1 /* The tunable framework. See the README to know how to use the tunable in
4 Copyright (C) 2016-2021 Free Software Foundation, Inc.
5 This file is part of the GNU C Library.
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public
9 License as published by the Free Software Foundation; either
10 version 2.1 of the License, or (at your option) any later version.
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; if not, see
19 <https://www.gnu.org/licenses/>. */
29 __tunables_init (char **unused
__attribute__ ((unused
)))
31 /* This is optimized out if tunables are not enabled. */
36 # include "dl-tunable-types.h"
41 const char *name
; /* Internal name of the tunable. */
42 tunable_type_t type
; /* Data type of the tunable. */
43 tunable_val_t val
; /* The value. */
44 bool initialized
; /* Flag to indicate that the tunable is
46 tunable_seclevel_t security_level
; /* Specify the security level for the
47 tunable with respect to AT_SECURE
48 programs. See description of
49 tunable_seclevel_t to see a
50 description of the values.
52 Note that even if the tunable is
53 read, it may not get used by the
54 target module if the value is
56 /* Compatibility elements. */
57 const char *env_alias
; /* The compatibility environment
61 typedef struct _tunable tunable_t
;
63 /* Full name for a tunable is top_ns.tunable_ns.id. */
64 # define TUNABLE_NAME_S(top,ns,id) #top "." #ns "." #id
66 # define TUNABLE_ENUM_NAME(__top,__ns,__id) TUNABLE_ENUM_NAME1 (__top,__ns,__id)
67 # define TUNABLE_ENUM_NAME1(__top,__ns,__id) __top ## _ ## __ns ## _ ## __id
69 # include "dl-tunable-list.h"
71 extern void __tunables_init (char **);
72 extern void __tunables_print (void);
73 extern void __tunable_get_val (tunable_id_t
, void *, tunable_callback_t
);
74 extern void __tunable_set_val (tunable_id_t
, void *, void *, void *);
75 rtld_hidden_proto (__tunables_init
)
76 rtld_hidden_proto (__tunables_print
)
77 rtld_hidden_proto (__tunable_get_val
)
78 rtld_hidden_proto (__tunable_set_val
)
80 /* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and
81 TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set
82 tunables within a module. */
83 #if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
84 # define TUNABLE_GET(__id, __type, __cb) \
85 TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
86 # define TUNABLE_SET(__id, __type, __val) \
87 TUNABLE_SET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __val)
88 # define TUNABLE_SET_WITH_BOUNDS(__id, __type, __val, __min, __max) \
89 TUNABLE_SET_WITH_BOUNDS_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, \
90 __type, __val, __min, __max)
92 # define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
93 TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
94 # define TUNABLE_SET(__top, __ns, __id, __type, __val) \
95 TUNABLE_SET_FULL (__top, __ns, __id, __type, __val)
96 # define TUNABLE_SET_WITH_BOUNDS(__top, __ns, __id, __type, __val, \
98 TUNABLE_SET_WITH_BOUNDS_FULL (__top, __ns, __id, __type, __val, \
102 /* Get and return a tunable value. If the tunable was set externally and __CB
103 is defined then call __CB before returning the value. */
104 # define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \
106 tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
108 __tunable_get_val (id, &ret, __cb); \
112 /* Set a tunable value. */
113 # define TUNABLE_SET_FULL(__top, __ns, __id, __type, __val) \
115 __tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \
116 & (__type) {__val}, NULL, NULL); \
119 /* Set a tunable value together with min/max values. */
120 # define TUNABLE_SET_WITH_BOUNDS_FULL(__top, __ns, __id, __type, __val, \
123 __tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \
124 & (__type) {__val}, & (__type) {__min}, \
125 & (__type) {__max}); \
128 /* Namespace sanity for callback functions. Use this macro to keep the
129 namespace of the modules clean. */
130 # define TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name
132 # define TUNABLES_FRONTEND_valstring 1
133 /* The default value for TUNABLES_FRONTEND. */
134 # define TUNABLES_FRONTEND_yes TUNABLES_FRONTEND_valstring
136 /* Compare two name strings, bounded by the name hardcoded in glibc. */
137 static __always_inline
bool
138 tunable_is_name (const char *orig
, const char *envname
)
140 for (;*orig
!= '\0' && *envname
!= '\0'; envname
++, orig
++)
141 if (*orig
!= *envname
)
144 /* The ENVNAME is immediately followed by a value. */
145 if (*orig
== '\0' && *envname
== '=')