Attachment 594740 Details for Bug 835849 – Preliminary dtach patch, provided to SF upstream ticket

[patch] Preliminary dtach patch, provided to SF upstream ticket

disconnect.patch (text/plain), 1.16 KB, created by Jan Lieskovsky on 2012-06-27 10:01:05 UTC

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Creator: Jan Lieskovsky

Created: 2012-06-27 10:01:05 UTC

Size: 1.16 KB

patch

obsolete

>Fixed broken check of read operation
>
>When client disconnects uncleanly, it might happen that an underlying
>read() operation returns with an error.  This error was interpreted
>wrongly because the negative return value was assigned to a variable
>of unsigned type and being checked for <= 0. As this condition does
>not hold in error case, a packet with wrong len (255) was sent instead
>of aborting the client:
>
>| read(0, 0x7fffa6dcfb12, 8) = -1 EIO (Input/output error)
>| write(3, "\0\377\0\0\0\0\0\0\0\0", 10) = 10
>
>
>For reference, the 'pkt' is defined as
>
>| struct packet
>| {
>| 	unsigned char type;
>| 	unsigned char len;
>| ...
>| }
>
>Index: dtach-0.8/attach.c
>===================================================================
>--- dtach-0.8.orig/attach.c
>+++ dtach-0.8/attach.c
>@@ -237,12 +237,16 @@ attach_main(int noerror)
> 		/* stdin activity */
> 		if (n > 0 && FD_ISSET(0, &readfds))
> 		{
>+			ssize_t l;
>+
> 			pkt.type = MSG_PUSH;
> 			memset(pkt.u.buf, 0, sizeof(pkt.u.buf));
>-			pkt.len = read(0, pkt.u.buf, sizeof(pkt.u.buf));
>+			l = read(0, pkt.u.buf, sizeof(pkt.u.buf));
> 
>-			if (pkt.len <= 0)
>+			if (l <= 0)
> 				exit(1);
>+
>+			pkt.len = l;
> 			process_kbd(s, &pkt);
> 			n--;
> 		}

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Attachments on bug 835849: 594740