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Re: CVS update: subversion/subversion/libsvn_fs id.c

From: Greg Stein <gstein_at_lyra.org>
Date: 2001-02-28 22:14:18 CET

Another alternative is to stash a pool into app_private field of the DBT
whenever you create it. Hmm... I wonder if that will be set properly for a
key pulled out of the database.

I recognize that compare_nodes_keys() isn't leaking memory, but
(accidentally) passing NULL to svn_fs_parse_id() from some other call point
could introduce leakage.



On Wed, Feb 28, 2001 at 10:27:05AM -0500, Jim Blandy wrote:
> Greg Stein <gstein@lyra.org> writes:
> > So the question becomes: wtf was NULL passed? I'm wary of anything that is
> > using malloc rather than a pool. IMO, we should always use a pool and never
> > fall back to malloc. Consider: who is calling free() on that thing?
> Don't fret --- we are of one mind on that issue.
> The documentation for svn_fs_parse_id reads:
> Allocate the parsed ID in POOL. If POOL is zero, malloc the ID; we
> need this in certain cases where we can't pass in a pool, but it's
> generally best to use a pool whenever possible. */
> I've added the following comment to nodes-table.c, above
> compare_nodes_keys, which is the only place where we use this:
> NOTE WELL: this function and its helpers use `malloc' to get space
> for the parsed node revision ID's. In general, we try to use pools
> for everything in Subversion, but in this case it's not practical.
> Berkeley DB doesn't provide any way to pass a baton through to the
> btree comparison function. Even if it did, since Berkeley DB needs
> to invoke the comparison function at pretty arbitrary times, you'd
> have to pass the baton to almost every Berkeley DB operation. You
> could stuff a pool pointer in a global variable, but then you'd
> have to make sure the pool was up to date before every Berkeley DB
> operation; you'd surely forget, leading to crashes... Using malloc
> is more maintainable. Since the comparison function isn't allowed
> to signal an error anyway, the need for pools isn't quite as urgent
> as in other code, but we still need to take care. */

Greg Stein, http://www.lyra.org/
Received on Sat Oct 21 14:36:23 2006

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