/*
OS Proolix-l
Utility for install boot program to boot sector 
*/

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

#define S1 "usage: patchboot source-bootfile new-bootfile result-bootfile\n"
#define S2 "can't open %s\n"
#define S3 "can't read %s\n"
#define S4 "can't write %s\n"
#define S5 "can't close %s\n"

int main (int argc, char *argv[])
{int i, h1, h2, h3;
unsigned char c[512], c2[512], c3[512];

#if 0
printf ("argc=%i\n",argc);
for (i=0;i<argc; i++) printf ("argv[%i]=%s\n",i,argv[i]);
#endif

if (argc!=4)
  {
  printf (S1);
  return 1;
  }

/* read old (original) boot sector */  
if ((h1=open(argv[1],0))<=0) {printf(S2,argv[1]); return 2; }
if (read(h1,c,512)!=512) {printf(S3,argv[1]); return 3; }

#if 0
for (i=0;i<512;i++) printf ("%02X",c[i]);
printf("\n");
#endif

/* read new boot sector */
if ((h2=open(argv[2],0))<=0) {printf(S2,argv[2]); return 4; }
if (read(h2,c2,512)==-1) {printf(S3,argv[2]); return 5; }

for (i=0;i<3+8;i++)c[i]=c2[i]; /* JMP and OEM name */
for (i=0x26; i<510; i++) c[i]=c2[i]; /* bootloader */
c[510]=0x55;
c[511]=0xaa;

/* write new boot sect */
if ((h3=creat(argv[3],S_IRUSR))<=0) {printf(S2,argv[3]); return 5; }
if (write(h3,c,512)!=512) {printf(S4,argv[3]); return 6; }
if (close(h3)==-1) {printf(S5,argv[3]); return 7; }
return 0;
}