modules/rosapps/applications/net/ncftp/Strn/Strnpcpy.c

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