#include <u.h>#include <libc.h>#include <../boot/boot.h> #define CMPSIZE 128voidnewkernel(void){	char *p;	char file[2*NAMELEN];	char partition[2*NAMELEN];	char prompt[8];	char boot[CMPSIZE], installed[CMPSIZE];	long x, i;	int in, out;	Dir d; 	/* get the boot kernel's first CMPSIZE bytes */	sprint(partition, "%sboot", bootdisk);	out = open(partition, ORDWR);	if(out < 0)		return;	if(read(out, boot, CMPSIZE) != CMPSIZE || seek(out, 0, 0) < 0){		close(out);		return;	} 	sprint(file, "/%s/9%s", cputype, conffile);	in = open(file, OREAD);	if(in < 0){		close(out);		return;	}	if(dirfstat(in, &d)<0 || read(in, installed, CMPSIZE)!=CMPSIZE || seek(in, 0, 0)<0){		close(in);		close(out);		return;	} 	/* if they agree in the first CMPSIZE, assume they are the same */	if(memcmp(installed, boot, CMPSIZE) == 0){		close(in);		close(out);		return;	} 	strcpy(prompt, "y/n");	outin("\nThis kernel is out of date.  Copy a new one to disk?",		prompt, sizeof(prompt));	if(*prompt != 'y')		return; 	/* copy all kernel into memory, then to disk */	x = ((d.length + 511)/512)*512;	p = sbrk(x);	if(p == (char*)-1){		print("sbrk %d failed\n", x);		return;	}	if(read(in, p, d.length) != d.length){		print("couldn't read %s\n", file);		close(in);		close(out);		return;	}	for(; x > 0; x -= i){		i = x > 4*1024 ? 4*1024 : x;		if(write(out, p, i) != i){			print("error writing %s, you may be in deep trouble!\n",				partition);			break;		}		p += i;	}	close(in);	close(out);}