From de65ad93b1b0a38c8a3f26eb1bc4090eb19db00f Mon Sep 17 00:00:00 2001

From: John Snow <jsnow@redhat.com>

Date: Wed, 18 Jul 2018 22:55:02 +0200

Subject: [PATCH 244/268] nbd/server: add nbd_meta_empty_or_pattern helper

RH-Author: John Snow <jsnow@redhat.com>

Message-id: <20180718225511.14878-27-jsnow@redhat.com>

Patchwork-id: 81398

O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH 26/35] nbd/server: add nbd_meta_empty_or_pattern helper

Bugzilla: 1207657

RH-Acked-by: Eric Blake <eblake@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Fam Zheng <famz@redhat.com>

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

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>

(cherry picked from commit b0769d8f8df0b51881f1f15c9e29722cf6191a43)

Signed-off-by: John Snow <jsnow@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 nbd/server.c | 89 ++++++++++++++++++++++++++++++++++++++++++------------------

 1 file changed, 62 insertions(+), 27 deletions(-)

diff --git a/nbd/server.c b/nbd/server.c

index 26cc41a..9171cd4 100644

--- a/nbd/server.c

+++ b/nbd/server.c

@@ -733,53 +733,87 @@ 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");

-

-    if (len == 0) {

-        if (client->opt == NBD_OPT_LIST_META_CONTEXT) {

-            meta->base_allocation = true;

-        }

-        trace_nbd_negotiate_meta_query_parse("base:");

-        return 1;

-    }

+    char *query;

+    size_t len = strlen(pattern);

-    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);

     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 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

+ * 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

  *

  * Parse namespace name and call corresponding function to parse body of the

@@ -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);

 }

-- 

1.8.3.1