[core] add option to write a small enough ISO to an ESP

* This is mostly aimed at Debian 11 netinst on the Raspberry Pi 4
* Only available for regular UEFI ISOs if GPT and FAT are selected (no MBR ESPs).
* Also fix a MinGW warning in GetUnusedDriveLetter()

res/loc/ChangeLog.txt

@@ -9,6 +9,8 @@ o v3.*
   - *UPDATED*  MSG_068 "Error while partitioning drive." -> "Could not partition drive."
   You can test this new message with <Alt>-<G>
   - *NEW*      MSG_308 "VHD detection"
+  // TODO: Add a test ISO for this.
+  - *NEW*      MSG_310 "The ISO you have selected uses UEFI and is small enough to be written as (...)"
 
 o v3.5 (2019.03.12)
   The following 3 messages can be tested by creating a UEFI:NTFS drive in Rufus ('Show advanced drive properties' must be enabled

res/loc/rufus.loc

@@ -566,6 +566,10 @@ t MSG_305 "Use this option to indicate whether you want to use this device to in
 t MSG_306 "Fast-zeroing drive: %s"
 t MSG_307 "This may take a while"
 t MSG_308 "VHD detection"
+t MSG_309 "ISO → ESP"
+t MSG_310 "The ISO you have selected uses UEFI and is small enough to be written as an EFI System Partition (ESP). "
+	"Writing to an ESP, instead of writing to a generic data partition occupying the whole disk, can be preferable "
+	"for some types of installations.\n\nPlease select the mode that you want to use to write this image:"
 
 #########################################################################
 l "ar-SA" "Arabic (العربية)" 0x0401, 0x0801, 0x0c01, 0x1001, 0x1401, 0x1801, 0x1c01, 0x2001, 0x2401, 0x2801, 0x2c01, 0x3001, 0x3401, 0x3801, 0x3c01, 0x4001

src/drive.c

@@ -71,7 +71,7 @@ PF_TYPE_DECL(NTAPI, NTSTATUS, NtQueryVolumeInformationFile, (HANDLE, PIO_STATUS_
  * Globals
  */
 RUFUS_DRIVE_INFO SelectedDrive;
-extern BOOL installed_uefi_ntfs;
+extern BOOL installed_uefi_ntfs, write_as_esp;
 uint64_t partition_offset[3];
 uint64_t persistence_size = 0;
 
@@ -913,7 +913,7 @@ UINT GetDriveTypeFromIndex(DWORD DriveIndex)
 }
 
 /*
- * Return the next unused drive letter from the system
+ * Return the next unused drive letter from the system or NUL on error.
  */
 char GetUnusedDriveLetter(void)
 {
@@ -923,11 +923,11 @@ char GetUnusedDriveLetter(void)
 	size = GetLogicalDriveStringsA(sizeof(drives), drives);
 	if (size == 0) {
 		uprintf("GetLogicalDriveStrings failed: %s", WindowsErrorString());
-		goto out;
+		return 0;
 	}
 	if (size > sizeof(drives)) {
 		uprintf("GetLogicalDriveStrings: Buffer too small (required %d vs. %d)", size, sizeof(drives));
-		goto out;
+		return 0;
 	}
 
 	for (drive_letter = 'C'; drive_letter <= 'Z'; drive_letter++) {
@@ -941,7 +941,6 @@ char GetUnusedDriveLetter(void)
 			break;
 	}
 
-out:
 	return (drive_letter > 'Z') ? 0 : drive_letter;
 }
 
@@ -1685,7 +1684,8 @@ static BOOL ClearPartition(HANDLE hDrive, LARGE_INTEGER offset, DWORD size)
 BOOL CreatePartition(HANDLE hDrive, int partition_style, int file_system, BOOL mbr_uefi_marker, uint8_t extra_partitions)
 {
 	const char* PartitionTypeName[] = { "MBR", "GPT", "SFD" };
-	const wchar_t *extra_part_name = L"", *main_part_name = L"Main Data Partition";
+	const wchar_t *extra_part_name = L"", *main_part_name = write_as_esp ? L"EFI System Partition" : L"Main Data Partition";
+	const LONGLONG main_part_size = write_as_esp ? MAX_ISO_TO_ESP_SIZE * MB : SelectedDrive.DiskSize;
 	const LONGLONG bytes_per_track = ((LONGLONG)SelectedDrive.SectorsPerTrack) * SelectedDrive.SectorSize;
 	const DWORD size_to_clear = MAX_SECTORS_TO_CLEAR * SelectedDrive.SectorSize;
 	uint8_t* buffer;
@@ -1694,7 +1694,7 @@ BOOL CreatePartition(HANDLE hDrive, int partition_style, int file_system, BOOL m
 	DRIVE_LAYOUT_INFORMATION_EX4 DriveLayoutEx = {0};
 	BOOL r;
 	DWORD i, size, bufsize, pn = 0;
-	LONGLONG main_part_size_in_sectors, extra_part_size_in_tracks = 0, ms_esp_size;
+	LONGLONG main_part_size_in_sectors, extra_part_size_in_tracks = 0, esp_size;
 
