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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;

}

/** @}

 */