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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 <assert.h>

#include <limits.h>

#include <ctype.h>

#include <malloc.h>

#include <errno.h>

#include <align.h>

#include <mem.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;

}

/** Get size of string.

 *

 * Get the number of bytes which are used by the string @a str (excluding the

 * NULL-terminator).

 *

 * @param str String to consider.

 *

 * @return Number of bytes used by the string

 *

 */

size_t str_size(const char *str)

{

    size_t size = 0;

    while (*str++ != 0)

        size++;

    return size;

}

/** Get size of wide string.

 *

 * Get the number of bytes which are used by the wide string @a str (excluding the

 * NULL-terminator).

 *

 * @param str Wide string to consider.

 *

 * @return Number of bytes used by the wide string

 *

 */

size_t wstr_size(const wchar_t *str)

{

    return (wstr_length(str) * sizeof(wchar_t));

}

/** Get size of string with length limit.

 *

 * Get the number of bytes which are used by up to @a max_len first

 * characters in the string @a str. If @a max_len is greater than

 * the length of @a str, the entire string is measured (excluding the

 * NULL-terminator).

 *

 * @param str     String to consider.

 * @param max_len Maximum number of characters to measure.

 *

 * @return Number of bytes used by the characters.

 *

 */

size_t str_lsize(const char *str, count_t max_len)

{

    count_t len = 0;

    size_t offset = 0;

    while (len < max_len) {

        if (str_decode(str, &offset, STR_NO_LIMIT) == 0)

            break;

        len++;

    }

    return offset;

}

/** Get size of wide string with length limit.

 *

 * Get the number of bytes which are used by up to @a max_len first

 * wide characters in the wide string @a str. If @a max_len is greater than

 * the length of @a str, the entire wide string is measured (excluding the

 * NULL-terminator).

 *

 * @param str     Wide string to consider.

 * @param max_len Maximum number of wide characters to measure.

 *

 * @return Number of bytes used by the wide characters.

 *

 */

size_t wstr_lsize(const wchar_t *str, count_t max_len)

{

    return (wstr_nlength(str, max_len * sizeof(wchar_t)) * sizeof(wchar_t));

}

/** Get number of characters in a string.

 *

 * @param str NULL-terminated string.

 *

 * @return Number of characters in string.

 *

 */

count_t str_length(const char *str)

{

    count_t len = 0;

    size_t offset = 0;

    while (str_decode(str, &offset, STR_NO_LIMIT) != 0)

        len++;

    return len;

}

/** Get number of characters in a wide string.

 *

 * @param str NULL-terminated wide string.

 *

 * @return Number of characters in @a str.

 *

 */

count_t wstr_length(const wchar_t *wstr)

{

    count_t len = 0;

    while (*wstr++ != 0)

        len++;

    return len;

}

/** Get number of characters in a string with size limit.

 *

 * @param str  NULL-terminated string.

 * @param size Maximum number of bytes to consider.

 *

 * @return Number of characters in string.

 *

 */

count_t str_nlength(const char *str, size_t size)

{

    count_t len = 0;

    size_t offset = 0;

    while (str_decode(str, &offset, size) != 0)

        len++;

    return len;

}

/** Get number of characters in a string with size limit.

 *

 * @param str  NULL-terminated string.

 * @param size Maximum number of bytes to consider.

 *

 * @return Number of characters in string.

 *

 */

count_t wstr_nlength(const wchar_t *str, size_t size)

{

    count_t len = 0;

    count_t limit = ALIGN_DOWN(size, sizeof(wchar_t));

    count_t offset = 0;

    while ((offset < limit) && (*str++ != 0)) {

        len++;

        offset += sizeof(wchar_t);

    }

    return len;

}

/** Check whether character is plain ASCII.

 *

 * @return True if character is plain ASCII.

 *

 */

bool ascii_check(wchar_t ch)

{

    if ((ch >= 0) && (ch <= 127))

        return true;

    return false;

}

/** Check whether character is valid

 *

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

 *

 */

bool chr_check(wchar_t ch)

{

    if ((ch >= 0) && (ch <= 1114111))

        return true;

    return false;

}

/** Compare two NULL terminated strings.

