[core] try not to clear MBR/GPT sectors higher than the lowest partition

* This ensures that a drive can be reformatted without error after writing
  an image such as super_grub2_disk_x86_64_efi_2.02s4.iso

src/drive.c

@@ -108,7 +108,7 @@ BOOL GetAutoMount(BOOL* enabled)
  */
 #define CheckDriveIndex(DriveIndex) do { \
 	if ((DriveIndex < DRIVE_INDEX_MIN) || (DriveIndex > DRIVE_INDEX_MAX)) { \
-		uprintf("ERROR: Bad index value. Please check the code!\n"); \
+		uprintf("ERROR: Bad index value %d. Please check the code!", DriveIndex); \
 		goto out; \
 	} \
 	DriveIndex -= DRIVE_INDEX_MIN; } while (0)
@@ -691,6 +691,7 @@ BOOL GetDrivePartitionData(DWORD DriveIndex, char* FileSystemName, DWORD FileSys
 	}
 	SelectedDrive.DiskSize = DiskGeometry->DiskSize.QuadPart;
 	SelectedDrive.SectorSize = DiskGeometry->Geometry.BytesPerSector;
+	SelectedDrive.FirstDataSector = MAXDWORD;
 	if (SelectedDrive.SectorSize < 512) {
 		suprintf("Warning: Drive 0x%02x reports a sector size of %d - Correcting to 512 bytes.\n",
 			DriveIndex, SelectedDrive.SectorSize);
@@ -741,12 +742,15 @@ BOOL GetDrivePartitionData(DWORD DriveIndex, char* FileSystemName, DWORD FileSys
 					}
 				}
 				// NB: MinGW's gcc 4.9.2 broke "%lld" printout on XP so we use the inttypes.h "PRI##" qualifiers
-				suprintf("  Type: %s (0x%02x)\r\n  Size: %s (%" PRIi64 " bytes)\r\n  Start Sector: %d, Boot: %s, Recognized: %s\n",
+				suprintf("  Type: %s (0x%02x)\r\n  Size: %s (%" PRIi64 " bytes)\r\n  Start Sector: %" PRIi64 ", Boot: %s, Recognized: %s\n",
 					((part_type==0x07)&&(FileSystemName[0]!=0))?FileSystemName:GetPartitionType(part_type), part_type,
 					SizeToHumanReadable(DriveLayout->PartitionEntry[i].PartitionLength.QuadPart, TRUE, FALSE),
-					DriveLayout->PartitionEntry[i].PartitionLength.QuadPart, DriveLayout->PartitionEntry[i].Mbr.HiddenSectors,
+					DriveLayout->PartitionEntry[i].PartitionLength.QuadPart,
+					DriveLayout->PartitionEntry[i].StartingOffset.QuadPart / SelectedDrive.SectorSize,
 					DriveLayout->PartitionEntry[i].Mbr.BootIndicator?"Yes":"No",
 					DriveLayout->PartitionEntry[i].Mbr.RecognizedPartition?"Yes":"No");
+				SelectedDrive.FirstDataSector = min(SelectedDrive.FirstDataSector,
+					(DWORD)(DriveLayout->PartitionEntry[i].StartingOffset.QuadPart / SelectedDrive.SectorSize));
 				if ((part_type == RUFUS_EXTRA_PARTITION_TYPE) || (isUefiNtfs))
 					// This is a partition Rufus created => we can safely ignore it
 					--SelectedDrive.nPartitions;
@@ -768,9 +772,13 @@ BOOL GetDrivePartitionData(DWORD DriveIndex, char* FileSystemName, DWORD FileSys
 			suprintf("Partition %d:\r\n  Type: %s\r\n  Name: '%s'\n", i+1,
 				GuidToString(&DriveLayout->PartitionEntry[i].Gpt.PartitionType), tmp);
 			suprintf("  ID: %s\r\n  Size: %s (%" PRIi64 " bytes)\r\n  Start Sector: %" PRIi64 ", Attributes: 0x%016" PRIX64 "\n",
-				GuidToString(&DriveLayout->PartitionEntry[i].Gpt.PartitionId), SizeToHumanReadable(DriveLayout->PartitionEntry[i].PartitionLength.QuadPart, TRUE, FALSE),
+				GuidToString(&DriveLayout->PartitionEntry[i].Gpt.PartitionId),
-				DriveLayout->PartitionEntry[i].PartitionLength, DriveLayout->PartitionEntry[i].StartingOffset.QuadPart / DiskGeometry->Geometry.BytesPerSector,
+				SizeToHumanReadable(DriveLayout->PartitionEntry[i].PartitionLength.QuadPart, TRUE, FALSE),
+				DriveLayout->PartitionEntry[i].PartitionLength,
+				DriveLayout->PartitionEntry[i].StartingOffset.QuadPart / SelectedDrive.SectorSize,
 				DriveLayout->PartitionEntry[i].Gpt.Attributes);
+			SelectedDrive.FirstDataSector = min(SelectedDrive.FirstDataSector,
+				(DWORD)(DriveLayout->PartitionEntry[i].StartingOffset.QuadPart / SelectedDrive.SectorSize));
 			// Don't register the partitions that we don't care about destroying
 			if ( (strcmp(tmp, "UEFI:NTFS") == 0) ||
 				 (CompareGUID(&DriveLayout->PartitionEntry[i].Gpt.PartitionType, &PARTITION_MSFT_RESERVED_GUID)) ||

