windowscodecs: Handle IFD fields with count 0 same way as with count 1.

dlls/windowscodecs/metadatahandler.c

@@ -718,6 +718,8 @@ static HRESULT load_IFD_entry(IStream *input, const struct IFD_entry *entry,
     {
      case IFD_BYTE:
      case IFD_SBYTE:
+        if (!count) count = 1;
+
         if (count <= 4)
         {
             const BYTE *data = (const BYTE *)&entry->value;
@@ -755,6 +757,8 @@ static HRESULT load_IFD_entry(IStream *input, const struct IFD_entry *entry,
         break;
     case IFD_SHORT:
     case IFD_SSHORT:
+        if (!count) count = 1;
+
         if (count <= 2)
         {
             const SHORT *data = (const SHORT *)&entry->value;
@@ -800,6 +804,8 @@ static HRESULT load_IFD_entry(IStream *input, const struct IFD_entry *entry,
     case IFD_LONG:
     case IFD_SLONG:
     case IFD_FLOAT:
+        if (!count) count = 1;
+
         if (count == 1)
         {
             item->value.u.ulVal = value;
@@ -830,6 +836,13 @@ static HRESULT load_IFD_entry(IStream *input, const struct IFD_entry *entry,
     case IFD_RATIONAL:
     case IFD_SRATIONAL:
     case IFD_DOUBLE:
+        if (!count)
+        {
+            FIXME("IFD field type %d, count 0\n", type);
+            item->value.vt = VT_EMPTY;
+            break;
+        }
+
         if (count == 1)
         {
             ULONGLONG ull;
@@ -882,6 +895,13 @@ static HRESULT load_IFD_entry(IStream *input, const struct IFD_entry *entry,
         item->value.u.pszVal[count] = 0;
         break;
     case IFD_UNDEFINED:
+        if (!count)
+        {
+            FIXME("IFD field type %d, count 0\n", type);
+            item->value.vt = VT_EMPTY;
+            break;
+        }
+
         item->value.u.blob.pBlobData = HeapAlloc(GetProcessHeap(), 0, count);
         if (!item->value.u.blob.pBlobData) return E_OUTOFMEMORY;
 

dlls/windowscodecs/tests/metadata.c

@@ -82,7 +82,7 @@ static const struct ifd_data
     FLOAT float_val[2];
 } IFD_data =
 {
-    23,
+    27,
     {
         { 0xfe,  IFD_SHORT, 1, 1 }, /* NEWSUBFILETYPE */
         { 0x100, IFD_LONG, 1, 222 }, /* IMAGEWIDTH */
@@ -107,6 +107,10 @@ static const struct ifd_data
         { 0xf00f, IFD_ASCII, 4, 'a' | 'b' << 8 | 'c' << 16 | 'd' << 24 },
         { 0xf010, IFD_UNDEFINED, 13, FIELD_OFFSET(struct ifd_data, string) },
         { 0xf011, IFD_UNDEFINED, 4, 'a' | 'b' << 8 | 'c' << 16 | 'd' << 24 },
+        { 0xf012, IFD_BYTE, 0, 0x11223344 },
+        { 0xf013, IFD_SHORT, 0, 0x11223344 },
+        { 0xf014, IFD_LONG, 0, 0x11223344 },
+        { 0xf015, IFD_FLOAT, 0, 0x11223344 },
     },
     0,
     { 900, 3 },
@@ -390,7 +394,7 @@ static void test_metadata_IFD(void)
         int count; /* if VT_VECTOR */
         LONGLONG value[13];
         const char *string;
-    } td[23] =
+    } td[27] =
     {
         { VT_UI2, 0xfe, 0, { 1 } },
         { VT_UI4, 0x100, 0, { 222 } },
@@ -415,6 +419,10 @@ static void test_metadata_IFD(void)
         { VT_LPSTR, 0xf00f, 4, { 0 }, "abcd" },
         { VT_BLOB, 0xf010, 13, { 0 }, "Hello World!" },
         { VT_BLOB, 0xf011, 4, { 0 }, "abcd" },
+        { VT_UI1, 0xf012, 0, { 0x44 } },
+        { VT_UI2, 0xf013, 0, { 0x3344 } },
+        { VT_UI4, 0xf014, 0, { 0x11223344 } },
+        { VT_R4, 0xf015, 0, { 0x11223344 } },
     };
     HRESULT hr;
     IWICMetadataReader *reader;