[winpr,utils] unify bitmap reading

* clipboard synthesizer needs to read the bitmap header, use the function
  from utils/image
* check bitmap header in utils/image and abort if wrong

winpr/libwinpr/clipboard/synthetic.c

@@ -24,6 +24,7 @@
 #include <winpr/user.h>
 #include <winpr/image.h>
 
+#include "../utils/image.h"
 #include "clipboard.h"
 
 static const char* mime_bitmap[] = { "image/bmp", "image/x-bmp", "image/x-MS-bmp",
@@ -234,14 +235,10 @@ static void* clipboard_synthesize_cf_dib(wClipboard* clipboard, UINT32 formatId,
 	}
 	else if (is_format_bitmap(clipboard, formatId))
 	{
-		const BITMAPFILEHEADER* pFileHeader = NULL;
-
-		if (SrcSize < (sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER)))
-			return NULL;
-
-		pFileHeader = (const BITMAPFILEHEADER*)data;
-
-		if (pFileHeader->bfType != 0x4D42)
+		WINPR_BITMAP_FILE_HEADER pFileHeader = { 0 };
+		wStream sbuffer = { 0 };
+		wStream* s = Stream_StaticConstInit(&sbuffer, data, SrcSize);
+		if (!readBitmapFileHeader(s, &pFileHeader))
 			return NULL;
 
 		DstSize = SrcSize - sizeof(BITMAPFILEHEADER);

winpr/libwinpr/utils/image.c

@@ -49,6 +49,7 @@
 #endif
 #include <winpr/stream.h>
 
+#include "image.h"
 #include "../log.h"
 #define TAG WINPR_TAG("utils.image")
 
@@ -73,9 +74,14 @@ static BOOL writeBitmapFileHeader(wStream* s, const WINPR_BITMAP_FILE_HEADER* bf
 	return TRUE;
 }
 
-static BOOL readBitmapFileHeader(wStream* s, WINPR_BITMAP_FILE_HEADER* bf)
+BOOL readBitmapFileHeader(wStream* s, WINPR_BITMAP_FILE_HEADER* bf)
 {
-	if (!s || !bf || (!Stream_CheckAndLogRequiredLength(TAG, s, sizeof(WINPR_BITMAP_FILE_HEADER))))
+	static wLog* log = NULL;
+	if (!log)
+		log = WLog_Get(TAG);
+
+	if (!s || !bf ||
+	    (!Stream_CheckAndLogRequiredLengthWLog(log, s, sizeof(WINPR_BITMAP_FILE_HEADER))))
 		return FALSE;
 
 	Stream_Read_UINT8(s, bf->bfType[0]);
@@ -87,12 +93,19 @@ static BOOL readBitmapFileHeader(wStream* s, WINPR_BITMAP_FILE_HEADER* bf)
 
 	if (bf->bfSize < sizeof(WINPR_BITMAP_FILE_HEADER))
 	{
-		WLog_ERR(TAG, "");
+		WLog_Print(log, WLOG_ERROR, "Invalid bitmap::bfSize=%" PRIu32 ", require at least %" PRIuz,
+		           bf->bfSize, sizeof(WINPR_BITMAP_FILE_HEADER));
 		return FALSE;
 	}
 
-	return Stream_CheckAndLogRequiredCapacity(TAG, s,
-	                                          bf->bfSize - sizeof(WINPR_BITMAP_FILE_HEADER));
+	if ((bf->bfType[0] != 'B') || (bf->bfType[1] != 'M'))
+	{
+		WLog_Print(log, WLOG_ERROR, "Invalid bitmap header [%c%c], expected [BM]", bf->bfType[0],
+		           bf->bfType[1]);
+		return FALSE;
+	}
+	return Stream_CheckAndLogRequiredCapacityWLog(log, s,
+	                                              bf->bfSize - sizeof(WINPR_BITMAP_FILE_HEADER));
 }
 
 static BOOL writeBitmapInfoHeader(wStream* s, const WINPR_BITMAP_INFO_HEADER* bi)

winpr/libwinpr/utils/image.h

@@ -0,0 +1,30 @@
+/*
+ * WinPR: Windows Portable Runtime
+ * Image Utils
+ *
+ * Copyright 2024 Armin Novak <anovak@thincast.com>
+ * Copyright 2024 Thincast Technologies GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef LIBWINPR_UTILS_IMAGE_H
+#define LIBWINPR_UTILS_IMAGE_H
+
+#include <winpr/wtypes.h>
+#include <winpr/stream.h>
+#include <winpr/image.h>
+
+BOOL readBitmapFileHeader(wStream* s, WINPR_BITMAP_FILE_HEADER* bf);
+
+#endif /* LIBWINPR_UTILS_IMAGE_H */