#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>

#define BMP_TYPE 19778

typedef struct{
    unsigned short type;                 /* Magic identifier            */
    unsigned int size;                       /* File size in bytes          */
    unsigned short int reserved1, reserved2;
    unsigned int offset;                     /* Offset to image data, bytes */
    unsigned int hsize;               /* Header size in bytes      */
    int width,height;                /* Width and height of image */
    unsigned short int planes;       /* Number of colour planes   */
    unsigned short int bits;         /* Bits per pixel            */
    unsigned int compression;        /* Compression type          */
    unsigned int imagesize;          /* Image size in bytes       */
    int xresolution,yresolution;     /* Pixels per meter          */
    unsigned int ncolours;           /* Number of colours         */
    unsigned int importantcolours;   /* Important colours         */
} HEADER;

typedef struct{
    HEADER header;
    char* data;
} BMP;


void loadFile( char* fileName, BMP** bmp  );
void writeFile( char* fileName, BMP* bmp  );

#include "bitmap.h"

void loadFile( char* filenName, BMP** pbmp  ){

    struct stat stat_file; 
    FILE* file; 
    BMP* bmp;

    // recover file statistics
    stat( filenName, &stat_file );

    *pbmp = (BMP*) malloc( stat_file.st_size );
    if( !(*pbmp) ){
	fprintf(stderr, "It was not possible to allocate some memory.\n");
	exit(1);
    }
    
    // to ease manipulation
    bmp = *pbmp;

    // open bitmap file
    file = fopen( filenName, "r" );

    // read all the file into pbmp structure
    fread( bmp, 1, stat_file.st_size, file );
    
    // we must convert from little-endian to big-endian
    // the error is here, inspection of the file 
    // shows that size is non zero
    //  printf("File size is %d\n", ntohl(bmp->header.size) );
    printf("File size is %d\n",  (((char*)bmp)[2]));
}

void writeFile( char* filenName, BMP* bmp  ){

    struct stat stat_file;

    int file = open( filenName, O_RDWR );
    if( write( file, bmp, stat_file.st_size ) < stat_file.st_size ){
	
	perror( "Error saving file.\n" );
	exit(1);
    }
}

typedef struct{
    HEADER header;
    RGBQUAD *palette;
    char* data;
} BMP;

*pbmp = (BMP*) malloc( stat_file.st_size );

file = fopen( filenName, "r" );

void SwapDword(unsigned long *ulIn)
{
    unsigned char *ucIn, ucTemp;

    ucIn = (unsigned char *)ulIn;
    ucTemp = *ucIn;
    *ucIn = *(ucIn + 3);
    *(ucIn + 3) = ucTemp;
    ucTemp = *(ucIn + 1);
    *(ucIn + 1) = *(ucIn + 2);
    *(ucIn + 2) = ucTemp;
}

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>


void
die (char *s)
{
  perror (s);
  printf ("\n");
  exit (EXIT_FAILURE);
}


unsigned int
get_dw (char *b)
{
  return ((((((b[3]  << 8) 
             | b[2]) << 8) 
             | b[1]) << 8)
             | b[0]);
}


void
load_bmp (char *fn)
{
  struct stat fs;  char *buf;  FILE *fp;

  if ((stat (fn, &fs)) == -1)
    die ("stat");

  buf = malloc (fs.st_size);
  if (buf == NULL)
    die ("malloc");

  fp = fopen (fn, "rb");
  if (fp == NULL)
    die ("fopen");

  fread (buf, 1, fs.st_size, fp);
  if (buf[0] != 'B' || buf[1] != 'M')
    printf ("This seems not to be a bmp file ...\n\n");
  else
    printf ("bmp size: %u bytes\n\n", get_dw (buf+2));

  fclose (fp);
  free (buf);
}


int
main (int argc, char **argv)
{
  if (argc != 2)
  {
    printf ("I need a (single) bmp file ...\n\n");
    exit (EXIT_FAILURE);
  }

  load_bmp (argv[1]);
  exit (EXIT_SUCCESS);
}