makes the forwarder fit for loading the "USB Loader GX" from USB-Device

Strategy to find the boot.dol from "USB Loader GX":

1. looking for "/config/GXGlobal.cfg" first on "SD:/" and then on "USB:/"
2.1. when cfg is found and update_path is set, then searches for "boot.dol"/"boot.elf" in "update_path"
2.2. when cfg isn't found or update_path isn't set, then looking for "boot.dol"/"boot.elf" in "apps/usbloader_gx/" first on "SD:/" and then on "USB:/" 
3. if the Loader is found, then LOAD and RUN it. Otherwise exits the for-warder

Primarily searched on SD-Card. This makes easier to test new versions.

source/cfg.c

@@ -8,6 +8,8 @@
 
 #include "cfg.h"
 
+char update_path[150]="";
+
 static char *cfg_name, *cfg_val;
 
 char* strcopy(char *dest, char *src, int size)

source/cfg.h

@@ -6,7 +6,7 @@ extern "C"
 {
 #endif
 
-char update_path[150];
+extern char update_path[150];
 
 void cfg_set(char *name, char *val);
 bool cfg_parsefile(char * fname, void (*set_func)(char*, char*));

source/fatmounter.c

@@ -0,0 +1,184 @@
+#include <fat.h>
+#include <string.h>
+#include <sys/dir.h>
+#include <sys/iosupport.h>
+#include <ogc/lwp_watchdog.h>
+#include <ogc/mutex.h>
+#include <ogc/system.h>
+#include <ogc/usbstorage.h>
+#include <sdcard/wiisd_io.h>
+
+//these are the only stable and speed is good
+#define CACHE 32
+#define SECTORS 128
+
+enum BPB {
+	BPB_jmpBoot = 0x00,
+	BPB_OEMName = 0x03,
+	// BIOS Parameter Block
+	BPB_bytesPerSector = 0x0B,
+	BPB_sectorsPerCluster = 0x0D,
+	BPB_reservedSectors = 0x0E,
+	BPB_numFATs = 0x10,
+	BPB_rootEntries = 0x11,
+	BPB_numSectorsSmall = 0x13,
+	BPB_mediaDesc = 0x15,
+	BPB_sectorsPerFAT = 0x16,
+	BPB_sectorsPerTrk = 0x18,
+	BPB_numHeads = 0x1A,
+	BPB_numHiddenSectors = 0x1C,
+	BPB_numSectors = 0x20,
+	// Ext BIOS Parameter Block for FAT16
+	BPB_FAT16_driveNumber = 0x24,
+	BPB_FAT16_reserved1 = 0x25,
+	BPB_FAT16_extBootSig = 0x26,
+	BPB_FAT16_volumeID = 0x27,
+	BPB_FAT16_volumeLabel = 0x2B,
+	BPB_FAT16_fileSysType = 0x36,
+	// Bootcode
+	BPB_FAT16_bootCode = 0x3E,
+	// FAT32 extended block
+	BPB_FAT32_sectorsPerFAT32 = 0x24,
+	BPB_FAT32_extFlags = 0x28,
+	BPB_FAT32_fsVer = 0x2A,
+	BPB_FAT32_rootClus = 0x2C,
+	BPB_FAT32_fsInfo = 0x30,
+	BPB_FAT32_bkBootSec = 0x32,
+	// Ext BIOS Parameter Block for FAT32
+	BPB_FAT32_driveNumber = 0x40,
+	BPB_FAT32_reserved1 = 0x41,
+	BPB_FAT32_extBootSig = 0x42,
+	BPB_FAT32_volumeID = 0x43,
+	BPB_FAT32_volumeLabel = 0x47,
+	BPB_FAT32_fileSysType = 0x52,
+	// Bootcode
+	BPB_FAT32_bootCode = 0x5A,
+	BPB_bootSig_55 = 0x1FE,
+	BPB_bootSig_AA = 0x1FF
+};
+
+static const char FAT_SIG[3] = {'F', 'A', 'T'};
+
+#define BYTES_PER_READ 512
+
+static bool _FAT_partition_isFAT(const DISC_INTERFACE* disc, sec_t startSector)
+{
+	uint8_t sectorBuffer[BYTES_PER_READ] = {0};
+	if (!disc->readSectors(startSector, 1, sectorBuffer)) {
+			return false;
+	}
+	// Make sure it is a valid BPB
+	if ( (sectorBuffer[BPB_bootSig_55] != 0x55) || (sectorBuffer[BPB_bootSig_AA] != 0xAA)) {
+		return false;
+	}
+
+	// Now verify that this is indeed a FAT partition
+	if (memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)) && 
+		memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
+	{
+		return false;
+	}
+
+	// check again for the last two cases to make sure that we really have a FAT filesystem here
