conhost advertises ccc Tektronix color support incorrectly #98

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opened 2026-01-30 21:42:15 +00:00 by claunia · 1 comment
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Originally created by @bitcrazed on GitHub (Feb 16, 2018).

From @mqudsi on October 15, 2017 15:57

Running 1709/17017.1000:

$TERM is set to xterm-256-color but in the termcap file that ships with WSL's Ubuntu copy, xterm-256-color includes ccc support:

#	Reconstructed via infocmp from file: /lib/terminfo/x/xterm-256color
xterm-256color|xterm with 256 colors,
	am, bce, ccc, km, mc5i, mir, msgr, npc, xenl,
	colors#256, cols#80, it#8, lines#24, pairs#32767,
	acsc=``aaffggiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz{{||}}~~,
	bel=^G, blink=\E[5m, bold=\E[1m, cbt=\E[Z, civis=\E[?25l,
	clear=\E[H\E[2J, cnorm=\E[?12l\E[?25h, cr=^M,
	csr=\E[%i%p1%d;%p2%dr, cub=\E[%p1%dD, cub1=^H,
	cud=\E[%p1%dB, cud1=^J, cuf=\E[%p1%dC, cuf1=\E[C,
	cup=\E[%i%p1%d;%p2%dH, cuu=\E[%p1%dA, cuu1=\E[A,
	cvvis=\E[?12;25h, dch=\E[%p1%dP, dch1=\E[P, dim=\E[2m,
	dl=\E[%p1%dM, dl1=\E[M, ech=\E[%p1%dX, ed=\E[J, el=\E[K,
	el1=\E[1K, flash=\E[?5h$<100/>\E[?5l, home=\E[H,
	hpa=\E[%i%p1%dG, ht=^I, hts=\EH, ich=\E[%p1%d@,
	il=\E[%p1%dL, il1=\E[L, ind=^J, indn=\E[%p1%dS,
	initc=\E]4;%p1%d;rgb\:%p2%{255}%*%{1000}%/%2.2X/%p3%{255}%*%{1000}%/%2.2X/%p4%{255}%*%{1000}%/%2.2X\E\\,
	invis=\E[8m, is2=\E[!p\E[?3;4l\E[4l\E>, kDC=\E[3;2~,
	kEND=\E[1;2F, kHOM=\E[1;2H, kIC=\E[2;2~, kLFT=\E[1;2D,
	kNXT=\E[6;2~, kPRV=\E[5;2~, kRIT=\E[1;2C, kb2=\EOE,
	kbs=\177, kcbt=\E[Z, kcub1=\EOD, kcud1=\EOB, kcuf1=\EOC,
	kcuu1=\EOA, kdch1=\E[3~, kend=\EOF, kent=\EOM, kf1=\EOP,
	kf10=\E[21~, kf11=\E[23~, kf12=\E[24~, kf13=\E[1;2P,
	kf14=\E[1;2Q, kf15=\E[1;2R, kf16=\E[1;2S, kf17=\E[15;2~,
	kf18=\E[17;2~, kf19=\E[18;2~, kf2=\EOQ, kf20=\E[19;2~,
	kf21=\E[20;2~, kf22=\E[21;2~, kf23=\E[23;2~,
	kf24=\E[24;2~, kf25=\E[1;5P, kf26=\E[1;5Q, kf27=\E[1;5R,
	kf28=\E[1;5S, kf29=\E[15;5~, kf3=\EOR, kf30=\E[17;5~,
	kf31=\E[18;5~, kf32=\E[19;5~, kf33=\E[20;5~,
	kf34=\E[21;5~, kf35=\E[23;5~, kf36=\E[24;5~,
	kf37=\E[1;6P, kf38=\E[1;6Q, kf39=\E[1;6R, kf4=\EOS,
	kf40=\E[1;6S, kf41=\E[15;6~, kf42=\E[17;6~,
	kf43=\E[18;6~, kf44=\E[19;6~, kf45=\E[20;6~,
	kf46=\E[21;6~, kf47=\E[23;6~, kf48=\E[24;6~,
	kf49=\E[1;3P, kf5=\E[15~, kf50=\E[1;3Q, kf51=\E[1;3R,
	kf52=\E[1;3S, kf53=\E[15;3~, kf54=\E[17;3~,
	kf55=\E[18;3~, kf56=\E[19;3~, kf57=\E[20;3~,
	kf58=\E[21;3~, kf59=\E[23;3~, kf6=\E[17~, kf60=\E[24;3~,
	kf61=\E[1;4P, kf62=\E[1;4Q, kf63=\E[1;4R, kf7=\E[18~,
	kf8=\E[19~, kf9=\E[20~, khome=\EOH, kich1=\E[2~,
	kind=\E[1;2B, kmous=\E[M, knp=\E[6~, kpp=\E[5~,
	kri=\E[1;2A, mc0=\E[i, mc4=\E[4i, mc5=\E[5i, meml=\El,
	memu=\Em, op=\E[39;49m, rc=\E8, rev=\E[7m, ri=\EM,
	rin=\E[%p1%dT, ritm=\E[23m, rmacs=\E(B, rmam=\E[?7l,
	rmcup=\E[?1049l, rmir=\E[4l, rmkx=\E[?1l\E>, rmso=\E[27m,
	rmul=\E[24m, rs1=\Ec, rs2=\E[!p\E[?3;4l\E[4l\E>, sc=\E7,
	setab=\E[%?%p1%{8}%<%t4%p1%d%e%p1%{16}%<%t10%p1%{8}%-%d%e48;5;%p1%d%;m,
	setaf=\E[%?%p1%{8}%<%t3%p1%d%e%p1%{16}%<%t9%p1%{8}%-%d%e38;5;%p1%d%;m,
	sgr=%?%p9%t\E(0%e\E(B%;\E[0%?%p6%t;1%;%?%p5%t;2%;%?%p2%t;4%;%?%p1%p3%|%t;7%;%?%p4%t;5%;%?%p7%t;8%;m,
	sgr0=\E(B\E[m, sitm=\E[3m, smacs=\E(0, smam=\E[?7h,
	smcup=\E[?1049h, smir=\E[4h, smkx=\E[?1h\E=, smso=\E[7m,
	smul=\E[4m, tbc=\E[3g, u6=\E[%i%d;%dR, u7=\E[6n,
	u8=\E[?1;2c, u9=\E[c, vpa=\E[%i%p1%dd,

