[6.0] 1518c09d0 STV temp buffer API

[Dridi Boukelmoune]

commit 1518c09d0744de2eb6fdd105e44c381463ab8097
Author: Martin Blix Grydeland <martin at varnish-software.com>
Date:   Tue Jun 22 11:48:49 2021 +0200

    STV temp buffer API
    
    This is an API for getting an arbitrary buffer through the
    stevedores. The stevedore in question may then deploy LRU nuking or other
    measures to control resource usage.

diff --git a/bin/varnishd/cache/cache_varnishd.h b/bin/varnishd/cache/cache_varnishd.h
index 0141cf2ff..d6f4c5f01 100644
--- a/bin/varnishd/cache/cache_varnishd.h
+++ b/bin/varnishd/cache/cache_varnishd.h
@@ -437,6 +437,11 @@ void STV_BanExport(const uint8_t *banlist, unsigned len);
 int STV_NewObject(struct worker *, struct objcore *,
     const struct stevedore *, unsigned len);
 
+struct stv_buffer;
+struct stv_buffer *STV_AllocBuf(struct worker *wrk, const struct stevedore *stv,
+    size_t size);
+void STV_FreeBuf(struct worker *wrk, struct stv_buffer **pstvbuf);
+void *STV_GetBufPtr(struct stv_buffer *stvbuf, size_t *psize);
 
 #if WITH_PERSISTENT_STORAGE
 /* storage_persistent.c */
diff --git a/bin/varnishd/storage/stevedore.c b/bin/varnishd/storage/stevedore.c
index c75d6bf65..72949db42 100644
--- a/bin/varnishd/storage/stevedore.c
+++ b/bin/varnishd/storage/stevedore.c
@@ -95,6 +95,74 @@ STV_NewObject(struct worker *wrk, struct objcore *oc,
 
 /*-------------------------------------------------------------------*/
 
+struct stv_buffer {
+	unsigned		magic;
+#define STV_BUFFER_MAGIC	0xf39cb6c2
+	const struct stevedore	*stv;
+	size_t			size;
+	uintptr_t		priv;
+};
+
+struct stv_buffer *
+STV_AllocBuf(struct worker *wrk, const struct stevedore *stv, size_t size)
+{
+	struct stv_buffer *stvbuf;
+	uint8_t *buf;
+	uintptr_t priv = 0;
+
+	CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
+	CHECK_OBJ_NOTNULL(stv, STEVEDORE_MAGIC);
+
+	if (size == 0)
+		return (NULL);
+	if (stv->allocbuf == NULL)
+		return (NULL);
+
+	buf = stv->allocbuf(wrk, stv, size + PRNDUP(sizeof *stvbuf), &priv);
+	if (buf == NULL)
+		return (NULL);
+
+	assert(PAOK(buf));
+	stvbuf = (void *)buf;
+	INIT_OBJ(stvbuf, STV_BUFFER_MAGIC);
+	stvbuf->stv = stv;
+	stvbuf->priv = priv;
+	stvbuf->size = size;
+
+	return (stvbuf);
+}
+
+void
+STV_FreeBuf(struct worker *wrk, struct stv_buffer **pstvbuf)
+{
+	struct stv_buffer *stvbuf;
+	const struct stevedore *stv;
+	uintptr_t priv;
+
+	CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
+	TAKE_OBJ_NOTNULL(stvbuf, pstvbuf, STV_BUFFER_MAGIC);
+	CHECK_OBJ_NOTNULL(stvbuf->stv, STEVEDORE_MAGIC);
+
+	stv = stvbuf->stv;
+	priv = stvbuf->priv;
+	CHECK_OBJ_NOTNULL(stv, STEVEDORE_MAGIC);
+	ZERO_OBJ(stvbuf, sizeof *stvbuf);
+
+	AN(stv->freebuf);
+	stv->freebuf(wrk, stv, priv);
+}
+
+void *
+STV_GetBufPtr(struct stv_buffer *stvbuf, size_t *psize)
+{
+	CHECK_OBJ_NOTNULL(stvbuf, STV_BUFFER_MAGIC);
+	if (psize)
+		*psize = stvbuf->size;
+	return (&stvbuf[1]);
+}
+
+/*-------------------------------------------------------------------*/
+
 void
 STV_open(void)
 {
diff --git a/bin/varnishd/storage/storage.h b/bin/varnishd/storage/storage.h
index 212142ceb..53208236c 100644
--- a/bin/varnishd/storage/storage.h
+++ b/bin/varnishd/storage/storage.h
@@ -73,6 +73,10 @@ typedef void storage_banexport_f(const struct stevedore *, const uint8_t *bans,
     unsigned len);
 typedef void storage_panic_f(struct vsb *vsb, const struct objcore *oc);
 
+typedef void *storage_allocbuf_f(struct worker *, const struct stevedore *,
+    size_t size, uintptr_t *ppriv);
+typedef void storage_freebuf_f(struct worker *, const struct stevedore *,
+    uintptr_t priv);
 
 typedef struct object *sml_getobj_f(struct worker *, struct objcore *);
 typedef struct storage *sml_alloc_f(const struct stevedore *, size_t size);
@@ -100,6 +104,8 @@ struct stevedore {
 	storage_baninfo_f	*baninfo;
 	storage_banexport_f	*banexport;
 	storage_panic_f		*panic;
+	storage_allocbuf_f	*allocbuf;
+	storage_freebuf_f	*freebuf;
 
 	/* Only if SML is used */
 	sml_alloc_f		*sml_alloc;