Add a VGZ_ObufFull() function

bin/varnishd/cache.h

@@ -643,6 +643,7 @@ struct vgz *VGZ_NewGzip(struct sess *sp);
 void VGZ_Ibuf(struct vgz *, const void *, ssize_t len);
 int VGZ_IbufEmpty(const struct vgz *vg);
 void VGZ_Obuf(struct vgz *, const void *, ssize_t len);
+int VGZ_ObufFull(const struct vgz *vg);
 int VGZ_ObufStorage(const struct sess *sp, struct vgz *vg);
 int VGZ_Gzip(struct vgz *, const void **, size_t *len, enum vgz_flag);
 int VGZ_Gunzip(struct vgz *, const void **, size_t *len);

bin/varnishd/cache_gzip.c

@@ -235,6 +235,14 @@ VGZ_Obuf(struct vgz *vg, const void *ptr, ssize_t len)
 	vg->vz.avail_out = len;
 }
 
+int
+VGZ_ObufFull(const struct vgz *vg)
+{
+
+	CHECK_OBJ_NOTNULL(vg, VGZ_MAGIC);
+	return (vg->vz.avail_out == 0);
+}
+
 /*--------------------------------------------------------------------
  * Keep the outbuffer supplied with storage and file it under the
  * sp->obj as it fills.