mmdevapi: Make IMMDeviceCollection immutable after creation.

dlls/mmdevapi/devenum.c

@@ -76,8 +76,8 @@ typedef struct MMDevColImpl
 {
     IMMDeviceCollection IMMDeviceCollection_iface;
     LONG ref;
-    EDataFlow flow;
-    DWORD state;
+    IMMDevice **devices;
+    UINT devices_count;
 } MMDevColImpl;
 
 typedef struct IPropertyBagImpl {
@@ -827,6 +827,8 @@ static const IMMEndpointVtbl MMEndpointVtbl =
 static HRESULT MMDevCol_Create(IMMDeviceCollection **ppv, EDataFlow flow, DWORD state)
 {
     MMDevColImpl *This;
+    MMDevice *cur;
+    UINT i = 0;
 
     This = malloc(sizeof(*This));
     *ppv = NULL;
@@ -834,14 +836,43 @@ static HRESULT MMDevCol_Create(IMMDeviceCollection **ppv, EDataFlow flow, DWORD
         return E_OUTOFMEMORY;
     This->IMMDeviceCollection_iface.lpVtbl = &MMDevColVtbl;
     This->ref = 1;
-    This->flow = flow;
-    This->state = state;
+    This->devices = NULL;
+    This->devices_count = 0;
     *ppv = &This->IMMDeviceCollection_iface;
+
+    LIST_FOR_EACH_ENTRY(cur, &device_list, MMDevice, entry)
+    {
+        if ((cur->flow == flow || flow == eAll) && (cur->state & state))
+            This->devices_count++;
+    }
+
+    if (This->devices_count)
+    {
+        This->devices = malloc(This->devices_count * sizeof(IMMDevice *));
+        if (!This->devices_count)
+            return E_OUTOFMEMORY;
+
+        LIST_FOR_EACH_ENTRY(cur, &device_list, MMDevice, entry)
+        {
+            if ((cur->flow == flow || flow == eAll) && (cur->state & state))
+            {
+                This->devices[i] = &cur->IMMDevice_iface;
+                IMMDevice_AddRef(This->devices[i]);
+                i++;
+            }
+        }
+    }
+
     return S_OK;
 }
 
 static void MMDevCol_Destroy(MMDevColImpl *This)
 {
+    UINT i;
+    for (i = 0; i < This->devices_count; i++)
+        IMMDevice_Release(This->devices[i]);
+
+    free(This->devices);
     free(This);
 }
 
@@ -884,46 +915,33 @@ static ULONG WINAPI MMDevCol_Release(IMMDeviceCollection *iface)
 static HRESULT WINAPI MMDevCol_GetCount(IMMDeviceCollection *iface, UINT *numdevs)
 {
     MMDevColImpl *This = impl_from_IMMDeviceCollection(iface);
-    MMDevice *cur;
 
     TRACE("(%p)->(%p)\n", This, numdevs);
     if (!numdevs)
         return E_POINTER;
 
-    *numdevs = 0;
-    LIST_FOR_EACH_ENTRY(cur, &device_list, MMDevice, entry)
-    {
-        if ((cur->flow == This->flow || This->flow == eAll)
-            && (cur->state & This->state))
-            ++(*numdevs);
-    }
+    *numdevs = This->devices_count;
     return S_OK;
 }
 
 static HRESULT WINAPI MMDevCol_Item(IMMDeviceCollection *iface, UINT n, IMMDevice **dev)
 {
     MMDevColImpl *This = impl_from_IMMDeviceCollection(iface);
-    MMDevice *cur;
-    DWORD i = 0;
 
     TRACE("(%p)->(%u, %p)\n", This, n, dev);
     if (!dev)
         return E_POINTER;
 
-    LIST_FOR_EACH_ENTRY(cur, &device_list, MMDevice, entry)
+    if (n >= This->devices_count)
     {
-        if ((cur->flow == This->flow || This->flow == eAll)
-            && (cur->state & This->state)
-            && i++ == n)
-        {
-            *dev = &cur->IMMDevice_iface;
-            IMMDevice_AddRef(*dev);
-            return S_OK;
-        }
+        WARN("Could not obtain item %u\n", n);
+        *dev = NULL;
+        return E_INVALIDARG;
     }
-    WARN("Could not obtain item %u\n", n);
-    *dev = NULL;
-    return E_INVALIDARG;
+
+    *dev = This->devices[n];
+    IMMDevice_AddRef(*dev);
+    return S_OK;
 }
 
 static const IMMDeviceCollectionVtbl MMDevColVtbl =