Re: [Xen-devel] [PATCH 12/18] xenstored support for in-memory rather than FS based trivial DB (needed to run on mini-OS)

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-01-12 at 23:35 +0000, Daniel De Graaf wrote:
> From: Alex Zeffertt <alex.zeffertt@xxxxxxxxxxxxx>
> 
> tdb_copy (a xen modification to tdb?)

I believe so, the original author of xenstored was also the author of
tdb, IIRC.

>  should honor the TDB_INTERNAL flag
> for in-memory databases.
> 
> TODO: leaks memory on error case

Does this happen on every/any transaction conflict or just if a bad
thing has occurred?

In any case, is fixing it not just a case of calling talloc_free?

FWIW this bit of C xenstored is the main reason I think oxenstored
is/would be a better fit for a stub xenstored.


> Signed-off-by: Diego Ongaro <diego.ongaro@xxxxxxxxxx>
> Signed-off-by: Alex Zeffertt <alex.zeffertt@xxxxxxxxxxxxx>
> Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>
> ---
>  tools/xenstore/tdb.c |   36 ++++++++++++++++++++++++++++++++++++
>  1 files changed, 36 insertions(+), 0 deletions(-)
> 
> diff --git a/tools/xenstore/tdb.c b/tools/xenstore/tdb.c
> index 63205e1..639ce6e 100644
> --- a/tools/xenstore/tdb.c
> +++ b/tools/xenstore/tdb.c
> @@ -2103,6 +2103,42 @@ TDB_CONTEXT *tdb_copy(TDB_CONTEXT *tdb, const char 
> *outfile)
>       int fd, saved_errno;
>       TDB_CONTEXT *copy;
>  
> +     if (tdb->flags & TDB_INTERNAL) {
> +             struct tdb_header *copydb;
> +             
> +             copy = talloc_zero(outfile, TDB_CONTEXT);
> +             if (copy == NULL) {
> +                     errno = ENOMEM;
> +                     goto intfail;
> +             }
> +             memcpy(copy, tdb, sizeof(TDB_CONTEXT));
> +
> +             if (copy->name || copy->locked || copy->device || copy->inode) {
> +                     fprintf(stderr, "tdb_copy assumption(s) failed\n");
> +                     goto intfail;
> +             }
> +
> +             copydb = talloc_zero_size(copy, copy->map_size);
> +             if (copydb == NULL) {
> +                     errno = ENOMEM;
> +                     goto intfail;
> +             }
> +             memcpy(copydb, copy->map_ptr, copy->map_size);
> +             copy->map_ptr = (char*) copydb;
> +
> +             if (tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0) == -1)
> +                     goto intfail;
> +
> +             copy->next = tdbs;
> +             tdbs = copy;
> +
> +
> +             return copy;
> +intfail:
> +             /* TODO (leaking memory is easier) */
> +             return NULL;
> +     }
> +
>       fd = open(outfile, O_TRUNC|O_CREAT|O_WRONLY, 0640);
>       if (fd < 0)
>               return NULL;



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