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#include <u.h>
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#include <libc.h>
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#include <auth.h>
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#include <fcall.h>
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#include "dat.h"
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#include "fns.h"
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static Xfile*	clean(Xfile*);
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#define	FIDMOD	127	/* prime */
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static Xdata*	xhead;
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static Xfile*	xfiles[FIDMOD];
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static Xfile*	freelist;
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Xdata*
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getxdata(char *name)
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{
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	int fd;
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	Dir *dir;
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	Xdata *xf, *fxf;
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	int flag;
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	if(name[0] == 0)
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		name = deffile;
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	if(name == 0)
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		error(Enofile);
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	flag = (access(name, 6) == 0) ? ORDWR : OREAD;
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	fd = open(name, flag);
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	if(fd < 0)
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		error(Enonexist);
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	dir = nil;
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	if(waserror()){
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		close(fd);
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		free(dir);
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		nexterror();
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	}
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	if((dir = dirfstat(fd)) == nil)
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		error("I/O error");
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	if((dir->qid.type & ~QTTMP) != QTFILE)
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		error("attach name not a plain file");
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	for(fxf=0,xf=xhead; xf; xf=xf->next){
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		if(xf->name == 0){
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			if(fxf == 0)
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				fxf = xf;
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			continue;
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		}
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		if(xf->qid.path != dir->qid.path || xf->qid.vers != dir->qid.vers)
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			continue;
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		if(xf->type != dir->type || xf->fdev != dir->dev)
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			continue;
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		xf->ref++;
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		chat("incref=%d, \"%s\", dev=%d...", xf->ref, xf->name, xf->dev);
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		close(fd);
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		poperror();
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		free(dir);
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		return xf;
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	}
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	if(fxf==0){
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		fxf = ealloc(sizeof(Xfs));
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		fxf->next = xhead;
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		xhead = fxf;
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	}
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	chat("alloc \"%s\", dev=%d...", name, fd);
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	fxf->ref = 1;
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	fxf->name = strcpy(ealloc(strlen(name)+1), name);
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	fxf->qid = dir->qid;
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	fxf->type = dir->type;
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	fxf->fdev = dir->dev;
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	fxf->dev = fd;
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	free(dir);
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	poperror();
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	return fxf;
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}
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static void
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putxdata(Xdata *d)
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{
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	if(d->ref <= 0)
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		panic(0, "putxdata");
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	d->ref--;
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	chat("decref=%d, \"%s\", dev=%d...", d->ref, d->name, d->dev);
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	if(d->ref == 0){
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		chat("purgebuf...");
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		purgebuf(d);
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		close(d->dev);
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		free(d->name);
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		d->name = 0;
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	}
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}
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void
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refxfs(Xfs *xf, int delta)
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{
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	xf->ref += delta;
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	if(xf->ref == 0){
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		if(xf->d)
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			putxdata(xf->d);
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		if(xf->ptr)
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			free(xf->ptr);
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		free(xf);
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	}
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}
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Xfile*
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xfile(int fid, int flag)
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{
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	int k = fid%FIDMOD;
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	Xfile **hp=&xfiles[k], *f, *pf;
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	for(f=*hp,pf=0; f; pf=f,f=f->next)
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		if(f->fid == fid)
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			break;
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	if(f && pf){
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		pf->next = f->next;
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		f->next = *hp;
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		*hp = f;
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	}
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	switch(flag){
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	default:
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		panic(0, "xfile");
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	case Asis:
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		if(f == 0)
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			error("unassigned fid");
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		return f;
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	case Clean:
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		break;
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	case Clunk:
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		if(f){
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			*hp = f->next;
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			clean(f);
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			f->next = freelist;
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			freelist = f;
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		}
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		return 0;
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	}
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	if(f)
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		return clean(f);
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	if(f = freelist)	/* assign = */
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		freelist = f->next;
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	else
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		f = ealloc(sizeof(Xfile));
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	f->next = *hp;
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	*hp = f;
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	f->xf = 0;
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	f->fid = fid;
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	f->flags = 0;
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	f->qid = (Qid){0,0,0};
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	f->len = 0;
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	f->ptr = 0;
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	return f;
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}
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static Xfile *
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clean(Xfile *f)
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{
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	if(f->xf){
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		refxfs(f->xf, -1);
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		f->xf = 0;
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	}
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	if(f->len){
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		free(f->ptr);
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		f->len = 0;
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	}
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	f->ptr = 0;
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	f->flags = 0;
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	f->qid = (Qid){0,0,0};
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	return f;
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}
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