source: mainline/uspace/lib/libc/generic/string.c@ 576845ec

/*
 * 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 <unistd.h>
#include <ctype.h>
#include <limits.h>
#include <align.h>
#include <sys/types.h>
#include <malloc.h>

/** Fill memory block with a constant value. */
void *memset(void *dest, int b, size_t n)
{
        char *pb;
        unsigned long *pw;
        size_t word_size;
        size_t n_words;

        unsigned long pattern;
        size_t i;
        size_t fill;

        /* Fill initial segment. */
        word_size = sizeof(unsigned long);
        fill = word_size - ((uintptr_t) dest & (word_size - 1));
        if (fill > n) fill = n;

        pb = dest;

        i = fill;
        while (i-- != 0)
                *pb++ = b;

        /* Compute remaining size. */
        n -= fill;
        if (n == 0) return dest;

        n_words = n / word_size;
        n = n % word_size;
        pw = (unsigned long *) pb;

        /* Create word-sized pattern for aligned segment. */
        pattern = 0;
        i = word_size;
        while (i-- != 0)
                pattern = (pattern << 8) | (uint8_t) b;

        /* Fill aligned segment. */
        i = n_words;
        while (i-- != 0)
                *pw++ = pattern;

        pb = (char *) pw;

        /* Fill final segment. */
        i = n;
        while (i-- != 0)
                *pb++ = b;

        return dest;
}

struct along {
        unsigned long n;
} __attribute__ ((packed));

static void *unaligned_memcpy(void *dst, const void *src, size_t n)
{
        int i, j;
        struct along *adst = dst;
        const struct along *asrc = src;

        for (i = 0; i < n / sizeof(unsigned long); i++)
                adst[i].n = asrc[i].n;
                
        for (j = 0; j < n % sizeof(unsigned long); j++)
                ((unsigned char *) (((unsigned long *) dst) + i))[j] =
                    ((unsigned char *) (((unsigned long *) src) + i))[j];
                
        return (char *) dst;
}

/** Copy memory block. */
void *memcpy(void *dst, const void *src, size_t n)
{
        size_t i;
        size_t mod, fill;
        size_t word_size;
        size_t n_words;

        const unsigned long *srcw;
        unsigned long *dstw;
        const uint8_t *srcb;
        uint8_t *dstb;

        word_size = sizeof(unsigned long);

        /*
         * Are source and destination addresses congruent modulo word_size?
         * If not, use unaligned_memcpy().
         */

        if (((uintptr_t) dst & (word_size - 1)) !=
            ((uintptr_t) src & (word_size - 1)))
                return unaligned_memcpy(dst, src, n);

        /*
         * mod is the address modulo word size. fill is the length of the
         * initial buffer segment before the first word boundary.
         * If the buffer is very short, use unaligned_memcpy(), too.
         */

        mod = (uintptr_t) dst & (word_size - 1);
        fill = word_size - mod;
        if (fill > n) fill = n;

        /* Copy the initial segment. */

        srcb = src;
        dstb = dst;

        i = fill;
        while (i-- != 0)
                *dstb++ = *srcb++;

        /* Compute remaining length. */

        n -= fill;
        if (n == 0) return dst;

        /* Pointers to aligned segment. */

        dstw = (unsigned long *) dstb;
        srcw = (const unsigned long *) srcb;

        n_words = n / word_size;        /* Number of whole words to copy. */
        n -= n_words * word_size;       /* Remaining bytes at the end. */

        /* "Fast" copy. */
        i = n_words;
        while (i-- != 0)
                *dstw++ = *srcw++;

        /*
         * Copy the rest.
         */

        srcb = (const uint8_t *) srcw;
        dstb = (uint8_t *) dstw;

        i = n;
        while (i-- != 0)
                *dstb++ = *srcb++;

        return dst;
}

/** Move memory block with possible overlapping. */
void *memmove(void *dst, const void *src, size_t n)
{
        uint8_t *dp, *sp;

        /* Nothing to do? */
        if (src == dst)
                return dst;

        /* Non-overlapping? */
        if (dst >= src + n || src >= dst + n) { 
                return memcpy(dst, src, n);
        }

        /* Which direction? */
        if (src > dst) {
                /* Forwards. */
                sp = src;
                dp = dst;

                while (n-- != 0)
                        *dp++ = *sp++;
        } else {
                /* Backwards. */
                sp = src + (n - 1);
                dp = dst + (n - 1);

                while (n-- != 0)
                        *dp-- = *sp--;
        }

        return dst;
}

/** Compare two memory areas.
 *
 * @param s1            Pointer to the first area to compare.
 * @param s2            Pointer to the second area to compare.
 * @param len           Size of the first area in bytes. Both areas must have
 *                      the same length.
 * @return              If len is 0, return zero. If the areas match, return
 *                      zero. Otherwise return non-zero.
 */
int bcmp(const char *s1, const char *s2, size_t len)
{
        for (; len && *s1++ == *s2++; len--)
                ;
        return len;
}

/** 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;
}

/** @}
 */