reactos/apps/utils/net/ncftp/Strn/Strnpcat.c

   1 #include <sys/types.h>
   2 #include <string.h>
   3 #include "Strn.h"
   4
   5 /*
   6  * Concatenate src on the end of dst.  The resulting string will have at most
   7  * n-1 characters, not counting the NUL terminator which is always appended
   8  * unlike strncat.  The other big difference is that strncpy uses n as the
   9  * max number of characters _appended_, while this routine uses n to limit
  10  * the overall length of dst.
  11  *
  12  * This routine also differs in that it returns a pointer to the end
  13  * of the buffer, instead of strncat which returns a pointer to the start.
  14  */
  15 char *
  16 Strnpcat(char *const dst, const char *const src, size_t n)
  17 {
  18         register size_t i;
  19         register char *d;
  20         register const char *s;
  21         register char c;
  22         char *ret;
  23
  24         if (n != 0 && ((i = strlen(dst)) < (n - 1))) {
  25                 d = dst + i;
  26                 s = src;
  27                 /* If they specified a maximum of n characters, use n - 1 chars to
  28                  * hold the copy, and the last character in the array as a NUL.
  29                  * This is the difference between the regular strncpy routine.
  30                  * strncpy doesn't guarantee that your new string will have a
  31                  * NUL terminator, but this routine does.
  32                  */
  33                 for (++i; i<n; i++) {
  34                         c = *s++;
  35                         if (c == '\0') {
  36                                 ret = d;        /* Return ptr to end byte. */
  37                                 *d++ = c;
  38 #if (STRNP_ZERO_PAD == 1)
  39                                 /* Pad with zeros. */
  40                                 for (; i<n; i++)
  41                                         *d++ = 0;
  42 #endif  /* STRNP_ZERO_PAD */
  43                                 return ret;
  44                         }
  45                         *d++ = c;
  46                 }
  47                 /* If we get here, then we have a full string, with n - 1 characters,
  48                  * so now we NUL terminate it and go home.
  49                  */
  50                 *d = 0;
  51                 return (d);     /* Return ptr to end byte. */
  52         }
  53         return (dst);
  54 }       /* Strnpcat */