source: mainline/uspace/lib/libc/generic/string.c@ cb01e1e

/*
 * 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;
}

/** @}
 */