Question

I have a function that reads a rom file into memory and automatically allocates to fit the file but every time I try to read from the file descriptor, fread() returns zero. I’m unsure what I’m doing wrong. can anybody help?

int read_rom(const char *filename, unsigned char ***rom) {
    int rom_size;
    FILE *fd = NULL;

    if((fd = fopen(filename, "r")) != NULL) {
        fseek(fd, 0, SEEK_END);
        rom_size = ftell(fd);
        (*rom) = malloc(rom_size);
        int read = fread(rom, 1, rom_size, fd);
        fclose(fd);

        printf("read: %d\n", read);

        return rom_size;
    }

    return -1;
}

int main(int argc, char **argv) {
    unsigned char rom_size = 0;
    unsigned char **rom = NULL;
    rom_size = read_rom(argv[1], &rom);

    return 1;
}

Any takers?

Answer 1

You aren’t reading anything in because you fseeked to the end of the file. Do a fseek(fd, 0, SEEK_SET); to return to the beginning of the file before you fread.