1/*
2 * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License").  You may not use
5 * this file except in compliance with the License.  You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#ifndef OSSL_INTERNAL_THREAD_ONCE_H
11# define OSSL_INTERNAL_THREAD_ONCE_H
12# pragma once
13
14# include <openssl/crypto.h>
15
16/*
17 * Initialisation of global data should never happen via "RUN_ONCE" inside the
18 * FIPS module. Global data should instead always be associated with a specific
19 * OSSL_LIB_CTX object. In this way data will get cleaned up correctly when the
20 * module gets unloaded.
21 */
22# if !defined(FIPS_MODULE) || defined(ALLOW_RUN_ONCE_IN_FIPS)
23/*
24 * DEFINE_RUN_ONCE: Define an initialiser function that should be run exactly
25 * once. It takes no arguments and returns an int result (1 for success or
26 * 0 for failure). Typical usage might be:
27 *
28 * DEFINE_RUN_ONCE(myinitfunc)
29 * {
30 *     do_some_initialisation();
31 *     if (init_is_successful())
32 *         return 1;
33 *
34 *     return 0;
35 * }
36 */
37#  define DEFINE_RUN_ONCE(init)                   \
38    static int init(void);                     \
39    int init##_ossl_ret_ = 0;                   \
40    void init##_ossl_(void)                     \
41    {                                           \
42        init##_ossl_ret_ = init();              \
43    }                                           \
44    static int init(void)
45
46/*
47 * DECLARE_RUN_ONCE: Declare an initialiser function that should be run exactly
48 * once that has been defined in another file via DEFINE_RUN_ONCE().
49 */
50#  define DECLARE_RUN_ONCE(init)                  \
51    extern int init##_ossl_ret_;                \
52    void init##_ossl_(void);
53
54/*
55 * DEFINE_RUN_ONCE_STATIC: Define an initialiser function that should be run
56 * exactly once. This function will be declared as static within the file. It
57 * takes no arguments and returns an int result (1 for success or 0 for
58 * failure). Typical usage might be:
59 *
60 * DEFINE_RUN_ONCE_STATIC(myinitfunc)
61 * {
62 *     do_some_initialisation();
63 *     if (init_is_successful())
64 *         return 1;
65 *
66 *     return 0;
67 * }
68 */
69#  define DEFINE_RUN_ONCE_STATIC(init)            \
70    static int init(void);                     \
71    static int init##_ossl_ret_ = 0;            \
72    static void init##_ossl_(void)              \
73    {                                           \
74        init##_ossl_ret_ = init();              \
75    }                                           \
76    static int init(void)
77
78/*
79 * DEFINE_RUN_ONCE_STATIC_ALT: Define an alternative initialiser function. This
80 * function will be declared as static within the file. It takes no arguments
81 * and returns an int result (1 for success or 0 for failure). An alternative
82 * initialiser function is expected to be associated with a primary initialiser
83 * function defined via DEFINE_ONCE_STATIC where both functions use the same
84 * CRYPTO_ONCE object to synchronise. Where an alternative initialiser function
85 * is used only one of the primary or the alternative initialiser function will
86 * ever be called - and that function will be called exactly once. Definition
87 * of an alternative initialiser function MUST occur AFTER the definition of the
88 * primary initialiser function.
89 *
90 * Typical usage might be:
91 *
92 * DEFINE_RUN_ONCE_STATIC(myinitfunc)
93 * {
94 *     do_some_initialisation();
95 *     if (init_is_successful())
96 *         return 1;
97 *
98 *     return 0;
99 * }
100 *
101 * DEFINE_RUN_ONCE_STATIC_ALT(myaltinitfunc, myinitfunc)
102 * {
103 *     do_some_alternative_initialisation();
104 *     if (init_is_successful())
105 *         return 1;
106 *
107 *     return 0;
108 * }
109 */
110#  define DEFINE_RUN_ONCE_STATIC_ALT(initalt, init) \
111    static int initalt(void);                     \
112    static void initalt##_ossl_(void)             \
113    {                                             \
114        init##_ossl_ret_ = initalt();             \
115    }                                             \
116    static int initalt(void)
117
118/*
119 * RUN_ONCE - use CRYPTO_THREAD_run_once, and check if the init succeeded
120 * @once: pointer to static object of type CRYPTO_ONCE
121 * @init: function name that was previously given to DEFINE_RUN_ONCE,
122 *        DEFINE_RUN_ONCE_STATIC or DECLARE_RUN_ONCE.  This function
123 *        must return 1 for success or 0 for failure.
124 *
125 * The return value is 1 on success (*) or 0 in case of error.
126 *
127 * (*) by convention, since the init function must return 1 on success.
128 */
129#  define RUN_ONCE(once, init)                                            \
130    (CRYPTO_THREAD_run_once(once, init##_ossl_) ? init##_ossl_ret_ : 0)
131
132/*
133 * RUN_ONCE_ALT - use CRYPTO_THREAD_run_once, to run an alternative initialiser
134 *                function and check if that initialisation succeeded
135 * @once:    pointer to static object of type CRYPTO_ONCE
136 * @initalt: alternative initialiser function name that was previously given to
137 *           DEFINE_RUN_ONCE_STATIC_ALT.  This function must return 1 for
138 *           success or 0 for failure.
139 * @init:    primary initialiser function name that was previously given to
140 *           DEFINE_RUN_ONCE_STATIC.  This function must return 1 for success or
141 *           0 for failure.
142 *
143 * The return value is 1 on success (*) or 0 in case of error.
144 *
145 * (*) by convention, since the init function must return 1 on success.
146 */
147#  define RUN_ONCE_ALT(once, initalt, init)                               \
148    (CRYPTO_THREAD_run_once(once, initalt##_ossl_) ? init##_ossl_ret_ : 0)
149
150# endif /* FIPS_MODULE */
151#endif /* OSSL_INTERNAL_THREAD_ONCE_H */
152