/*

 * Copyright 2026 Richard Hughes <richard@hughsie.com>

 *

 * SPDX-License-Identifier: LGPL-2.1-or-later

 */

#define G_LOG_DOMAIN "FuCommon"

#include "config.h"

#include "fu-mem-private.h"

#include "fu-xor.h"

/**

 * fu_xor8:

 * @buf: memory buffer

 * @bufsz: size of @buf

 *

 * Returns the bitwise XOR of all bytes in @buf.

 *

 * Returns: xor value

 *

 * Since: 2.1.1

 **/

guint8

fu_xor8(const guint8 *buf, gsize bufsz)

{

  guint8 tmp = 0;

  g_return_val_if_fail(buf != NULL, G_MAXUINT8);

  for (gsize i = 0; i < bufsz; i++)

    tmp ^= buf[i];

  return tmp;

}

/**

 * fu_xor8_safe:

 * @buf: source buffer

 * @bufsz: maximum size of @buf, typically `sizeof(buf)`

 * @offset: offset in bytes into @buf where XOR should start

 * @n: number of bytes to XOR from @buf

 * @value: (inout) (nullable): the initial value, and result

 * @error: (nullable): optional return location for an error

 *

 * Returns the bitwise XOR of all bytes in @buf in a safe way.

 *

 * You don't need to use this function in "obviously correct" cases, nor should

 * you use it when performance is a concern. Only use it when you're not sure if

 * malicious data from a device or firmware could cause memory corruption.

 *

 * Returns: %TRUE if @value was set, %FALSE otherwise

 *

 * Since: 2.1.1

 **/

gboolean

fu_xor8_safe(const guint8 *buf, gsize bufsz, gsize offset, gsize n, guint8 *value, GError **error)

{

  g_return_val_if_fail(buf != NULL, FALSE);

  g_return_val_if_fail(error == NULL || *error == NULL, FALSE);

  if (!fu_memchk_read(bufsz, offset, n, error))

    return FALSE;

  if (value != NULL)

    *value ^= fu_xor8(buf + offset, n);

  return TRUE;

}