Re: [PATCH i2c-tools v3 2/2] i2ctransfer: Add optional message modifier flags

["Benoît Monin" <benoit.monin@bootlin.com>]

Hi Wolfram,

On Wednesday, 3 June 2026 at 09:33:37 CEST, Wolfram Sang wrote:
[...]
> This error message now only shows up if the 'rw'-flag is missing at the
> end of the commandline:
> 
> # ./i2ctransfer -y 0 p
> Error: Missing direction flag 'r' or 'w'
> Error: faulty argument is 'p'
> 
> Otherwise it complains about '@' not being a flag:
> 
> # ./i2ctransfer -y 0 p@0x1a
> Error: Unsupported flag '@'
> Error: faulty argument is 'p@0x1a'
> 
> It would be nice if '@' would be recognized as a terminator for the
> flags and would then complain about the missing direction flag, or?

It's true that the error message is imprecise but I wanted to avoid
duplicating the parsing that is done after parsing the flags. I can add
something like the following in the switch case in add_flag_if_supported():


@@ -202,6 +202,20 @@ static int add_flag_if_supported(__u16 *flags, unsigned long funcs, char arg)
                        break;
 #endif
 
+               case '0':
+               case '1':
+               case '2':
+               case '3':
+               case '4':
+               case '5':
+               case '6':
+               case '7':
+               case '8':
+               case '9':
+               case '?':
+               case '@':
+                       return 0;
+
                default:


With this we get out of the flags parsing and the "Missing direction flag"
error message is shown. What's your opinion on this?

Best regards,
-- 
Benoît Monin, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com