fix unicode glitch in DCS strings, patch by Tim Allen
Reported on the mailinglist: " I discovered recently that if an application running inside st tries to send a DCS string, subsequent Unicode characters get messed up. For example, consider the following test-case: printf '\303\277\033P\033\\\303\277' ...where: - \303\277 is the UTF-8 encoding of U+00FF LATIN SMALL LETTER Y WITH DIAERESIS (ÿ). - \033P is ESC P, the token that begins a DCS string. - \033\\ is ESC \, a token that ends a DCS string. - \303\277 is the same ÿ character again. If I run the above command in a VTE-based terminal, or xterm, or QTerminal, or pterm (PuTTY), I get the output: ÿÿ ...which is to say, the empty DCS string is ignored. However, if I run that command inside st (as of commitmaster
9ba7ecf), I get: ÿÃ¿ ...where those last two characters are \303\277 interpreted as ISO8859-1 characters, instead of UTF-8. I spent some time tracing through the state machines in st.c, and so far as I can tell, this is how it works currently: - ESC P sets the "ESC_DCS" and "ESC_STR" flags, indicating that incoming bytes should be collected into the strescseq buffer, rather than being interpreted. - ESC \ sets the "ESC_STR_END" flag (when ESC is received), and then calls strhandle() (when \ is received) to interpret the collected bytes. - If the collected bytes begin with 'P' (i.e. if this was a DCS string) strhandle() sets the "ESC_DCS" flag again, confusing the state machine. If my understanding is correct, fixing the problem should be as easy as removing the line that sets ESC_DCS from strhandle(): diff --git a/st.c b/st.c index ef8abd5..b5b805a 100644 --- a/st.c +++ b/st.c @@ -1897,7 +1897,6 @@ strhandle(void) xsettitle(strescseq.args); return; case 'P': /* DCS -- Device Control String */ - term.mode |= ESC_DCS; case '_': /* APC -- Application Program Command */ case '^': /* PM -- Privacy Message */ return; I've tried the above patch and it fixes my problem, but I don't know if it introduces any others. "
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