linux/drivers/acpi/acpica/utstrtoul64.c

/*******************************************************************************
 *
 * Module Name: utstrtoul64 - string to 64-bit integer support
 *
 ******************************************************************************/

/*
 * Copyright (C) 2000 - 2017, Intel Corp.
 * 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,
 *    without modification.
 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
 *    substantially similar to the "NO WARRANTY" disclaimer below
 *    ("Disclaimer") and any redistribution must be conditioned upon
 *    including a substantially similar Disclaimer requirement for further
 *    binary redistribution.
 * 3. Neither the names of the above-listed copyright holders nor the names
 *    of any contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * 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 MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR 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 DAMAGES.
 */

#include <acpi/acpi.h>
#include "accommon.h"

/*******************************************************************************
 *
 * The functions in this module satisfy the need for 64-bit string-to-integer
 * conversions on both 32-bit and 64-bit platforms.
 *
 ******************************************************************************/

#define _COMPONENT          ACPI_UTILITIES
ACPI_MODULE_NAME("utstrtoul64")

/* Local prototypes */
static u64 acpi_ut_strtoul_base10(char *string, u32 flags);

static u64 acpi_ut_strtoul_base16(char *string, u32 flags);

/*******************************************************************************
 *
 * String conversion rules as written in the ACPI specification. The error
 * conditions and behavior are different depending on the type of conversion.
 *
 *
 * Implicit data type conversion: string-to-integer
 * --------------------------------------------------
 *
 * Base is always 16. This is the ACPI_STRTOUL_BASE16 case.
 *
 * Example:
 *      Add ("BA98", Arg0, Local0)
 *
 * The integer is initialized to the value zero.
 * The ASCII string is interpreted as a hexadecimal constant.
 *
 *  1)  A "0x" prefix is not allowed. However, ACPICA allows this for
 *      compatibility with previous ACPICA. (NO ERROR)
 *
 *  2)  Terminates when the size of an integer is reached (32 or 64 bits).
 *      (NO ERROR)
 *
 *  3)  The first non-hex character terminates the conversion without error.
 *      (NO ERROR)
 *
 *  4)  Conversion of a null (zero-length) string to an integer is not
 *      allowed. However, ACPICA allows this for compatibility with previous
 *      ACPICA. This conversion returns the value 0. (NO ERROR)
 *
 *
 * Explicit data type conversion:  to_integer() with string operand
 * ---------------------------------------------------------------
 *
 * Base is either 10 (default) or 16 (with 0x prefix)
 *
 * Examples:
 *      to_integer ("1000")
 *      to_integer ("0xABCD")
 *
 *  1)  Can be (must be) either a decimal or hexadecimal numeric string.
 *      A hex value must be prefixed by "0x" or it is interpreted as a decimal.
 *
 *  2)  The value must not exceed the maximum of an integer value. ACPI spec
 *      states the behavior is "unpredictable", so ACPICA matches the behavior
 *      of the implicit conversion case.(NO ERROR)
 *
 *  3)  Behavior on the first non-hex character is not specified by the ACPI
 *      spec, so ACPICA matches the behavior of the implicit conversion case
 *      and terminates. (NO ERROR)
 *
 *  4)  A null (zero-length) string is illegal.
 *      However, ACPICA allows this for compatibility with previous ACPICA.
 *      This conversion returns the value 0. (NO ERROR)
 *
 ******************************************************************************/

/*******************************************************************************
 *
 * FUNCTION:    acpi_ut_strtoul64
 *
 * PARAMETERS:  string                  - Null terminated input string
 *              flags                   - Conversion info, see below
 *              return_value            - Where the converted integer is
 *                                        returned
 *
 * RETURN:      Status and Converted value
 *
 * DESCRIPTION: Convert a string into an unsigned value. Performs either a
 *              32-bit or 64-bit conversion, depending on the input integer
 *              size in Flags (often the current mode of the interpreter).
 *
 * Values for Flags:
 *      ACPI_STRTOUL_32BIT      - Max integer value is 32 bits
 *      ACPI_STRTOUL_64BIT      - Max integer value is 64 bits
 *      ACPI_STRTOUL_BASE16     - Input string is hexadecimal. Default
 *                                is 10/16 based on string prefix (0x).
 *
 * NOTES:
 *   Negative numbers are not supported, as they are not supported by ACPI.
 *
 *   Supports only base 16 or base 10 strings/values. Does not
 *   support Octal strings, as these are not supported by ACPI.
 *
 * Current users of this support:
 *
 *  interpreter - Implicit and explicit conversions, GPE method names
 *  debugger    - Command line input string conversion
 *  iASL        - Main parser, conversion of constants to integers
 *  iASL        - Data Table Compiler parser (constant math expressions)
 *  iASL        - Preprocessor (constant math expressions)
 *  acpi_dump   - Input table addresses
 *  acpi_exec   - Testing of the acpi_ut_strtoul64 function
 *
 * Note concerning callers:
 *   acpi_gbl_integer_byte_width can be used to set the 32/64 limit. If used,
 *   this global should be set to the proper width. For the core ACPICA code,
 *   this width depends on the DSDT version. For iASL, the default byte
 *   width is always 8 for the parser, but error checking is performed later
 *   to flag cases where a 64-bit constant is defined in a 32-bit DSDT/SSDT.
 *
 ******************************************************************************/

acpi_status acpi_ut_strtoul64(char *string, u32 flags, u64 *return_value)
{
	acpi_status status = AE_OK;
	u32 base;