 	PrintInfoDebug(0, MSG_238, PartitionTypeName[partition_style]);
 
@@ -1743,9 +1743,16 @@ BOOL CreatePartition(HANDLE hDrive, int partition_style, int file_system, BOOL m
 	}
 
 	// Set our main data partition
-	main_part_size_in_sectors = (SelectedDrive.DiskSize - DriveLayoutEx.PartitionEntry[pn].StartingOffset.QuadPart) /
+	if (write_as_esp) {
-		// Need 33 sectors at the end for secondary GPT
+		// Align ESP to 64 MB while leaving at least 32 MB free space
-		SelectedDrive.SectorSize - ((partition_style == PARTITION_STYLE_GPT)?33:0);
+		esp_size = (((img_report.projected_size / MB) + 96) / 64) * 64 * MB;
+		main_part_size_in_sectors = (esp_size - DriveLayoutEx.PartitionEntry[pn].StartingOffset.QuadPart) /
+			SelectedDrive.SectorSize;
+	} else {
+		main_part_size_in_sectors = (main_part_size - DriveLayoutEx.PartitionEntry[pn].StartingOffset.QuadPart) /
+			// Need 33 sectors at the end for secondary GPT
+			SelectedDrive.SectorSize - ((partition_style == PARTITION_STYLE_GPT) ? 33 : 0);
+	}
 	if (extra_partitions) {
 		// Adjust the size according to extra partitions (which we always align to a track)
 		if (extra_partitions & XP_ESP) {
@@ -1756,10 +1763,10 @@ BOOL CreatePartition(HANDLE hDrive, int partition_style, int file_system, BOOL m
 			// https://docs.microsoft.com/en-us/windows-hardware/manufacture/desktop/configure-uefigpt-based-hard-drive-partitions
 			// is too small. See: https://github.com/pbatard/rufus/issues/979
 			if (SelectedDrive.SectorSize <= 4096)
-				ms_esp_size = 300 * MB;
+				esp_size = 300 * MB;
 			else
-				ms_esp_size = 1200 * MB;	// That'll teach you to have a nonstandard disk!
+				esp_size = 1200 * MB;	// That'll teach you to have a nonstandard disk!
-			extra_part_size_in_tracks = (ms_esp_size + bytes_per_track - 1) / bytes_per_track;
+			extra_part_size_in_tracks = (esp_size + bytes_per_track - 1) / bytes_per_track;
 		} else if (extra_partitions & XP_UEFI_NTFS) {
 			extra_part_name = L"UEFI:NTFS";
 			extra_part_size_in_tracks = (max(MIN_EXTRA_PART_SIZE, uefi_ntfs_size) + bytes_per_track - 1) / bytes_per_track;
@@ -1812,7 +1819,7 @@ BOOL CreatePartition(HANDLE hDrive, int partition_style, int file_system, BOOL m
 			return FALSE;
 		}
 	} else {
-		DriveLayoutEx.PartitionEntry[pn].Gpt.PartitionType = PARTITION_MICROSOFT_DATA;
+		DriveLayoutEx.PartitionEntry[pn].Gpt.PartitionType = write_as_esp ? PARTITION_GENERIC_ESP : PARTITION_MICROSOFT_DATA;
 		IGNORE_RETVAL(CoCreateGuid(&DriveLayoutEx.PartitionEntry[pn].Gpt.PartitionId));
 		wcsncpy(DriveLayoutEx.PartitionEntry[pn].Gpt.Name, main_part_name, ARRAYSIZE(DriveLayoutEx.PartitionEntry[pn].Gpt.Name));
 	}

src/format.c

@@ -66,7 +66,7 @@ extern uint32_t dur_mins, dur_secs;
 extern uint32_t wim_nb_files, wim_proc_files, wim_extra_files;
 static int actual_fs_type, wintogo_index = -1, wininst_index = 0;
 extern BOOL force_large_fat32, enable_ntfs_compression, lock_drive, zero_drive, fast_zeroing, enable_file_indexing, write_as_image;
-extern BOOL use_vds;
+extern BOOL use_vds, write_as_esp;
 uint8_t *grub2_buf = NULL, *sec_buf = NULL;
 long grub2_len;
 
