[Qemu-devel] [PATCH 08/18] nbd: Limit nbdflags to 16 bits

[Eric Blake <eblake@redhat.com>]

Rather than asserting that nbdflags is within range, just give
it the correct type to begin with :)  nbdflags corresponds to
the per-export portion of NBD Protocol "transmission flags", which
is 16 bits in response to NBD_OPT_EXPORT_NAME and NBD_OPT_GO.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 include/block/nbd.h |  2 +-
 nbd/server.c        | 10 ++++------
 qemu-nbd.c          |  2 +-
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/include/block/nbd.h b/include/block/nbd.h
index 2c61901..42fd670 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -105,7 +105,7 @@ typedef struct NBDExport NBDExport;
 typedef struct NBDClient NBDClient;

 NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size,
-                          uint32_t nbdflags, void (*close)(NBDExport *),
+                          uint16_t nbdflags, void (*close)(NBDExport *),
                           Error **errp);
 void nbd_export_close(NBDExport *exp);
 void nbd_export_get(NBDExport *exp);
diff --git a/nbd/server.c b/nbd/server.c
index 93c077e..c8666ab 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -63,7 +63,7 @@ struct NBDExport {
     char *name;
     off_t dev_offset;
     off_t size;
-    uint32_t nbdflags;
+    uint16_t nbdflags;
     QTAILQ_HEAD(, NBDClient) clients;
     QTAILQ_ENTRY(NBDExport) next;

@@ -525,8 +525,8 @@ static coroutine_fn int nbd_negotiate(NBDClientNewData *data)
     NBDClient *client = data->client;
     char buf[8 + 8 + 8 + 128];
     int rc;
-    const int myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
-                         NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA);
+    const uint16_t myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
+                              NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA);
     bool oldStyle;

     /* Old style negotiation header without options
@@ -556,7 +556,6 @@ static coroutine_fn int nbd_negotiate(NBDClientNewData *data)

     oldStyle = client->exp != NULL && !client->tlscreds;
     if (oldStyle) {
-        assert ((client->exp->nbdflags & ~65535) == 0);
         stq_be_p(buf + 8, NBD_CLIENT_MAGIC);
         stq_be_p(buf + 16, client->exp->size);
         stw_be_p(buf + 26, client->exp->nbdflags | myflags);
@@ -585,7 +584,6 @@ static coroutine_fn int nbd_negotiate(NBDClientNewData *data)
             goto fail;
         }

-        assert ((client->exp->nbdflags & ~65535) == 0);
         stq_be_p(buf + 18, client->exp->size);
         stw_be_p(buf + 26, client->exp->nbdflags | myflags);
         if (nbd_negotiate_write(client->ioc, buf + 18, sizeof(buf) - 18) !=
@@ -807,7 +805,7 @@ static void nbd_eject_notifier(Notifier *n, void *data)
 }

 NBDExport *nbd_export_new(BlockBackend *blk, off_t dev_offset, off_t size,
-                          uint32_t nbdflags, void (*close)(NBDExport *),
+                          uint16_t nbdflags, void (*close)(NBDExport *),
                           Error **errp)
 {
     NBDExport *exp = g_malloc0(sizeof(NBDExport));
diff --git a/qemu-nbd.c b/qemu-nbd.c
index c2e4d3f..8880ac3 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -454,7 +454,7 @@ int main(int argc, char **argv)
     BlockBackend *blk;
     BlockDriverState *bs;
     off_t dev_offset = 0;
-    uint32_t nbdflags = 0;
+    uint16_t nbdflags = 0;
     bool disconnect = false;
     const char *bindto = "0.0.0.0";
     const char *port = NULL;
-- 
2.5.5