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/*

 * Copyright (c) 2005 Martin Decky

 * Copyright (c) 2008 Jiri Svoboda

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - 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.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.

 */

/** @addtogroup libc

 * @{

 */

/** @file

 */

#include <string.h>

#include <stdlib.h>

#include <limits.h>

#include <ctype.h>

#include <malloc.h>

#include <errno.h>

#include <string.h>

/** Byte mask consisting of lowest @n bits (out of 8) */

#define LO_MASK_8(n)  ((uint8_t) ((1 << (n)) - 1))

/** Byte mask consisting of lowest @n bits (out of 32) */

#define LO_MASK_32(n)  ((uint32_t) ((1 << (n)) - 1))

/** Byte mask consisting of highest @n bits (out of 8) */

#define HI_MASK_8(n)  (~LO_MASK_8(8 - (n)))

/** Number of data bits in a UTF-8 continuation byte */

#define CONT_BITS  6

/** Decode a single character from a string.

 *

 * Decode a single character from a string of size @a size. Decoding starts

 * at @a offset and this offset is moved to the beginning of the next

 * character. In case of decoding error, offset generally advances at least

 * by one. However, offset is never moved beyond size.

 *

 * @param str    String (not necessarily NULL-terminated).

 * @param offset Byte offset in string where to start decoding.

 * @param size   Size of the string (in bytes).

 *

 * @return Value of decoded character, U_SPECIAL on decoding error or

 *         NULL if attempt to decode beyond @a size.

 *

 */

wchar_t str_decode(const char *str, size_t *offset, size_t size)

{

	if (*offset + 1 > size)

		return 0;

	/* First byte read from string */

	uint8_t b0 = (uint8_t) str[(*offset)++];

	/* Determine code length */

	unsigned int b0_bits;  /* Data bits in first byte */

	unsigned int cbytes;   /* Number of continuation bytes */

	if ((b0 & 0x80) == 0) {

		/* 0xxxxxxx (Plain ASCII) */

		b0_bits = 7;

		cbytes = 0;

	} else if ((b0 & 0xe0) == 0xc0) {

		/* 110xxxxx 10xxxxxx */

		b0_bits = 5;

		cbytes = 1;

	} else if ((b0 & 0xf0) == 0xe0) {

		/* 1110xxxx 10xxxxxx 10xxxxxx */

		b0_bits = 4;

		cbytes = 2;

	} else if ((b0 & 0xf8) == 0xf0) {

		/* 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx */

		b0_bits = 3;

		cbytes = 3;

	} else {

		/* 10xxxxxx -- unexpected continuation byte */

		return U_SPECIAL;

	}

	if (*offset + cbytes > size)

		return U_SPECIAL;

	wchar_t ch = b0 & LO_MASK_8(b0_bits);

	/* Decode continuation bytes */

	while (cbytes > 0) {

		uint8_t b = (uint8_t) str[(*offset)++];

		/* Must be 10xxxxxx */

		if ((b & 0xc0) != 0x80)

			return U_SPECIAL;

		/* Shift data bits to ch */

		ch = (ch << CONT_BITS) | (wchar_t) (b & LO_MASK_8(CONT_BITS));

		cbytes--;

	}

	return ch;

}

/** Encode a single character to string representation.

 *

 * Encode a single character to string representation (i.e. UTF-8) and store

 * it into a buffer at @a offset. Encoding starts at @a offset and this offset

 * is moved to the position where the next character can be written to.

 *

 * @param ch     Input character.

 * @param str    Output buffer.

 * @param offset Byte offset where to start writing.

 * @param size   Size of the output buffer (in bytes).

 *

 * @return EOK if the character was encoded successfully, EOVERFLOW if there

 *	   was not enough space in the output buffer or EINVAL if the character

 *	   code was invalid.