@@ -1997,7 +1997,7 @@ DWORD WINAPI FormatThread(void* param)
 	if (fs_type < FS_EXT2)
 		ToValidLabel(label, (fs_type == FS_FAT16) || (fs_type == FS_FAT32) || (fs_type == FS_EXFAT));
 	ClusterSize = (DWORD)ComboBox_GetItemData(hClusterSize, ComboBox_GetCurSel(hClusterSize));
-	if (ClusterSize < 0x200)
+	if ((ClusterSize < 0x200) || (write_as_esp))
 		ClusterSize = 0;	// 0 = default cluster size
 
 	Flags = FP_FORCE;

src/rufus.c

@@ -116,7 +116,7 @@ BOOL enable_HDDs = FALSE, enable_VHDs = TRUE, enable_ntfs_compression = FALSE, n
 BOOL advanced_mode_device, advanced_mode_format, allow_dual_uefi_bios, detect_fakes, enable_vmdk, force_large_fat32, usb_debug;
 BOOL use_fake_units, preserve_timestamps = FALSE, fast_zeroing = FALSE, app_changed_size = FALSE;
 BOOL zero_drive = FALSE, list_non_usb_removable_drives = FALSE, enable_file_indexing, large_drive = FALSE;
-BOOL write_as_image = FALSE, installed_uefi_ntfs = FALSE, enable_fido = FALSE, use_vds = FALSE;
+BOOL write_as_image = FALSE, write_as_esp = FALSE, installed_uefi_ntfs = FALSE, enable_fido = FALSE, use_vds = FALSE;
 float fScale = 1.0f;
 int dialog_showing = 0, selection_default = BT_IMAGE, windows_to_go_selection = 0, persistence_unit_selection = -1;
 int default_fs, fs_type, boot_type, partition_type, target_type; // file system, boot type, partition type, target type
@@ -2287,6 +2287,7 @@ static INT_PTR CALLBACK MainCallback(HWND hDlg, UINT message, WPARAM wParam, LPA
 			target_type = (int)ComboBox_GetItemData(hTargetSystem, ComboBox_GetCurSel(hTargetSystem));
 			fs_type = (int)ComboBox_GetItemData(hFileSystem, ComboBox_GetCurSel(hFileSystem));
 			write_as_image = FALSE;
+			write_as_esp = FALSE;
 			installed_uefi_ntfs = FALSE;
 			// Disable all controls except Cancel
 			EnableControls(FALSE, FALSE);
@@ -2681,17 +2682,44 @@ static INT_PTR CALLBACK MainCallback(HWND hDlg, UINT message, WPARAM wParam, LPA
 					if (persistence_size == 0) {
 						char* iso_image = lmprintf(MSG_036);
 						char* dd_image = lmprintf(MSG_095);
-						char* choices[2] = { lmprintf(MSG_276, iso_image), lmprintf(MSG_277, dd_image) };
+						char* esp_image = lmprintf(MSG_309);
-						i = SelectionDialog(lmprintf(MSG_274), lmprintf(MSG_275, iso_image, dd_image, iso_image, dd_image),
+						// If the ISO is small enough to be written as an ESP and we are using GPT add the ISO → ESP option
-							choices, 2);
+						if ((img_report.projected_size < MAX_ISO_TO_ESP_SIZE * MB) && HAS_REGULAR_EFI(img_report) &&
-						if (i < 0)	// Cancel
+							(partition_type == PARTITION_STYLE_GPT) && IS_FAT(fs_type)) {
-							goto aborted_start;
+							char* choices[3] = { lmprintf(MSG_276, iso_image), lmprintf(MSG_277, esp_image), lmprintf(MSG_277, dd_image) };
-						else if (i == 2)
+							i = SelectionDialog(lmprintf(MSG_274), lmprintf(MSG_275, iso_image, dd_image, iso_image, dd_image),
-							write_as_image = TRUE;
+								choices, 3);
+							if (i < 0)	// Cancel
+								goto aborted_start;
+							else if (i == 2)
+								write_as_esp = TRUE;
+							else if (i == 3)
+								write_as_image = TRUE;
+						} else {
+							char* choices[2] = { lmprintf(MSG_276, iso_image), lmprintf(MSG_277, dd_image) };
+							i = SelectionDialog(lmprintf(MSG_274), lmprintf(MSG_275, iso_image, dd_image, iso_image, dd_image),
+								choices, 2);
+							if (i < 0)	// Cancel
+								goto aborted_start;
+							else if (i == 2)
+								write_as_image = TRUE;
+						}
 					}
 				} else {
 					write_as_image = TRUE;
 				}
+			} else if ((img_report.projected_size < MAX_ISO_TO_ESP_SIZE * MB) && HAS_REGULAR_EFI(img_report) &&
+				(partition_type == PARTITION_STYLE_GPT) && IS_FAT(fs_type)) {
+				// The ISO is small enough to be written as an ESP and we are using GPT
+				// so ask the users if they want to write it as an ESP.
+				char* iso_image = lmprintf(MSG_036);
+				char* esp_image = lmprintf(MSG_309);
+				char* choices[2] = { lmprintf(MSG_276, iso_image), lmprintf(MSG_277, esp_image) };
+				i = SelectionDialog(lmprintf(MSG_274), lmprintf(MSG_310), choices, 2);
+				if (i < 0)	// Cancel
+					goto aborted_start;
+				else if (i == 2)
+					write_as_esp = TRUE;
 			}
 		}
 

