#include <u.h>#include <libc.h>#include <venti.h> static char *okvers[] = {	"02",	nil,}; /*static char EBigString[] = "string too long";static char EBigPacket[] = "packet too long";static char ENullString[] = "missing string";*/static char EBadVersion[] = "bad format in version string"; static intvtreadversion(VtConn *z, char *q, char *v, int nv){	int n; 	for(;;){		if(nv <= 1){			werrstr("version too long");			return -1;		}		n = read(z->infd, v, 1);		if(n <= 0){			if(n == 0)				werrstr("unexpected eof");			return -1;		}		if(*v == '\n'){			*v = 0;			break;		}		if((uchar)*v < ' ' || (uchar)*v > 0x7f || (*q && *v != *q)){			werrstr(EBadVersion);			return -1;		}		v++;		nv--;		if(*q)			q++;	}	return 0;} intvtversion(VtConn *z){	char buf[VtMaxStringSize], *p, *ep, *prefix, *pp;	int i; 	qlock(&z->lk);	if(z->state != VtStateAlloc){		werrstr("bad session state");		qunlock(&z->lk);		return -1;	} 	qlock(&z->inlk);	qlock(&z->outlk); 	p = buf;	ep = buf + sizeof buf;	prefix = "venti-";	p = seprint(p, ep, "%s", prefix);	p += strlen(p);	for(i=0; okvers[i]; i++)		p = seprint(p, ep, "%s%s", i ? ":" : "", okvers[i]);	p = seprint(p, ep, "-libventi\n");	assert(p-buf < sizeof buf); 	if(write(z->outfd, buf, p-buf) != p-buf)		goto Err;	vtdebug(z, "version string out: %s", buf); 	if(vtreadversion(z, prefix, buf, sizeof buf) < 0)		goto Err;	vtdebug(z, "version string in: %s", buf); 	p = buf+strlen(prefix);	for(; *p; p=pp){		if(*p == ':' || *p == '-')			p++;		pp = strpbrk(p, ":-");		if(pp == nil)			pp = p+strlen(p);		for(i=0; okvers[i]; i++)			if(strlen(okvers[i]) == pp-p && memcmp(okvers[i], p, pp-p) == 0){				*pp = 0;				z->version = vtstrdup(p);				goto Okay;			}	}	werrstr("unable to negotiate version");	goto Err; Okay:	z->state = VtStateConnected;	qunlock(&z->inlk);	qunlock(&z->outlk);	qunlock(&z->lk);	return 0; Err:	werrstr("vtversion: %r");	if(z->infd >= 0)		close(z->infd);	if(z->outfd >= 0 && z->outfd != z->infd)		close(z->outfd);	z->infd = -1;	z->outfd = -1;	z->state = VtStateClosed;	qunlock(&z->inlk);	qunlock(&z->outlk);	qunlock(&z->lk);	return -1;}