/* *  linux/zBoot/xtract.c * *  Copyright (C) 1993  Hannu Savolainen * *	Extracts the system image and writes it to the stdout. *	based on tools/build.c by Linus Torvalds */#include <stdio.h>	/* fprintf */#include <string.h>#include <stdlib.h>	/* contains exit */#include <sys/types.h>	/* unistd.h needs this */#include <sys/stat.h>#include <sys/sysmacros.h>#include <unistd.h>	/* contains read/write */#include <fcntl.h>#include <a.out.h>#include <linux/config.h>#define GCC_HEADER 1024#define STRINGIFY(x) #xvoid die(char * str){	fprintf(stderr,"%s\n",str);	exit(1);}void usage(void){	die("Usage: xtract system [ | gzip | piggyback > piggy.s]");}int main(int argc, char ** argv){	int i,c,id, sz;	char buf[1024];	char major_root, minor_root;	struct stat sb;	struct exec *ex = (struct exec *)buf;	if (argc  != 2)		usage();		if ((id=open(argv[1],O_RDONLY,0))<0)		die("Unable to open 'system'");	if (read(id,buf,GCC_HEADER) != GCC_HEADER)		die("Unable to read header of 'system'");	if (N_MAGIC(*ex) != ZMAGIC)		die("Non-GCC header of 'system'");	sz = N_SYMOFF(*ex) - GCC_HEADER + 4;	/* +4 to get the same result than tools/build */	fprintf(stderr, "System size is %d\n", sz);	while (sz)	{		int l, n;		l = sz;		if (l > sizeof(buf)) l = sizeof(buf);		if ((n=read(id, buf, l)) !=l)		{			if (n == -1) 			   perror(argv[1]);			else			   fprintf(stderr, "Unexpected EOF\n");			die("Can't read system");		}		write(1, buf, l);		sz -= l;	}	close(id);	return(0);}