1 /* The tunable framework. See the README to know how to use the tunable in
4 Copyright (C) 2016-2023 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/>. */
28 typedef intmax_t tunable_num_t
;
36 typedef void (*tunable_callback_t
) (tunable_val_t
*);
38 /* Full name for a tunable is top_ns.tunable_ns.id. */
39 #define TUNABLE_NAME_S(top,ns,id) #top "." #ns "." #id
41 #define TUNABLE_ENUM_NAME(__top,__ns,__id) TUNABLE_ENUM_NAME1 (__top,__ns,__id)
42 #define TUNABLE_ENUM_NAME1(__top,__ns,__id) __top ## _ ## __ns ## _ ## __id
44 #include "dl-tunable-list.h"
46 extern void __tunables_init (char **);
47 extern void __tunables_print (void);
48 extern void __tunable_get_val (tunable_id_t
, void *, tunable_callback_t
);
49 extern void __tunable_set_val (tunable_id_t
, tunable_val_t
*, tunable_num_t
*,
51 rtld_hidden_proto (__tunables_init
)
52 rtld_hidden_proto (__tunables_print
)
53 rtld_hidden_proto (__tunable_get_val
)
54 rtld_hidden_proto (__tunable_set_val
)
56 /* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and
57 TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set
58 tunables within a module. */
59 #if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
60 # define TUNABLE_GET(__id, __type, __cb) \
61 TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
62 # define TUNABLE_SET(__id, __val) \
63 TUNABLE_SET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __val)
64 # define TUNABLE_SET_WITH_BOUNDS(__id, __val, __min, __max) \
65 TUNABLE_SET_WITH_BOUNDS_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, \
68 # define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
69 TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
70 # define TUNABLE_SET(__top, __ns, __id, __val) \
71 TUNABLE_SET_FULL (__top, __ns, __id, __val)
72 # define TUNABLE_SET_WITH_BOUNDS(__top, __ns, __id, __val, __min, __max) \
73 TUNABLE_SET_WITH_BOUNDS_FULL (__top, __ns, __id, __val, __min, __max)
76 /* Get and return a tunable value. If the tunable was set externally and __CB
77 is defined then call __CB before returning the value. */
78 #define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \
80 tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
82 __tunable_get_val (id, &ret, __cb); \
86 /* Set a tunable value. */
87 #define TUNABLE_SET_FULL(__top, __ns, __id, __val) \
89 __tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \
90 & (tunable_val_t) {.numval = __val}, NULL, NULL); \
93 /* Set a tunable value together with min/max values. */
94 #define TUNABLE_SET_WITH_BOUNDS_FULL(__top, __ns, __id,__val, __min, __max) \
96 __tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \
97 & (tunable_val_t) {.numval = __val}, \
98 & (tunable_num_t) {__min}, \
99 & (tunable_num_t) {__max}); \
102 /* Namespace sanity for callback functions. Use this macro to keep the
103 namespace of the modules clean. */
104 #define TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name
106 static __always_inline
bool
107 tunable_val_lt (tunable_num_t lhs
, tunable_num_t rhs
, bool unsigned_cmp
)
110 return (uintmax_t) lhs
< (uintmax_t) rhs
;
115 static __always_inline
bool
116 tunable_val_gt (tunable_num_t lhs
, tunable_num_t rhs
, bool unsigned_cmp
)
119 return (uintmax_t) lhs
> (uintmax_t) rhs
;
124 /* Compare two name strings, bounded by the name hardcoded in glibc. */
125 static __always_inline
bool
126 tunable_is_name (const char *orig
, const char *envname
)
128 for (;*orig
!= '\0' && *envname
!= '\0'; envname
++, orig
++)
129 if (*orig
!= *envname
)
132 /* The ENVNAME is immediately followed by a value. */
133 if (*orig
== '\0' && *envname
== '=')