Date: Thu, 9 May 96 23:29:56 BST From: Tom Crummey (ADM) <tom@uces.bangor.ac.uk> To: freebsd-questions@freebsd.org Subject: write and pty's Message-ID: <16010.9605092229@bowden.uces.bangor.ac.uk>
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Hello, I have been trying to track down a problem in the xview library code which causes the cmdtool program to continuously output to the pty it is using. For example, start a cmdtool and type return. You will get a continuous stream of prompts as if you were continually typing the return key. After some hours with xxgdb and libraries compiled with debugging symbols, I tracked the problem to a write call. This write call returns 0 even though it appears that a charater has been written. The fact that this call returns 0 means that the write pointer in the cmdtool code is not updated and so it is written again etc. (you get the picture) It seems that there is a problem with the write system call returning 0 instead of the number of characters written in this particular case. The pty is supposedly not in remote mode. Does anyone have any idea why the write call would return 0 even when characters have been written? Could anyone who knows the pty kernel code comment? I can send the segment of code involved, but I suspect it won't help as there is too much context requried to see what is going on. I think I might be getting slightly out of my depth..... glug ..glug... -- Tom. ---------------------------------------------------------------------------- Tom Crummey, EMAIL: tom@uces.bangor.ac.uk | /\ University of Wales, Bangor, | / \/\ Unit for Coastal and Estuarine Studies, | /\/ \ \ Ynys Faelog, Menai Bridge, TEL: +44 (0)1248 713808 |/ ======\=\ Gwynedd, LL59 5EY, U.K. FAX: +44 (0)1248 716729 | B A N G O R ----------------------------------------------------------------------------
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