Why does fread segfault?

Question

I have been tasked with implementing an ls function for files in an .iso file system. I need to use fread but it is segfaulting. I know the file exists and i know it has data in it. I have the format for calling fread and I have set it up as follows

static void ls(File *file, int32_t root_dir_size)
{
   void* sector;
   int result;
   result = fread(sector, 1, 1, file);
}

Why does this segfault? I am new to C and I am coming from C++ so not sure what I am missing here.

Answer 1

fread needs memory into which to put the data it's reading. That memory is pointed to by the first parameter, in your case sector . However, you have not initialized sector . You will need to allocate some memory, in this case just one byte and have sector point to that. For instance:

void *sector = malloc(1);

As always, don't forget to free the memory after you're done using it.