source: trunk/third/sendmail/libsm/strl.c @ 19204

/*
 * Copyright (c) 1999-2002 Sendmail, Inc. and its suppliers.
 *      All rights reserved.
 *
 * By using this file, you agree to the terms and conditions set
 * forth in the LICENSE file which can be found at the top level of
 * the sendmail distribution.
 *
 */

#include <sm/gen.h>
SM_RCSID("@(#)$Id: strl.c,v 1.1.1.1 2003-04-08 15:06:50 zacheiss Exp $")
#include <sm/config.h>
#include <sm/string.h>

/*
**  Notice: this file is used by libmilter. Please try to avoid
**      using libsm specific functions.
*/

/*
**  XXX the type of the length parameter has been changed
**  from size_t to ssize_t to avoid theoretical problems with negative
**  numbers passed into these functions.
**  The real solution to this problem is to make sure that this doesn't
**  happen, but for now we'll use this workaround.
*/

/*
**  SM_STRLCPY -- size bounded string copy
**
**      This is a bounds-checking variant of strcpy.
**      If size > 0, copy up to size-1 characters from the nul terminated
**      string src to dst, nul terminating the result.  If size == 0,
**      the dst buffer is not modified.
**      Additional note: this function has been "tuned" to run fast and tested
**      as such (versus versions in some OS's libc).
**
**      The result is strlen(src).  You can detect truncation (not all
**      of the characters in the source string were copied) using the
**      following idiom:
**
**              char *s, buf[BUFSIZ];
**              ...
**              if (sm_strlcpy(buf, s, sizeof(buf)) >= sizeof(buf))
**                      goto overflow;
**
**      Parameters:
**              dst -- destination buffer
**              src -- source string
**              size -- size of destination buffer
**
**      Returns:
**              strlen(src)
*/

size_t
sm_strlcpy(dst, src, size)
        register char *dst;
        register const char *src;
        ssize_t size;
{
        register ssize_t i;

        if (size-- <= 0)
                return strlen(src);
        for (i = 0; i < size && (dst[i] = src[i]) != 0; i++)
                continue;
        dst[i] = '\0';
        if (src[i] == '\0')
                return i;
        else
                return i + strlen(src + i);
}

/*
**  SM_STRLCAT -- size bounded string concatenation
**
**      This is a bounds-checking variant of strcat.
**      If strlen(dst) < size, then append at most size - strlen(dst) - 1
**      characters from the source string to the destination string,
**      nul terminating the result.  Otherwise, dst is not modified.
**
**      The result is the initial length of dst + the length of src.
**      You can detect overflow (not all of the characters in the
**      source string were copied) using the following idiom:
**
**              char *s, buf[BUFSIZ];
**              ...
**              if (sm_strlcat(buf, s, sizeof(buf)) >= sizeof(buf))
**                      goto overflow;
**
**      Parameters:
**              dst -- nul-terminated destination string buffer
**              src -- nul-terminated source string
**              size -- size of destination buffer
**
**      Returns:
**              total length of the string tried to create
**              (= initial length of dst + length of src)
*/

size_t
sm_strlcat(dst, src, size)
        register char *dst;
        register const char *src;
        ssize_t size;
{
        register ssize_t i, j, o;

        o = strlen(dst);
        if (size < o + 1)
                return o + strlen(src);
        size -= o + 1;
        for (i = 0, j = o; i < size && (dst[j] = src[i]) != 0; i++, j++)
                continue;
        dst[j] = '\0';
        if (src[i] == '\0')
                return j;
        else
                return j + strlen(src + i);
}
/*
**  SM_STRLCAT2 -- append two strings to dst obeying length and
**              '\0' terminate it
**
**              strlcat2 will append at most len - strlen(dst) - 1 chars.
**              terminates with '\0' if len > 0
**              dst = dst "+" src1 "+" src2
**              use this instead of sm_strlcat(dst,src1); sm_strlcat(dst,src2);
**              for better speed.
**
**      Parameters:
**              dst -- "destination" string.
**              src1 -- "from" string 1.
**              src2 -- "from" string 2.
**              len -- max. length of "destination" string.
**
**      Returns:
**              total length of the string tried to create
**              (= initial length of dst + length of src)
**              if this is greater than len then an overflow would have
**              occurred.
**
*/

size_t
sm_strlcat2(dst, src1, src2, len)
        register char *dst;
        register const char *src1;
        register const char *src2;
        ssize_t len;
{
        register ssize_t i, j, o;

        /* current size of dst */
        o = strlen(dst);

