hw/9pfs: add 9P2000.L renameat operation

rename - change name of file or directory

size[4] Trenameat tag[2] olddirfid[4] oldname[s] newdirfid[4] newname[s]
size[4] Rrenameat tag[2]

older Trename have the below request format

size[4] Trename tag[2] fid[4] newdirfid[4] name[s]

The rename message is used to change the name of a file, possibly moving it
to a new directory. The rename opreation is actually a directory opertation
and should ideally have olddirfid, if not we cannot represent the fid on server
with anything other than name. We will have to derive the old directory name
from fid in the Trename request.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

hw/9pfs/virtio-9p.c

@@ -2440,6 +2440,87 @@ out_nofid:
     v9fs_string_free(&name);
 }
 
+static int v9fs_complete_renameat(V9fsState *s, int32_t olddirfid,
+                                  V9fsString *old_name, int32_t newdirfid,
+                                  V9fsString *new_name)
+{
+    int err = 0;
+    V9fsString old_full_name, new_full_name;
+    V9fsFidState *newdirfidp = NULL, *olddirfidp = NULL;
+
+    olddirfidp = get_fid(s, olddirfid);
+    if (olddirfidp == NULL) {
+        err = -ENOENT;
+        goto out;
+    }
+    v9fs_string_init(&old_full_name);
+    v9fs_string_init(&new_full_name);
+
+    v9fs_string_sprintf(&old_full_name, "%s/%s",
+                        olddirfidp->path.data, old_name->data);
+    if (newdirfid != -1) {
+        newdirfidp = get_fid(s, newdirfid);
+        if (newdirfidp == NULL) {
+            err = -ENOENT;
+            goto out;
+        }
+        v9fs_string_sprintf(&new_full_name, "%s/%s",
+                            newdirfidp->path.data, new_name->data);
+    } else {
+        v9fs_string_sprintf(&new_full_name, "%s/%s",
+                            olddirfidp->path.data, new_name->data);
+    }
+
+    if (strcmp(old_full_name.data, new_full_name.data) != 0) {
+        V9fsFidState *tfidp;
+        err = v9fs_co_rename(s, &old_full_name, &new_full_name);
+        if (err < 0) {
+            goto out;
+        }
+        /*
+         * Fixup fid's pointing to the old name to
+         * start pointing to the new name
+         */
+        for (tfidp = s->fid_list; tfidp; tfidp = tfidp->next) {
+            if (v9fs_path_is_ancestor(&old_full_name, &tfidp->path)) {
+                /* replace the name */
+                v9fs_fix_path(&tfidp->path, &new_full_name, old_full_name.size);
+            }
+        }
+    }
+out:
+    if (olddirfidp) {
+        put_fid(s, olddirfidp);
+    }
+    if (newdirfidp) {
+        put_fid(s, newdirfidp);
+    }
+    v9fs_string_free(&old_full_name);
+    v9fs_string_free(&new_full_name);
+    return err;
+}
+
+static void v9fs_renameat(void *opaque)
+{
+    ssize_t err = 0;
+    size_t offset = 7;
+    V9fsPDU *pdu = opaque;
+    V9fsState *s = pdu->s;
+    int32_t olddirfid, newdirfid;
+    V9fsString old_name, new_name;
+
+    pdu_unmarshal(pdu, offset, "dsds", &olddirfid,
+                  &old_name, &newdirfid, &new_name);
+
+    err = v9fs_complete_renameat(s, olddirfid, &old_name, newdirfid, &new_name);
+    if (!err) {
+        err = offset;
+    }
+    complete_pdu(s, pdu, err);
+    v9fs_string_free(&old_name);
+    v9fs_string_free(&new_name);
+}
+
 static void v9fs_wstat(void *opaque)
 {
     int32_t fid;
@@ -2957,6 +3038,7 @@ static CoroutineEntry *pdu_co_handlers[] = {
     [P9_TRENAME] = v9fs_rename,
     [P9_TLOCK] = v9fs_lock,
     [P9_TGETLOCK] = v9fs_getlock,
+    [P9_TRENAMEAT] = v9fs_renameat,
     [P9_TREADLINK] = v9fs_readlink,
     [P9_TMKDIR] = v9fs_mkdir,
     [P9_TVERSION] = v9fs_version,

hw/9pfs/virtio-9p.h

@@ -50,6 +50,8 @@ enum {
     P9_RLINK,
     P9_TMKDIR = 72,
     P9_RMKDIR,
+    P9_TRENAMEAT = 74,
+    P9_RRENAMEAT,
     P9_TVERSION = 100,
     P9_RVERSION,
     P9_TAUTH = 102,