* [9fans] IOHDRSZ
@ 2013-04-04 19:50 erik quanstrom
2013-04-04 20:14 ` Charles Forsyth
0 siblings, 1 reply; 3+ messages in thread
From: erik quanstrom @ 2013-04-04 19:50 UTC (permalink / raw)
To: 9fans
i wonder if the typical use of IOHDRSZ is correct.
many programs set
msize = bufsize + IOHDRSIZE
but Twrite has 2+4+8+4=18 bytes overhead, so
i think this assumption is going to lead to
6-byte buffer overruns.
- erik
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [9fans] IOHDRSZ
2013-04-04 19:50 [9fans] IOHDRSZ erik quanstrom
@ 2013-04-04 20:14 ` Charles Forsyth
2013-04-04 20:49 ` erik quanstrom
0 siblings, 1 reply; 3+ messages in thread
From: Charles Forsyth @ 2013-04-04 20:14 UTC (permalink / raw)
To: Fans of the OS Plan 9 from Bell Labs
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On 4 April 2013 20:50, erik quanstrom <quanstro@quanstro.net> wrote:
> so
> i think this assumption is going to lead to
> 6-byte buffer overruns.
>
I don't follow the reasoning. bufsize + Rread or Twrite will always fit.
bufsize is the limit for application data. The receiving 9P also trims the
count
to match the receiving buffer.
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [9fans] IOHDRSZ
2013-04-04 20:14 ` Charles Forsyth
@ 2013-04-04 20:49 ` erik quanstrom
0 siblings, 0 replies; 3+ messages in thread
From: erik quanstrom @ 2013-04-04 20:49 UTC (permalink / raw)
To: 9fans
> On 4 April 2013 20:50, erik quanstrom <quanstro@quanstro.net> wrote:
>
> > so
> > i think this assumption is going to lead to
> > 6-byte buffer overruns.
> >
>
> I don't follow the reasoning. bufsize + Rread or Twrite will always fit.
> bufsize is the limit for application data. The receiving 9P also trims the
> count
> to match the receiving buffer.
i'm thinking of applications that have a seperate buffer for data.
in this case, i can't think of a clean way of sizing that seperate buffer
correctly. if msize=bufsize+IOHDRSZ, then incoming bytes would
be too big.
- erik
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-04-04 20:49 UTC | newest]
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2013-04-04 19:50 [9fans] IOHDRSZ erik quanstrom
2013-04-04 20:14 ` Charles Forsyth
2013-04-04 20:49 ` erik quanstrom
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