tools/xen-9pfsd: add 9pfs write request support

Add the write request of the 9pfs protocol.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>
Acked-by: Anthony PERARD <anthony.perard@citrix.com>

tools/9pfsd/io.c

@@ -33,6 +33,7 @@
 #define P9_CMD_WALK       110
 #define P9_CMD_OPEN       112
 #define P9_CMD_CREATE     114
+#define P9_CMD_WRITE      118
 #define P9_CMD_CLUNK      120
 #define P9_CMD_STAT       124
 
@@ -1244,6 +1245,55 @@ static void p9_stat(struct ring *ring, struct p9_header *hdr)
     free_fid(device, fidp);
 }
 
+static void p9_write(struct ring *ring, struct p9_header *hdr)
+{
+    device *device = ring->device;
+    uint32_t fid;
+    uint64_t off;
+    unsigned int len;
+    uint32_t written;
+    void *buf;
+    struct p9_fid *fidp;
+    int ret;
+
+    ret = fill_data(ring, "ULD", &fid, &off, &len, ring->buffer);
+    if ( ret != 3 )
+    {
+        p9_error(ring, hdr->tag, EINVAL);
+        return;
+    }
+
+    fidp = get_fid_ref(device, fid);
+    if ( !fidp || !fidp->opened || fidp->isdir )
+    {
+        p9_error(ring, hdr->tag, EBADF);
+        goto out;
+    }
+
+    buf = ring->buffer;
+
+    while ( len != 0 )
+    {
+        ret = pwrite(fidp->fd, buf, len, off);
+        if ( ret < 0 )
+            break;
+        len -= ret;
+        buf += ret;
+        off += ret;
+    }
+
+    written = buf - ring->buffer;
+    if ( written == 0 )
+    {
+        p9_error(ring, hdr->tag, errno);
+        goto out;
+    }
+    fill_buffer(ring, hdr->cmd + 1, hdr->tag, "U", &written);
+
+ out:
+    free_fid(device, fidp);
+}
+
 void *io_thread(void *arg)
 {
     struct ring *ring = arg;
@@ -1319,6 +1369,10 @@ void *io_thread(void *arg)
                 p9_create(ring, &hdr);
                 break;
 
+            case P9_CMD_WRITE:
+                p9_write(ring, &hdr);
+                break;
+
             case P9_CMD_CLUNK:
                 p9_clunk(ring, &hdr);
                 break;