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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: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20180609151758.17343-4-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: comment tweaks]
Signed-off-by: Eric Blake <eblake@redhat.com>
master
Vladimir Sementsov-Ogievskiy 2018-06-19 16:55:09 -05:00 committed by Eric Blake
parent af736e5467
commit b0769d8f8d
1 changed files with 68 additions and 33 deletions
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101
nbd/server.c
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@ -733,6 +733,71 @@ static int nbd_negotiate_send_meta_context(NBDClient *client,
return qio_channel_writev_all(client->ioc, iov, 2, errp) < 0 ? -EIO : 0;
}
/* 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 read exactly @pattern.
* It only means that there are no errors.
*/
static int nbd_meta_pattern(NBDClient *client, const char *pattern, bool *match,
Error **errp)
{
int ret;
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) {
*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 queries to 'base' namespace. For now, only the base:allocation
@ -741,43 +806,12 @@ static int nbd_negotiate_send_meta_context(NBDClient *client,
*
* 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.
*/
static int nbd_meta_base_query(NBDClient *client, NBDExportMetaContexts *meta,
uint32_t len, Error **errp)
{
int ret;
char query[sizeof("allocation") - 1];
size_t alen = strlen("allocation");
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);
}
ret = nbd_opt_read(client, query, len, errp);
if (ret <= 0) {
return ret;
}
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;
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);
}