varnish-cache/lib/libvcc/vcc_storage.c
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/*-
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 * Copyright (c) 2010-2015 Varnish Software AS
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 * All rights reserved.
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 *
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 * Author: Poul-Henning Kamp <phk@phk.freebsd.dk>
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 *
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 * SPDX-License-Identifier: BSD-2-Clause
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 *
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 * All stuff related to the storage.* part of the namespace.
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 *
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 * "All" is actually only a wildcard function, which instantiates variables
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 * on demand under the storage.* tree of the namespace.
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 *
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 * About the syntax:
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 * -----------------
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 *
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 * One of our long term goals is to have dynamic storage configuration, such
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 * as the ability to add or remove a stevedore on the fly, without restarting
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 * the worker process.
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 *
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 * Even though this goal is far out in the future, it influences the syntax
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 * design of storage selection from VCL.
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 *
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 * In difference from backends, where we know the possible set of backends at
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 * compile time, we will not in the future know the identity of the stevedores
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 * available at compile time, so we have to rely on VRT name resolution.
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 *
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 * This indicates a namespace on the form storage.<stevedore>.<property>
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 *
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 * For each property, we must define a default value if the named stevedore
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 * does not exists, such that for instance stevedore.forgetit.freespace
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 * returns zero etc.
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 *
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 */
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#include "config.h"
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#include <stdlib.h>
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#include <string.h>
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#include "vcc_compile.h"
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void
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vcc_stevedore(struct vcc *vcc, const char *stv_name)
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{
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        struct symbol *sym;
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        char buf[1024];
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        CHECK_OBJ_NOTNULL(vcc, VCC_MAGIC);
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        bprintf(buf, "storage.%s", stv_name);
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        sym = VCC_MkSym(vcc, buf, SYM_MAIN, SYM_VAR, VCL_LOW, VCL_41);
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        AN(sym);
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        sym->type = STEVEDORE;
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        sym->eval = vcc_Eval_Var;
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        bprintf(buf, "VRT_stevedore(\"%s\")", stv_name);
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        sym->rname = TlDup(vcc, buf);
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        sym->r_methods = ~0;
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}