20060303a

1 files changed, 114 insertions, 0 deletions

diff --git a/emu/port/uqid.c b/emu/port/uqid.c
new file mode 100644
index 00000000..bd43db3d
--- /dev/null
+++ b/emu/port/uqid.c
@@ -0,0 +1,114 @@
+#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;
+}