On 06/09/2018 10:17 AM, Vladimir Sementsov-Ogievskiy wrote:
Add nbd_meta_pattern() and nbd_meta_empty_or_pattern() helpers for
metadata query parsing. nbd_meta_pattern() will be reused for "qemu"
s/for/for the/
namespace in following patches.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
nbd/server.c | 86 +++++++++++++++++++++++++++++++++++++++++-------------------
1 file changed, 59 insertions(+), 27 deletions(-)
Feels like growth, even though the goal of refactoring is reuse; but the
reuse comes later so I'm okay with it.
diff --git a/nbd/server.c b/nbd/server.c
index 567561a77e..2d762d7289 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -733,52 +733,83 @@ 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 query to 'base' namespace. For now, only base:allocation context is
[1]...
- * available in it. '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 "base:allocation"
- * namespace. It only means that there are no errors.*/
-static int nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta,
- uint32_t len, Error **errp)
+ * Note: return code = 1 doesn't mean that we've read exactly @pattern
+ * It only means that there are no errors. */
Comment tail on its own line (now that we've got a patch pending for
HACKING to document that, I'll start abiding by it...)
+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;
+ int len = strlen(pattern);
size_t is better than len for strlen() results.
- if (len == 0) {
- if (client->opt == NBD_OPT_LIST_META_CONTEXT) {
- meta->base_allocation = true;
- }
- trace_nbd_negotiate_meta_query_parse("base:");
- return 1;
- }
-
- if (len != alen) {
- trace_nbd_negotiate_meta_query_skip("not base:allocation");
- return nbd_opt_skip(client, len, errp);
- }
+ assert(len);
+ query = g_malloc(len);
At first, I wondered if we could just use a pre-allocated stack buffer
larger than any string we ever anticipate. But thinking about it, your
dirty bitmap exports expose a name under user control, which means a
user could (spitefully) pick a name longer than our buffer (well, up to
the 4k name limit imposed by the NBD protocol). So I can live with the
malloc.
ret = nbd_opt_read(client, query, len, errp);
if (ret <= 0) {
+ g_free(query);
return ret;
}
- if (strncmp(query, "allocation", alen) == 0) {
- trace_nbd_negotiate_meta_query_parse("base:allocation");
- meta->base_allocation = true;
+ if (strncmp(query, pattern, len) == 0) {
+ trace_nbd_negotiate_meta_query_parse(pattern);
+ *match = true;
} else {
- trace_nbd_negotiate_meta_query_skip("not base:allocation");
+ trace_nbd_negotiate_meta_query_skip(pattern);
Would this one read better as "not %s", pattern?
}
+ 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. */
More comment formatting.
+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) {
+ *match = true;
+ }
+ trace_nbd_negotiate_meta_query_parse("empty");
+ return 1;
+ }
+
+ if (len != strlen(pattern)) {
+ trace_nbd_negotiate_meta_query_skip("different lengths");
+ return nbd_opt_skip(client, len, errp);
+ }
+
+ return nbd_meta_pattern(client, pattern, match, errp);
+}
+
+/* nbd_meta_base_query
+ *
+ * Handle query to 'base' namespace. For now, only base:allocation context is
Pre-existing (see [1]), but reads better as "Handle queries to the
'base' namespace"
+ * available in it. '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
*
* Parse namespace name and call corresponding function to parse body of the
@@ -822,6 +853,7 @@ 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);
}
My findings were trivial; the code refactoring itself looks sane.
Reviewed-by: Eric Blake <ebl...@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