 *

 * Do a char-by-char comparison of two NULL-terminated strings.

 * The strings are considered equal iff they consist of the same

 * characters on the minimum of their lengths.

 *

 * @param s1 First string to compare.

 * @param s2 Second string to compare.

 *

 * @return 0 if the strings are equal, -1 if first is smaller,

 *         1 if second smaller.

 *

 */

int str_cmp(const char *s1, const char *s2)

{

    wchar_t c1 = 0;

    wchar_t c2 = 0;

    size_t off1 = 0;

    size_t off2 = 0;

    while (true) {

        c1 = str_decode(s1, &off1, STR_NO_LIMIT);

        c2 = str_decode(s2, &off2, STR_NO_LIMIT);

        if (c1 < c2)

            return -1;

        if (c1 > c2)

            return 1;

        if (c1 == 0 || c2 == 0)

            break;     

    }

    return 0;

}

/** Compare two NULL terminated strings with length limit.

 *

 * Do a char-by-char comparison of two NULL-terminated strings.

 * The strings are considered equal iff they consist of the same

 * characters on the minimum of their lengths and the length limit.

 *

 * @param s1      First string to compare.

 * @param s2      Second string to compare.

 * @param max_len Maximum number of characters to consider.

 *

 * @return 0 if the strings are equal, -1 if first is smaller,

 *         1 if second smaller.

 *

 */

int str_lcmp(const char *s1, const char *s2, count_t max_len)

{

    wchar_t c1 = 0;

    wchar_t c2 = 0;

    size_t off1 = 0;

    size_t off2 = 0;

    count_t len = 0;

    while (true) {

        if (len >= max_len)

            break;

        c1 = str_decode(s1, &off1, STR_NO_LIMIT);

        c2 = str_decode(s2, &off2, STR_NO_LIMIT);

        if (c1 < c2)

            return -1;

        if (c1 > c2)

            return 1;

        if (c1 == 0 || c2 == 0)

            break;

        ++len; 

    }

    return 0;

}

/** Copy string.

 *

 * Copy source string @a src to destination buffer @a dest.

 * No more than @a size bytes are written. If the size of the output buffer

 * is at least one byte, the output string will always be well-formed, i.e.

 * null-terminated and containing only complete characters.

 *

 * @param dst   Destination buffer.

 * @param count Size of the destination buffer (must be > 0).

 * @param src   Source string.

 */

void str_cpy(char *dest, size_t size, const char *src)

{

    wchar_t ch;

    size_t src_off;

    size_t dest_off;

    /* There must be space for a null terminator in the buffer. */

    assert(size > 0);

    src_off = 0;

    dest_off = 0;

    while ((ch = str_decode(src, &src_off, STR_NO_LIMIT)) != 0) {

        if (chr_encode(ch, dest, &dest_off, size - 1) != EOK)

            break;

    }

    dest[dest_off] = '\0';

}

/** Copy size-limited substring.

 *

 * Copy prefix of string @a src of max. size @a size to destination buffer

 * @a dest. No more than @a size bytes are written. The output string will

 * always be well-formed, i.e. null-terminated and containing only complete

 * characters.

 *

 * No more than @a n bytes are read from the input string, so it does not

 * have to be null-terminated.

 *

 * @param dst   Destination buffer.

 * @param count Size of the destination buffer (must be > 0).

 * @param src   Source string.

 * @param n Maximum number of bytes to read from @a src.

 */

void str_ncpy(char *dest, size_t size, const char *src, size_t n)

{

    wchar_t ch;

    size_t src_off;

    size_t dest_off;

    /* There must be space for a null terminator in the buffer. */

    assert(size > 0);

    src_off = 0;

    dest_off = 0;

    while ((ch = str_decode(src, &src_off, n)) != 0) {

        if (chr_encode(ch, dest, &dest_off, size - 1) != EOK)

            break;

    }

    dest[dest_off] = '\0';

}

/** Append one string to another.

