#ifndef sodium_utils_H
#define sodium_utils_H

#include <stddef.h>

#include "export.h"

#ifdef __cplusplus
extern "C"
{
#endif

#ifndef SODIUM_C99
#if defined(__cplusplus) || !defined(__STDC_VERSION__) \
    || __STDC_VERSION__ < 199901L
#define SODIUM_C99(X)
#else
#define SODIUM_C99(X) X
#endif
#endif

  SODIUM_EXPORT
  void
  sodium_memzero(void *const pnt, const size_t len);

  SODIUM_EXPORT
  void
  sodium_stackzero(const size_t len);

  /*
   * WARNING: sodium_memcmp() must be used to verify if two secret keys
   * are equal, in constant time.
   * It returns 0 if the keys are equal, and -1 if they differ.
   * This function is not designed for lexicographical comparisons.
   */
  SODIUM_EXPORT
  int
  sodium_memcmp(const void *const b1_, const void *const b2_, size_t len)
      __attribute__((warn_unused_result));

  /*
   * sodium_compare() returns -1 if b1_ < b2_, 1 if b1_ > b2_ and 0 if b1_ ==
   * b2_ It is suitable for lexicographical comparisons, or to compare nonces
   * and counters stored in little-endian format.
   * However, it is slower than sodium_memcmp().
   */
  SODIUM_EXPORT
  int
  sodium_compare(const unsigned char *b1_, const unsigned char *b2_, size_t len)
      __attribute__((warn_unused_result));

  SODIUM_EXPORT
  int
  sodium_is_zero(const unsigned char *n, const size_t nlen);

  SODIUM_EXPORT
  void
  sodium_increment(unsigned char *n, const size_t nlen);

  SODIUM_EXPORT
  void
  sodium_add(unsigned char *a, const unsigned char *b, const size_t len);

  SODIUM_EXPORT
  char *
  sodium_bin2hex(char *const hex, const size_t hex_maxlen,
                 const unsigned char *const bin, const size_t bin_len);

  SODIUM_EXPORT
  int
  sodium_hex2bin(unsigned char *const bin, const size_t bin_maxlen,
                 const char *const hex, const size_t hex_len,
                 const char *const ignore, size_t *const bin_len,
                 const char **const hex_end);

#define sodium_base64_VARIANT_ORIGINAL 1
#define sodium_base64_VARIANT_ORIGINAL_NO_PADDING 3
#define sodium_base64_VARIANT_URLSAFE 5
#define sodium_base64_VARIANT_URLSAFE_NO_PADDING 7

/*
 * Computes the required length to encode BIN_LEN bytes as a base64 string
 * using the given variant. The computed length includes a trailing \0.
 */
#define sodium_base64_ENCODED_LEN(BIN_LEN, VARIANT)         \
  (((BIN_LEN) / 3U) * 4U                                    \
   + ((((BIN_LEN) - ((BIN_LEN) / 3U) * 3U)                  \
       | (((BIN_LEN) - ((BIN_LEN) / 3U) * 3U) >> 1))        \
      & 1U)                                                 \
       * (4U                                                \
          - (~((((VARIANT)&2U) >> 1) - 1U)                  \
             & (3U - ((BIN_LEN) - ((BIN_LEN) / 3U) * 3U)))) \
   + 1U)

  SODIUM_EXPORT
  size_t
  sodium_base64_encoded_len(const size_t bin_len, const int variant);

  SODIUM_EXPORT
  char *
  sodium_bin2base64(char *const b64, const size_t b64_maxlen,
                    const unsigned char *const bin, const size_t bin_len,
                    const int variant);

  SODIUM_EXPORT
  int
  sodium_base642bin(unsigned char *const bin, const size_t bin_maxlen,
                    const char *const b64, const size_t b64_len,
                    const char *const ignore, size_t *const bin_len,
                    const char **const b64_end, const int variant);

  SODIUM_EXPORT
  int
  sodium_mlock(void *const addr, const size_t len);

  SODIUM_EXPORT
  int
  sodium_munlock(void *const addr, const size_t len);

  /* WARNING: sodium_malloc() and sodium_allocarray() are not general-purpose
   * allocation functions.
   *
   * They return a pointer to a region filled with 0xd0 bytes, immediately
   * followed by a guard page.
   * As a result, accessing a single byte after the requested allocation size
   * will intentionally trigger a segmentation fault.
   *
   * A canary and an additional guard page placed before the beginning of the
   * region may also kill the process if a buffer underflow is detected.
   *
   * The memory layout is:
   * [unprotected region size (read only)][guard page (no access)][unprotected
   * pages (read/write)][guard page (no access)] With the layout of the
   * unprotected pages being: [optional padding][16-bytes canary][user region]
   *
   * However:
   * - These functions are significantly slower than standard functions
   * - Each allocation requires 3 or 4 additional pages
   * - The returned address will not be aligned if the allocation size is not
   *   a multiple of the required alignment. For this reason, these functions
   *   are designed to store data, such as secret keys and messages.
   *
   * sodium_malloc() can be used to allocate any libsodium data structure.
   *
   * The crypto_generichash_state structure is packed and its length is
   * either 357 or 361 bytes. For this reason, when using sodium_malloc() to
   * allocate a crypto_generichash_state structure, padding must be added in
   * order to ensure proper alignment. crypto_generichash_statebytes()
   * returns the rounded up structure size, and should be prefered to sizeof():
   * state = sodium_malloc(crypto_generichash_statebytes());
   */

  SODIUM_EXPORT
  void *
  sodium_malloc(const size_t size) __attribute__((malloc));

  SODIUM_EXPORT
  void *
  sodium_allocarray(size_t count, size_t size) __attribute__((malloc));

  SODIUM_EXPORT
  void
  sodium_free(void *ptr);

  SODIUM_EXPORT
  int
  sodium_mprotect_noaccess(void *ptr);

  SODIUM_EXPORT
  int
  sodium_mprotect_readonly(void *ptr);

  SODIUM_EXPORT
  int
  sodium_mprotect_readwrite(void *ptr);

  SODIUM_EXPORT
  int
  sodium_pad(size_t *padded_buflen_p, unsigned char *buf,
             size_t unpadded_buflen, size_t blocksize, size_t max_buflen);

  SODIUM_EXPORT
  int
  sodium_unpad(size_t *unpadded_buflen_p, const unsigned char *buf,
               size_t padded_buflen, size_t blocksize);

  /* -------- */

  int
  _sodium_alloc_init(void);

#ifdef __cplusplus
}
#endif

#endif