1 files changed, 19 insertions, 9 deletions

diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c
index 943f930404..380b465621 100644
--- a/hw/usb/dev-mtp.c
+++ b/hw/usb/dev-mtp.c
@@ -46,6 +46,7 @@ enum mtp_code {
 
     /* response codes */
     RES_OK                         = 0x2001,
+    RES_GENERAL_ERROR              = 0x2002,
     RES_SESSION_NOT_OPEN           = 0x2003,
     RES_INVALID_TRANSACTION_ID     = 0x2004,
     RES_OPERATION_NOT_SUPPORTED    = 0x2005,
@@ -109,7 +110,8 @@ struct MTPObject {
     struct stat  stat;
     MTPObject    *parent;
     MTPObject    **children;
-    int32_t      nchildren;
+    uint32_t     nchildren;
+    bool         have_children;
     QTAILQ_ENTRY(MTPObject) next;
 };
 
@@ -273,7 +275,6 @@ static MTPObject *usb_mtp_object_alloc(MTPState *s, uint32_t handle,
     o->handle = handle;
     o->parent = parent;
     o->name = g_strdup(name);
-    o->nchildren = -1;
     if (parent == NULL) {
         o->path = g_strdup(name);
     } else {
@@ -340,7 +341,11 @@ static void usb_mtp_object_readdir(MTPState *s, MTPObject *o)
     struct dirent *entry;
     DIR *dir;
 
-    o->nchildren = 0;
+    if (o->have_children) {
+        return;
+    }
+    o->have_children = true;
+
     dir = opendir(o->path);
     if (!dir) {
         return;
@@ -698,7 +703,10 @@ static MTPData *usb_mtp_get_partial_object(MTPState *s, MTPControl *c,
     if (offset > o->stat.st_size) {
         offset = o->stat.st_size;
     }
-    lseek(d->fd, offset, SEEK_SET);
+    if (lseek(d->fd, offset, SEEK_SET) < 0) {
+        usb_mtp_data_free(d);
+        return NULL;
+    }
 
     d->length = c->argv[2];
     if (d->length > o->stat.st_size - offset) {
@@ -789,9 +797,7 @@ static void usb_mtp_command(MTPState *s, MTPControl *c)
                                  c->trans, 0, 0, 0);
             return;
         }
-        if (o->nchildren == -1) {
-            usb_mtp_object_readdir(s, o);
-        }
+        usb_mtp_object_readdir(s, o);
         if (c->code == CMD_GET_NUM_OBJECTS) {
             trace_usb_mtp_op_get_num_objects(s->dev.addr, o->handle, o->path);
             nres = 1;
@@ -823,7 +829,9 @@ static void usb_mtp_command(MTPState *s, MTPControl *c)
         }
         data_in = usb_mtp_get_object(s, c, o);
         if (NULL == data_in) {
-            fprintf(stderr, "%s: TODO: handle error\n", __func__);
+            usb_mtp_queue_result(s, RES_GENERAL_ERROR,
+                                 c->trans, 0, 0, 0);
+            return;
         }
         break;
     case CMD_GET_PARTIAL_OBJECT:
@@ -840,7 +848,9 @@ static void usb_mtp_command(MTPState *s, MTPControl *c)
         }
         data_in = usb_mtp_get_partial_object(s, c, o);
         if (NULL == data_in) {
-            fprintf(stderr, "%s: TODO: handle error\n", __func__);
+            usb_mtp_queue_result(s, RES_GENERAL_ERROR,
+                                 c->trans, 0, 0, 0);
+            return;
         }
         nres = 1;
         res0 = data_in->length;