From: Nathaniel W Filardo <nwf@cs.jhu.edu>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
Subject: Re: [9fans] P9P venti/copy bug?
Date: Tue, 31 Mar 2009 03:15:40 -0400 [thread overview]
Message-ID: <20090331071540.GT22497@masters6.cs.jhu.edu> (raw)
In-Reply-To: <20090209165505.GA11908@unknown>
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On Mon, Feb 09, 2009 at 11:55:05AM -0500, Venkatesh Srinivas wrote:
> On Mon, Feb 09, 2009 at 08:48:33AM -0800, Russ Cox wrote:
>> On Mon, Feb 9, 2009 at 4:56 AM, Venkatesh Srinivas <me@acm.jhu.edu> wrote:
>>> vcopy: reading block 0000000000000000000000000000000000000000 (type 16):
>>> read asked for 0000000000000000000000000000000000000000 got
>>> da39a3ee5e6b4b0d3255bfef95601890afd80709
>>
>> The real question is how you got an archive with an all zeros score in it.
>> There are some programs that use that internally to mean "no block"
>> but any time such a block is written to venti, the score should be the
>> zero-byte sha1 da39...0709.
>>
>
> When I use -V with Plan 9's vcopy, the zero score block isn't listed...
> I suspect that the block with the zero score is not actually in the
> archive?
>
> -- vs
>
I just tripped over this myself and found that apparently Plan 9 native vac
sets root.prev to all zeros when there is no previous root. So I applied
the diff below. I'm not sure this is a correct fix?
--nwf;
diff -r 74392a7c323c src/cmd/venti/copy.c
--- a/src/cmd/venti/copy.c Wed Mar 11 13:37:29 2009 -0700
+++ b/src/cmd/venti/copy.c Tue Mar 31 03:12:53 2009 -0400
@@ -10,6 +10,8 @@
int fast;
int verbose;
VtConn *zsrc, *zdst;
+
+uchar allzeros[VtScoreSize];
void
usage(void)
@@ -54,7 +56,8 @@
break;
}
walk(root.score, VtDirType, 0);
- walk(root.prev, VtRootType, 0);
+ if(memcmp(root.prev, allzeros, VtScoreSize))
+ walk(root.prev, VtRootType, 0);
if(rewrite)
vtrootpack(&root, buf); /* walk might have changed score */
break;
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prev parent reply other threads:[~2009-03-31 7:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-09 12:56 Venkatesh Srinivas
2009-02-09 16:48 ` Russ Cox
2009-02-09 16:55 ` Venkatesh Srinivas
2009-03-31 7:15 ` Nathaniel W Filardo [this message]
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