virtio-9p: Implement TXATTRWALK

TXATTRWALK: Descend a ATTR namespace

 size[4] TXATTRWALK tag[2] fid[4] newfid[4] name[s]
 size[4] RXATTRWALK tag[2] size[8]

txattrwalk gets a fid pointing to xattr. This fid can later be
used to get read the xattr value. If name is NULL the fid returned
can be used to get the list of extended attribute associated to
the file system object.
Signed-off-by: NAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

hw/file-op-9p.h

@@ -75,6 +75,9 @@ typedef struct FileOperations
     int (*truncate)(FsContext *, const char *, off_t);
     int (*fsync)(FsContext *, int);
     int (*statfs)(FsContext *s, const char *path, struct statfs *stbuf);
+    ssize_t (*lgetxattr)(FsContext *, const char *,
+                         const char *, void *, size_t);
+    ssize_t (*llistxattr)(FsContext *, const char *, void *, size_t);
     void *opaque;
 } FileOperations;
 #endif

hw/virtio-9p-debug.c

@@ -579,6 +579,16 @@ void pprint_pdu(V9fsPDU *pdu)
     case P9_RWSTAT:
         fprintf(llogfile, "RWSTAT: (");
         break;
+    case P9_TXATTRWALK:
+        fprintf(llogfile, "TXATTRWALK: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        pprint_int32(pdu, 0, &offset, ", newfid");
+        pprint_str(pdu, 0, &offset, ", xattr name");
+        break;
+    case P9_RXATTRWALK:
+        fprintf(llogfile, "RXATTRWALK: (");
+        pprint_int64(pdu, 1, &offset, "xattrsize");
+        break;
     default:
         fprintf(llogfile, "unknown(%d): (", pdu->id);
         break;

hw/virtio-9p-local.c

@@ -474,6 +474,18 @@ static int local_statfs(FsContext *s, const char *path, struct statfs *stbuf)
    return statfs(rpath(s, path), stbuf);
 }
 
+static ssize_t local_lgetxattr(FsContext *ctx, const char *path,
+                               const char *name, void *value, size_t size)
+{
+    return lgetxattr(rpath(ctx, path), name, value, size);
+}
+
+static ssize_t local_llistxattr(FsContext *ctx, const char *path,
+                                void *value, size_t size)
+{
+    return llistxattr(rpath(ctx, path), value, size);
+}
+
 FileOperations local_ops = {
     .lstat = local_lstat,
     .readlink = local_readlink,
@@ -502,4 +514,6 @@ FileOperations local_ops = {
     .remove = local_remove,
     .fsync = local_fsync,
     .statfs = local_statfs,
+    .lgetxattr = local_lgetxattr,
+    .llistxattr = local_llistxattr,
 };

hw/virtio-9p.c

@@ -263,6 +263,21 @@ static int v9fs_do_statfs(V9fsState *s, V9fsString *path, struct statfs *stbuf)
     return s->ops->statfs(&s->ctx, path->data, stbuf);
 }
 
+static ssize_t v9fs_do_lgetxattr(V9fsState *s, V9fsString *path,
+                             V9fsString *xattr_name,
+                             void *value, size_t size)
+{
+    return s->ops->lgetxattr(&s->ctx, path->data,
+                             xattr_name->data, value, size);
+}
+
+static ssize_t v9fs_do_llistxattr(V9fsState *s, V9fsString *path,
+                              void *value, size_t size)
+{
+    return s->ops->llistxattr(&s->ctx, path->data,
+                              value, size);
+}
+
 static void v9fs_string_init(V9fsString *str)
 {
     str->data = NULL;
@@ -1946,6 +1961,31 @@ out:
     qemu_free(vs);
 }
 
