Thread: sizeof() no good with array pointers? Or am I screwing this up?

Ok, I'm sending this function a pointer to an unsigned char array and I want to find the length of it within the function so I can loop and process it or write with fwrite(), etc. Funny, I can malloc the array in a function I passed the pointer to, but I can find how much was malloc'd later.

Code:

unsigned char *ELFData;

BOOL CALLBACK DlgProc(HWND hwnd, UINT Message, WPARAM wParam, LPARAM lParam)
{
//obviously there's a ton of message handling being done here. This is how I'm calling the functions from here though

LoadFile(&ELFData, &hData, eFileName, ELFheader, 0);

SaveFile(&ELFData, &hData, eFileName, ELFheader, 0);
}

int LoadFile(u8 **buffer, u8 **headerdata, char* filename, int headerlen, u8 endian){
    FILE *f;
    int i, filesize;
	f = fopen(filename,"rb");
	fseek(f,0,SEEK_END);
	filesize = ftell(f);
        if (*buffer) { free(*buffer); *buffer = 0; }
	if (!(*buffer = (unsigned char*)malloc(filesize))) { 
	    MessageBox(NULL,"Unable to allocate buffer memory (loadfile,2).","Error",0);
        fclose(f); return 0;
	}
        //etc
}

int SaveFile(u8 **buffer, u8 **headerdata, char* filename, int headerlen, u8 endian){
    FILE *f;
    int i;
    int filesize = sizeof(*buffer); //if there was 3 meg allocated to it by an earlier call to LoadFile, it still says '4' or whatever.
}