patchsideband: allow ANSI SGR with colon-separated subfields
4 messages between May 13, 2026 and Jul 7, 2026, from grawity@nullroute.lt, Johannes Schindelin, Junio C Hamano, Mantas.
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From: Mantas Mikulėnas <grawity@gmail.com>
The SGR values used for 256-color formatting are officially defined to be a single field with :-separated subfields (e.g. "\e[1;38:5:XX;40m") despite the more common but kludgy use of separate values (which then become context-dependent and lead to misinterpretation by incompatible terminals).
See also: https://github.com/ThomasDickey/xterm-snapshots/blob/6380a3eaed857c182ea6cfa78cd706966b2628d0/charproc.c#L2047-L2118
Signed-off-by: Mantas Mikulėnas <grawity@gmail.com>
---
sideband.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
Show changes to sideband.c +5 −1
diff --git a/sideband.c b/sideband.c
index 04282a568e..6cf70ef6f6 100644
--- a/sideband.c
+++ b/sideband.c
@@ -163,6 +163,10 @@ static int handle_ansi_sequence(struct strbuf *dest, const char *src, int n)
*
* ESC [ [<n> [; <n>]*] m
*
+ * where <n> can be either zero-length, or a decimal number, or a
+ * series of decimal numbers separated by a colon (for 256-color or
+ * true-color codes).
+ *
* These are part of the Select Graphic Rendition sequences which
* contain more than just color sequences, for more details see
* https://en.wikipedia.org/wiki/ANSI_escape_code#SGR.
@@ -210,7 +214,7 @@ static int handle_ansi_sequence(struct strbuf *dest, const char *src, int n)
strbuf_add(dest, src, i + 1);
return i;
}
- if (!isdigit(src[i]) && src[i] != ';')
+ if (!isdigit(src[i]) && src[i] != ':' && src[i] != ';')
break;
}
--
2.54.0
Re: [PATCH] sideband: allow ANSI SGR with colon-separated subfields
Hi Mantas,
On Wed, 13 May 2026, grawity@nullroute.lt wrote:
Show 9 quoted lines
> From: Mantas Mikulėnas <grawity@gmail.com>
>
> The SGR values used for 256-color formatting are officially defined to
> be a single field with :-separated subfields (e.g. "\e[1;38:5:XX;40m")
> despite the more common but kludgy use of separate values (which then
> become context-dependent and lead to misinterpretation by incompatible
> terminals).
>
> See also: https://github.com/ThomasDickey/xterm-snapshots/blob/6380a3eaed857c182ea6cfa78cd706966b2628d0/charproc.c#L2047-L2118
This change seems well-motivated and well-executed to me. Just in case anybody was waiting for my objections, there ain't any coming ;-)
Ciao, Johannes
Show 34 quoted lines
>
> Signed-off-by: Mantas Mikulėnas <grawity@gmail.com>
> ---
> sideband.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/sideband.c b/sideband.c
> index 04282a568e..6cf70ef6f6 100644
> --- a/sideband.c
> +++ b/sideband.c
> @@ -163,6 +163,10 @@ static int handle_ansi_sequence(struct strbuf *dest, const char *src, int n)
> *
> * ESC [ [<n> [; <n>]*] m
> *
> + * where <n> can be either zero-length, or a decimal number, or a
> + * series of decimal numbers separated by a colon (for 256-color or
> + * true-color codes).
> + *
> * These are part of the Select Graphic Rendition sequences which
> * contain more than just color sequences, for more details see
> * https://en.wikipedia.org/wiki/ANSI_escape_code#SGR.
> @@ -210,7 +214,7 @@ static int handle_ansi_sequence(struct strbuf *dest, const char *src, int n)
> strbuf_add(dest, src, i + 1);
> return i;
> }
> - if (!isdigit(src[i]) && src[i] != ';')
> + if (!isdigit(src[i]) && src[i] != ':' && src[i] != ';')
> break;
> }
>
> --
> 2.54.0
>
>
Re: [PATCH] sideband: allow ANSI SGR with colon-separated subfields
Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
Show 16 quoted lines
> Hi Mantas,
>
> On Wed, 13 May 2026, grawity@nullroute.lt wrote:
>
>> From: Mantas Mikulėnas <grawity@gmail.com>
>>
>> The SGR values used for 256-color formatting are officially defined to
>> be a single field with :-separated subfields (e.g. "\e[1;38:5:XX;40m")
>> despite the more common but kludgy use of separate values (which then
>> become context-dependent and lead to misinterpretation by incompatible
>> terminals).
>>
>> See also: https://github.com/ThomasDickey/xterm-snapshots/blob/6380a3eaed857c182ea6cfa78cd706966b2628d0/charproc.c#L2047-L2118
>
> This change seems well-motivated and well-executed to me. Just in case
> anybody was waiting for my objections, there ain't any coming ;-)
Should I take it as an Ack?