+static void v9fs_xattr_read(V9fsState *s, V9fsReadState *vs)
+{
+    ssize_t err = 0;
+    int read_count;
+    int64_t xattr_len;
+
+    xattr_len = vs->fidp->fs.xattr.len;
+    read_count = xattr_len - vs->off;
+    if (read_count > vs->count) {
+        read_count = vs->count;
+    } else if (read_count < 0) {
+        /*
+         * read beyond XATTR value
+         */
+        read_count = 0;
+    }
+    vs->offset += pdu_marshal(vs->pdu, vs->offset, "d", read_count);
+    vs->offset += pdu_pack(vs->pdu, vs->offset,
+                           ((char *)vs->fidp->fs.xattr.value) + vs->off,
+                           read_count);
+    err = vs->offset;
+    complete_pdu(s, vs->pdu, err);
+    qemu_free(vs);
+}
+
 static void v9fs_read(V9fsState *s, V9fsPDU *pdu)
 {
     int32_t fid;
@@ -1967,7 +2007,7 @@ static void v9fs_read(V9fsState *s, V9fsPDU *pdu)
         goto out;
     }
 
-    if (vs->fidp->fs.dir) {
+    if (vs->fidp->fid_type == P9_FID_DIR) {
         vs->max_count = vs->count;
         vs->count = 0;
         if (vs->off == 0) {
@@ -1975,12 +2015,15 @@ static void v9fs_read(V9fsState *s, V9fsPDU *pdu)
         }
         v9fs_read_post_rewinddir(s, vs, err);
         return;
-    } else if (vs->fidp->fs.fd != -1) {
+    } else if (vs->fidp->fid_type == P9_FID_FILE) {
         vs->sg = vs->iov;
         pdu_marshal(vs->pdu, vs->offset + 4, "v", vs->sg, &vs->cnt);
         err = v9fs_do_lseek(s, vs->fidp->fs.fd, vs->off, SEEK_SET);
         v9fs_read_post_lseek(s, vs, err);
         return;
+    } else if (vs->fidp->fid_type == P9_FID_XATTR) {
+        v9fs_xattr_read(s, vs);
+        return;
     } else {
         err = -EINVAL;
     }
@@ -3090,6 +3133,150 @@ out:
     qemu_free(vs);
 }
 
