[Libguestfs] [nbdkit PATCH] connections: Extract common export flag computation code

[Eric Blake]

No need to duplicate maintenance of export flag computation between
old and new style handshakes.

Signed-off-by: Eric Blake <eblake at redhat.com>
---
 src/connections.c | 120 +++++++++++++++++++++---------------------------------
 1 file changed, 47 insertions(+), 73 deletions(-)

diff --git a/src/connections.c b/src/connections.c
index 8dc1925..f9edea7 100644
--- a/src/connections.c
+++ b/src/connections.c
@@ -237,13 +237,57 @@ free_connection (struct connection *conn)
 }

 static int
+compute_eflags (struct connection *conn, uint16_t *flags)
+{
+  uint16_t eflags = NBD_FLAG_HAS_FLAGS;
+  int fl;
+
+  fl = plugin_can_write (conn);
+  if (fl == -1)
+    return -1;
+  if (readonly || !fl) {
+    eflags |= NBD_FLAG_READ_ONLY;
+    conn->readonly = 1;
+  }
+  if (!conn->readonly) {
+    eflags |= NBD_FLAG_SEND_WRITE_ZEROES;
+  }
+
+  fl = plugin_can_flush (conn);
+  if (fl == -1)
+    return -1;
+  if (fl) {
+    eflags |= NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA;
+    conn->can_flush = 1;
+  }
+
+  fl = plugin_is_rotational (conn);
+  if (fl == -1)
+    return -1;
+  if (fl) {
+    eflags |= NBD_FLAG_ROTATIONAL;
+    conn->is_rotational = 1;
+  }
+
+  fl = plugin_can_trim (conn);
+  if (fl == -1)
+    return -1;
+  if (fl) {
+    eflags |= NBD_FLAG_SEND_TRIM;
+    conn->can_trim = 1;
+  }
+
+  *flags = eflags;
+  return 0;
+}
+
+static int
 _negotiate_handshake_oldstyle (struct connection *conn)
 {
   struct old_handshake handshake;
   int64_t r;
   uint64_t exportsize;
   uint16_t gflags, eflags;
-  int fl;

   /* In --tls=require / FORCEDTLS mode, old style handshakes are
    * rejected because they cannot support TLS.
@@ -265,43 +309,8 @@ _negotiate_handshake_oldstyle (struct connection *conn)
   conn->exportsize = exportsize;

   gflags = 0;
-  eflags = NBD_FLAG_HAS_FLAGS;
-
-  fl = plugin_can_write (conn);
-  if (fl == -1)
+  if (compute_eflags (conn, &eflags) < 0)
     return -1;
-  if (readonly || !fl) {
-    eflags |= NBD_FLAG_READ_ONLY;
-    conn->readonly = 1;
-  }
-  if (!conn->readonly) {
-    eflags |= NBD_FLAG_SEND_WRITE_ZEROES;
-  }
-
-
-  fl = plugin_can_flush (conn);
-  if (fl == -1)
-    return -1;
-  if (fl) {
-    eflags |= NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA;
-    conn->can_flush = 1;
-  }
-
-  fl = plugin_is_rotational (conn);
-  if (fl == -1)
-    return -1;
-  if (fl) {
-    eflags |= NBD_FLAG_ROTATIONAL;
-    conn->is_rotational = 1;
-  }
-
-  fl = plugin_can_trim (conn);
-  if (fl == -1)
-    return -1;
-  if (fl) {
-    eflags |= NBD_FLAG_SEND_TRIM;
-    conn->can_trim = 1;
-  }

   debug ("oldstyle negotiation: flags: global 0x%x export 0x%x",
          gflags, eflags);
@@ -552,7 +561,6 @@ _negotiate_handshake_newstyle (struct connection *conn)
   int64_t r;
   uint64_t exportsize;
   uint16_t eflags;
-  int fl;

   gflags = NBD_FLAG_FIXED_NEWSTYLE | NBD_FLAG_NO_ZEROES;

@@ -596,42 +604,8 @@ _negotiate_handshake_newstyle (struct connection *conn)
   exportsize = (uint64_t) r;
   conn->exportsize = exportsize;

-  eflags = NBD_FLAG_HAS_FLAGS;
-
-  fl = plugin_can_write (conn);
-  if (fl == -1)
+  if (compute_eflags (conn, &eflags) < 0)
     return -1;
-  if (readonly || !fl) {
-    eflags |= NBD_FLAG_READ_ONLY;
-    conn->readonly = 1;
-  }
-  if (!conn->readonly) {
-    eflags |= NBD_FLAG_SEND_WRITE_ZEROES;
-  }
-
-  fl = plugin_can_flush (conn);
-  if (fl == -1)
-    return -1;
-  if (fl) {
-    eflags |= NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA;
-    conn->can_flush = 1;
-  }
-
-  fl = plugin_is_rotational (conn);
-  if (fl == -1)
-    return -1;
-  if (fl) {
-    eflags |= NBD_FLAG_ROTATIONAL;
-    conn->is_rotational = 1;
-  }
-
-  fl = plugin_can_trim (conn);
-  if (fl == -1)
-    return -1;
-  if (fl) {
-    eflags |= NBD_FLAG_SEND_TRIM;
-    conn->can_trim = 1;
-  }

   debug ("newstyle negotiation: flags: export 0x%x", eflags);

-- 
2.13.6