/* The tunable framework.  See the README to know how to use the tunable in

   a glibc module.

   Copyright (C) 2016-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#ifndef _TUNABLES_H_

#define _TUNABLES_H_

#if !HAVE_TUNABLES

static inline void

__always_inline

__tunables_init (char **unused __attribute__ ((unused)))

{

  /* This is optimized out if tunables are not enabled.  */

}

#else

# include <stddef.h>

# include "dl-tunable-types.h"

/* A tunable.  */

struct _tunable

{

  const char *name;			/* Internal name of the tunable.  */

  tunable_type_t type;			/* Data type of the tunable.  */

  tunable_val_t val;			/* The value.  */

  bool initialized;			/* Flag to indicate that the tunable is

					   initialized.  */

  tunable_seclevel_t security_level;	/* Specify the security level for the

					   tunable with respect to AT_SECURE

					   programs.  See description of

					   tunable_seclevel_t to see a

					   description of the values.

					   Note that even if the tunable is

					   read, it may not get used by the

					   target module if the value is

					   considered unsafe.  */

  /* Compatibility elements.  */

  const char *env_alias;		/* The compatibility environment

					   variable name.  */

};

typedef struct _tunable tunable_t;

/* Full name for a tunable is top_ns.tunable_ns.id.  */

# define TUNABLE_NAME_S(top,ns,id) #top "." #ns "." #id

# define TUNABLE_ENUM_NAME(__top,__ns,__id) TUNABLE_ENUM_NAME1 (__top,__ns,__id)

# define TUNABLE_ENUM_NAME1(__top,__ns,__id) __top ## _ ## __ns ## _ ## __id

# include "dl-tunable-list.h"

extern void __tunables_init (char **);

extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t);

extern void __tunable_set_val (tunable_id_t, void *);

rtld_hidden_proto (__tunables_init)

rtld_hidden_proto (__tunable_get_val)

/* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and

   TUNABLE_NAMESPACE are defined.  This is useful shorthand to get and set

   tunables within a module.  */

#if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE

# define TUNABLE_GET(__id, __type, __cb) \

  TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)

# define TUNABLE_SET(__id, __type, __val) \

  TUNABLE_SET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __val)

#else

# define TUNABLE_GET(__top, __ns, __id, __type, __cb) \

  TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)

# define TUNABLE_SET(__top, __ns, __id, __type, __val) \

  TUNABLE_SET_FULL (__top, __ns, __id, __type, __val)

#endif

/* Get and return a tunable value.  If the tunable was set externally and __CB

   is defined then call __CB before returning the value.  */

# define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \

({									      \

  tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id);		      \

  __type ret;								      \

  __tunable_get_val (id, &ret, __cb);					      \

  ret;									      \

})

/* Set a tunable value.  */

# define TUNABLE_SET_FULL(__top, __ns, __id, __type, __val) \

({									      \

  __tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id),		      \

			& (__type) {__val});				      \

})

/* Namespace sanity for callback functions.  Use this macro to keep the

   namespace of the modules clean.  */

# define TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name

# define TUNABLES_FRONTEND_valstring 1

/* The default value for TUNABLES_FRONTEND.  */

# define TUNABLES_FRONTEND_yes TUNABLES_FRONTEND_valstring

/* Compare two name strings, bounded by the name hardcoded in glibc.  */

static inline bool

__always_inline

tunable_is_name (const char *orig, const char *envname)

{

  for (;*orig != '\0' && *envname != '\0'; envname++, orig++)

    if (*orig != *envname)

      break;

  /* The ENVNAME is immediately followed by a value.  */

  if (*orig == '\0' && *envname == '=')

    return true;

  else

    return false;

}

#endif

#endif