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%%	options

copyright owner	=	Dirk Krause
copyright year	=	2015-xxxx
SPDX-License-Identifier:	BSD-3-Clause


%%	header

/**	@file	dk4memrs.h	Secure memory reset.

	Securely reset byte buffer to 0x00 bytes.
*/

#ifdef __cplusplus
extern "C" {
#endif

/**	Secure memory reset.

	CRT on Windows: Not used.
	@param	ptr	Start address of memory range.
	@param	sz	Size of memory range in bytes.
	@param	erp	Error report, may be NULL.
	@return	1 on success, 0 on error. You should not ignore the
	return value.

	Error codes:
	- DK4_E_INVALID_ARGUMENTS<br>
	  if ptr is NULL or sz is 0,
	- DK4_E_BUG<br>
	  if one of the bytes in the buffer is not 0 during check.
*/
int
dk4mem_reset_secure(void *ptr, size_t sz, dk4_er_t *erp);


#ifdef __cplusplus
}
#endif



%%	module

#include "dk4conf.h"

#ifndef STDIO_H_INCLUDED
#include <stdio.h>
#define STDIO_H_INCLUDED 1
#endif
#ifndef STDLIB_H_INCLUDED
#include <stdlib.h>
#define STDLIB_H_INCLUDED 1
#endif
#if DK4_ON_WINDOWS
#ifndef WINDOWS_H_INCLUDED
#include <windows.h>
#define	WINDOWS_H_INCLUDED 1
#endif
#endif

#if DK4_HAVE_ASSERT_H
#ifndef	ASSERT_H_INCLUDED
#include <assert.h>
#define	ASSERT_H_INCLUDED 1
#endif
#endif

#include "dk4mem.h"
#include "dk4memrs.h"


$!trace-include


#ifndef	DK4MEMRS_PARANOID_CHECK
#define	DK4MEMRS_PARANOID_CHECK 0
#endif


int
dk4mem_reset_secure(void *ptr, size_t sz, dk4_er_t *erp)
{
#if (!DK4_ON_WINDOWS) && (DK4MEMRS_PARANOID_CHECK)
  unsigned char	*p1;
#endif
  int		 back = 0;
#if	DK4_USE_ASSERT
  assert(NULL != ptr);
  assert(0 < sz);
#endif
  if ((NULL != ptr) && (0 < sz)) {
#if DK4_ON_WINDOWS
    SecureZeroMemory(ptr, sz);
    back = 1;
#else
    DK4_MEMRES(ptr, sz);
    back = 1;
#if DK4MEMRS_PARANOID_CHECK
    p1 = (unsigned char *)ptr;
    while((0 != back) && (sz--)) {
      if ('\0' != *(p1++)) {
        back = 0;
	dk4error_set_simple_error_code(erp, DK4_E_BUG);
      }
    }
#endif
#endif
  } else {
    dk4error_set_simple_error_code(erp, DK4_E_INVALID_ARGUMENTS);
  }
  return back;
}