1/*
2 * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (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#include <openssl/crypto.h>
11
12/*
13 * DEFINE_RUN_ONCE: Define an initialiser function that should be run exactly
14 * once. It takes no arguments and returns and int result (1 for success or
15 * 0 for failure). Typical usage might be:
16 *
17 * DEFINE_RUN_ONCE(myinitfunc)
18 * {
19 *     do_some_initialisation();
20 *     if (init_is_successful())
21 *         return 1;
22 *
23 *     return 0;
24 * }
25 */
26#define DEFINE_RUN_ONCE(init)                   \
27    static int init(void);                     \
28    int init##_ossl_ret_ = 0;                   \
29    void init##_ossl_(void)                     \
30    {                                           \
31        init##_ossl_ret_ = init();              \
32    }                                           \
33    static int init(void)
34
35/*
36 * DECLARE_RUN_ONCE: Declare an initialiser function that should be run exactly
37 * once that has been defined in another file via DEFINE_RUN_ONCE().
38 */
39#define DECLARE_RUN_ONCE(init)                  \
40    extern int init##_ossl_ret_;                \
41    void init##_ossl_(void);
42
43/*
44 * DEFINE_RUN_ONCE_STATIC: Define an initialiser function that should be run
45 * exactly once. This function will be declared as static within the file. It
46 * takes no arguments and returns and int result (1 for success or 0 for
47 * failure). Typical usage might be:
48 *
49 * DEFINE_RUN_ONCE_STATIC(myinitfunc)
50 * {
51 *     do_some_initialisation();
52 *     if (init_is_successful())
53 *         return 1;
54 *
55 *     return 0;
56 * }
57 */
58#define DEFINE_RUN_ONCE_STATIC(init)            \
59    static int init(void);                     \
60    static int init##_ossl_ret_ = 0;            \
61    static void init##_ossl_(void)              \
62    {                                           \
63        init##_ossl_ret_ = init();              \
64    }                                           \
65    static int init(void)
66
67/*
68 * DEFINE_RUN_ONCE_STATIC_ALT: Define an alternative initialiser function. This
69 * function will be declared as static within the file. It takes no arguments
70 * and returns an int result (1 for success or 0 for failure). An alternative
71 * initialiser function is expected to be associated with a primary initialiser
72 * function defined via DEFINE_ONCE_STATIC where both functions use the same
73 * CRYPTO_ONCE object to synchronise. Where an alternative initialiser function
74 * is used only one of the primary or the alternative initialiser function will
75 * ever be called - and that function will be called exactly once. Definition
76 * of an alternative initialiser function MUST occur AFTER the definition of the
77 * primary initialiser function.
78 *
79 * Typical usage might be:
80 *
81 * DEFINE_RUN_ONCE_STATIC(myinitfunc)
82 * {
83 *     do_some_initialisation();
84 *     if (init_is_successful())
85 *         return 1;
86 *
87 *     return 0;
88 * }
89 *
90 * DEFINE_RUN_ONCE_STATIC_ALT(myaltinitfunc, myinitfunc)
91 * {
92 *     do_some_alternative_initialisation();
93 *     if (init_is_successful())
94 *         return 1;
95 *
96 *     return 0;
97 * }
98 */
99#define DEFINE_RUN_ONCE_STATIC_ALT(initalt, init) \
100    static int initalt(void);                     \
101    static void initalt##_ossl_(void)             \
102    {                                             \
103        init##_ossl_ret_ = initalt();             \
104    }                                             \
105    static int initalt(void)
106
107/*
108 * RUN_ONCE - use CRYPTO_THREAD_run_once, and check if the init succeeded
109 * @once: pointer to static object of type CRYPTO_ONCE
110 * @init: function name that was previously given to DEFINE_RUN_ONCE,
111 *        DEFINE_RUN_ONCE_STATIC or DECLARE_RUN_ONCE.  This function
112 *        must return 1 for success or 0 for failure.
113 *
114 * The return value is 1 on success (*) or 0 in case of error.
115 *
116 * (*) by convention, since the init function must return 1 on success.
117 */
118#define RUN_ONCE(once, init)                                            \
119    (CRYPTO_THREAD_run_once(once, init##_ossl_) ? init##_ossl_ret_ : 0)
120
121/*
122 * RUN_ONCE_ALT - use CRYPTO_THREAD_run_once, to run an alternative initialiser
123 *                function and check if that initialisation succeeded
124 * @once:    pointer to static object of type CRYPTO_ONCE
125 * @initalt: alternative initialiser function name that was previously given to
126 *           DEFINE_RUN_ONCE_STATIC_ALT.  This function must return 1 for
127 *           success or 0 for failure.
128 * @init:    primary initialiser function name that was previously given to
129 *           DEFINE_RUN_ONCE_STATIC.  This function must return 1 for success or
130 *           0 for failure.
131 *
132 * The return value is 1 on success (*) or 0 in case of error.
133 *
134 * (*) by convention, since the init function must return 1 on success.
135 */
136#define RUN_ONCE_ALT(once, initalt, init)                               \
137    (CRYPTO_THREAD_run_once(once, initalt##_ossl_) ? init##_ossl_ret_ : 0)
138