FWIW, this patch literally flew below my radar coverage. Thanks for noticing.
A need for fix-up like this does makes me doubt out decision to go with whitelisting very narrow cases that are known to be OK (and finding that the cases were too narrow and we need to extend), instead of rejecting known-bad cases, by the way.
Thanks.
Show 37 quoted lines
> Ciao,
> Johannes
>
>>
>> Signed-off-by: Mantas Mikulėnas <grawity@gmail.com>
>> ---
>> sideband.c | 6 +++++-
>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/sideband.c b/sideband.c
>> index 04282a568e..6cf70ef6f6 100644
>> --- a/sideband.c
>> +++ b/sideband.c
>> @@ -163,6 +163,10 @@ static int handle_ansi_sequence(struct strbuf *dest, const char *src, int n)
>> *
>> * ESC [ [<n> [; <n>]*] m
>> *
>> + * where <n> can be either zero-length, or a decimal number, or a
>> + * series of decimal numbers separated by a colon (for 256-color or
>> + * true-color codes).
>> + *
>> * These are part of the Select Graphic Rendition sequences which
>> * contain more than just color sequences, for more details see
>> * https://en.wikipedia.org/wiki/ANSI_escape_code#SGR.
>> @@ -210,7 +214,7 @@ static int handle_ansi_sequence(struct strbuf *dest, const char *src, int n)
>> strbuf_add(dest, src, i + 1);
>> return i;
>> }
>> - if (!isdigit(src[i]) && src[i] != ';')
>> + if (!isdigit(src[i]) && src[i] != ':' && src[i] != ';')
>> break;
>> }
>>
>> --
>> 2.54.0
>>
>>
Re: [PATCH] sideband: allow ANSI SGR with colon-separated subfields
On 2026-07-07 21:19, Junio C Hamano wrote:
> A need for fix-up like this does makes me doubt out decision to go
> with whitelisting very narrow cases that are known to be OK (and
> finding that the cases were too narrow and we need to extend),
> instead of rejecting known-bad cases, by the way.
For the SGR sequence (CSI ... m) AFAIK there are no other value types besides what this patch adds (i.e. colon-separated decimal subparameters), so the filter will now include all possible cases. It already isn't picky about individual values.
As for everything else (that is escape sequences in general), I'd say there are way too many "bad" cases – which can toggle terminal modes, display images, send notifications, copy to clipboard, move windows around... which a remote "status text" output has no reason to include – and basically zero "good" cases. Though the code already disallows the majority of harmful cases by only accepting those starting with CSI ("ESC [").
In fact I might personally go further and disallow even all of the cursor movement sequences and leave only SGR and EL (clear line). I can imagine a use-case for free cursor movement (parallel progress bars like in Arch's pacman?) but it practically requires the sender to know terminal dimensions to be useful, so IMO is entirely out of scope for sideband status output.
(Progress bar for example (OSC 9;4;n ST) might be useful, but IMO it should be generated client-side, with the server instead having some way to report an integer percentage through the protocol. In theory the "hyperlink" sequence (OSC 8 ; ... ST) could also be useful to send as part of status text, but I'd personally disallow that as well, given all the reporting last time someone discovered it was possible to link to a file:// URL.)
Show 38 quoted lines
> Thanks.
>
>> Ciao,
>> Johannes
>>
>>> Signed-off-by: Mantas Mikulėnas <grawity@gmail.com>
>>> ---
>>> sideband.c | 6 +++++-
>>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/sideband.c b/sideband.c
>>> index 04282a568e..6cf70ef6f6 100644
>>> --- a/sideband.c
>>> +++ b/sideband.c
>>> @@ -163,6 +163,10 @@ static int handle_ansi_sequence(struct strbuf *dest, const char *src, int n)
>>> *
>>> * ESC [ [<n> [; <n>]*] m
>>> *
>>> + * where <n> can be either zero-length, or a decimal number, or a
>>> + * series of decimal numbers separated by a colon (for 256-color or
>>> + * true-color codes).
>>> + *
>>> * These are part of the Select Graphic Rendition sequences which
>>> * contain more than just color sequences, for more details see
>>> * https://en.wikipedia.org/wiki/ANSI_escape_code#SGR.
>>> @@ -210,7 +214,7 @@ static int handle_ansi_sequence(struct strbuf *dest, const char *src, int n)
>>> strbuf_add(dest, src, i + 1);
>>> return i;
>>> }
>>> - if (!isdigit(src[i]) && src[i] != ';')
>>> + if (!isdigit(src[i]) && src[i] != ':' && src[i] != ';')
>>> break;
>>> }
>>>
>>> --
>>> 2.54.0
>>>
>>>