#include <u.h>#include <libc.h>#include <thread.h>#include "dat.h"#include "fns.h" Dev *devs; voiddevwork(void *v){	Dev *d;	Buf *b;	Channel *r;	uchar buf[BLOCK]; 	d = v;	for(;;){		qlock(&d->workl);		while(d->work.wnext == &d->work)			rsleep(&d->workr);		b = d->work.wnext;		b->wnext->wprev = b->wprev;		b->wprev->wnext = b->wnext;		b->wnext = b->wprev = nil;		qunlock(&d->workl);		if(b->d == nil) /* this is a sync request */			goto reply;		if(b->off >= d->size){			b->error = Einval;			goto reply;		}		b->error = nil;		if(b->op & BWRITE){			memset(buf, 0, sizeof(buf));			pack(b, buf);			if(pwrite(d->fd, buf, BLOCK, b->off*BLOCK) < BLOCK){				dprint("write: %r\n");				b->error = Eio;			}		}else{			int n, m; 			for(n = 0; n < BLOCK; n += m){				m = pread(d->fd, buf+n, BLOCK-n, b->off*BLOCK+n);				if(m < 0)					dprint("read: %r\n");				if(m <= 0)					break;			}			if(n < BLOCK)				b->error = Eio;			else				unpack(b, buf);		}	reply:		r = b->resp;		b->resp = nil;		if(r != nil)			send(r, &b);	}} Dev *newdev(char *file){	Dev *d, **e;	Dir *dir;	Buf *b;		d = emalloc(sizeof(*d));	d->fd = open(file, ORDWR);	if(d->fd < 0){		free(d);		return nil;	}	dir = dirfstat(d->fd);	if(dir == nil){	error:		close(d->fd);		free(d);		return nil;	}	d->size = dir->length / BLOCK;	free(dir);	if(d->size == 0){		werrstr("device file too short");		goto error;	}	d->name = estrdup(file);	for(b = d->buf; b < d->buf + BUFHASH + 1; b++)		b->dnext = b->dprev = b;	d->workr.l = &d->workl;	d->work.wnext = d->work.wprev = &d->work;	proccreate(devwork, d, mainstacksize);	for(e = &devs; *e != nil; e = &(*e)->next)		;	*e = d;	return d;}