[core] refactor fast-zeroing code and fix warnings

* Fox coverity and MinGW warnings

src/format.c

@@ -1553,7 +1553,7 @@ static BOOL WriteDrive(HANDLE hPhysicalDrive, HANDLE hSourceImage)
 	int64_t bled_ret;
 	uint8_t *buffer = NULL;
 	uint8_t *cmp_buffer = NULL;
-	int i, throttle_fast_zeroing = 0;
+	int i, *ptr, zero_data, throttle_fast_zeroing = 0;
 
 	// We poked the MBR and other stuff, so we need to rewind
 	li.QuadPart = 0;
@@ -1630,11 +1630,10 @@ static BOOL WriteDrive(HANDLE hPhysicalDrive, HANDLE hSourceImage)
 			// we might speed things up by skipping empty blocks, or skipping the write if the data is the same.
 			// Notes: A block is declared empty when all bits are either 0 (zeros) or 1 (flash block erased).
 			// Also, a back-off strategy is used to limit reading.
-
 			if (throttle_fast_zeroing) {
 				throttle_fast_zeroing--;
-			} else if ((fast_zeroing) && (hSourceImage == NULL)) { // currently only enabled for erase
-
+			} else if (fast_zeroing) {
+				assert(hSourceImage == NULL);	// Only enabled for zeroing
 				CHECK_FOR_USER_CANCEL;
 
 				// Read block and compare against the block that needs to be written
@@ -1644,30 +1643,22 @@ static BOOL WriteDrive(HANDLE hPhysicalDrive, HANDLE hSourceImage)
 					goto out;
 				}
 
-				// erase or write
-				if (hSourceImage == NULL) {
-					// Erase, check for an empty block
-					int *ptr = (int*)(cmp_buffer);
+				// Check for an empty block
+				ptr = (int*)(cmp_buffer);
 				// Get first element
-					int value = ptr[0];
+				zero_data = ptr[0];
 				// Check all bits are the same
-					if ((value != 0) && (value != -1)) {
-						goto blocknotempty;
-					}
+				if ((zero_data == 0) || (zero_data == -1)) {
 					// Compare the rest of the block against the first element
 					for (i = 1; i < (int)(rSize / sizeof(int)); i++) {
-						if (ptr[i] != value)
-							goto blocknotempty;
+						if (ptr[i] != zero_data)
+							break;
 					}
+					if (i >= (int)(rSize / sizeof(int))) {
 						// Block is empty, skip write
 						wSize = rSize;
 						continue;
-				blocknotempty:
-					;
-				} else if (memcmp(cmp_buffer, buffer, rSize) == 0) {
-					// Write, block is unchanged, skip write
-					wSize = rSize;
-					continue;
+					}
 				}
 
 				// Move the file pointer position back for writing
@@ -1676,7 +1667,7 @@ static BOOL WriteDrive(HANDLE hPhysicalDrive, HANDLE hSourceImage)
 					uprintf("Error: Could not reset position - %s", WindowsErrorString());
 					goto out;
 				}
-				// throttle read operations
+				// Throttle read operations
 				throttle_fast_zeroing = 15;
 			}
 

src/rufus.rc

@@ -33,7 +33,7 @@ LANGUAGE LANG_NEUTRAL, SUBLANG_NEUTRAL
 IDD_DIALOG DIALOGEX 12, 12, 232, 326
 STYLE DS_SETFONT | DS_MODALFRAME | DS_CENTER | WS_MINIMIZEBOX | WS_POPUP | WS_CAPTION | WS_SYSMENU
 EXSTYLE WS_EX_ACCEPTFILES
-CAPTION "Rufus 3.2.1338"
+CAPTION "Rufus 3.2.1339"
 FONT 9, "Segoe UI Symbol", 400, 0, 0x0
 BEGIN
     LTEXT           "Drive Properties",IDS_DRIVE_PROPERTIES_TXT,8,6,53,12,NOT WS_GROUP
@@ -392,8 +392,8 @@ END
 //
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 3,2,1338,0
- PRODUCTVERSION 3,2,1338,0
+ FILEVERSION 3,2,1339,0
+ PRODUCTVERSION 3,2,1339,0
  FILEFLAGSMASK 0x3fL
 #ifdef _DEBUG
  FILEFLAGS 0x1L
@@ -411,13 +411,13 @@ BEGIN
             VALUE "Comments", "https://akeo.ie"
             VALUE "CompanyName", "Akeo Consulting"
             VALUE "FileDescription", "Rufus"
-            VALUE "FileVersion", "3.2.1338"
+            VALUE "FileVersion", "3.2.1339"
             VALUE "InternalName", "Rufus"
             VALUE "LegalCopyright", "© 2011-2018 Pete Batard (GPL v3)"
             VALUE "LegalTrademarks", "https://www.gnu.org/copyleft/gpl.html"
             VALUE "OriginalFilename", "rufus-3.2.exe"
             VALUE "ProductName", "Rufus"
-            VALUE "ProductVersion", "3.2.1338"
+            VALUE "ProductVersion", "3.2.1339"
         END
     END
     BLOCK "VarFileInfo"

src/ui.c

@@ -638,7 +638,7 @@ void ToggleAdvancedFormatOptions(BOOL enable)
 void SetPersistenceSize(uint64_t pos, uint64_t max)
 {
 	char tmp[12];
-	int i, proposed_unit_selection;
+	int i, proposed_unit_selection = 0;
 	LONGLONG base_unit = MB;
 	HWND hCtrl;