NCBI C++ ToolKit
platform_util.h
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1 /**
2  * \file platform_util.h
3  *
4  * \brief Common and shared functions used by multiple modules in the Mbed TLS
5  * library.
6  */
7 /*
8  * Copyright The Mbed TLS Contributors
9  * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
10  */
11 #ifndef MBEDTLS_PLATFORM_UTIL_H
12 #define MBEDTLS_PLATFORM_UTIL_H
13 
14 #include "mbedtls/build_info.h"
15 
16 #include <stddef.h>
17 #if defined(MBEDTLS_HAVE_TIME_DATE)
18 #include "mbedtls/platform_time.h"
19 #include <time.h>
20 #endif /* MBEDTLS_HAVE_TIME_DATE */
21 
22 #ifdef __cplusplus
23 extern "C" {
24 #endif
25 
26 /* Internal helper macros for deprecating API constants. */
27 #if !defined(MBEDTLS_DEPRECATED_REMOVED)
28 #if defined(MBEDTLS_DEPRECATED_WARNING)
29 #define MBEDTLS_DEPRECATED __attribute__((deprecated))
30 MBEDTLS_DEPRECATED typedef char const *mbedtls_deprecated_string_constant_t;
31 #define MBEDTLS_DEPRECATED_STRING_CONSTANT(VAL) \
32  ((mbedtls_deprecated_string_constant_t) (VAL))
33 MBEDTLS_DEPRECATED typedef int mbedtls_deprecated_numeric_constant_t;
34 #define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT(VAL) \
35  ((mbedtls_deprecated_numeric_constant_t) (VAL))
36 #else /* MBEDTLS_DEPRECATED_WARNING */
37 #define MBEDTLS_DEPRECATED
38 #define MBEDTLS_DEPRECATED_STRING_CONSTANT(VAL) VAL
39 #define MBEDTLS_DEPRECATED_NUMERIC_CONSTANT(VAL) VAL
40 #endif /* MBEDTLS_DEPRECATED_WARNING */
41 #endif /* MBEDTLS_DEPRECATED_REMOVED */
42 
43 /* Implementation of the check-return facility.
44  * See the user documentation in mbedtls_config.h.
45  *
46  * Do not use this macro directly to annotate function: instead,
47  * use one of MBEDTLS_CHECK_RETURN_CRITICAL or MBEDTLS_CHECK_RETURN_TYPICAL
48  * depending on how important it is to check the return value.
49  */
50 #if !defined(MBEDTLS_CHECK_RETURN)
51 #if defined(__GNUC__)
52 #define MBEDTLS_CHECK_RETURN __attribute__((__warn_unused_result__))
53 #elif defined(_MSC_VER) && _MSC_VER >= 1700
54 #include <sal.h>
55 #define MBEDTLS_CHECK_RETURN _Check_return_
56 #else
57 #define MBEDTLS_CHECK_RETURN
58 #endif
59 #endif
60 
61 /** Critical-failure function
62  *
63  * This macro appearing at the beginning of the declaration of a function
64  * indicates that its return value should be checked in all applications.
65  * Omitting the check is very likely to indicate a bug in the application
66  * and will result in a compile-time warning if #MBEDTLS_CHECK_RETURN
67  * is implemented for the compiler in use.
68  *
69  * \note The use of this macro is a work in progress.
70  * This macro may be added to more functions in the future.
71  * Such an extension is not considered an API break, provided that
72  * there are near-unavoidable circumstances under which the function
73  * can fail. For example, signature/MAC/AEAD verification functions,
74  * and functions that require a random generator, are considered
75  * return-check-critical.
76  */
77 #define MBEDTLS_CHECK_RETURN_CRITICAL MBEDTLS_CHECK_RETURN
78 
79 /** Ordinary-failure function
80  *
81  * This macro appearing at the beginning of the declaration of a function
82  * indicates that its return value should be generally be checked in portable
83  * applications. Omitting the check will result in a compile-time warning if
84  * #MBEDTLS_CHECK_RETURN is implemented for the compiler in use and
85  * #MBEDTLS_CHECK_RETURN_WARNING is enabled in the compile-time configuration.
86  *
87  * You can use #MBEDTLS_IGNORE_RETURN to explicitly ignore the return value
88  * of a function that is annotated with #MBEDTLS_CHECK_RETURN.
89  *
90  * \note The use of this macro is a work in progress.
91  * This macro will be added to more functions in the future.
92  * Eventually this should appear before most functions returning
93  * an error code (as \c int in the \c mbedtls_xxx API or
94  * as ::psa_status_t in the \c psa_xxx API).
