/** @file
  This library provides helper functions to prevent integer overflow during
  type conversion, addition, subtraction, and multiplication.

  Copyright (c) 2017, Microsoft Corporation

  All rights reserved.
  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:
  1. Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.
  2. Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
  INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
  OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

**/

#include <Base.h>
#include <Library/SafeIntLib.h>
#include <Library/BaseLib.h>

/**
  INT32 -> UINTN conversion

  Converts the value specified by Operand to a value specified by Result type
  and stores the converted value into the caller allocated output buffer
  specified by Result.  The caller must pass in a Result buffer that is at
  least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the conversion results in an overflow or an underflow condition, then
  Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Operand  Operand to be converted to new type
  @param[out]  Result   Pointer to the result of conversion

  @retval  RETURN_SUCCESS            Successful conversion
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeInt32ToUintn (
  IN  INT32  Operand,
  OUT UINTN  *Result
  )
{
  return SafeInt32ToUint32 (Operand, (UINT32 *)Result);
}

/**
  UINT32 -> INTN conversion

  Converts the value specified by Operand to a value specified by Result type
  and stores the converted value into the caller allocated output buffer
  specified by Result.  The caller must pass in a Result buffer that is at
  least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the conversion results in an overflow or an underflow condition, then
  Result is set to INTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Operand  Operand to be converted to new type
  @param[out]  Result   Pointer to the result of conversion

  @retval  RETURN_SUCCESS            Successful conversion
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeUint32ToIntn (
  IN  UINT32  Operand,
  OUT INTN    *Result
  )
{
  return SafeUint32ToInt32 (Operand, (INT32 *)Result);
}

/**
  INTN -> INT32 conversion

  Converts the value specified by Operand to a value specified by Result type
  and stores the converted value into the caller allocated output buffer
  specified by Result.  The caller must pass in a Result buffer that is at
  least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the conversion results in an overflow or an underflow condition, then
  Result is set to INT32_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Operand  Operand to be converted to new type
  @param[out]  Result   Pointer to the result of conversion

  @retval  RETURN_SUCCESS            Successful conversion
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeIntnToInt32 (
  IN  INTN   Operand,
  OUT INT32  *Result
  )
{
  if (Result == NULL) {
    return RETURN_INVALID_PARAMETER;
  }

  *Result = (INT32)Operand;
  return RETURN_SUCCESS;
}

/**
  INTN -> UINT32 conversion

  Converts the value specified by Operand to a value specified by Result type
  and stores the converted value into the caller allocated output buffer
  specified by Result.  The caller must pass in a Result buffer that is at
  least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the conversion results in an overflow or an underflow condition, then
  Result is set to UINT32_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Operand  Operand to be converted to new type
  @param[out]  Result   Pointer to the result of conversion

  @retval  RETURN_SUCCESS            Successful conversion
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeIntnToUint32 (
  IN  INTN    Operand,
  OUT UINT32  *Result
  )
{
  RETURN_STATUS  Status;

  if (Result == NULL) {
    return RETURN_INVALID_PARAMETER;
  }

  if (Operand >= 0) {
    *Result = (UINT32)Operand;
    Status = RETURN_SUCCESS;
  } else {
    *Result = UINT32_ERROR;
    Status = RETURN_BUFFER_TOO_SMALL;
  }

  return Status;
}

/**
  UINTN -> UINT32 conversion

  Converts the value specified by Operand to a value specified by Result type
  and stores the converted value into the caller allocated output buffer
  specified by Result.  The caller must pass in a Result buffer that is at
  least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the conversion results in an overflow or an underflow condition, then
  Result is set to UINT32_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Operand  Operand to be converted to new type
  @param[out]  Result   Pointer to the result of conversion

  @retval  RETURN_SUCCESS            Successful conversion
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeUintnToUint32 (
  IN  UINTN   Operand,
  OUT UINT32  *Result
  )
{
  if (Result == NULL) {
    return RETURN_INVALID_PARAMETER;
  }

