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       1                 :             : /**
       2                 :             :  * \file psa_crypto_core_common.h
       3                 :             :  *
       4                 :             :  * \brief Utility macros for internal use in the PSA cryptography core.
       5                 :             :  */
       6                 :             : /*
       7                 :             :  *  Copyright The Mbed TLS Contributors
       8                 :             :  *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
       9                 :             :  */
      10                 :             : 
      11                 :             : #ifndef PSA_CRYPTO_CORE_COMMON_H
      12                 :             : #define PSA_CRYPTO_CORE_COMMON_H
      13                 :             : 
      14                 :             : /** Return an offset into a buffer.
      15                 :             :  *
      16                 :             :  * This is just the addition of an offset to a pointer, except that this
      17                 :             :  * function also accepts an offset of 0 into a buffer whose pointer is null.
      18                 :             :  * (`p + n` has undefined behavior when `p` is null, even when `n == 0`.
      19                 :             :  * A null pointer is a valid buffer pointer when the size is 0, for example
      20                 :             :  * as the result of `malloc(0)` on some platforms.)
      21                 :             :  *
      22                 :             :  * \param p     Pointer to a buffer of at least n bytes.
      23                 :             :  *              This may be \p NULL if \p n is zero.
      24                 :             :  * \param n     An offset in bytes.
      25                 :             :  * \return      Pointer to offset \p n in the buffer \p p.
      26                 :             :  *              Note that this is only a valid pointer if the size of the
      27                 :             :  *              buffer is at least \p n + 1.
      28                 :             :  */
      29                 :           0 : static inline unsigned char *psa_crypto_buffer_offset(
      30                 :             :     unsigned char *p, size_t n)
      31                 :             : {
      32         [ #  # ]:           0 :     return p == NULL ? NULL : p + n;
      33                 :             : }
      34                 :             : 
      35                 :             : /** Return an offset into a read-only buffer.
      36                 :             :  *
      37                 :             :  * Similar to mbedtls_buffer_offset(), but for const pointers.
      38                 :             :  *
      39                 :             :  * \param p     Pointer to a buffer of at least n bytes.
      40                 :             :  *              This may be \p NULL if \p n is zero.
      41                 :             :  * \param n     An offset in bytes.
      42                 :             :  * \return      Pointer to offset \p n in the buffer \p p.
      43                 :             :  *              Note that this is only a valid pointer if the size of the
      44                 :             :  *              buffer is at least \p n + 1.
      45                 :             :  */
      46                 :             : static inline const unsigned char *psa_crypto_buffer_offset_const(
      47                 :             :     const unsigned char *p, size_t n)
      48                 :             : {
      49                 :             :     return p == NULL ? NULL : p + n;
      50                 :             : }
      51                 :             : 
      52                 :             : #endif /* PSA_CRYPTO_CORE_COMMON_H */