malloc inside a function

[galapogos]

Hi,

I'm trying to pass a pointer to a function, and then have the function allocate some memory for that pointer. Is this possible?

I tried the following code, but doesn't seem to work. Once I return from the function, the pointer seems to be void. The program crashes when I try to access it in main with memcpy() or some other function.

int main()
{
  unsigned char *ptr;
  int memSize;
  unsigned char temp[1024]; // 1024 is larger than memSize

  foo(ptr, &memSize);
  memcpy(temp, ptr, memSize);
}

void foo(unsigned char *ptr, int memSize)
{
  *memSize = someotherfunction();
  ptr = (unsigned char *)malloc(*memSize)
}