        /* max. size is less than current? */
        if (len < o + 1)
                return o + strlen(src1) + strlen(src2);

        len -= o + 1;   /* space left in dst */

        /* copy the first string; i: index in src1; j: index in dst */
        for (i = 0, j = o; i < len && (dst[j] = src1[i]) != 0; i++, j++)
                continue;

        /* src1: end reached? */
        if (src1[i] != '\0')
        {
                /* no: terminate dst; there is space since i < len */
                dst[j] = '\0';
                return j + strlen(src1 + i) + strlen(src2);
        }

        len -= i;       /* space left in dst */

        /* copy the second string; i: index in src2; j: index in dst */
        for (i = 0; i < len && (dst[j] = src2[i]) != 0; i++, j++)
                continue;
        dst[j] = '\0';  /* terminate dst; there is space since i < len */
        if (src2[i] == '\0')
                return j;
        else
                return j + strlen(src2 + i);
}

/*
**  SM_STRLCPYN -- concatenate n strings and assign the result to dst
**              while obeying length and '\0' terminate it
**
**              dst = src1 "+" src2 "+" ...
**              use this instead of sm_snprintf() for string values
**              and repeated sm_strlc*() calls for better speed.
**
**      Parameters:
**              dst -- "destination" string.
**              len -- max. length of "destination" string.
**              n -- number of strings
**              strings...
**
**      Returns:
**              total length of the string tried to create
**              (= initial length of dst + length of src)
**              if this is greater than len then an overflow would have
**              occurred.
*/

size_t
#ifdef __STDC__
sm_strlcpyn(char *dst, ssize_t len, int n, ...)
#else /* __STDC__ */
sm_strlcpyn(dst, len, n, va_alist)
        register char *dst;
        ssize_t len;
        int n;
        va_dcl
#endif /* __STDC__ */
{
        register ssize_t i, j;
        char *str;
        SM_VA_LOCAL_DECL

        SM_VA_START(ap, n);

        if (len-- <= 0) /* This allows space for the terminating '\0' */
        {
                i = 0;
                while (n-- > 0)
                        i += strlen(SM_VA_ARG(ap, char *));
                SM_VA_END(ap);
                return i;
        }

        j = 0;  /* index in dst */

        /* loop through all source strings */
        while (n-- > 0)
        {
                str = SM_VA_ARG(ap, char *);

                /* copy string; i: index in str; j: index in dst */
                for (i = 0; j < len && (dst[j] = str[i]) != 0; i++, j++)
                        continue;

                /* str: end reached? */
                if (str[i] != '\0')
                {
                        /* no: terminate dst; there is space since j < len */
                        dst[j] = '\0';
                        j += strlen(str + i);
                        while (n-- > 0)
                                j += strlen(SM_VA_ARG(ap, char *));
                        SM_VA_END(ap);
                        return j;
                }
        }
        SM_VA_END(ap);

        dst[j] = '\0';  /* terminate dst; there is space since j < len */
        return j;
}

#if 0
/*
**  SM_STRLAPP -- append string if it fits into buffer.
**
**      If size > 0, copy up to size-1 characters from the nul terminated
**      string src to dst, nul terminating the result.  If size == 0,
**      the dst buffer is not modified.
**
**      This routine is useful for appending strings in a loop, e.g, instead of
**      s = buf;
**      for (ptr, ptr != NULL, ptr = next->ptr)
**      {
**              (void) sm_strlcpy(s, ptr->string, sizeof buf - (s - buf));
**              s += strlen(s);
**      }
**      replace the loop body with:
**              if (!sm_strlapp(*s, ptr->string, sizeof buf - (s - buf)))
**                      break;
**      it's faster...
**
**      XXX interface isn't completely clear (yet), hence this code is
**      not available.
**
**
**      Parameters:
**              dst -- (pointer to) destination buffer
**              src -- source string
**              size -- size of destination buffer
**
**      Returns:
**              true if strlen(src) < size
**
**      Side Effects:
**              modifies dst if append succeeds (enough space).
*/

bool
sm_strlapp(dst, src, size)
        register char **dst;
        register const char *src;
        ssize_t size;
{
        register size_t i;

        if (size-- <= 0)
                return false;
        for (i = 0; i < size && ((*dst)[i] = src[i]) != '\0'; i++)
                continue;
        (*dst)[i] = '\0';
        if (src[i] == '\0')
        {
                *dst += i;
                return true;
        }

        /* undo */
        (*dst)[0] = '\0';
        return false;
}
#endif /* 0 */