[Qemu-devel] [PATCH] virtio-9p: readdir implementation for 9p2000.L

[Sripathi Kodi]

This patch implements the server part of readdir() implementation for
9p2000.L

SYNOPSIS

size[4] Treaddir tag[2] fid[4] offset[8] count[4]
size[4] Rreaddir tag[2] count[4] data[count]

DESCRIPTION

The readdir request asks the server to read the directory specified by 'fid'
at an offset specified by 'offset' and return as many dirent structures as
possible that fit into count bytes. Each dirent structure is laid out as
follows.

        inode[8]
          inode number of the file.

        offset[8]
          offset into the next dirent.

        type[1]
          type of this directory entry.

        name[256]
          name of this directory entry.

Signed-off-by: Sripathi Kodi <address@hidden>
Reviewed-by: M. Mohan Kumar <address@hidden>
Reviewed-by: Venkateswararao Jujjuri <address@hidden>
---

 hw/virtio-9p-debug.c |   13 ++++++
 hw/virtio-9p.c       |  110 ++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/virtio-9p.h       |    2 +
 3 files changed, 125 insertions(+), 0 deletions(-)

diff --git a/hw/virtio-9p-debug.c b/hw/virtio-9p-debug.c
index 2fb2673..a82b771 100644
--- a/hw/virtio-9p-debug.c
+++ b/hw/virtio-9p-debug.c
@@ -328,6 +328,19 @@ void pprint_pdu(V9fsPDU *pdu)
     }
 
     switch (pdu->id) {
+    case P9_TREADDIR:
+        fprintf(llogfile, "TREADDIR: (");
+        pprint_int32(pdu, 0, &offset, "fid");
+        pprint_int64(pdu, 0, &offset, ", initial offset");
+        pprint_int32(pdu, 0, &offset, ", max count");
+        break;
+    case P9_RREADDIR:
+        fprintf(llogfile, "RREADDIR: (");
+        pprint_int32(pdu, 1, &offset, "count");
+#ifdef DEBUG_DATA
+        pprint_data(pdu, 1, &offset, ", data");
+#endif
+        break;
     case P9_TVERSION:
         fprintf(llogfile, "TVERSION: (");
         pprint_int32(pdu, 0, &offset, "msize");
diff --git a/hw/virtio-9p.c b/hw/virtio-9p.c
index e5d0112..39a535a 100644
--- a/hw/virtio-9p.c
+++ b/hw/virtio-9p.c
@@ -1606,6 +1606,115 @@ typedef struct V9fsWriteState {
     int cnt;
 } V9fsWriteState;
 
+typedef struct V9fsReadDirState {
+    V9fsPDU *pdu;
+    V9fsFidState *fidp;
+    off_t saved_dir_pos;
+    struct dirent *dent;
+    int32_t count;
+    int32_t max_count;
+    size_t offset;
+    int64_t initial_offset;
+    V9fsString name;
+} V9fsReadDirState;
+
+static void v9fs_readdir_post_seekdir(V9fsState *s, V9fsReadDirState *vs)
+{
+    vs->offset += pdu_marshal(vs->pdu, vs->offset, "d", vs->count);
+    vs->offset += vs->count;
+    complete_pdu(s, vs->pdu, vs->offset);
+    qemu_free(vs);
+    return;
+}
+
+/* Size of each dirent on the wire: size of inode (8) + size of offset (8)
+ * size of type (1) + size of name.size (2) + strlen(name.data)
+ */
+#define V9_READDIR_DATA_SZ (19+strlen(vs->name.data))
+
+static void v9fs_readdir_post_readdir(V9fsState *s, V9fsReadDirState *vs)
+{
+    int len;
+
+    if (vs->dent) {
+        v9fs_string_init(&vs->name);
+        v9fs_string_sprintf(&vs->name, "%s", vs->dent->d_name);
+
+        if ((vs->count + V9_READDIR_DATA_SZ) > vs->max_count) {
+            /* Ran out of buffer. Set dir back to old position and return */
+            v9fs_do_seekdir(s, vs->fidp->dir, vs->saved_dir_pos);
+            v9fs_readdir_post_seekdir(s, vs);
+            return;
+        }
+
+        len = pdu_marshal(vs->pdu, vs->offset+4+vs->count, "qqbs",
+                              vs->dent->d_ino, vs->dent->d_off,
+                              vs->dent->d_type, &vs->name);
+        vs->count += len;
+        v9fs_string_free(&vs->name);
+        vs->saved_dir_pos = vs->dent->d_off;
+        vs->dent = v9fs_do_readdir(s, vs->fidp->dir);
+        v9fs_readdir_post_readdir(s, vs);
+        return;
+    }
+
+    vs->offset += pdu_marshal(vs->pdu, vs->offset, "d", vs->count);
+    vs->offset += vs->count;
+    complete_pdu(s, vs->pdu, vs->offset);
+    qemu_free(vs);
+    return;
+}
+
+static void v9fs_readdir_post_telldir(V9fsState *s, V9fsReadDirState *vs)
+{
+    vs->dent = v9fs_do_readdir(s, vs->fidp->dir);
+    v9fs_readdir_post_readdir(s, vs);
+    return;
+}
+
+static void v9fs_readdir_post_setdir(V9fsState *s, V9fsReadDirState *vs)
+{
+    vs->saved_dir_pos = v9fs_do_telldir(s, vs->fidp->dir);
+    v9fs_readdir_post_telldir(s, vs);
+    return;
+}
+
+static void v9fs_readdir(V9fsState *s, V9fsPDU *pdu)
+{
+    int32_t fid;
+    V9fsReadDirState *vs;
+    ssize_t err = 0;
+    size_t offset = 7;
+
+    vs = qemu_malloc(sizeof(*vs));
+    vs->pdu = pdu;
+    vs->offset = 7;
+    vs->count = 0;
+
+    pdu_unmarshal(vs->pdu, offset, "dqd", &fid, &vs->initial_offset,
+                                                        &vs->max_count);
+
+    vs->fidp = lookup_fid(s, fid);
+    if (vs->fidp == NULL || !(vs->fidp->dir)) {
+        err = -EINVAL;
+        goto out;
+    }
+
+    if (vs->initial_offset == 0) {
+        v9fs_do_rewinddir(s, vs->fidp->dir);
+    } else {
+        v9fs_do_seekdir(s, vs->fidp->dir, vs->initial_offset);
+    }
+
+    v9fs_readdir_post_setdir(s, vs);
+    return;
+
+out:
+    complete_pdu(s, pdu, err);
+    qemu_free(vs);
+    return;
+}
+
 static void v9fs_write_post_writev(V9fsState *s, V9fsWriteState *vs,
                                    ssize_t err)
 {
@@ -2225,6 +2334,7 @@ out:
 typedef void (pdu_handler_t)(V9fsState *s, V9fsPDU *pdu);
 
 static pdu_handler_t *pdu_handlers[] = {
+    [P9_TREADDIR] = v9fs_readdir,
     [P9_TVERSION] = v9fs_version,
     [P9_TATTACH] = v9fs_attach,
     [P9_TSTAT] = v9fs_stat,
diff --git a/hw/virtio-9p.h b/hw/virtio-9p.h
index b95dbe4..85fbe87 100644
--- a/hw/virtio-9p.h
+++ b/hw/virtio-9p.h
@@ -13,6 +13,8 @@
 #define VIRTIO_9P_MOUNT_TAG 0
 
 enum {
+    P9_TREADDIR = 40,
+    P9_RREADDIR,
     P9_TVERSION = 100,
     P9_RVERSION,
     P9_TAUTH = 102,