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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
#pragma once
#define s2n_likely(x) __builtin_expect(!!(x), 1)
#define s2n_unlikely(x) __builtin_expect(!!(x), 0)
/**
* s2n_ensure provides low-level safety check functionality
*
* This should only consumed directly by s2n_safety.
*
* Note: This module can be replaced by static analyzer implementation
* to insert additional safety checks.
*/
/**
* Ensures `cond` is true, otherwise `action` will be performed
*/
#define __S2N_ENSURE(cond, action) \
do { \
if (!(cond)) { \
action; \
} \
} while (0)
#define __S2N_ENSURE_LIKELY(cond, action) \
do { \
if (s2n_unlikely(!(cond))) { \
action; \
} \
} while (0)
#ifdef NDEBUG
#define __S2N_ENSURE_DEBUG(cond, action) \
do { \
} while (0)
#else
#define __S2N_ENSURE_DEBUG(cond, action) __S2N_ENSURE_LIKELY((cond), action)
#endif
#define __S2N_ENSURE_PRECONDITION(result) (s2n_likely(s2n_result_is_ok(result)) ? S2N_RESULT_OK : S2N_RESULT_ERROR)
#ifdef NDEBUG
#define __S2N_ENSURE_POSTCONDITION(result) (S2N_RESULT_OK)
#else
#define __S2N_ENSURE_POSTCONDITION(result) (s2n_likely(s2n_result_is_ok(result)) ? S2N_RESULT_OK : S2N_RESULT_ERROR)
#endif
#define __S2N_ENSURE_SAFE_MEMCPY(d, s, n, guard) \
do { \
__typeof(n) __tmp_n = (n); \
if (s2n_likely(__tmp_n)) { \
void *r = s2n_ensure_memcpy_trace((d), (s), (__tmp_n)); \
guard(r); \
} \
} while (0)
#define __S2N_ENSURE_SAFE_MEMSET(d, c, n, guard) \
do { \
__typeof(n) __tmp_n = (n); \
if (s2n_likely(__tmp_n)) { \
__typeof(d) __tmp_d = (d); \
guard(__tmp_d); \
memset(__tmp_d, (c), __tmp_n); \
} \
} while (0)
#if defined(S2N_DIAGNOSTICS_PUSH_SUPPORTED) && defined(S2N_DIAGNOSTICS_POP_SUPPORTED)
#define __S2N_ENSURE_CHECKED_RETURN(v) \
do { \
_Pragma("GCC diagnostic push") \
_Pragma("GCC diagnostic error \"-Wconversion\"") return v; \
_Pragma("GCC diagnostic pop") \
} while (0)
#else
#define __S2N_ENSURE_CHECKED_RETURN(v) return v
#endif
/**
* `restrict` is a part of the c99 standard and will work with any C compiler. If you're trying to
* compile with a C++ compiler `restrict` is invalid. However some C++ compilers support the behavior
* of `restrict` using the `__restrict__` keyword. Therefore if the compiler supports `__restrict__`
* use it.
*
* This is helpful for the benchmarks in tests/benchmark which use Google's Benchmark library and
* are all written in C++.
*
* https://gcc.gnu.org/onlinedocs/gcc/Restricted-Pointers.html
*
*/
#if defined(S2N___RESTRICT__SUPPORTED)
void *s2n_ensure_memcpy_trace(void *__restrict__ to, const void *__restrict__ from, size_t size);
#else
void *s2n_ensure_memcpy_trace(void *restrict to, const void *restrict from, size_t size);
#endif
/**
* These macros should not be used in validate functions.
* All validate functions are also used in assumptions for CBMC proofs,
* which should not contain __CPROVER_*_ok primitives. The use of these primitives
* in assumptions may lead to spurious results.
* When the code is being verified using CBMC, these properties are formally verified;
* When the code is built in debug mode, they are checked as much as possible using assertions.
* When the code is built in production mode, non-fatal properties are not checked.
* Violations of these properties are undefined behaviour.
*/
#ifdef CBMC
#define S2N_MEM_IS_READABLE_CHECK(base, len) (((len) == 0) || __CPROVER_r_ok((base), (len)))
#define S2N_MEM_IS_WRITABLE_CHECK(base, len) (((len) == 0) || __CPROVER_w_ok((base), (len)))
#else
/* the C runtime does not give a way to check these properties,
* but we can at least check for nullness. */
#define S2N_MEM_IS_READABLE_CHECK(base, len) (((len) == 0) || (base) != NULL)
#define S2N_MEM_IS_WRITABLE_CHECK(base, len) (((len) == 0) || (base) != NULL)
#endif /* CBMC */
/**
* These macros can safely be used in validate functions.
*/
#define S2N_MEM_IS_READABLE(base, len) (((len) == 0) || (base) != NULL)
#define S2N_MEM_IS_WRITABLE(base, len) (((len) == 0) || (base) != NULL)
#define S2N_OBJECT_PTR_IS_READABLE(ptr) ((ptr) != NULL)
#define S2N_OBJECT_PTR_IS_WRITABLE(ptr) ((ptr) != NULL)
#define S2N_IMPLIES(a, b) (!(a) || (b))
/**
* If and only if (iff) is a biconditional logical connective between statements a and b.
* Equivalent to (S2N_IMPLIES(a, b) && S2N_IMPLIES(b, a)).
*/
#define S2N_IFF(a, b) (!!(a) == !!(b))
/**
* These macros are used to specify code contracts in CBMC proofs.
* Define function contracts.
* When the code is being verified using CBMC, these contracts are formally verified;
* When the code is built in production mode, contracts are not checked.
* Violations of the function contracts are undefined behaviour.
*/
#ifdef CBMC
#define CONTRACT_ASSIGNS(...) __CPROVER_assigns(__VA_ARGS__)
#define CONTRACT_ASSIGNS_ERR(...) CONTRACT_ASSIGNS(__VA_ARGS__, _s2n_debug_info, s2n_errno)
#define CONTRACT_REQUIRES(...) __CPROVER_requires(__VA_ARGS__)
#define CONTRACT_ENSURES(...) __CPROVER_ensures(__VA_ARGS__)
#define CONTRACT_INVARIANT(...) __CPROVER_loop_invariant(__VA_ARGS__)
#define CONTRACT_RETURN_VALUE (__CPROVER_return_value)
#else
#define CONTRACT_ASSIGNS(...)
#define CONTRACT_ASSIGNS_ERR(...)
#define CONTRACT_REQUIRES(...)
#define CONTRACT_ENSURES(...)
#define CONTRACT_INVARIANT(...)
#define CONTRACT_RETURN_VALUE
#endif
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