Please Help Me With File Into Memory

[(TNT)]

Hey,

I really need to work out how to do this, i need to basically load a .rar file into the memory so i can decompress it, currently i am loading the rar file from a resource into the memory then decompressing it, but i need to load it from a file rather than resource.

Heres how im loading it from resource:

void openRARResource(MemoryFile *memfile, int resource_id)
{
  HRSRC hsResourceFH;            
  HGLOBAL hgResourceLH;
  HINSTANCE hInstance  = GetModuleHandleA(NULL); 

  memfile->data   = 0;                     
  memfile->size   = 0;
  memfile->offset = 0;

  hsResourceFH = FindResource(hInstance, MAKEINTRESOURCE(resource_id), "RARFILE");

  if(hsResourceFH)
  {
    hgResourceLH = LoadResource(hInstance, hsResourceFH);
    if(hgResourceLH)
    {
       memfile->size = SizeofResource(hInstance, hsResourceFH);
       memfile->data = (void*)LockResource(hgResourceLH);
    }
  } 

}

This is how its called:

MemoryFile rarfile;
openRARResource(&rarfile, IDR_RAR);

This is how MemoryFile Is defined:

typedef struct  memory_file               
{                                          
  void *data;         /* pointer to the file data     */
  unsigned long size;          /* total size of the file data  */
  unsigned long offset;        /* offset within "memory-file"  */  
} MemoryFile;

You can see there that i need the file data, file size, and memory offset...


I would like if possible to load the file into the MemoryFile varible, but as i said from a .rar on the hdd rather than from the programs resources.

I would majorly appreciate any help,

Thanks guys
TNT

[no-one]

since i don't know an enormous amount about the rar format, try this.

NOTE: if the file is large, you might want to manage it in small chunks if thats possible, this is for one large chunk.

int LoadRar(char* filename, MemoryFile* rar)
{
    // open file
    FILE* fp = fopen(filename,"rb");
    // check to see if it opened
    if(!fp)
        return -1;

    memset(rar,0,sizeof(MemoryFile));

    // find the end of the file
    fseek(fp,0,SEEK_END);

    // get the length in bytes by using the file position.
    rar.size = ftell(fp);

    // allocate memory
    rar.data = (void*) malloc(rar.size);

    // go back to the beginning of the file
    fseek(fp,0,SEEK_SET);

    // read the data an check for errors
    if(fread(rar.data,1,rar.size,fp) < rar.size)
    {
        free(rar.data);
        rar.size = 0;
        return -1;
    }

    return rar.size;
}

you might wanna add some more error checking maybe for the memory allocation, and like i said you might manage the file in chunks if its to big.