[rc5] Buffer corruption on Win32

Francois Gouget fgouget at club-internet.fr
Sat Jul 19 18:08:47 EDT 1997


	The symptom is that the number of blocks remaining in the
buffer file gets corrupted as is shown by the following commands (tools
of mine).

> rc5count buff-in.rc5
buff-in.rc5: -16767 blocks
> rc5dump buff-in.rc5
0000 00000000 ffffbe81
0008 56866048 3e657951 62ca338c b8d2e862 5518ded3 9f054c11 0178c5d3 b5e03e
^C

	In the log file (further below) this corresponds to
"GetBufferError" messages which I believe are only a by-product. I had
this problem on 4 hosts, all running rc5v2b2-p5.exe on Windows NT 3.51 and
NT4.0. It never happened on other platforms. 

	This seems to only happen when the buff-in file gets empty but I 
don't think it's systematic (I'm not sure though).

	The buff-in files are stored on Unix. In fact it's a link to the
actual buffer file, and all this is exported via Samba (1.9.16pl9). The
filesystem is not "mounted" but accessed via it's UNC name if that
matters. Also these buffered are not shared with any other rc5 process and
no network error is known to have occured at that time.

	Here is the log extract. Sometimes after a large number of
"GetBufferError" it resumes, generates a random block, and everything is
fine until it tries to read the buffer file again.

[07/18/97 04:30:38 GMT] Block: 41B675:80000000 being processed
[07/18/97 04:30:38 GMT] 2 Blocks remain in file buff-in.rc5

[07/18/97 04:58:45 GMT] Completed block 41B675:80000000 (268435456 keys)
                        00:28:07.84 - [159040.60 keys/sec]
[07/18/97 04:58:45 GMT] Block: 41B674:E0000000 being processed
[07/18/97 04:58:45 GMT] 1 Blocks remain in file buff-in.rc5

[07/18/97 05:26:52 GMT] Completed block 41B674:E0000000 (268435456 keys)
                        00:28:07.83 - [159041.54 keys/sec]
[07/18/97 05:26:53 GMT] Block: 41B674:A0000000 being processed
[07/18/97 05:26:53 GMT] 0 Blocks remain in file buff-in.rc5

[07/18/97 05:55:00 GMT] Completed block 41B674:A0000000 (268435456 keys)
                        00:28:07.45 - [159077.01 keys/sec]
Bad buffer entry 32

GetBufferError
Bad buffer entry 32

GetBufferError
Bad buffer entry 32
...


-- 
Francois Gouget
fgouget at club-internet.fr                http://www.mygale.org/~fgouget/


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