[Printing-architecture] Fix for STR #4187 incomplete, missing part attached

[Till Kamppeter <till.kamppeter@gmail.com>]

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Hi,

it seems that if a CUPS client (like the print dialog of LibreOffice)
stays connected to CUPS for a long time, the connection can get dropped
and the client does not reconnect.

This is handled by the following Ubuntu bug report:

https://bugs.launchpad.net/ubuntu/+source/libreoffice/+bug/1020048

and also upstream by the following report in the former STR system:

http://www.cups.org/str.php?L4187

The STR was considered fixed by applying a patch, but the reporter of
the Ubuntu bug has found out that another patch is needed to complete
the fix. See comment #37 in the Ubuntu report:

https://bugs.launchpad.net/ubuntu/+source/libreoffice/+bug/1020048/comments/37

The current CUPS 1.7.0rc1 has this "else" part but there is still
missing that "if" has also to close the connection when the result of
the recv() function is zero, meaning EOF, which happens when the server
terminates the connection.-

The attached patch adds this missing part.

In comment #44 of the Ubuntu report it is confirmed that this missing
piece applied fixes the problem completely:

https://bugs.launchpad.net/ubuntu/+source/libreoffice/+bug/1020048/comments/44

Can you apply this patch to the final CUPS 1.7.0? Thanks.

   Till


[-- Attachment #2: handle-server-terminating-connection.patch --]
[-- Type: text/x-patch, Size: 643 bytes --]

--- a/cups/request.c
+++ b/cups/request.c
@@ -1018,13 +1018,14 @@
       */
 
       char ch;				/* Connection check byte */
+      int n;
 
 #ifdef WIN32
-      if (recv(cg->http->fd, &ch, 1, MSG_PEEK) < 0 &&
-          WSAGetLastError() != WSAEWOULDBLOCK)
+      if ((n = recv(cg->http->fd, &ch, 1, MSG_PEEK) == 0) ||
+          (n < 0 && WSAGetLastError() != WSAEWOULDBLOCK))
 #else
-      if (recv(cg->http->fd, &ch, 1, MSG_PEEK | MSG_DONTWAIT) < 0 &&
-          errno != EWOULDBLOCK)
+      if ((n = recv(cg->http->fd, &ch, 1, MSG_PEEK | MSG_DONTWAIT) == 0) ||
+	  (n < 0 && errno != EWOULDBLOCK))
 #endif /* WIN32 */
       {
        /*