[iso] add support for distros using a NONSTANDARD GRUB 2.0 prefix directory

* Looking at you, openSUSE Live and GeckoLinux!

.vs/rufus.vcxproj

@@ -375,6 +375,8 @@
     <ClCompile Include="..\src\vhd.c" />
   </ItemGroup>
   <ItemGroup>
+    <ClInclude Include="..\res\grub2\grub2_version.h" />
+    <ClInclude Include="..\res\grub\grub_version.h" />
     <ClInclude Include="..\src\badblocks.h" />
     <ClInclude Include="..\src\bled\bled.h" />
     <ClInclude Include="..\src\drive.h" />

.vs/rufus.vcxproj.filters

@@ -176,6 +176,12 @@
     <ClInclude Include="..\src\re.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="..\res\grub\grub_version.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+    <ClInclude Include="..\res\grub2\grub2_version.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <None Include="..\res\rufus.ico">

res/grub2/grub2_version.h

@@ -2,4 +2,38 @@
  * This file contains the version string of the GRUB 2.x binary embedded in Rufus.
  * Should be the same as GRUB's PACKAGE_VERSION in config.h.
  */
+#pragma once
+
 #define GRUB2_PACKAGE_VERSION "2.06"
+
+/*
+ * Also include the 'core.img' patch data for distros using a 
+ * NONSTANDARD '/boot/grub2/' prefix directory (openSUSE, Gecko, ...)
+ * This is basically a diff of the 'core.img' generated with
+ * 'grub-mkimage -p/boot/grub' vs 'grub-mkimage -p/boot/grub2'
+ */
+ 
+// For GRUB 2.04
+static const chunk_t grub_204_chunk1_src = { 0x0208, 1, { 0xce } };
+static const chunk_t grub_204_chunk1_rep = { 0x0208, 1, { 0xcf } };
+static const chunk_t grub_204_chunk2_src = { 0x7cf8, 6, { 0x63, 0x25, 0x7e, 0x04, 0xf6, 0x14 } };
+static const chunk_t grub_204_chunk2_rep = { 0x7cf8, 7, { 0x62, 0xdb, 0x77, 0x57, 0x0c, 0x4e, 0x00 } };
+
+// For GRUB 2.06
+static const chunk_t grub_206_chunk1_src = { 0x0208, 1, { 0xcf } };
+static const chunk_t grub_206_chunk1_rep = { 0x0208, 1, { 0xd0 } };
+static const chunk_t grub_206_chunk2_src = { 0x95f9, 6, { 0xac, 0x1a, 0xc6, 0x4f, 0x45, 0x2c } };
+static const chunk_t grub_206_chunk2_rep = { 0x95f9, 7, { 0xab, 0xe7, 0xe4, 0x0a, 0x2e, 0x38, 0x00 } };
+
+const grub_patch_t grub_patch[2] = {
+	{	"2.04", {
+			{ &grub_204_chunk1_src, &grub_204_chunk1_rep },
+			{ &grub_204_chunk2_src, &grub_204_chunk2_rep },
+		}
+	},
+	{	"2.06", {
+			{ &grub_206_chunk1_src, &grub_206_chunk1_rep },
+			{ &grub_206_chunk2_src, &grub_206_chunk2_rep },
+		}
+	},
+};

src/format.c

@@ -73,6 +73,7 @@ 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, write_as_esp, is_vds_available;
+extern const grub_patch_t grub_patch[2];
 uint8_t *grub2_buf = NULL, *sec_buf = NULL;
 long grub2_len;
 
@@ -909,8 +910,8 @@ static BOOL WriteSBR(HANDLE hPhysicalDrive)
 {
 	// TODO: Do we need anything special for 4K sectors?
 	DWORD size, max_size, br_size = 0x200;
-	int r, sub_type = boot_type;
+	int i, j, r, sub_type = boot_type;
-	unsigned char* buf = NULL;
+	uint8_t *buf = NULL, *patched = NULL;
 	FAKE_FD fake_fd = { 0 };
 	FILE* fp = (FILE*)&fake_fd;
 
