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[/] [openrisc/] [tags/] [gnu-src/] [newlib-1.18.0/] [newlib-1.18.0-or32-1.0rc2/] [newlib/] [libc/] [string/] [strncat.c] - Blame information for rev 802

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Line No. Rev Author Line
1 207 jeremybenn
/*
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FUNCTION
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        <<strncat>>---concatenate strings
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INDEX
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        strncat
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ANSI_SYNOPSIS
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        #include <string.h>
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        char *strncat(char *<[dst]>, const char *<[src]>, size_t <[length]>);
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TRAD_SYNOPSIS
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        #include <string.h>
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        char *strncat(<[dst]>, <[src]>, <[length]>)
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        char *<[dst]>;
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        char *<[src]>;
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        size_t <[length]>;
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DESCRIPTION
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        <<strncat>> appends not more than <[length]> characters from
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        the string pointed to by <[src]> (including the terminating
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        null character) to the end of the string pointed to by
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        <[dst]>.  The initial character of <[src]> overwrites the null
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        character at the end of <[dst]>.  A terminating null character
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        is always appended to the result
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WARNINGS
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        Note that a null is always appended, so that if the copy is
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        limited by the <[length]> argument, the number of characters
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        appended to <[dst]> is <<n + 1>>.
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RETURNS
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        This function returns the initial value of <[dst]>
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PORTABILITY
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<<strncat>> is ANSI C.
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<<strncat>> requires no supporting OS subroutines.
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QUICKREF
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        strncat ansi pure
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*/
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#include <string.h>
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#include <limits.h>
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/* Nonzero if X is aligned on a "long" boundary.  */
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#define ALIGNED(X) \
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  (((long)X & (sizeof (long) - 1)) == 0)
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#if LONG_MAX == 2147483647L
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#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
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#else
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#if LONG_MAX == 9223372036854775807L
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/* Nonzero if X (a long int) contains a NULL byte. */
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#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
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#else
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#error long int is not a 32bit or 64bit type.
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#endif
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#endif
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#ifndef DETECTNULL
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#error long int is not a 32bit or 64bit byte
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#endif
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char *
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_DEFUN (strncat, (s1, s2, n),
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        char *s1 _AND
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        _CONST char *s2 _AND
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        size_t n)
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{
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#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
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  char *s = s1;
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  while (*s1)
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    s1++;
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  while (n-- != 0 && (*s1++ = *s2++))
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    {
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      if (n == 0)
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        *s1 = '\0';
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    }
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  return s;
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#else
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  char *s = s1;
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  /* Skip over the data in s1 as quickly as possible.  */
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  if (ALIGNED (s1))
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    {
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      unsigned long *aligned_s1 = (unsigned long *)s1;
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      while (!DETECTNULL (*aligned_s1))
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        aligned_s1++;
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      s1 = (char *)aligned_s1;
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    }
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  while (*s1)
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    s1++;
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  /* s1 now points to the its trailing null character, now copy
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     up to N bytes from S2 into S1 stopping if a NULL is encountered
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     in S2.
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     It is not safe to use strncpy here since it copies EXACTLY N
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     characters, NULL padding if necessary.  */
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  while (n-- != 0 && (*s1++ = *s2++))
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    {
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      if (n == 0)
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        *s1 = '\0';
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    }
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  return s;
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#endif /* not PREFER_SIZE_OVER_SPEED */
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}

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