  *Result = (UINT32)Operand;
  return RETURN_SUCCESS;
}

/**
  UINTN -> INT64 conversion

  Converts the value specified by Operand to a value specified by Result type
  and stores the converted value into the caller allocated output buffer
  specified by Result.  The caller must pass in a Result buffer that is at
  least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the conversion results in an overflow or an underflow condition, then
  Result is set to INT64_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Operand  Operand to be converted to new type
  @param[out]  Result   Pointer to the result of conversion

  @retval  RETURN_SUCCESS            Successful conversion
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeUintnToInt64 (
  IN  UINTN  Operand,
  OUT INT64  *Result
  )
{
  if (Result == NULL) {
    return RETURN_INVALID_PARAMETER;
  }

  *Result = (INT64)Operand;
  return RETURN_SUCCESS;
}

/**
  INT64 -> INTN conversion

  Converts the value specified by Operand to a value specified by Result type
  and stores the converted value into the caller allocated output buffer
  specified by Result.  The caller must pass in a Result buffer that is at
  least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the conversion results in an overflow or an underflow condition, then
  Result is set to INTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Operand  Operand to be converted to new type
  @param[out]  Result   Pointer to the result of conversion

  @retval  RETURN_SUCCESS            Successful conversion
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeInt64ToIntn (
  IN  INT64  Operand,
  OUT INTN   *Result
  )
{
  return SafeInt64ToInt32 (Operand, (INT32 *)Result);
}

/**
  INT64 -> UINTN conversion

  Converts the value specified by Operand to a value specified by Result type
  and stores the converted value into the caller allocated output buffer
  specified by Result.  The caller must pass in a Result buffer that is at
  least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the conversion results in an overflow or an underflow condition, then
  Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Operand  Operand to be converted to new type
  @param[out]  Result   Pointer to the result of conversion

  @retval  RETURN_SUCCESS            Successful conversion
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeInt64ToUintn (
  IN  INT64  Operand,
  OUT UINTN  *Result
  )
{
  return SafeInt64ToUint32 (Operand, (UINT32 *)Result);
}

/**
  UINT64 -> UINTN conversion

  Converts the value specified by Operand to a value specified by Result type
  and stores the converted value into the caller allocated output buffer
  specified by Result.  The caller must pass in a Result buffer that is at
  least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the conversion results in an overflow or an underflow condition, then
  Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Operand  Operand to be converted to new type
  @param[out]  Result   Pointer to the result of conversion

  @retval  RETURN_SUCCESS            Successful conversion
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeUint64ToUintn (
  IN  UINT64  Operand,
  OUT UINTN   *Result
  )
{
  return SafeUint64ToUint32 ((UINT64) Operand, (UINT32 *)Result);
}

/**
  UINTN addition

  Performs the requested operation using the input parameters into a value
  specified by Result type and stores the converted value into the caller
  allocated output buffer specified by Result.  The caller must pass in a
  Result buffer that is at least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the requested operation results in an overflow or an underflow condition,
  then Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Augend  A number to which addend will be added
  @param[in]   Addend  A number to be added to another
  @param[out]  Result  Pointer to the result of addition

  @retval  RETURN_SUCCESS            Successful addition
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeUintnAdd (
  IN  UINTN  Augend,
  IN  UINTN  Addend,
  OUT UINTN  *Result
  )
{
  RETURN_STATUS  Status;

  if (Result == NULL) {
    return RETURN_INVALID_PARAMETER;
  }

  if ((Augend + Addend) >= Augend) {
    *Result = (Augend + Addend);
    Status = RETURN_SUCCESS;
  } else {
    *Result = UINTN_ERROR;
    Status = RETURN_BUFFER_TOO_SMALL;
  }

  return Status;
}

/**
  UINTN subtraction

  Performs the requested operation using the input parameters into a value
  specified by Result type and stores the converted value into the caller
  allocated output buffer specified by Result.  The caller must pass in a
  Result buffer that is at least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the requested operation results in an overflow or an underflow condition,
  then Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Minuend     A number from which another is to be subtracted.
  @param[in]   Subtrahend  A number to be subtracted from another
  @param[out]  Result      Pointer to the result of subtraction

