hw/9pfs: Add open flag mapping

Some of the flags are OS/arch dependent we need to use
9P defined value on wire,

Based on the original patch from Venkateswararao Jujjuri <jvrao@linux.vnet.ibm.com>

Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
index d476485..dcbcdb0 100644
--- a/hw/9pfs/virtio-9p.c
+++ b/hw/9pfs/virtio-9p.c
@@ -72,6 +72,55 @@
     return ret;
 }
 
+static int dotl_to_at_flags(int flags)
+{
+    int rflags = 0;
+    if (flags & P9_DOTL_AT_REMOVEDIR) {
+        rflags |= AT_REMOVEDIR;
+    }
+    return rflags;
+}
+
+struct dotl_openflag_map {
+    int dotl_flag;
+    int open_flag;
+};
+
+static int dotl_to_open_flags(int flags)
+{
+    int i;
+    /*
+     * We have same bits for P9_DOTL_READONLY, P9_DOTL_WRONLY
+     * and P9_DOTL_NOACCESS
+     */
+    int oflags = flags & O_ACCMODE;
+
+    struct dotl_openflag_map dotl_oflag_map[] = {
+        { P9_DOTL_CREATE, O_CREAT },
+        { P9_DOTL_EXCL, O_EXCL },
+        { P9_DOTL_NOCTTY , O_NOCTTY },
+        { P9_DOTL_TRUNC, O_TRUNC },
+        { P9_DOTL_APPEND, O_APPEND },
+        { P9_DOTL_NONBLOCK, O_NONBLOCK } ,
+        { P9_DOTL_DSYNC, O_DSYNC },
+        { P9_DOTL_FASYNC, FASYNC },
+        { P9_DOTL_DIRECT, O_DIRECT },
+        { P9_DOTL_LARGEFILE, O_LARGEFILE },
+        { P9_DOTL_DIRECTORY, O_DIRECTORY },
+        { P9_DOTL_NOFOLLOW, O_NOFOLLOW },
+        { P9_DOTL_NOATIME, O_NOATIME },
+        { P9_DOTL_SYNC, O_SYNC },
+    };
+
+    for (i = 0; i < ARRAY_SIZE(dotl_oflag_map); i++) {
+        if (flags & dotl_oflag_map[i].dotl_flag) {
+            oflags |= dotl_oflag_map[i].open_flag;
+        }
+    }
+
+    return oflags;
+}
+
 void cred_init(FsCred *credp)
 {
     credp->fc_uid = -1;
@@ -86,7 +135,8 @@
     /*
      * Filter the client open flags
      */
-    flags = oflags & ~(O_NOCTTY | O_ASYNC | O_CREAT);
+    flags = dotl_to_open_flags(oflags);
+    flags &= ~(O_NOCTTY | O_ASYNC | O_CREAT);
     /*
      * Ignore direct disk access hint until the server supports it.
      */
@@ -2427,6 +2477,7 @@
     V9fsPDU *pdu = opaque;
 
     pdu_unmarshal(pdu, offset, "dsd", &dfid, &name, &flags);
+    flags = dotl_to_at_flags(flags);
 
     dfidp = get_fid(pdu, dfid);
     if (dfidp == NULL) {