95  */
96 #if defined(MBEDTLS_CHECK_RETURN_WARNING)
97 #define MBEDTLS_CHECK_RETURN_TYPICAL MBEDTLS_CHECK_RETURN
98 #else
99 #define MBEDTLS_CHECK_RETURN_TYPICAL
100 #endif
101 
102 /** Benign-failure function
103  *
104  * This macro appearing at the beginning of the declaration of a function
105  * indicates that it is rarely useful to check its return value.
106  *
107  * This macro has an empty expansion. It exists for documentation purposes:
108  * a #MBEDTLS_CHECK_RETURN_OPTIONAL annotation indicates that the function
109  * has been analyzed for return-check usefulness, whereas the lack of
110  * an annotation indicates that the function has not been analyzed and its
111  * return-check usefulness is unknown.
112  */
113 #define MBEDTLS_CHECK_RETURN_OPTIONAL
114 
115 /** \def MBEDTLS_IGNORE_RETURN
116  *
117  * Call this macro with one argument, a function call, to suppress a warning
118  * from #MBEDTLS_CHECK_RETURN due to that function call.
119  */
120 #if !defined(MBEDTLS_IGNORE_RETURN)
121 /* GCC doesn't silence the warning with just (void)(result).
122  * (void)!(result) is known to work up at least up to GCC 10, as well
123  * as with Clang and MSVC.
124  *
125  * https://gcc.gnu.org/onlinedocs/gcc-3.4.6/gcc/Non_002dbugs.html
126  * https://stackoverflow.com/questions/40576003/ignoring-warning-wunused-result
127  * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66425#c34
128  */
129 #define MBEDTLS_IGNORE_RETURN(result) ((void) !(result))
130 #endif
131 
132 /* If the following macro is defined, the library is being built by the test
133  * framework, and the framework is going to provide a replacement
134  * mbedtls_platform_zeroize() using a preprocessor macro, so the function
135  * declaration should be omitted. */
136 #if !defined(MBEDTLS_TEST_DEFINES_ZEROIZE) //no-check-names
137 /**
138  * \brief Securely zeroize a buffer
139  *
140  * The function is meant to wipe the data contained in a buffer so
141  * that it can no longer be recovered even if the program memory
142  * is later compromised. Call this function on sensitive data
143  * stored on the stack before returning from a function, and on
144  * sensitive data stored on the heap before freeing the heap
145  * object.
146  *
147  * It is extremely difficult to guarantee that calls to
148  * mbedtls_platform_zeroize() are not removed by aggressive
149  * compiler optimizations in a portable way. For this reason, Mbed
150  * TLS provides the configuration option
151  * MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
152  * mbedtls_platform_zeroize() to use a suitable implementation for
153  * their platform and needs
154  *
155  * \param buf Buffer to be zeroized
156  * \param len Length of the buffer in bytes
157  *
158  */
159 void mbedtls_platform_zeroize(void *buf, size_t len);
160 #endif
161 
162 #if defined(MBEDTLS_HAVE_TIME_DATE)
163 /**
164  * \brief Platform-specific implementation of gmtime_r()
165  *
166  * The function is a thread-safe abstraction that behaves
167  * similarly to the gmtime_r() function from Unix/POSIX.
168  *
169  * Mbed TLS will try to identify the underlying platform and
170  * make use of an appropriate underlying implementation (e.g.
171  * gmtime_r() for POSIX and gmtime_s() for Windows). If this is
172  * not possible, then gmtime() will be used. In this case, calls
173  * from the library to gmtime() will be guarded by the mutex
174  * mbedtls_threading_gmtime_mutex if MBEDTLS_THREADING_C is
175  * enabled. It is recommended that calls from outside the library
176  * are also guarded by this mutex.
177  *
178  * If MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, then Mbed TLS will
179  * unconditionally use the alternative implementation for
180  * mbedtls_platform_gmtime_r() supplied by the user at compile time.
181  *
182  * \param tt Pointer to an object containing time (in seconds) since the
183  * epoch to be converted
184  * \param tm_buf Pointer to an object where the results will be stored
185  *
186  * \return Pointer to an object of type struct tm on success, otherwise
187  * NULL
188  */
189 struct tm *mbedtls_platform_gmtime_r(const mbedtls_time_t *tt,
190  struct tm *tm_buf);
191 #endif /* MBEDTLS_HAVE_TIME_DATE */
192 
193 #ifdef __cplusplus
194 }
195 #endif
196 
197 #endif /* MBEDTLS_PLATFORM_UTIL_H */
char * buf
int len
Build-time configuration info.
#define mbedtls_platform_gmtime_r
Mbed TLS Platform time abstraction.
time_t mbedtls_time_t
Definition: platform_time.h:27
void mbedtls_platform_zeroize(void *buf, size_t len)
Securely zeroize a buffer.
Definition: platform_util.c:94
#define MBEDTLS_DEPRECATED
Definition: platform_util.h:37
Modified on Wed Jun 12 11:11:03 2024 by modify_doxy.py rev. 669887