  @retval  RETURN_SUCCESS            Successful subtraction
  @retval  RETURN_BUFFER_TOO_SMALL   Underflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeUintnSub (
  IN  UINTN  Minuend,
  IN  UINTN  Subtrahend,
  OUT UINTN  *Result
  )
{
  RETURN_STATUS  Status;

  if (Result == NULL) {
    return RETURN_INVALID_PARAMETER;
  }

  if (Minuend >= Subtrahend) {
    *Result = (Minuend - Subtrahend);
    Status = RETURN_SUCCESS;
  } else {
    *Result = UINTN_ERROR;
    Status = RETURN_BUFFER_TOO_SMALL;
  }

  return Status;
}

/**
  UINTN multiplication

  Performs the requested operation using the input parameters into a value
  specified by Result type and stores the converted value into the caller
  allocated output buffer specified by Result.  The caller must pass in a
  Result buffer that is at least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the requested operation results in an overflow or an underflow condition,
  then Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Multiplicand  A number that is to be multiplied by another
  @param[in]   Multiplier    A number by which the multiplicand is to be multiplied
  @param[out]  Result        Pointer to the result of multiplication

  @retval  RETURN_SUCCESS            Successful multiplication
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeUintnMult (
  IN  UINTN  Multiplicand,
  IN  UINTN  Multiplier,
  OUT UINTN  *Result
  )
{
  UINT64  IntermediateResult;

  IntermediateResult = ((UINT64) Multiplicand) *((UINT64) Multiplier);

  return SafeUint64ToUintn (IntermediateResult, Result);
}

/**
  INTN Addition

  Performs the requested operation using the input parameters into a value
  specified by Result type and stores the converted value into the caller
  allocated output buffer specified by Result.  The caller must pass in a
  Result buffer that is at least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the requested operation results in an overflow or an underflow condition,
  then Result is set to INTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Augend  A number to which addend will be added
  @param[in]   Addend  A number to be added to another
  @param[out]  Result  Pointer to the result of addition

  @retval  RETURN_SUCCESS            Successful addition
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeIntnAdd (
  IN  INTN  Augend,
  IN  INTN  Addend,
  OUT INTN  *Result
  )
{
  return SafeInt64ToIntn (((INT64)Augend) + ((INT64)Addend), Result);
}

/**
  INTN Subtraction

  Performs the requested operation using the input parameters into a value
  specified by Result type and stores the converted value into the caller
  allocated output buffer specified by Result.  The caller must pass in a
  Result buffer that is at least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the requested operation results in an overflow or an underflow condition,
  then Result is set to INTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Minuend     A number from which another is to be subtracted.
  @param[in]   Subtrahend  A number to be subtracted from another
  @param[out]  Result      Pointer to the result of subtraction

  @retval  RETURN_SUCCESS            Successful subtraction
  @retval  RETURN_BUFFER_TOO_SMALL   Underflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeIntnSub (
  IN  INTN  Minuend,
  IN  INTN  Subtrahend,
  OUT INTN  *Result
  )
{
  return SafeInt64ToIntn (((INT64)Minuend) - ((INT64)Subtrahend), Result);
}

/**
  INTN multiplication

  Performs the requested operation using the input parameters into a value
  specified by Result type and stores the converted value into the caller
  allocated output buffer specified by Result.  The caller must pass in a
  Result buffer that is at least as large as the Result type.

  If Result is NULL, RETURN_INVALID_PARAMETER is returned.

  If the requested operation results in an overflow or an underflow condition,
  then Result is set to INTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.

  @param[in]   Multiplicand  A number that is to be multiplied by another
  @param[in]   Multiplier    A number by which the multiplicand is to be multiplied
  @param[out]  Result        Pointer to the result of multiplication

  @retval  RETURN_SUCCESS            Successful multiplication
  @retval  RETURN_BUFFER_TOO_SMALL   Overflow
  @retval  RETURN_INVALID_PARAMETER  Result is NULL
**/
RETURN_STATUS
EFIAPI
SafeIntnMult (
  IN  INTN  Multiplicand,
  IN  INTN  Multiplier,
  OUT INTN  *Result
  )
{
  return SafeInt64ToIntn (MultS64x64 (Multiplicand, Multiplier), Result);
}