 */

int chr_encode(const wchar_t ch, char *str, size_t *offset, size_t size)

{

	if (*offset >= size)

		return EOVERFLOW;

	if (!chr_check(ch))

		return EINVAL;

	/* Unsigned version of ch (bit operations should only be done

	   on unsigned types). */

	uint32_t cc = (uint32_t) ch;

	/* Determine how many continuation bytes are needed */

	unsigned int b0_bits;  /* Data bits in first byte */

	unsigned int cbytes;   /* Number of continuation bytes */

	if ((cc & ~LO_MASK_32(7)) == 0) {

		b0_bits = 7;

		cbytes = 0;

	} else if ((cc & ~LO_MASK_32(11)) == 0) {

		b0_bits = 5;

		cbytes = 1;

	} else if ((cc & ~LO_MASK_32(16)) == 0) {

		b0_bits = 4;

		cbytes = 2;

	} else if ((cc & ~LO_MASK_32(21)) == 0) {

		b0_bits = 3;

		cbytes = 3;

	} else {

		/* Codes longer than 21 bits are not supported */

		return EINVAL;

	}

	/* Check for available space in buffer */

	if (*offset + cbytes >= size)

		return EOVERFLOW;

	/* Encode continuation bytes */

	unsigned int i;

	for (i = cbytes; i > 0; i--) {

		str[*offset + i] = 0x80 | (cc & LO_MASK_32(CONT_BITS));

		cc = cc >> CONT_BITS;

	}

	/* Encode first byte */

	str[*offset] = (cc & LO_MASK_32(b0_bits)) | HI_MASK_8(8 - b0_bits - 1);

	/* Advance offset */

	*offset += cbytes + 1;

	return EOK;

}

/** Check whether character is valid

 *

 * @return True if character is a valid Unicode code point.

 *

 */

bool chr_check(const wchar_t ch)

{

	if ((ch >= 0) && (ch <= 1114111))

		return true;

	return false;

}

/** Count the number of characters in the string, not including terminating 0.

 *

 * @param str		String.

 * @return		Number of characters in string.

 */

size_t strlen(const char *str) 

{

	size_t counter = 0;

	while (str[counter] != 0)

		counter++;

	return counter;

}

int strcmp(const char *a, const char *b)

{

	int c = 0;

	while (a[c] && b[c] && (!(a[c] - b[c])))

		c++;

	return (a[c] - b[c]);

}

int strncmp(const char *a, const char *b, size_t n)

{

	size_t c = 0;

	while (c < n && a[c] && b[c] && (!(a[c] - b[c])))

		c++;

	return ( c < n ? a[c] - b[c] : 0);

}

int stricmp(const char *a, const char *b)

{

	int c = 0;

	while (a[c] && b[c] && (!(tolower(a[c]) - tolower(b[c]))))

		c++;

	return (tolower(a[c]) - tolower(b[c]));

}

/** Return pointer to the first occurence of character c in string.

 *

 * @param str		Scanned string.

 * @param c		Searched character (taken as one byte).

 * @return		Pointer to the matched character or NULL if it is not

 * 			found in given string.

 */

char *strchr(const char *str, int c)

{

	while (*str != '\0') {

		if (*str == (char) c)

			return (char *) str;

		str++;

	}

	return NULL;

}

/** Return pointer to the last occurence of character c in string.

 *

 * @param str		Scanned string.

 * @param c		Searched character (taken as one byte).

 * @return		Pointer to the matched character or NULL if it is not

 * 			found in given string.

 */

char *strrchr(const char *str, int c)

{

	char *retval = NULL;

	while (*str != '\0') {

		if (*str == (char) c)

			retval = (char *) str;

		str++;

	}

	return (char *) retval;

}

/** Convert string to a number. 

 * Core of strtol and strtoul functions.

 *

 * @param nptr		Pointer to string.

 * @param endptr	If not NULL, function stores here pointer to the first

 * 			invalid character.

 * @param base		Zero or number between 2 and 36 inclusive.

 * @param sgn		It's set to 1 if minus found.

 * @return		Result of conversion.

 */

static unsigned long

_strtoul(const char *nptr, char **endptr, int base, char *sgn)

{

	unsigned char c;

	unsigned long result = 0;

	unsigned long a, b;

	const char *str = nptr;

	const char *tmpptr;

	while (isspace(*str))

		str++;

	if (*str == '-') {

		*sgn = 1;

		++str;

	} else if (*str == '+')

		++str;

	if (base) {

		if ((base == 1) || (base > 36)) {

			/* FIXME: set errno to EINVAL */

			return 0;

		}

		if ((base == 16) && (*str == '0') && ((str[1] == 'x') ||

		    (str[1] == 'X'))) {

			str += 2;

		}

	} else {

		base = 10;

		if (*str == '0') {

			base = 8;

			if ((str[1] == 'X') || (str[1] == 'x'))  {

				base = 16;

				str += 2;

			}

		} 

	}

	tmpptr = str;

	while (*str) {

		c = *str;

		c = (c >= 'a' ? c - 'a' + 10 : (c >= 'A' ? c - 'A' + 10 :

		    (c <= '9' ? c - '0' : 0xff)));

		if (c > base) {

			break;

		}

		a = (result & 0xff) * base + c;

		b = (result >> 8) * base + (a >> 8);

		if (b > (ULONG_MAX >> 8)) {

			/* overflow */

			/* FIXME: errno = ERANGE*/

			return ULONG_MAX;

		}

		result = (b << 8) + (a & 0xff);

		++str;

	}

	if (str == tmpptr) {

		/*

		 * No number was found => first invalid character is the first

		 * character of the string.

