fact it has three.  I think the attached patch
will catch and work around this issue.


Benno

0001-input-avoid-hanging-on-a-mangled-bracketed-paste-in-.patch (text/x-patch, 2.4 KB)

From 5376564e4818fd7095f7f9d203342c06cc3c7291 Mon Sep 17 00:00:00 2001
From: Benno Schulenberg <[email protected]>
Date: Tue, 25 Feb 2025 17:24:25 +0100
Subject: [PATCH] input: avoid hanging on a mangled bracketed paste in a
 different way

Instead of recognizing a truncated end-of-paste sequence, notice that
the final tilde (~) comes in alone and decide that this is wrong: a
bracketed paste should be a large batch (or several batches) of bytes,
not single bytes coming in one by one.  When the latter happens, end
the bracketed paste and display a warning, while discarding the byte
that came in alone.

This change was inspired by this report:
  https://lists.gnu.org/archive/html/nano-devel/2025-02/msg00001.html
---
 src/nano.c  | 13 +++++++++++--
 src/winio.c |  6 ------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/src/nano.c b/src/nano.c
index b3f51e06..b72f2962 100644
--- a/src/nano.c
+++ b/src/nano.c
@@ -1444,9 +1444,13 @@ void suck_up_input_and_paste_it(void)
 	cutbuffer = line;
 
 	while (bracketed_paste) {
+		size_t were_waiting = waiting_keycodes();
 		int input = get_kbinput(midwin, BLIND);
 
-		if (input == '\r' || input == '\n') {
+		/* If key codes come singly, something is wrong. */
+		if (were_waiting == 0 && waiting_keycodes() == 0)
+			break;
+		else if (input == '\r' || input == '\n') {
 			line->next = make_new_node(line);
 			line = line->next;
 			line->data = copy_of("");
@@ -1457,7 +1461,7 @@ void suck_up_input_and_paste_it(void)
 			line->data[index++] = (char)input;
 			line->data[index] = '\0';
 		} else if (input != BRACKETED_PASTE_MARKER)
-			beep();
+			break;
 	}
 
 	if (ISSET(VIEW_MODE))
@@ -1465,6 +1469,11 @@ void suck_up_input_and_paste_it(void)
 	else
 		paste_text();
 
+	if (bracketed_paste) {
+		statusline(ALERT, _("Broken paste"));
+		bracketed_paste = FALSE;
+	}
+
 	free_lines(cutbuffer);
 	cutbuffer = was_cutbuffer;
 }
diff --git a/src/winio.c b/src/winio.c
index 2fff0d9e..f82eb27e 100644
--- a/src/winio.c
+++ b/src/winio.c
@@ -735,12 +735,6 @@ int convert_CSI_sequence(const int *seq, size_t length, int *consumed)
 					bracketed_paste = FALSE;
 					return BRACKETED_PASTE_MARKER;
 				}
-			} else {
-				/* When invalid, assume it's a truncated end-of-paste sequence,
-				 * in order to avoid a hang -- https://sv.gnu.org/bugs/?64996. */
-				bracketed_paste = FALSE;
-				*consumed = length;
-				return ERR;
 			}
 #endif
 			break;
-- 
2.48.1

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