133 lines
4.5 KiB
C++
133 lines
4.5 KiB
C++
/* The tunable framework. See the README to know how to use the tunable in
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a glibc module.
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Copyright (C) 2016-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _TUNABLES_H_
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#define _TUNABLES_H_
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#if !HAVE_TUNABLES
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static inline void
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__always_inline
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__tunables_init (char **unused __attribute__ ((unused)))
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{
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/* This is optimized out if tunables are not enabled. */
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}
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#else
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# include <stddef.h>
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# include "dl-tunable-types.h"
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/* A tunable. */
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struct _tunable
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{
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const char *name; /* Internal name of the tunable. */
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tunable_type_t type; /* Data type of the tunable. */
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tunable_val_t val; /* The value. */
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bool initialized; /* Flag to indicate that the tunable is
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initialized. */
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tunable_seclevel_t security_level; /* Specify the security level for the
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tunable with respect to AT_SECURE
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programs. See description of
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tunable_seclevel_t to see a
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description of the values.
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Note that even if the tunable is
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read, it may not get used by the
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target module if the value is
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considered unsafe. */
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/* Compatibility elements. */
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const char *env_alias; /* The compatibility environment
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variable name. */
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};
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typedef struct _tunable tunable_t;
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/* Full name for a tunable is top_ns.tunable_ns.id. */
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# define TUNABLE_NAME_S(top,ns,id) #top "." #ns "." #id
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# define TUNABLE_ENUM_NAME(__top,__ns,__id) TUNABLE_ENUM_NAME1 (__top,__ns,__id)
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# define TUNABLE_ENUM_NAME1(__top,__ns,__id) __top ## _ ## __ns ## _ ## __id
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# include "dl-tunable-list.h"
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extern void __tunables_init (char **);
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extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t);
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extern void __tunable_set_val (tunable_id_t, void *);
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rtld_hidden_proto (__tunables_init)
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rtld_hidden_proto (__tunable_get_val)
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/* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and
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TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set
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tunables within a module. */
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#if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
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# define TUNABLE_GET(__id, __type, __cb) \
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TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
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# define TUNABLE_SET(__id, __type, __val) \
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TUNABLE_SET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __val)
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#else
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# define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
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TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
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# define TUNABLE_SET(__top, __ns, __id, __type, __val) \
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TUNABLE_SET_FULL (__top, __ns, __id, __type, __val)
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#endif
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/* Get and return a tunable value. If the tunable was set externally and __CB
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is defined then call __CB before returning the value. */
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# define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \
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({ \
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tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
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__type ret; \
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__tunable_get_val (id, &ret, __cb); \
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ret; \
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})
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/* Set a tunable value. */
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# define TUNABLE_SET_FULL(__top, __ns, __id, __type, __val) \
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({ \
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__tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \
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& (__type) {__val}); \
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})
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/* Namespace sanity for callback functions. Use this macro to keep the
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namespace of the modules clean. */
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# define TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name
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# define TUNABLES_FRONTEND_valstring 1
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/* The default value for TUNABLES_FRONTEND. */
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# define TUNABLES_FRONTEND_yes TUNABLES_FRONTEND_valstring
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/* Compare two name strings, bounded by the name hardcoded in glibc. */
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static inline bool
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__always_inline
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tunable_is_name (const char *orig, const char *envname)
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{
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for (;*orig != '\0' && *envname != '\0'; envname++, orig++)
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if (*orig != *envname)
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break;
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/* The ENVNAME is immediately followed by a value. */
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if (*orig == '\0' && *envname == '=')
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return true;
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else
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return false;
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}
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#endif
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#endif
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