| /* 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 |