Commit b0769d8f authored by Vladimir Sementsov-Ogievskiy's avatar Vladimir Sementsov-Ogievskiy Committed by Eric Blake
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nbd/server: add nbd_meta_empty_or_pattern helper 



Add nbd_meta_pattern() and nbd_meta_empty_or_pattern() helpers for
metadata query parsing. nbd_meta_pattern() will be reused for the
"qemu" namespace in following patches.

Signed-off-by: default avatarVladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20180609151758.17343-4-vsementsov@virtuozzo.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
[eblake: comment tweaks]
Signed-off-by: default avatarEric Blake <eblake@redhat.com>
parent af736e54

nbd/server.c

+62 −27
Original line number Diff line number Diff line
@@ -733,51 +733,85 @@ static int nbd_negotiate_send_meta_context(NBDClient *client, 
    return qio_channel_writev_all(client->ioc, iov, 2, errp) < 0 ? -EIO : 0;

}



/* nbd_meta_base_query

 *

 * Handle queries to 'base' namespace. For now, only the base:allocation

 * context is available.  'len' is the amount of text remaining to be read from

 * the current name, after the 'base:' portion has been stripped.

/* Read strlen(@pattern) bytes, and set @match to true if they match @pattern.

 * @match is never set to false.

 *

 * Return -errno on I/O error, 0 if option was completely handled by

 * sending a reply about inconsistent lengths, or 1 on success.

 *

 * Note: return code = 1 doesn't mean that we've parsed the "base:allocation"

 * namespace. It only means that there are no errors.

 * Note: return code = 1 doesn't mean that we've read exactly @pattern.

 * It only means that there are no errors.

 */

static int nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta,

                               uint32_t len, Error **errp)

static int nbd_meta_pattern(NBDClient *client, const char *pattern, bool *match,

                            Error **errp)

{

    int ret;

    char query[sizeof("allocation") - 1];

    size_t alen = strlen("allocation");

    char *query;

    size_t len = strlen(pattern);



    assert(len);



    query = g_malloc(len);

    ret = nbd_opt_read(client, query, len, errp);

    if (ret <= 0) {

        g_free(query);

        return ret;

    }



    if (strncmp(query, pattern, len) == 0) {

        trace_nbd_negotiate_meta_query_parse(pattern);

        *match = true;

    } else {

        trace_nbd_negotiate_meta_query_skip("pattern not matched");

    }

    g_free(query);



    return 1;

}



/*

 * Read @len bytes, and set @match to true if they match @pattern, or if @len

 * is 0 and the client is performing _LIST_. @match is never set to false.

 *

 * Return -errno on I/O error, 0 if option was completely handled by

 * sending a reply about inconsistent lengths, or 1 on success.

 *

 * Note: return code = 1 doesn't mean that we've read exactly @pattern.

 * It only means that there are no errors.

 */

static int nbd_meta_empty_or_pattern(NBDClient *client, const char *pattern,

                                     uint32_t len, bool *match, Error **errp)

{

    if (len == 0) {

        if (client->opt == NBD_OPT_LIST_META_CONTEXT) {

            meta->base_allocation = true;

            *match = true;

        }

        trace_nbd_negotiate_meta_query_parse("base:");

        trace_nbd_negotiate_meta_query_parse("empty");

        return 1;

    }



    if (len != alen) {

        trace_nbd_negotiate_meta_query_skip("not base:allocation");

    if (len != strlen(pattern)) {

        trace_nbd_negotiate_meta_query_skip("different lengths");

        return nbd_opt_skip(client, len, errp);

    }



    ret = nbd_opt_read(client, query, len, errp);

    if (ret <= 0) {

        return ret;

    return nbd_meta_pattern(client, pattern, match, errp);

}



    if (strncmp(query, "allocation", alen) == 0) {

        trace_nbd_negotiate_meta_query_parse("base:allocation");

        meta->base_allocation = true;

    } else {

        trace_nbd_negotiate_meta_query_skip("not base:allocation");

    }



    return 1;

/* nbd_meta_base_query

 *

 * Handle queries to 'base' namespace. For now, only the base:allocation

 * context is available.  'len' is the amount of text remaining to be read from

 * the current name, after the 'base:' portion has been stripped.

 *

 * Return -errno on I/O error, 0 if option was completely handled by

 * sending a reply about inconsistent lengths, or 1 on success.

 */

static int nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta,

                               uint32_t len, Error **errp)

{

    return nbd_meta_empty_or_pattern(client, "allocation", len,

                                     &meta->base_allocation, errp);

}



/* nbd_negotiate_meta_query
@@ -823,6 +857,7 @@ static int nbd_negotiate_meta_query(NBDClient *client, 
        return nbd_opt_skip(client, len, errp);

    }



    trace_nbd_negotiate_meta_query_parse("base:");

    return nbd_meta_base_query(client, meta, len, errp);

}