As such, the terminal is advertising support for ccc, but it does not seem to support it in practice. Per https://linux.die.net/man/5/terminfo:

On a Tektronix-like terminal, the capability ccc may be present to indicate that colors can be modified. If so, the initc capability will take a color number (0 to colors - 1)and three more parameters which describe the color. These three parameters default to being interpreted as RGB (Red, Green, Blue) values. If the boolean capability hls is present, they are instead as HLS (Hue, Lightness, Saturation) indices. The ranges are terminal-dependent.

As far as I can tell, conhost only supports the HP-like color API:

On an HP-like terminal, initp may give a capability for changing a color-pair value. It will take seven parameters; a color-pair number (0 to max_pairs - 1), and two triples describing first background and then foreground colors. These parameters must be (Red, Green, Blue) or (Hue, Lightness, Saturation) depending on hls.

WSL should probably ship with a patched termcap file that drops ccc from xterm-256-color.

Copied from original issue: Microsoft/WSL#2566

Originally created by @bitcrazed on GitHub (Feb 16, 2018). _From @mqudsi on October 15, 2017 15:57_ Running 1709/17017.1000: `$TERM` is set to `xterm-256-color` but in the termcap file that ships with WSL's Ubuntu copy, `xterm-256-color` includes `ccc` support: ``` # Reconstructed via infocmp from file: /lib/terminfo/x/xterm-256color xterm-256color|xterm with 256 colors, am, bce, ccc, km, mc5i, mir, msgr, npc, xenl, colors#256, cols#80, it#8, lines#24, pairs#32767, acsc=``aaffggiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz{{||}}~~, bel=^G, blink=\E[5m, bold=\E[1m, cbt=\E[Z, civis=\E[?25l, clear=\E[H\E[2J, cnorm=\E[?12l\E[?25h, cr=^M, csr=\E[%i%p1%d;%p2%dr, cub=\E[%p1%dD, cub1=^H, cud=\E[%p1%dB, cud1=^J, cuf=\E[%p1%dC, cuf1=\E[C, cup=\E[%i%p1%d;%p2%dH, cuu=\E[%p1%dA, cuu1=\E[A, cvvis=\E[?12;25h, dch=\E[%p1%dP, dch1=\E[P, dim=\E[2m, dl=\E[%p1%dM, dl1=\E[M, ech=\E[%p1%dX, ed=\E[J, el=\E[K, el1=\E[1K, flash=\E[?5h$<100/>\E[?5l, home=\E[H, hpa=\E[%i%p1%dG, ht=^I, hts=\EH, ich=\E[%p1%d@, il=\E[%p1%dL, il1=\E[L, ind=^J, indn=\E[%p1%dS, initc=\E]4;%p1%d;rgb\:%p2%{255}%*%{1000}%/%2.2X/%p3%{255}%*%{1000}%/%2.2X/%p4%{255}%*%{1000}%/%2.2X\E\\, invis=\E[8m, is2=\E[!p\E[?3;4l\E[4l\E>, kDC=\E[3;2~, kEND=\E[1;2F, kHOM=\E[1;2H, kIC=\E[2;2~, kLFT=\E[1;2D, kNXT=\E[6;2~, kPRV=\E[5;2~, kRIT=\E[1;2C, kb2=\EOE, kbs=\177, kcbt=\E[Z, kcub1=\EOD, kcud1=\EOB, kcuf1=\EOC, kcuu1=\EOA, kdch1=\E[3~, kend=\EOF, kent=\EOM, kf1=\EOP, kf10=\E[21~, kf11=\E[23~, kf12=\E[24~, kf13=\E[1;2P, kf14=\E[1;2Q, kf15=\E[1;2R, kf16=\E[1;2S, kf17=\E[15;2~, kf18=\E[17;2~, kf19=\E[18;2~, kf2=\EOQ, kf20=\E[19;2~, kf21=\E[20;2~, kf22=\E[21;2~, kf23=\E[23;2~, kf24=\E[24;2~, kf25=\E[1;5P, kf26=\E[1;5Q, kf27=\E[1;5R, kf28=\E[1;5S, kf29=\E[15;5~, kf3=\EOR, kf30=\E[17;5~, kf31=\E[18;5~, kf32=\E[19;5~, kf33=\E[20;5~, kf34=\E[21;5~, kf35=\E[23;5~, kf36=\E[24;5~, kf37=\E[1;6P, kf38=\E[1;6Q, kf39=\E[1;6R, kf4=\EOS, kf40=\E[1;6S, kf41=\E[15;6~, kf42=\E[17;6~, kf43=\E[18;6~, kf44=\E[19;6~, kf45=\E[20;6~, kf46=\E[21;6~, kf47=\E[23;6~, kf48=\E[24;6~, kf49=\E[1;3P, kf5=\E[15~, kf50=\E[1;3Q, kf51=\E[1;3R, kf52=\E