[9fans] wctl

[9fans] wctl

[有澤健治]

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Hello, 9fans

In writing a program I met a problem on finding window size.
cat /dev/wctl
shows something like this:
hebe% cat /dev/wctl
        456          91        1214         603     current     visible
hebe%
Need DEL key to stop. I want to get this info without manual intervention.

I tried a experimental code:

#include <u.h>
#include <libc.h>

void
main(void)
{ char buf[256];
int fd,n;
fd = open("/dev/wctl",OREAD);
print("%d\n",fd);
//n = readn(fd,buf,1);//NG. buffer too small
//n = readn(fd,buf,48);//NG. truncated
//n = readn(fd,buf,56);//NG. truncated
//n = readn(fd,buf,70);//NG. truncated
n = readn(fd,buf,71);//OK, n=71
//n = readn(fd,buf,111);//OK.  n=71
//n = readn(fd,buf,117);//OK.  n=71
//n = readn(fd,buf,128);//NG. hungup
/* I donn't know the reasnalbe value m for readn(fd,buf,m) */
if(n < 0){
print("%r\n");
}
buf[n] = 0;
print("n=%d\n%s\n",n,buf);
close(fd);
exits(nil);
}

I don't know whether m in readn(fd,buf,m) depends on something or not.
If depends. then how to know getting OK value?

Kenji Arisawa

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Re: [9fans] wctl

[umbraticus]

; read -c 72 /dev/wctl

rio(4)

umbraticus

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Re: [9fans] wctl

[Richard Miller]

> ; read -c 72 /dev/wctl

Or, if your chosen flavour of Plan 9 doesn't have the 'read -c'
option, one of these will do:

dd -if /dev/wctl -bs 72 -count 1 -quiet 1
syscall -o read 0 buf 72 </dev/wctl >[2]/dev/null


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Re: [9fans] wctl

[有澤健治]

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Thanks for umbraticus and Richard.

The value 72 is experimentally OK.
However I am not convinced yet.
I can't find the value in the manual.

Kenji Arisawa

2023年5月9日(火) 17:00 Richard Miller <9fans@hamnavoe.com>:

> > ; read -c 72 /dev/wctl
> 
> Or, if your chosen flavour of Plan 9 doesn't have the 'read -c'
> option, one of these will do:
> 
> dd -if /dev/wctl -bs 72 -count 1 -quiet 1
> syscall -o read 0 buf 72 </dev/wctl >[2]/dev/null
> 

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Re: [9fans] wctl

[sirjofri]

09.05.2023 15:04:07 有澤健治 <karisawa@gmail.com>:

> Thanks for umbraticus and Richard.
>
> The value 72 is experimentally OK.
> However I am not convinced yet.
> I can't find the value in the manual.

Not experimentally. According to rio(4), it's 4 values padded to 12 chars, plus the window state as two strings, also padded to 12. If you do the math: 6*12=72.

sirjofri

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Re: [9fans] wctl

[有澤健治]

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Thanks. sirjofri

OK. I have understood!
I have misunderstood the meaning "padded".
Sorry for may poor english.

2023年5月10日(水) 0:06 sirjofri <sirjofri+ml-9fans@sirjofri.de>:

>
> 09.05.2023 15:04:07 有澤健治 <karisawa@gmail.com>:
>
> > Thanks for umbraticus and Richard.
> >
> > The value 72 is experimentally OK.
> > However I am not convinced yet.
> > I can't find the value in the manual.
> 
> Not experimentally. According to rio(4), it's 4 values padded to 12 chars,
> plus the window state as two strings, also padded to 12. If you do the
> math: 6*12=72.
> 
> sirjofri

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