src/drive.h

@@ -61,7 +61,7 @@ typedef struct {
 	DWORD DeviceNumber;
 	DWORD SectorsPerTrack;
 	DWORD SectorSize;
-	DWORD FirstSector;
+	DWORD FirstDataSector;
 	MEDIA_TYPE MediaType;
 	int PartitionType;
 	int nPartitions;	// number of partitions we actually care about

src/format.c

@@ -808,7 +808,7 @@ out:
 static BOOL ClearMBRGPT(HANDLE hPhysicalDrive, LONGLONG DiskSize, DWORD SectorSize, BOOL add1MB)
 {
 	BOOL r = FALSE;
-	uint64_t i, last_sector = DiskSize/SectorSize;
+	uint64_t i, last_sector = DiskSize/SectorSize, num_sectors_to_clear;
 	unsigned char* pBuf = (unsigned char*) calloc(SectorSize, 1);
 
 	PrintInfoDebug(0, MSG_224);
@@ -820,10 +820,14 @@ static BOOL ClearMBRGPT(HANDLE hPhysicalDrive, LONGLONG DiskSize, DWORD SectorSi
 	// beginning and 33 at the end. We bump these values to MAX_SECTORS_TO_CLEAR each end to help
 	// with reluctant access to large drive.
 
-	// Must clear at least 1MB + the PBR for large FAT32 format to work on a large drive
+	// We try to clear at least 1MB + the PBR when Large FAT32 is selected (add1MB), but
-	// Don't do it if Large FAT32 is not enabled, as it can take time for slow drives.
+	// don't do it otherwise, as it seems unnecessary and may take time for slow drives.
-	uprintf("Erasing %d sectors", (add1MB?2048:0)+MAX_SECTORS_TO_CLEAR);
+	// Also, for various reasons (one of which being that Windows seems to have issues
-	for (i=0; i<((add1MB?2048:0)+MAX_SECTORS_TO_CLEAR); i++) {
+	// with GPT drives that contain a lot of small partitions) we try not not to clear
+	// sectors further than the lowest partition already residing on the disk.
+	num_sectors_to_clear = min(SelectedDrive.FirstDataSector, (add1MB ? 2048 : 0) + MAX_SECTORS_TO_CLEAR);
+	uprintf("Erasing %d sectors", num_sectors_to_clear);
+	for (i=0; i<num_sectors_to_clear; i++) {
 		if ((IS_ERROR(FormatStatus)) || (write_sectors(hPhysicalDrive, SectorSize, i, 1, pBuf) != SectorSize)) {
 			goto out;
 		}
@@ -1678,7 +1682,7 @@ DWORD WINAPI FormatThread(void* param)
 	// Note, Microsoft's way of cleaning partitions (IOCTL_DISK_CREATE_DISK, which is what we apply
 	// in InitializeDisk) is *NOT ENOUGH* to reset a disk and can render it inoperable for partitioning
 	// or formatting under Windows. See https://github.com/pbatard/rufus/issues/759 for details.
-	if ((!ClearMBRGPT(hPhysicalDrive, SelectedDrive.DiskSize, SelectedDrive.SectorSize, FALSE)) || (!InitializeDisk(hPhysicalDrive)) ) {
+	if ((!ClearMBRGPT(hPhysicalDrive, SelectedDrive.DiskSize, SelectedDrive.SectorSize, use_large_fat32)) || (!InitializeDisk(hPhysicalDrive)) ) {
 		uprintf("Could not reset partitions\n");
 		FormatStatus = ERROR_SEVERITY_ERROR|FAC(FACILITY_STORAGE)|ERROR_PARTITION_FAILURE;
 		goto out;

src/rufus.rc

@@ -33,7 +33,7 @@ LANGUAGE LANG_NEUTRAL, SUBLANG_NEUTRAL
 IDD_DIALOG DIALOGEX 12, 12, 242, 376
 STYLE DS_SETFONT | DS_MODALFRAME | DS_CENTER | WS_MINIMIZEBOX | WS_POPUP | WS_CAPTION | WS_SYSMENU
 EXSTYLE WS_EX_ACCEPTFILES
-CAPTION "Rufus 2.10.966"
+CAPTION "Rufus 2.10.967"
 FONT 8, "Segoe UI Symbol", 400, 0, 0x0
 BEGIN
     LTEXT           "Device",IDS_DEVICE_TXT,9,6,200,8
@@ -320,8 +320,8 @@ END
 //
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 2,10,966,0
+ FILEVERSION 2,10,967,0
- PRODUCTVERSION 2,10,966,0
+ PRODUCTVERSION 2,10,967,0
  FILEFLAGSMASK 0x3fL
 #ifdef _DEBUG
  FILEFLAGS 0x1L
@@ -338,13 +338,13 @@ BEGIN
         BEGIN
             VALUE "CompanyName", "Akeo Consulting (http://akeo.ie)"
             VALUE "FileDescription", "Rufus"
-            VALUE "FileVersion", "2.10.966"
+            VALUE "FileVersion", "2.10.967"
             VALUE "InternalName", "Rufus"
             VALUE "LegalCopyright", "© 2011-2016 Pete Batard (GPL v3)"
             VALUE "LegalTrademarks", "http://www.gnu.org/copyleft/gpl.html"
             VALUE "OriginalFilename", "rufus.exe"
             VALUE "ProductName", "Rufus"
-            VALUE "ProductVersion", "2.10.966"
+            VALUE "ProductVersion", "2.10.967"
         END
     END
     BLOCK "VarFileInfo"