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#include "dat.h"
#include "fns.h"
#include "error.h"
/*
* unique Qid path generation,
* for exportfs.c and various devfs-*
*/
#define QIDMASK (((vlong)1<<48)-1)
void
uqidinit(Uqidtab *tab)
{
memset(tab, 0, sizeof(*tab));
}
static int
uqidhash(vlong path)
{
ulong p;
p = (ulong)path;
return ((p>>16) ^ (p>>8) ^ p) & (Nqidhash-1);
}
static Uqid **
uqidlook(Uqid **tab, Chan *c, vlong path)
{
Uqid **hp, *q;
for(hp = &tab[uqidhash(path)]; (q = *hp) != nil; hp = &q->next)
if(q->type == c->type && q->dev == c->dev && q->oldpath == path)
break;
return hp;
}
static int
uqidexists(Uqid **tab, vlong path)
{
int i;
Uqid *q;
for(i=0; i<Nqidhash; i++)
for(q = tab[i]; q != nil; q = q->next)
if(q->newpath == path)
return 1;
return 0;
}
Uqid *
uqidalloc(Uqidtab *tab, Chan *c)
{
Uqid **hp, *q;
qlock(&tab->l);
hp = uqidlook(tab->qids, c, c->qid.path);
if((q = *hp) != nil){
incref(&q->r);
qunlock(&tab->l);
return q;
}
q = mallocz(sizeof(*q), 1);
if(q == nil){
qunlock(&tab->l);
error(Enomem);
}
q->r.ref = 1;
q->type = c->type;
q->dev = c->dev;
q->oldpath = c->qid.path;
q->newpath = c->qid.path;
while(uqidexists(tab->qids, q->newpath)){
if(++tab->pathgen >= (1<<16))
tab->pathgen = 1;
q->newpath = ((vlong)tab->pathgen<<48) | (q->newpath & QIDMASK);
}
q->next = nil;
*hp = q;
qunlock(&tab->l);
return q;
}
void
freeuqid(Uqidtab *tab, Uqid *q)
{
Uqid **hp;
if(q == nil)
return;
qlock(&tab->l);
if(decref(&q->r) == 0){
hp = &tab->qids[uqidhash(q->oldpath)];
for(; *hp != nil; hp = &(*hp)->next)
if(*hp == q){
*hp = q->next;
free(q);
break;
}
}
qunlock(&tab->l);
}
Qid
mkuqid(Chan *c, Uqid *qid)
{
Qid q;
if(qid == nil)
return c->qid;
q.path = qid->newpath;
q.vers = c->qid.vers;
q.type = c->qid.type;
return q;
}
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