 *

 * Append source string @a src to string in destination buffer @a dest.

 * Size of the destination buffer is @a dest. If the size of the output buffer

 * is at least one byte, the output string will always be well-formed, i.e.

 * null-terminated and containing only complete characters.

 *

 * @param dst   Destination buffer.

 * @param count Size of the destination buffer.

 * @param src   Source string.

 */

void str_append(char *dest, size_t size, const char *src)

{

    size_t dstr_size;

    dstr_size = str_size(dest);

    str_cpy(dest + dstr_size, size - dstr_size, src);

}

/** Copy NULL-terminated wide string to string

 *

 * Copy source wide string @a src to destination buffer @a dst.

 * No more than @a size bytes are written. NULL-terminator is always

 * written after the last succesfully copied character (i.e. if the

 * destination buffer is has at least 1 byte, it will be always

 * NULL-terminated).

 *

 * @param src   Source wide string.

 * @param dst   Destination buffer.

 * @param count Size of the destination buffer.

 *

 */

void wstr_nstr(char *dst, const wchar_t *src, size_t size)

{

    /* No space for the NULL-terminator in the buffer */

    if (size == 0)

        return;

    wchar_t ch;

    count_t src_idx = 0;

    size_t dst_off = 0;

    while ((ch = src[src_idx++]) != 0) {

        if (chr_encode(ch, dst, &dst_off, size) != EOK)

            break;

    }

    if (dst_off >= size)

        dst[size - 1] = 0;

    else

        dst[dst_off] = 0;

}

/** Find first occurence of character in string.

 *

 * @param str String to search.

 * @param ch  Character to look for.

 *

 * @return Pointer to character in @a str or NULL if not found.

 */

const char *str_chr(const char *str, wchar_t ch)

{

    wchar_t acc;

    size_t off = 0;

    size_t last = 0;

    while ((acc = str_decode(str, &off, STR_NO_LIMIT)) != 0) {

        if (acc == ch)

            return (str + last);

        last = off;

    }

    return NULL;

}

/** Find last occurence of character in string.

 *

 * @param str String to search.

 * @param ch  Character to look for.

 *

 * @return Pointer to character in @a str or NULL if not found.

 */

const char *str_rchr(const char *str, wchar_t ch)

{

    wchar_t acc;

    size_t off = 0;

    size_t last = 0;

    char *res = NULL;

    while ((acc = str_decode(str, &off, STR_NO_LIMIT)) != 0) {

        if (acc == ch)

            res = (str + last);

        last = off;

    }

    return res;

}

/** Insert a wide character into a wide string.

 *

 * Insert a wide character into a wide string at position

 * @a pos. The characters after the position are shifted.

 *

 * @param str     String to insert to.

 * @param ch      Character to insert to.

 * @param pos     Character index where to insert.

 @ @param max_pos Characters in the buffer.

 *

 * @return True if the insertion was sucessful, false if the position

 *         is out of bounds.

 *

 */

bool wstr_linsert(wchar_t *str, wchar_t ch, count_t pos, count_t max_pos)

{

    count_t len = wstr_length(str);

    if ((pos > len) || (pos + 1 > max_pos))

        return false;

    count_t i;

    for (i = len; i + 1 > pos; i--)

        str[i + 1] = str[i];

    str[pos] = ch;

    return true;

}

/** Remove a wide character from a wide string.

 *

 * Remove a wide character from a wide string at position

 * @a pos. The characters after the position are shifted.

 *

 * @param str String to remove from.

 * @param pos Character index to remove.

 *

 * @return True if the removal was sucessful, false if the position

 *         is out of bounds.

 *

 */

bool wstr_remove(wchar_t *str, count_t pos)

{

    count_t len = wstr_length(str);

    if (pos >= len)

        return false;

    count_t i;

    for (i = pos + 1; i <= len; i++)

        str[i - 1] = str[i];

    return true;

}

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]));

}

/** 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.