+static void v9fs_post_xattr_getvalue(V9fsState *s, V9fsXattrState *vs, int err)
+{
+
+    if (err < 0) {
+        err = -errno;
+        free_fid(s, vs->xattr_fidp->fid);
+        goto out;
+    }
+    vs->offset += pdu_marshal(vs->pdu, vs->offset, "q", vs->size);
+    err = vs->offset;
+out:
+    complete_pdu(s, vs->pdu, err);
+    v9fs_string_free(&vs->name);
+    qemu_free(vs);
+    return;
+}
+
+static void v9fs_post_xattr_check(V9fsState *s, V9fsXattrState *vs, ssize_t err)
+{
+    if (err < 0) {
+        err = -errno;
+        free_fid(s, vs->xattr_fidp->fid);
+        goto out;
+    }
+    /*
+     * Read the xattr value
+     */
+    vs->xattr_fidp->fs.xattr.len = vs->size;
+    vs->xattr_fidp->fid_type = P9_FID_XATTR;
+    vs->xattr_fidp->fs.xattr.copied_len = -1;
+    if (vs->size) {
+        vs->xattr_fidp->fs.xattr.value = qemu_malloc(vs->size);
+        err = v9fs_do_lgetxattr(s, &vs->xattr_fidp->path,
+                                &vs->name, vs->xattr_fidp->fs.xattr.value,
+                                vs->xattr_fidp->fs.xattr.len);
+    }
+    v9fs_post_xattr_getvalue(s, vs, err);
+    return;
+out:
+    complete_pdu(s, vs->pdu, err);
+    v9fs_string_free(&vs->name);
+    qemu_free(vs);
+}
+
+static void v9fs_post_lxattr_getvalue(V9fsState *s,
+                                      V9fsXattrState *vs, int err)
+{
+    if (err < 0) {
+        err = -errno;
+        free_fid(s, vs->xattr_fidp->fid);
+        goto out;
+    }
+    vs->offset += pdu_marshal(vs->pdu, vs->offset, "q", vs->size);
+    err = vs->offset;
+out:
+    complete_pdu(s, vs->pdu, err);
+    v9fs_string_free(&vs->name);
+    qemu_free(vs);
+    return;
+}
+
+static void v9fs_post_lxattr_check(V9fsState *s,
+                                   V9fsXattrState *vs, ssize_t err)
+{
+    if (err < 0) {
+        err = -errno;
+        free_fid(s, vs->xattr_fidp->fid);
+        goto out;
+    }
+    /*
+     * Read the xattr value
+     */
+    vs->xattr_fidp->fs.xattr.len = vs->size;
+    vs->xattr_fidp->fid_type = P9_FID_XATTR;
+    vs->xattr_fidp->fs.xattr.copied_len = -1;
+    if (vs->size) {
+        vs->xattr_fidp->fs.xattr.value = qemu_malloc(vs->size);
+        err = v9fs_do_llistxattr(s, &vs->xattr_fidp->path,
+                                 vs->xattr_fidp->fs.xattr.value,
+                                 vs->xattr_fidp->fs.xattr.len);
+    }
+    v9fs_post_lxattr_getvalue(s, vs, err);
+    return;
+out:
+    complete_pdu(s, vs->pdu, err);
+    v9fs_string_free(&vs->name);
+    qemu_free(vs);
+}
+
+static void v9fs_xattrwalk(V9fsState *s, V9fsPDU *pdu)
+{
+    ssize_t err = 0;
+    V9fsXattrState *vs;
+    int32_t fid, newfid;
+
+    vs = qemu_malloc(sizeof(*vs));
+    vs->pdu = pdu;
+    vs->offset = 7;
+
+    pdu_unmarshal(vs->pdu, vs->offset, "dds", &fid, &newfid, &vs->name);
+    vs->file_fidp = lookup_fid(s, fid);
+    if (vs->file_fidp == NULL) {
+        err = -ENOENT;
+        goto out;
+    }
+
+    vs->xattr_fidp = alloc_fid(s, newfid);
+    if (vs->xattr_fidp == NULL) {
+        err = -EINVAL;
+        goto out;
+    }
+
+    v9fs_string_copy(&vs->xattr_fidp->path, &vs->file_fidp->path);
+    if (vs->name.data[0] == 0) {
+        /*
+         * listxattr request. Get the size first
+         */
+        vs->size = v9fs_do_llistxattr(s, &vs->xattr_fidp->path,
+                                      NULL, 0);
+        if (vs->size < 0) {
+            err = vs->size;
+        }
+        v9fs_post_lxattr_check(s, vs, err);
+        return;
+    } else {
+        /*
+         * specific xattr fid. We check for xattr
+         * presence also collect the xattr size
+         */
+        vs->size = v9fs_do_lgetxattr(s, &vs->xattr_fidp->path,
+                                     &vs->name, NULL, 0);
+        if (vs->size < 0) {
+            err = vs->size;
+        }
+        v9fs_post_xattr_check(s, vs, err);
+        return;
+    }
+out:
+    complete_pdu(s, vs->pdu, err);
+    v9fs_string_free(&vs->name);
+    qemu_free(vs);
+}
+
+
 typedef void (pdu_handler_t)(V9fsState *s, V9fsPDU *pdu);
 
 static pdu_handler_t *pdu_handlers[] = {
@@ -3097,6 +3284,7 @@ static pdu_handler_t *pdu_handlers[] = {
     [P9_TSTATFS] = v9fs_statfs,
     [P9_TGETATTR] = v9fs_getattr,
     [P9_TSETATTR] = v9fs_setattr,
+    [P9_TXATTRWALK] = v9fs_xattrwalk,
     [P9_TMKNOD] = v9fs_mknod,
     [P9_TRENAME] = v9fs_rename,
     [P9_TMKDIR] = v9fs_mkdir,

hw/virtio-9p.h

@@ -29,6 +29,8 @@ enum {
     P9_RGETATTR,
     P9_TSETATTR = 26,
     P9_RSETATTR,
+    P9_TXATTRWALK = 30,
+    P9_RXATTRWALK,
     P9_TREADDIR = 40,
     P9_RREADDIR,
     P9_TLINK = 70,
@@ -416,6 +418,18 @@ typedef struct V9fsRenameState {
     V9fsString name;
 } V9fsRenameState;
 
+typedef struct V9fsXattrState
+{
+    V9fsPDU *pdu;
+    size_t offset;
+    V9fsFidState *file_fidp;
+    V9fsFidState *xattr_fidp;
+    V9fsString name;
+    int64_t size;
+    int flags;
+    void *value;
+} V9fsXattrState;
+
 extern size_t pdu_packunpack(void *addr, struct iovec *sg, int sg_count,
                             size_t offset, size_t size, int pack);