	ACPI_FUNCTION_TRACE_STR(ut_strtoul64, string);

	/* Parameter validation */

	if (!string || !return_value) {
		return_ACPI_STATUS(AE_BAD_PARAMETER);
	}

	*return_value = 0;

	/* Check for zero-length string, returns 0 */

	if (*string == 0) {
		return_ACPI_STATUS(AE_OK);
	}

	/* Skip over any white space at start of string */

	while (isspace((int)*string)) {
		string++;
	}

	/* End of string? return 0 */

	if (*string == 0) {
		return_ACPI_STATUS(AE_OK);
	}

	/*
	 * 1) The "0x" prefix indicates base 16. Per the ACPI specification,
	 * the "0x" prefix is only allowed for implicit (non-strict) conversions.
	 * However, we always allow it for compatibility with older ACPICA.
	 */
	if ((*string == ACPI_ASCII_ZERO) &&
	    (tolower((int)*(string + 1)) == 'x')) {
		string += 2;	/* Go past the 0x */
		if (*string == 0) {
			return_ACPI_STATUS(AE_OK);	/* Return value 0 */
		}

		base = 16;
	}

	/* 2) Force to base 16 (implicit conversion case) */

	else if (flags & ACPI_STRTOUL_BASE16) {
		base = 16;
	}

	/* 3) Default fallback is to Base 10 */

	else {
		base = 10;
	}

	/* Skip all leading zeros */

	while (*string == ACPI_ASCII_ZERO) {
		string++;
		if (*string == 0) {
			return_ACPI_STATUS(AE_OK);	/* Return value 0 */
		}
	}

	/* Perform the base 16 or 10 conversion */

	if (base == 16) {
		*return_value = acpi_ut_strtoul_base16(string, flags);
	} else {
		*return_value = acpi_ut_strtoul_base10(string, flags);
	}

	return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ut_strtoul_base10
 *
 * PARAMETERS:  string                  - Null terminated input string
 *              flags                   - Conversion info
 *
 * RETURN:      64-bit converted integer
 *
 * DESCRIPTION: Performs a base 10 conversion of the input string to an
 *              integer value, either 32 or 64 bits.
 *              Note: String must be valid and non-null.
 *
 ******************************************************************************/

static u64 acpi_ut_strtoul_base10(char *string, u32 flags)
{
	int ascii_digit;
	u64 next_value;
	u64 return_value = 0;

	/* Main loop: convert each ASCII byte in the input string */

	while (*string) {
		ascii_digit = *string;
		if (!isdigit(ascii_digit)) {

			/* Not ASCII 0-9, terminate */

			goto exit;
		}

		/* Convert and insert (add) the decimal digit */

		acpi_ut_short_multiply(return_value, 10, &next_value);
		next_value += (ascii_digit - ACPI_ASCII_ZERO);

		/* Check for overflow (32 or 64 bit) - return current converted value */

		if (((flags & ACPI_STRTOUL_32BIT) && (next_value > ACPI_UINT32_MAX)) || (next_value < return_value)) {	/* 64-bit overflow case */
			goto exit;
		}

		return_value = next_value;
		string++;
	}

exit:
	return (return_value);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ut_strtoul_base16
 *
 * PARAMETERS:  string                  - Null terminated input string
 *              flags                   - conversion info
 *
 * RETURN:      64-bit converted integer
 *
 * DESCRIPTION: Performs a base 16 conversion of the input string to an
 *              integer value, either 32 or 64 bits.
 *              Note: String must be valid and non-null.
 *
 ******************************************************************************/

static u64 acpi_ut_strtoul_base16(char *string, u32 flags)
{
	int ascii_digit;
	u32 valid_digits = 1;
	u64 return_value = 0;

	/* Main loop: convert each ASCII byte in the input string */

	while (*string) {

		/* Check for overflow (32 or 64 bit) - return current converted value */

		if ((valid_digits > 16) ||
		    ((valid_digits > 8) && (flags & ACPI_STRTOUL_32BIT))) {
			goto exit;
		}

		ascii_digit = *string;
		if (!isxdigit(ascii_digit)) {

			/* Not Hex ASCII A-F, a-f, or 0-9, terminate */

			goto exit;
		}

		/* Convert and insert the hex digit */

		acpi_ut_short_shift_left(return_value, 4, &return_value);
		return_value |= acpi_ut_ascii_char_to_hex(ascii_digit);

		string++;
		valid_digits++;
	}

exit:
	return (return_value);
}