[1;3S, kf53=\E[15;3~, kf54=\E[17;3~, kf55=\E[18;3~, kf56=\E[19;3~, kf57=\E[20;3~, kf58=\E[21;3~, kf59=\E[23;3~, kf6=\E[17~, kf60=\E[24;3~, kf61=\E[1;4P, kf62=\E[1;4Q, kf63=\E[1;4R, kf7=\E[18~, kf8=\E[19~, kf9=\E[20~, khome=\EOH, kich1=\E[2~, kind=\E[1;2B, kmous=\E[M, knp=\E[6~, kpp=\E[5~, kri=\E[1;2A, mc0=\E[i, mc4=\E[4i, mc5=\E[5i, meml=\El, memu=\Em, op=\E[39;49m, rc=\E8, rev=\E[7m, ri=\EM, rin=\E[%p1%dT, ritm=\E[23m, rmacs=\E(B, rmam=\E[?7l, rmcup=\E[?1049l, rmir=\E[4l, rmkx=\E[?1l\E>, rmso=\E[27m, rmul=\E[24m, rs1=\Ec, rs2=\E[!p\E[?3;4l\E[4l\E>, sc=\E7, setab=\E[%?%p1%{8}%<%t4%p1%d%e%p1%{16}%<%t10%p1%{8}%-%d%e48;5;%p1%d%;m, setaf=\E[%?%p1%{8}%<%t3%p1%d%e%p1%{16}%<%t9%p1%{8}%-%d%e38;5;%p1%d%;m, sgr=%?%p9%t\E(0%e\E(B%;\E[0%?%p6%t;1%;%?%p5%t;2%;%?%p2%t;4%;%?%p1%p3%|%t;7%;%?%p4%t;5%;%?%p7%t;8%;m, sgr0=\E(B\E[m, sitm=\E[3m, smacs=\E(0, smam=\E[?7h, smcup=\E[?1049h, smir=\E[4h, smkx=\E[?1h\E=, smso=\E[7m, smul=\E[4m, tbc=\E[3g, u6=\E[%i%d;%dR, u7=\E[6n, u8=\E[?1;2c, u9=\E[c, vpa=\E[%i%p1%dd, ``` As such, the terminal is advertising support for `ccc`, but it does not seem to support it in practice. Per https://linux.die.net/man/5/terminfo: > On a Tektronix-like terminal, the capability ccc may be present to indicate that colors can be modified. If so, the initc capability will take a color number (0 to colors - 1)and three more parameters which describe the color. These three parameters default to being interpreted as RGB (Red, Green, Blue) values. If the boolean capability hls is present, they are instead as HLS (Hue, Lightness, Saturation) indices. The ranges are terminal-dependent. As far as I can tell, conhost only supports the HP-like color API: > On an HP-like terminal, initp may give a capability for changing a color-pair value. It will take seven parameters; a color-pair number (0 to max_pairs - 1), and two triples describing first background and then foreground colors. These parameters must be (Red, Green, Blue) or (Hue, Lightness, Saturation) depending on hls. WSL should probably ship with a patched termcap file that drops `ccc` from `xterm-256-color`. _Copied from original issue: Microsoft/WSL#2566_
claunia added the Issue-FeatureProduct-ConhostResolution-Fix-Available labels 2026-01-30 21:42:16 +00:00
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@bitcrazed commented on GitHub (Feb 16, 2018):

From @zadjii-msft on October 16, 2017 20:10

... Or we could just add support for it :)

That particular sequence is one that's been in my personal feature request backlog for a couple releases now. I'm hoping I can get to it in the next release. It would let me implement colortool in a way that would actually work with WSL too. It's definitely higher on the backlog.

@bitcrazed commented on GitHub (Feb 16, 2018): _From @zadjii-msft on October 16, 2017 20:10_ ... Or we could just add support for it :) That particular sequence is one that's been in my personal feature request backlog for a couple releases now. I'm hoping I can get to it in the next release. It would let me implement colortool in a way that would actually work with WSL too. It's definitely higher on the backlog.
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Reference: starred/terminal#98