+	// and won't corrupt any data
+	if(memcmp(sectorBuffer + BPB_FAT16_fileSysType, "FAT", 3) != 0 && memcmp(sectorBuffer + BPB_FAT32_fileSysType, "FAT32", 5) != 0)
+	{
+		return false;
+	}
+	return true;
+}
+static inline uint32_t u8array_to_u32 (const uint8_t* item, int offset) {
+	return ( item[offset] | (item[offset + 1] << 8) | (item[offset + 2] << 16) | (item[offset + 3] << 24));
+}
+
+sec_t GetFATPartition(const DISC_INTERFACE* disc)
+{
+	int i;
+	uint8_t sectorBuffer[BYTES_PER_READ] = {0};
+	sec_t startSector = 0;
+	
+	if(!disc->startup())
+		return 0;
+
+	// Read first sector of disc
+	if (!disc->readSectors(0, 1, sectorBuffer))
+		startSector = 0;
+
+	// Make sure it is a valid MBR or boot sector
+	if ( (sectorBuffer[BPB_bootSig_55] != 0x55) || (sectorBuffer[BPB_bootSig_AA] != 0xAA))
+		startSector = 0;
+
+	if (!memcmp(sectorBuffer + BPB_FAT16_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
+	{
+		// Check if there is a FAT string, which indicates this is a boot sector
+		startSector = 0;
+	}
+	else if (!memcmp(sectorBuffer + BPB_FAT32_fileSysType, FAT_SIG, sizeof(FAT_SIG)))
+	{
+		// Check for FAT32
+		startSector = 0;
+	}
+	else
+	{
+		// This is an MBR
+		// Find first valid partition from MBR
+		// First check for an active partition
+		for (i=0x1BE; (i < 0x1FE) && (sectorBuffer[i] != 0x80); i+= 0x10);
+		// If it find an active partition, check for FAT-Partition
+		if ( i != 0x1FE && !_FAT_partition_isFAT(disc, u8array_to_u32(sectorBuffer, 0x8 + i)) )
+			i = 0x1FE;
+
+		// If it didn't find an active partition, search for any valid partition
+		if (i == 0x1FE)
+		{
+			for (i=0x1BE; i < 0x1FE; i+= 0x10)
+			{
+				if ( sectorBuffer[i+0x04] != 0x00 && _FAT_partition_isFAT(disc, u8array_to_u32(sectorBuffer, 0x8 + i)) )
+					break;
+			}
+		}
+		if (i != 0x1FE)
+			startSector = u8array_to_u32(sectorBuffer, 0x8 + i);;
+	}
+	disc->shutdown();
+	return startSector;
+}
+
+int USBDevice_Init()
+{
+	//closing all open Files write back the cache and then shutdown em!
+	fatUnmount("USB:/");
+	//right now mounts first FAT-partition
+	if (fatMount("USB", &__io_usbstorage, GetFATPartition(&__io_usbstorage), CACHE, SECTORS)) {
+		//try first mount with libogc
+		return 1;
+	}
+	return -1;
+}
+
+void USBDevice_deInit()
+{
+	//closing all open Files write back the cache and then shutdown em!
+	fatUnmount("USB:/");
+}
+
+int isSdInserted()
+{
+    return __io_wiisd.isInserted();
+}
+
+int SDCard_Init()
+{
+	//closing all open Files write back the cache and then shutdown em!
+	fatUnmount("SD:/");
+	//right now mounts first FAT-partition
+	if (fatMount("SD", &__io_wiisd, GetFATPartition(&__io_wiisd), CACHE, SECTORS))
+		return 1;
+	return -1;
+}
+
+void SDCard_deInit()
+{
+	//closing all open Files write back the cache and then shutdown em!
+	fatUnmount("SD:/");
+}

source/fatmounter.h

@@ -0,0 +1,19 @@
+#ifndef _FATMOUNTER_H_
+#define _FATMOUNTER_H_
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+int USBDevice_Init();
+void USBDevice_deInit();
+int isSdInserted();
+int SDCard_Init();
+void SDCard_deInit();
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

source/main.cpp

@@ -31,6 +31,7 @@
 #include <malloc.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <ogc/machine/processor.h>
 
