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54 lines
1.5 KiB
C
54 lines
1.5 KiB
C
#include <sys/types.h>
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#include <string.h>
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#include "Strn.h"
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/*
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* Concatenate src on the end of dst. The resulting string will have at most
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* n-1 characters, not counting the NUL terminator which is always appended
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* unlike strncat. The other big difference is that strncpy uses n as the
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* max number of characters _appended_, while this routine uses n to limit
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* the overall length of dst.
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*
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* This routine also differs in that it returns a pointer to the end
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* of the buffer, instead of strncat which returns a pointer to the start.
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*/
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char *
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Strnpcat(char *const dst, const char *const src, size_t n)
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{
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register size_t i;
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register char *d;
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register const char *s;
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register char c;
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char *ret;
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if (n != 0 && ((i = strlen(dst)) < (n - 1))) {
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d = dst + i;
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s = src;
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/* If they specified a maximum of n characters, use n - 1 chars to
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* hold the copy, and the last character in the array as a NUL.
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* This is the difference between the regular strncpy routine.
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* strncpy doesn't guarantee that your new string will have a
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* NUL terminator, but this routine does.
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*/
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for (++i; i<n; i++) {
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c = *s++;
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if (c == '\0') {
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ret = d; /* Return ptr to end byte. */
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*d++ = c;
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#if (STRNP_ZERO_PAD == 1)
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/* Pad with zeros. */
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for (; i<n; i++)
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*d++ = 0;
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#endif /* STRNP_ZERO_PAD */
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return ret;
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}
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*d++ = c;
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}
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/* If we get here, then we have a full string, with n - 1 characters,
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* so now we NUL terminate it and go home.
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*/
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*d = 0;
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return (d); /* Return ptr to end byte. */
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}
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return (dst);
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} /* Strnpcat */
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