#ifndef sodium_utils_H
#define sodium_utils_H

#include <stddef.h>

#include "export.h"

#ifdef __cplusplus
extern "C" {
#endif

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

SODIUM_EXPORT
void sodium_memzero(void * const pnt, 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);

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);

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,
 * with the exception of crypto_generichash_state.
 *
 * 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:
 * state = sodium_malloc((sizeof(crypto_generichash_state)
 *                            + (size_t) 63U) & ~(size_t) 63U);
 */

SODIUM_EXPORT
void *sodium_malloc(const size_t size);

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

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);

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

int _sodium_alloc_init(void);

#ifdef __cplusplus
}
#endif

#endif