Subject: Re: [PATCH v2 4/4] sideband: add options to allow more control sequences to be passed through

From: Junio C Hamano <[email-masked]>
Date: Mon, 02 Feb 2026 17:11:39 -0800

"brian m. carlson" <[email-masked]> writes:

> On 2026-01-15 at 21:14:48, Jeff King wrote:
>> Is there any reason we cannot introduce the new functionality as a
>> config option but _not_ enable it by default?
>> 
>> That gives people the tools to protect themselves if they want to bear
>> the potential cost. It just feels a shame to deny them the tool because
>> we can't agree on the default.
>
> Yes, I think that would be a fine and reasonable approach.

Absolutely.

After a few weeks, however, nobody seems to have stepped up to help
us move forward (unless I missed a patch or two, of course), so here
is my attempt.  To be applied on top of Dscho's 5-patch series (v3)
that ends at c5b95e19 (sideband: offer to configure sanitizing on a
per-URL basis, 2026-01-16).

Thanks.

--- >8 ---
From: Junio C Hamano <[email-masked]>
Date: Mon, 2 Feb 2026 17:06:03 -0800
Subject: [PATCH 5/4] sideband: neuter the sideband filtering

To prevent breaking settings that are working well for existing
users, tone down the sideband filtering feature and turn it off by
default.  This hopefully matches the way how distros like Fedora and
RHEL are shipping this feature in theirs.

Signed-off-by: Junio C Hamano <[email-masked]>
---
 Documentation/config/sideband.txt   | 14 +++++++-------
 sideband.c                          |  6 ++----
 t/t5409-colorize-remote-messages.sh | 12 ++++++++----
 3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/Documentation/config/sideband.txt b/Documentation/config/sideband.txt
index 32088bbf2f..d2cd86fa60 100644
--- a/Documentation/config/sideband.txt
+++ b/Documentation/config/sideband.txt
@@ -1,15 +1,15 @@
 sideband.allowControlCharacters::
-	By default, control characters that are delivered via the sideband
-	are masked, except ANSI color sequences. This prevents potentially
-	unwanted ANSI escape sequences from being sent to the terminal. Use
-	this config setting to override this behavior (the value can be
-	a comma-separated list of the following keywords):
+	By default, control characters that are delivered via the
+	sideband are all passed through.  To prevent potentially
+	unwanted ANSI escape sequences from being sent to the
+	terminal, use this config setting to override this behavior
+	(the value can be a comma-separated list of the following
+	keywords):
 +
 --
-	`default`::
 	`color`::
 		Allow ANSI color sequences, line feeds and horizontal tabs,
-		but mask all other control characters. This is the default.
+		but mask all other control characters.
 	`cursor:`:
 		Allow control sequences that move the cursor. This is
 		disabled by default.
diff --git a/sideband.c b/sideband.c
index a8cd142cd7..3d8534671e 100644
--- a/sideband.c
+++ b/sideband.c
@@ -61,9 +61,7 @@ int sideband_allow_control_characters_config(const char *var, const char *value)
 
 	allow_control_characters = ALLOW_NO_CONTROL_CHARACTERS;
 	while (*value) {
-		if (skip_prefix_in_csv(value, "default", &value))
-			allow_control_characters |= ALLOW_DEFAULT_ANSI_SEQUENCES;
-		else if (skip_prefix_in_csv(value, "color", &value))
+		if (skip_prefix_in_csv(value, "color", &value))
 			allow_control_characters |= ALLOW_ANSI_COLOR_SEQUENCES;
 		else if (skip_prefix_in_csv(value, "cursor", &value))
 			allow_control_characters |= ALLOW_ANSI_CURSOR_MOVEMENTS;
@@ -125,7 +123,7 @@ static int use_sideband_colors(void)
 			sideband_allow_control_characters_config("sideband.allowcontrolcharacters", value);
 
 		if (allow_control_characters == ALLOW_CONTROL_SEQUENCES_UNSET)
-			allow_control_characters = ALLOW_DEFAULT_ANSI_SEQUENCES;
+			allow_control_characters = ALLOW_ALL_CONTROL_CHARACTERS;
 	}
 
 	if (!git_config_get_string_tmp(key, &value))
diff --git a/t/t5409-colorize-remote-messages.sh b/t/t5409-colorize-remote-messages.sh
index 1d039cbdaf..47bc8bbef2 100755
--- a/t/t5409-colorize-remote-messages.sh
+++ b/t/t5409-colorize-remote-messages.sh
@@ -107,7 +107,8 @@ test_expect_success 'disallow (color) control sequences in sideband' '
 	test_config_global uploadPack.packObjectsHook ./color-me-surprised &&
 	test_commit need-at-least-one-commit &&
 
-	git clone --no-local . throw-away 2>stderr &&
+	git -c sideband.allowControlCharacters=color \
+		clone --no-local . throw-away 2>stderr &&
 	test_decode_color <stderr >decoded &&
 	test_grep RED decoded &&
 	test_grep "\\^G" stderr &&
@@ -122,7 +123,8 @@ test_expect_success 'disallow (color) control sequences in sideband' '
 	test_grep "\\^G" stderr &&
 
 	rm -rf throw-away &&
-	git -c sideband.allowControlCharacters clone --no-local . throw-away 2>stderr &&
+	git -c sideband.allowControlCharacters \
+		clone --no-local . throw-away 2>stderr &&
 	test_decode_color <stderr >decoded &&
 	test_grep RED decoded &&
 	tr -dc "\\007" <stderr >actual &&
@@ -148,7 +150,8 @@ test_expect_success 'control sequences in sideband allowed by default' '
 	test_commit need-at-least-one-commit-at-least &&
 
 	rm -rf throw-away &&
-	git clone --no-local . throw-away 2>stderr &&
+	git -c sideband.allowControlCharacters=color \
+		clone --no-local . throw-away 2>stderr &&
 	test_decode_color <stderr >color-decoded &&
 	test_decode_csi <color-decoded >decoded &&
 	test_grep ! "CSI \\[K" decoded &&
@@ -176,7 +179,8 @@ test_expect_success 'allow all control sequences for a specific URL' '
 	test_commit one-more-please &&
 
 	rm -rf throw-away &&
-	git clone --no-local . throw-away 2>stderr &&
+	git -c sideband.allowControlCharacters=color \
+		clone --no-local . throw-away 2>stderr &&
 	test_decode_color <stderr >color-decoded &&
 	test_decode_csi <color-decoded >decoded &&
 	test_grep ! "CSI \\[K" decoded &&
-- 
2.53.0-162-gcda875bd0b