		 */

		/* FIXME: set errno to EINVAL */

		str = nptr;

		result = 0;

	}

	if (endptr)

		*endptr = (char *) str;

	if (nptr == str) { 

		/*FIXME: errno = EINVAL*/

		return 0;

	}

	return result;

}

/** Convert initial part of string to long int according to given base.

 * The number may begin with an arbitrary number of whitespaces followed by

 * optional sign (`+' or `-'). If the base is 0 or 16, the prefix `0x' may be

 * inserted and the number will be taken as hexadecimal one. If the base is 0

 * and the number begin with a zero, number will be taken as octal one (as with

 * base 8). Otherwise the base 0 is taken as decimal.

 *

 * @param nptr		Pointer to string.

 * @param endptr	If not NULL, function stores here pointer to the first

 * 			invalid character.

 * @param base		Zero or number between 2 and 36 inclusive.

 * @return		Result of conversion.

 */

long int strtol(const char *nptr, char **endptr, int base)

{

	char sgn = 0;

	unsigned long number = 0;

	number = _strtoul(nptr, endptr, base, &sgn);

	if (number > LONG_MAX) {

		if ((sgn) && (number == (unsigned long) (LONG_MAX) + 1)) {

			/* FIXME: set 0 to errno */

			return number;		

		}

		/* FIXME: set ERANGE to errno */

		return (sgn ? LONG_MIN : LONG_MAX);	

	}

	return (sgn ? -number : number);

}

/** Convert initial part of string to unsigned long according to given base.

 * The number may begin with an arbitrary number of whitespaces followed by

 * optional sign (`+' or `-'). If the base is 0 or 16, the prefix `0x' may be

 * inserted and the number will be taken as hexadecimal one. If the base is 0

 * and the number begin with a zero, number will be taken as octal one (as with

 * base 8). Otherwise the base 0 is taken as decimal.

 *

 * @param nptr		Pointer to string.

 * @param endptr	If not NULL, function stores here pointer to the first

 * 			invalid character

 * @param base		Zero or number between 2 and 36 inclusive.

 * @return		Result of conversion.

 */

unsigned long strtoul(const char *nptr, char **endptr, int base)

{

	char sgn = 0;

	unsigned long number = 0;

	number = _strtoul(nptr, endptr, base, &sgn);

	return (sgn ? -number : number);

}

char *strcpy(char *dest, const char *src)

{

	char *orig = dest;

	while ((*(dest++) = *(src++)))

		;

	return orig;

}

char *strncpy(char *dest, const char *src, size_t n)

{

	char *orig = dest;

	while ((*(dest++) = *(src++)) && --n)

		;

	return orig;

}

char *strcat(char *dest, const char *src)

{

	char *orig = dest;

	while (*dest++)

		;

	--dest;

	while ((*dest++ = *src++))

		;

	return orig;

}

char * strdup(const char *s1)

{

	size_t len = strlen(s1) + 1;

	void *ret = malloc(len);

	if (ret == NULL)

		return (char *) NULL;

	return (char *) memcpy(ret, s1, len);

}

char *strtok(char *s, const char *delim)

{

	static char *next;

	return strtok_r(s, delim, &next);

}

char *strtok_r(char *s, const char *delim, char **next)

{

	char *start, *end;

	if (s == NULL)

		s = *next;

	/* Skip over leading delimiters. */

	while (*s && (strchr(delim, *s) != NULL)) ++s;

	start = s;

	/* Skip over token characters. */

	while (*s && (strchr(delim, *s) == NULL)) ++s;

	end = s;

	*next = (*s ? s + 1 : s);

	if (start == end) {

		return NULL;	/* No more tokens. */

	}

	/* Overwrite delimiter with NULL terminator. */

	*end = '\0';

	return start;

}

/** @}

 */