@@ -953,6 +954,31 @@ static BOOL WriteSBR(HANDLE hPhysicalDrive)
 				return FALSE;
 			}
 		}
+		// TODO: Compute the projected increase in size instead of harcoding it
+		if (img_report.has_grub2 == 2 && ((patched = malloc(size + 16)) != NULL)) {
+			memcpy(patched, buf, size);
+			// Patch GRUB for nonstandard prefix directory
+			for (i = 0; i < ARRAYSIZE(grub_patch); i++) {
+				if (strcmp(img_report.grub2_version, grub_patch[i].version) == 0) {
+					for (j = 0; j < ARRAYSIZE(grub_patch[i].patch); j++) {
+						if (memcmp(&patched[grub_patch[i].patch[j].src->offset], grub_patch[i].patch[j].src->data,
+							grub_patch[i].patch[j].src->size) != 0) {
+							uprintf("ERROR: Did not find expected source data for GRUB patch");
+							return FALSE;
+						}
+						memcpy(&patched[grub_patch[i].patch[j].rep->offset], grub_patch[i].patch[j].rep->data,
+							grub_patch[i].patch[j].rep->size);
+						if (grub_patch[i].patch[j].rep->size > grub_patch[i].patch[j].src->size)
+							size += grub_patch[i].patch[j].rep->size - grub_patch[i].patch[j].src->size;
+					}
+					safe_free(grub2_buf);
+					grub2_buf = patched;
+					buf = grub2_buf;
+					uprintf("Patched Grub 2.0 SBR for NONSTANDARD prefix");
+					break;
+				}
+			}
+		}
 		break;
 	case BT_MAX:
 		uprintf("Writing protective message SBR");

src/iso.c

@@ -82,6 +82,7 @@ RUFUS_IMG_REPORT img_report;
 int64_t iso_blocking_status = -1;
 extern BOOL preserve_timestamps, enable_ntfs_compression;
 extern char* archive_path;
+extern const grub_patch_t grub_patch[2];
 BOOL enable_iso = TRUE, enable_joliet = TRUE, enable_rockridge = TRUE, has_ldlinux_c32;
 #define ISO_BLOCKING(x) do {x; iso_blocking_status++; } while(0)
 static const char* psz_extract_dir;
@@ -100,7 +101,7 @@ static const char* sources_str = "/sources";
 static const char* wininst_name[] = { "install.wim", "install.esd", "install.swm" };
 // We only support GRUB/BIOS (x86) that uses a standard config dir (/boot/grub/i386-pc/)
 // If the disc was mastered properly, GRUB/EFI will take care of itself
-static const char* grub_dirname = "/boot/grub/i386-pc";
+static const char* grub_dirname[] = { "/boot/grub/i386-pc", "/boot/grub2/i386-pc" };
 static const char* grub_cfg[] = { "grub.cfg", "loopback.cfg" };
 static const char* compatresources_dll = "compatresources.dll";
 static const char* menu_cfg = "menu.cfg";
@@ -211,8 +212,10 @@ static BOOL check_iso_props(const char* psz_dirname, int64_t file_length, const
 		}
 	} else {	// Scan-time checks
 		// Check for GRUB artifacts
-		if (safe_stricmp(psz_dirname, grub_dirname) == 0)
+		for (i = 0; i < ARRAYSIZE(grub_dirname); i++) {
-			img_report.has_grub2 = TRUE;
+			if (safe_stricmp(psz_dirname, grub_dirname[i]) == 0)
+				img_report.has_grub2 = (uint8_t)i + 1;
+		}
 
