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#include	<u.h>
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#include	<libc.h>
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#include	"compat.h"
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#include	"error.h"
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Chan*
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newchan(void)
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{
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	Chan *c;
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	c = smalloc(sizeof(Chan));
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	/* if you get an error before associating with a dev,
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	   close calls rootclose, a nop */
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	c->type = 0;
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	c->flag = 0;
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	c->ref = 1;
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	c->dev = 0;
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	c->offset = 0;
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	c->iounit = 0;
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	c->aux = 0;
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	c->name = 0;
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	return c;
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}
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void
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chanfree(Chan *c)
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{
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	c->flag = CFREE;
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	cnameclose(c->name);
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	free(c);
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}
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void
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cclose(Chan *c)
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{
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	if(c->flag&CFREE)
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		panic("cclose %#p", getcallerpc(&c));
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	if(decref(c))
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		return;
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	if(!waserror()){
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		devtab[c->type]->close(c);
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		poperror();
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	}
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	chanfree(c);
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}
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Chan*
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cclone(Chan *c)
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{
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	Chan *nc;
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	Walkqid *wq;
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	wq = devtab[c->type]->walk(c, nil, nil, 0);
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	if(wq == nil)
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		error("clone failed");
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	nc = wq->clone;
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	free(wq);
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	nc->name = c->name;
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	if(c->name)
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		incref(c->name);
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	return nc;
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}
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enum
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{
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	CNAMESLOP	= 20
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};
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static Ref ncname;
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void cleancname(Cname*);
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int
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isdotdot(char *p)
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{
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	return p[0]=='.' && p[1]=='.' && p[2]=='\0';
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}
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int
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incref(Ref *r)
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{
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	int x;
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	lock(r);
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	x = ++r->ref;
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	unlock(r);
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	return x;
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}
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int
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decref(Ref *r)
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{
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	int x;
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	lock(r);
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	x = --r->ref;
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	unlock(r);
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	if(x < 0)
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		panic("decref");
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	return x;
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}
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Cname*
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newcname(char *s)
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{
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	Cname *n;
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	int i;
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	n = smalloc(sizeof(Cname));
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	i = strlen(s);
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	n->len = i;
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	n->alen = i+CNAMESLOP;
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	n->s = smalloc(n->alen);
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	memmove(n->s, s, i+1);
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	n->ref = 1;
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	incref(&ncname);
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	return n;
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}
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void
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cnameclose(Cname *n)
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{
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	if(n == nil)
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		return;
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	if(decref(n))
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		return;
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	decref(&ncname);
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	free(n->s);
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	free(n);
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}
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Cname*
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addelem(Cname *n, char *s)
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{
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	int i, a;
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	char *t;
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	Cname *new;
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	if(s[0]=='.' && s[1]=='\0')
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		return n;
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	if(n->ref > 1){
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		/* copy on write */
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		new = newcname(n->s);
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		cnameclose(n);
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		n = new;
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	}
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	i = strlen(s);
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	if(n->len+1+i+1 > n->alen){
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		a = n->len+1+i+1 + CNAMESLOP;
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		t = smalloc(a);
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		memmove(t, n->s, n->len+1);
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		free(n->s);
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		n->s = t;
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		n->alen = a;
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	}
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	if(n->len>0 && n->s[n->len-1]!='/' && s[0]!='/')	/* don't insert extra slash if one is present */
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		n->s[n->len++] = '/';
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	memmove(n->s+n->len, s, i+1);
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	n->len += i;
167 
	if(isdotdot(s))
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		cleancname(n);
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	return n;
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}
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172 
/*
173 
 * In place, rewrite name to compress multiple /, eliminate ., and process ..
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 */
175 
void
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cleancname(Cname *n)
177 
{
178 
	char *p;
179 
 
180 
	if(n->s[0] == '#'){
181 
		p = strchr(n->s, '/');
182 
		if(p == nil)
183 
			return;
184 
		cleanname(p);
185 
 
186 
		/*
187 
		 * The correct name is #i rather than #i/,
188 
		 * but the correct name of #/ is #/.
189 
		 */
190 
		if(strcmp(p, "/")==0 && n->s[1] != '/')
191 
			*p = '\0';
192 
	}else
193 
		cleanname(n->s);
194 
	n->len = strlen(n->s);
195 
}
196 
 
197 
void
198 
isdir(Chan *c)
199 
{
200 
	if(c->qid.type & QTDIR)
201 
		return;
202 
	error(Enotdir);
203 
}