src/rufus.h

@@ -72,6 +72,7 @@
 #define MAX_GUID_STRING_LENGTH      40
 #define MAX_PARTITIONS              16			// Maximum number of partitions we handle
 #define MAX_ESP_TOGGLE              8			// Maximum number of entries we record to toggle GPT ESP back and forth
+#define MAX_ISO_TO_ESP_SIZE         512			// Maximum size we allow for the ISO → ESP option (in MB)
 #define MAX_SECTORS_TO_CLEAR        128			// nb sectors to zap when clearing the MBR/GPT (must be >34)
 #define MAX_WININST                 4			// Max number of install[.wim|.esd] we can handle on an image
 #define MBR_UEFI_MARKER             0x49464555	// 'U', 'E', 'F', 'I', as a 32 bit little endian longword
@@ -303,6 +304,7 @@ enum checksum_type {
 #define HAS_BOOTMGR_BIOS(r) (r.has_bootmgr)
 #define HAS_BOOTMGR_EFI(r)  (r.has_bootmgr_efi)
 #define HAS_BOOTMGR(r)      (HAS_BOOTMGR_BIOS(r) || HAS_BOOTMGR_EFI(r))
+#define HAS_REGULAR_EFI(r)  (r.has_efi & 0x7E)
 #define HAS_WININST(r)      (r.wininst_index != 0)
 #define HAS_WINPE(r)        (((r.winpe & WINPE_I386) == WINPE_I386)||((r.winpe & WINPE_AMD64) == WINPE_AMD64)||((r.winpe & WINPE_MININT) == WINPE_MININT))
 #define HAS_WINDOWS(r)      (HAS_BOOTMGR(r) || (r.uses_minint) || HAS_WINPE(r))

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 3.11.1668"
+CAPTION "Rufus 3.11.1669"
 FONT 9, "Segoe UI Symbol", 400, 0, 0x0
 BEGIN
     LTEXT           "Drive Properties",IDS_DRIVE_PROPERTIES_TXT,8,6,53,12,NOT WS_GROUP
@@ -395,8 +395,8 @@ END
 //
 
 VS_VERSION_INFO VERSIONINFO
- FILEVERSION 3,11,1668,0
+ FILEVERSION 3,11,1669,0
- PRODUCTVERSION 3,11,1668,0
+ PRODUCTVERSION 3,11,1669,0
  FILEFLAGSMASK 0x3fL
 #ifdef _DEBUG
  FILEFLAGS 0x1L
@@ -414,13 +414,13 @@ BEGIN
             VALUE "Comments", "https://rufus.ie"
             VALUE "CompanyName", "Akeo Consulting"
             VALUE "FileDescription", "Rufus"
-            VALUE "FileVersion", "3.11.1668"
+            VALUE "FileVersion", "3.11.1669"
             VALUE "InternalName", "Rufus"
             VALUE "LegalCopyright", "© 2011-2020 Pete Batard (GPL v3)"
             VALUE "LegalTrademarks", "https://www.gnu.org/licenses/gpl-3.0.html"
             VALUE "OriginalFilename", "rufus-3.11.exe"
             VALUE "ProductName", "Rufus"
-            VALUE "ProductVersion", "3.11.1668"
+            VALUE "ProductVersion", "3.11.1669"
         END
     END
     BLOCK "VarFileInfo"