 		// Check for a syslinux v5.0+ file anywhere
 		if (safe_stricmp(psz_basename, ldlinux_c32) == 0) {
@@ -1092,15 +1095,17 @@ out:
 			img_report.wininst_version = GetInstallWimVersion(src_iso);
 		}
 		if (img_report.has_grub2) {
+			char grub_path[128];
+			static_sprintf(grub_path, "%s/normal.mod", &grub_dirname[img_report.has_grub2 - 1][1]);
 			// In case we have a GRUB2 based iso, we extract boot/grub/i386-pc/normal.mod to parse its version
 			img_report.grub2_version[0] = 0;
 			// coverity[swapped_arguments]
 			if (GetTempFileNameU(temp_dir, APPLICATION_NAME, 0, path) != 0) {
-				size = (size_t)ExtractISOFile(src_iso, "boot/grub/i386-pc/normal.mod", path, FILE_ATTRIBUTE_NORMAL);
+				size = (size_t)ExtractISOFile(src_iso, grub_path, path, FILE_ATTRIBUTE_NORMAL);
 				buf = (char*)calloc(size, 1);
 				fd = fopen(path, "rb");
 				if ((size == 0) || (buf == NULL) || (fd == NULL)) {
-					uprintf("  Could not read Grub version from 'boot/grub/i386-pc/normal.mod'");
+					uprintf("  Could not read Grub version from '%s'", grub_path);
 				} else {
 					fread(buf, 1, size, fd);
 					fclose(fd);
@@ -1109,11 +1114,43 @@ out:
 				free(buf);
 				DeleteFileU(path);
 			}
-			if (img_report.grub2_version[0] != 0)
+			if (img_report.grub2_version[0] != 0) {
-				uprintf("  Detected Grub version: %s", img_report.grub2_version);
+				// (Insert "Why is it always you three" meme, with Fedora, Manjaro and openSUSE)
-			else {
+				// For some obscure reason, openSUSE have decided that their Live images should
+				// use /boot/grub2/ as their prefix directory instead of the standard /boot/grub/
+				// This creates a MAJOR issue because the prefix directory is hardcoded in
+				// 'core.img', and Rufus must install a 'core.img', that is not provided by the
+				// ISO, for the USB to boot (since even trying to pick the one from ISOHybrid
+				// does usually not guarantees the presence of the FAT driver which is mandatory
+				// for ISO boot).
+				// Therefore, when *someone* uses a nonstandard GRUB prefix directory, our base
+				// 'core.img' can't work with their image, since it isn't able to load modules
+				// like 'normal.mod', that are required to access the configuration files. Oh and
+				// you can forget about direct editing the prefix string inside 'core.img' since
+				// GRUB are forcing LZMA compression for BIOS payloads. And it gets even better,
+				// because even if you're trying to be smart and use GRUB's earlyconfig features
+				// to do something like:
+				//   if [ -e /boot/grub2/i386-pc/normal.mod ]; then set prefix = ...
+				// you still must embed 'configfile.mod' and 'normal.mod' in 'core.img' in order
+				// to do that, which ends up tripling the file size...
+				// Soooo, since the universe is conspiring against us and in order to cut a long
+				// story short about developers making annoying decisions, we'll take advantage
+				// of the fact that the LZMA replacement section for the 2.04 and 2.06 'core.img'
+				// when using '/boot/grub2' as a prefix is very small and always located at the
+				// very end the file to patch the damn thing and get on with our life!
+				uprintf("  Detected Grub version: %s%s", img_report.grub2_version,
+					img_report.has_grub2 >= 1 ? " with NONSTANDARD prefix" : "");
+				for (k = 0; k < ARRAYSIZE(grub_patch); k++) {
+					if (strcmp(img_report.grub2_version, grub_patch[k].version) == 0)
+						break;
+				}
+				if (k >= ARRAYSIZE(grub_patch)) {
+					uprintf("  • Don't have a prefix patch for this version => DROPPED!");
+					img_report.has_grub2 = 0;
+				}
+			} else {
 				uprintf("  Could not detect Grub version");
-				img_report.has_grub2 = FALSE;
+				img_report.has_grub2 = 0;
 			}
 		}
 		if (img_report.has_compatresources_dll) {

src/rufus.h

@@ -384,7 +384,7 @@ typedef struct {
 	BOOLEAN has_efi_syslinux;
 	BOOLEAN needs_syslinux_overwrite;
 	BOOLEAN has_grub4dos;
-	BOOLEAN has_grub2;
+	uint8_t has_grub2;
 	BOOLEAN has_compatresources_dll;
 	BOOLEAN has_kolibrios;
 	BOOLEAN uses_casper;
@@ -666,6 +666,23 @@ extern void StrArrayClear(StrArray* arr);
 extern void StrArrayDestroy(StrArray* arr);
 #define IsStrArrayEmpty(arr) (arr.Index == 0)
 
+/* Patch structs for GRUB */
+typedef struct {
+	const uint32_t offset;
+	const uint32_t size;
+	const uint8_t data[];
+} chunk_t;
+
+typedef struct {
+	const chunk_t* src;
+	const chunk_t* rep;
+} patch_t;
+
+typedef struct {
+	const char* version;
+	const patch_t patch[2];
+} grub_patch_t;
+
 /*
  * typedefs for the function prototypes. Use the something like:
  *   PF_DECL(FormatEx);

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 3.19.1880"
+CAPTION "Rufus 3.19.1881"
 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 3,19,1880,0
+ FILEVERSION 3,19,1881,0
- PRODUCTVERSION 3,19,1880,0
+ PRODUCTVERSION 3,19,1881,0
  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", "3.19.1880"
+            VALUE "FileVersion", "3.19.1881"
             VALUE "InternalName", "Rufus"
             VALUE "LegalCopyright", "© 2011-2022 Pete Batard (GPL v3)"
             VALUE "LegalTrademarks", "https://www.gnu.org/licenses/gpl-3.0.html"
             VALUE "OriginalFilename", "rufus-3.19.exe"
             VALUE "ProductName", "Rufus"
-            VALUE "ProductVersion", "3.19.1880"
+            VALUE "ProductVersion", "3.19.1881"
         END
     END
     BLOCK "VarFileInfo"