 #include "pngu/pngu.h"
@@ -39,6 +40,7 @@
 #include "dolloader.h"
 #include "elfloader.h"
 #include "cfg.h"
+#include "fatmounter.h"
 
 
 PNGUPROP imgProp;
@@ -78,105 +80,123 @@ void Background_Show(int x, int y, int z, u8 * data, int angle, int scaleX, int
 }
 
 
-int main(int argc, char **argv) {
+int main(int argc, char **argv) 
-
+{
 	u32 cookie;
 	FILE *exeFile = NULL;
 	void *exeBuffer          = (void *)EXECUTABLE_MEM_ADDR;
 	int exeSize              = 0;
 	u32 exeEntryPointAddress = 0;
 	entrypoint exeEntryPoint;
+	/* int videomod */
+	InitVideo();
+	/* get imagedata */
+	u8 * imgdata = GetImageData();
+	/* fadein of image */
+	for(int i = 0; i < 255; i = i+10)
+	{
+		if(i>255) i = 255;
+		Background_Show(0, 0, 0, imgdata, 0, 1, 1, i);
+		Menu_Render();
+	}
+	/* check devices */
+	SDCard_Init();
+	USBDevice_Init();
+	char cfgpath[256];
 	
-
+	sprintf(cfgpath, "SD:/config/GXGlobal.cfg");
-    /* int videomod */
+	if(!cfg_parsefile(cfgpath, &cfg_set)) //no cfg-File on SD: try USB:
-    InitVideo();
+	{
-
+		sprintf(cfgpath, "USB:/config/GXGlobal.cfg");
-    /* get imagedata */
+		cfg_parsefile(cfgpath, &cfg_set);
-    u8 * imgdata = GetImageData();
+	}
-
+	if(update_path[0] == '\0') // non cfg-File loaded or update_path not set
-    /* fadein of image */
+	{
-    for(int i = 0; i < 255; i = i+10) {
+		/* Open dol File and check exist */
-    if(i>255) i = 255;
+		strcpy(cfgpath, "SD:/apps/usbloader_gx/boot.dol");
-	Background_Show(0, 0, 0, imgdata, 0, 1, 1, i);
+		exeFile = fopen (cfgpath ,"rb");
-    Menu_Render();
+		if (exeFile==NULL)
-    }
+		{
-    /* check devices */
+			strcpy(cfgpath, "SD:/apps/usbloader_gx/boot.elf");
-    __io_wiisd.startup();
+			exeFile = fopen (cfgpath ,"rb");
-	fatMount("SD", &__io_wiisd, 0, 32, 128);
+		}
-
+		if (exeFile==NULL)
-    char cfgpath[40];
+		{
-    sprintf(cfgpath, "SD:/config/GXGlobal.cfg");
+			strcpy(cfgpath, "USB:/apps/usbloader_gx/boot.dol");
-
+			exeFile = fopen (cfgpath ,"rb");
-	if(!cfg_parsefile(cfgpath, &cfg_set)) {
+		}
-        /* Open dol File and check exist */
+		if (exeFile==NULL)
-        exeFile = fopen ("SD:/apps/usbloader_gx/boot.dol" ,"rb");
+		{
-        if (exeFile==NULL) {
+			strcpy(cfgpath, "USB:/apps/usbloader_gx/boot.elf");
-            fclose(exeFile);
+			exeFile = fopen (cfgpath ,"rb");
-            exeFile = fopen ("SD:/apps/usbloader_gx/boot.elf" ,"rb");
+		}
-            if (exeFile==NULL) {
+		if (exeFile==NULL)
-            fclose(exeFile);
+			SYS_ResetSystem(SYS_RETURNTOMENU, 0, 0);
-            SYS_ResetSystem(SYS_RETURNTOMENU, 0, 0);
+	}
-            }
+	else
-        }
+	{
-	} else {
+		sprintf(cfgpath, "%sboot.dol", update_path);
-        sprintf(cfgpath, "%sboot.dol", update_path);
+		/* Open dol File and check exist */
-        /* Open dol File and check exist */
+		exeFile = fopen (cfgpath, "rb");
-        exeFile = fopen (cfgpath, "rb");
+		if (exeFile==NULL)
-        if (exeFile==NULL) {
+		{
-            fclose(exeFile);
+			sprintf(cfgpath, "%sboot.elf", update_path);
-            sprintf(cfgpath, "%sboot.elf", update_path);
+			exeFile = fopen (cfgpath,"rb");
-            exeFile = fopen (cfgpath,"rb");
+		}
-            if (exeFile==NULL) {
+		if (exeFile==NULL)
-            fclose(exeFile);
+			SYS_ResetSystem(SYS_RETURNTOMENU, 0, 0);
-            SYS_ResetSystem(SYS_RETURNTOMENU, 0, 0);
-            }
-        }
 	}
 
