dos33fsprogs/dos33fs-utils/make_b.c

#include <stdio.h>
#include <sys/stat.h> /* struct stat */
#include <stdlib.h> /* exit() */
#include <fcntl.h>  /* open() */
#include <unistd.h> /* close() */

#include "version.h"

int main(int argc, char **argv) {

	int in_fd,out_fd,offset,write_result;

	unsigned char buffer[256];
	int result,file_size;

	struct stat file_info;

	if (argc!=4) {
		printf("MAKE_B version %s\b",VERSION);
		printf(" Usage: %s in_file out_file offset\n\n",argv[0]);
		printf("\tin_file  : input file\n");
		printf("\tout_file : output file\n");
		printf("\toffset   : offset which file should be loaded\n\n");
		exit(1);
	}

	if (stat(argv[1],&file_info)<0) {
		printf("Error!  %s not found!\n",argv[1]);
		exit(2);
	}
	file_size=(int)file_info.st_size;

	if ((in_fd=open(argv[1],O_RDONLY))<0) {
		printf("Error opening %s!\n",argv[1]);
		exit(3);
	}

	if ((out_fd=open(argv[2],O_WRONLY|O_CREAT,0666))<0) {
		printf("Error opening %s\n",argv[2]);
		exit(4);
	}

	offset=strtol(argv[3],NULL,0);

	buffer[0]=offset&0xff;
	buffer[1]=(offset>>8)&0xff;
	buffer[2]=file_size&0xff;
	buffer[3]=(file_size>>8)&0xff;

	write_result=write(out_fd,&buffer,4);

	while( (result=read(in_fd,&buffer,256))>0) {
		write_result=write(out_fd,&buffer,result);
	}

	if (write_result<0) fprintf(stderr,"Error writing\n");

	close(in_fd);
	close(out_fd);

	return 0;
}