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1 | /* The tunable framework. See the README to know how to use the tunable in |
2 | a glibc module. | |
3 | ||
688903eb | 4 | Copyright (C) 2016-2018 Free Software Foundation, Inc. |
67e58f39 SP |
5 | This file is part of the GNU C Library. |
6 | ||
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. | |
11 | ||
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. | |
16 | ||
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 | <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #ifndef _TUNABLES_H_ | |
22 | #define _TUNABLES_H_ | |
23 | ||
24 | #if !HAVE_TUNABLES | |
25 | static inline void | |
26 | __always_inline | |
3c589b1a | 27 | __tunables_init (char **unused __attribute__ ((unused))) |
67e58f39 SP |
28 | { |
29 | /* This is optimized out if tunables are not enabled. */ | |
30 | } | |
31 | #else | |
32 | ||
33 | # include <stddef.h> | |
34 | # include "dl-tunable-types.h" | |
35 | ||
36 | /* A tunable. */ | |
37 | struct _tunable | |
38 | { | |
39 | const char *name; /* Internal name of the tunable. */ | |
40 | tunable_type_t type; /* Data type of the tunable. */ | |
41 | tunable_val_t val; /* The value. */ | |
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42 | bool initialized; /* Flag to indicate that the tunable is |
43 | initialized. */ | |
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44 | tunable_seclevel_t security_level; /* Specify the security level for the |
45 | tunable with respect to AT_SECURE | |
46 | programs. See description of | |
47 | tunable_seclevel_t to see a | |
48 | description of the values. | |
49 | ||
50 | Note that even if the tunable is | |
51 | read, it may not get used by the | |
52 | target module if the value is | |
53 | considered unsafe. */ | |
67e58f39 SP |
54 | /* Compatibility elements. */ |
55 | const char *env_alias; /* The compatibility environment | |
56 | variable name. */ | |
57 | }; | |
58 | ||
59 | typedef struct _tunable tunable_t; | |
60 | ||
61 | /* Full name for a tunable is top_ns.tunable_ns.id. */ | |
62 | # define TUNABLE_NAME_S(top,ns,id) #top "." #ns "." #id | |
63 | ||
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64 | # define TUNABLE_ENUM_NAME(__top,__ns,__id) TUNABLE_ENUM_NAME1 (__top,__ns,__id) |
65 | # define TUNABLE_ENUM_NAME1(__top,__ns,__id) __top ## _ ## __ns ## _ ## __id | |
67e58f39 SP |
66 | |
67 | # include "dl-tunable-list.h" | |
68 | ||
69 | extern void __tunables_init (char **); | |
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70 | extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t); |
71 | extern void __tunable_set_val (tunable_id_t, void *); | |
81efada5 | 72 | rtld_hidden_proto (__tunables_init) |
44330b6d SP |
73 | rtld_hidden_proto (__tunable_get_val) |
74 | ||
75 | /* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and | |
76 | TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set | |
77 | tunables within a module. */ | |
78 | #if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE | |
79 | # define TUNABLE_GET(__id, __type, __cb) \ | |
80 | TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb) | |
81 | # define TUNABLE_SET(__id, __type, __val) \ | |
82 | TUNABLE_SET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __val) | |
83 | #else | |
84 | # define TUNABLE_GET(__top, __ns, __id, __type, __cb) \ | |
85 | TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb) | |
86 | # define TUNABLE_SET(__top, __ns, __id, __type, __val) \ | |
87 | TUNABLE_SET_FULL (__top, __ns, __id, __type, __val) | |
88 | #endif | |
81efada5 | 89 | |
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90 | /* Get and return a tunable value. If the tunable was set externally and __CB |
91 | is defined then call __CB before returning the value. */ | |
92 | # define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \ | |
67e58f39 | 93 | ({ \ |
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94 | tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \ |
95 | __type ret; \ | |
96 | __tunable_get_val (id, &ret, __cb); \ | |
97 | ret; \ | |
67e58f39 SP |
98 | }) |
99 | ||
44330b6d SP |
100 | /* Set a tunable value. */ |
101 | # define TUNABLE_SET_FULL(__top, __ns, __id, __type, __val) \ | |
67e58f39 | 102 | ({ \ |
44330b6d SP |
103 | __tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \ |
104 | & (__type) {__val}); \ | |
67e58f39 SP |
105 | }) |
106 | ||
107 | /* Namespace sanity for callback functions. Use this macro to keep the | |
108 | namespace of the modules clean. */ | |
44330b6d | 109 | # define TUNABLE_CALLBACK(__name) _dl_tunable_ ## __name |
6765d5d3 SP |
110 | |
111 | # define TUNABLES_FRONTEND_valstring 1 | |
112 | /* The default value for TUNABLES_FRONTEND. */ | |
113 | # define TUNABLES_FRONTEND_yes TUNABLES_FRONTEND_valstring | |
28cfa3a4 SP |
114 | |
115 | /* Compare two name strings, bounded by the name hardcoded in glibc. */ | |
116 | static inline bool | |
117 | __always_inline | |
118 | tunable_is_name (const char *orig, const char *envname) | |
119 | { | |
120 | for (;*orig != '\0' && *envname != '\0'; envname++, orig++) | |
121 | if (*orig != *envname) | |
122 | break; | |
123 | ||
124 | /* The ENVNAME is immediately followed by a value. */ | |
125 | if (*orig == '\0' && *envname == '=') | |
126 | return true; | |
127 | else | |
128 | return false; | |
129 | } | |
130 | ||
67e58f39 SP |
131 | #endif |
132 | #endif |