 	fseek (exeFile, 0, SEEK_END);
 	exeSize = ftell(exeFile);
 	fseek (exeFile, 0, SEEK_SET);
-	if(fread (exeBuffer, 1, exeSize, exeFile) != (unsigned int) exeSize) {
-		printf("Can't open DOL File...\n");
-		SYS_ResetSystem(SYS_RETURNTOMENU, 0, 0);;
-	}
 
+	if(fread (exeBuffer, 1, exeSize, exeFile) != (unsigned int) exeSize)
+	{
+		printf("Can't open DOL File...\n");
+		SYS_ResetSystem(SYS_RETURNTOMENU, 0, 0);
+	}
 	fclose (exeFile);
 	
-    /* load entry point */
+	/* load entry point */
-	struct __argv args[10];
+	struct __argv args;
+	bzero(&args, sizeof(args));
+	args.argvMagic = ARGV_MAGIC;
+	args.length = strlen(cfgpath) + 2;
+	args.commandLine = (char*)malloc(args.length);
+	if (!args.commandLine) SYS_ResetSystem(SYS_RETURNTOMENU, 0, 0);
+	strcpy(args.commandLine, cfgpath);
+	args.commandLine[args.length - 1] = '\x00';
+	args.argc = 1;
+	args.argv = &args.commandLine;
+	args.endARGV = args.argv + 1;
 
 	int ret = valid_elf_image(exeBuffer);
-	if (ret == 1) {
+	if (ret == 1)
-        exeEntryPointAddress = load_elf_image(exeBuffer);
+		exeEntryPointAddress = load_elf_image(exeBuffer);
-	} else {
+	else
-        exeEntryPointAddress = load_dol_image(exeBuffer, args);
+		exeEntryPointAddress = load_dol_image(exeBuffer, &args);
+
+	/* fadeout of image */
+	for(int i = 255; i > 1; i = i-7)
+	{
+		if(i < 0) i = 0;
+		Background_Show(0, 0, 0, imgdata, 0, 1, 1, i);
+		Menu_Render();
 	}
-
+	SDCard_deInit();
-    /* fadeout of image */
+	USBDevice_deInit();
-    for(int i = 255; i > 1; i = i-7) {
+	StopGX();
-        if(i < 0) i = 0;
-        Background_Show(0, 0, 0, imgdata, 0, 1, 1, i);
-        Menu_Render();
-	}
-
-	fatUnmount("SD");
-    __io_wiisd.shutdown();
-    StopGX();
-
 	if (exeEntryPointAddress == 0) {
-		printf("EntryPointAddress failed...\n");
+		printf("EntryPointAddress  failed...\n");
 		SYS_ResetSystem(SYS_RETURNTOMENU, 0, 0);;
 	}
-
 	exeEntryPoint = (entrypoint) exeEntryPointAddress;
-
+	/* cleaning up and load dol */
-    /* cleaning up and load dol */
 	SYS_ResetSystem(SYS_SHUTDOWN, 0, 0);
 	_CPU_ISR_Disable (cookie);
 	__exception_closeall ();
 	exeEntryPoint ();
 	_CPU_ISR_Restore (cookie);
 	return 0;
-
 }