0,0 → 1,125 |
/* |
FUNCTION |
<<strncpy>>---counted copy string |
|
INDEX |
strncpy |
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ANSI_SYNOPSIS |
#include <string.h> |
char *strncpy(char *<[dst]>, const char *<[src]>, size_t <[length]>); |
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TRAD_SYNOPSIS |
#include <string.h> |
char *strncpy(<[dst]>, <[src]>, <[length]>) |
char *<[dst]>; |
char *<[src]>; |
size_t <[length]>; |
|
DESCRIPTION |
<<strncpy>> copies not more than <[length]> characters from the |
the string pointed to by <[src]> (including the terminating |
null character) to the array pointed to by <[dst]>. If the |
string pointed to by <[src]> is shorter than <[length]> |
characters, null characters are appended to the destination |
array until a total of <[length]> characters have been |
written. |
|
RETURNS |
This function returns the initial value of <[dst]>. |
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PORTABILITY |
<<strncpy>> is ANSI C. |
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<<strncpy>> requires no supporting OS subroutines. |
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QUICKREF |
strncpy ansi pure |
*/ |
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#include <string.h> |
#include <limits.h> |
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/*SUPPRESS 560*/ |
/*SUPPRESS 530*/ |
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/* Nonzero if either X or Y is not aligned on a "long" boundary. */ |
#define UNALIGNED(X, Y) \ |
(((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1))) |
|
#if LONG_MAX == 2147483647L |
#define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080) |
#else |
#if LONG_MAX == 9223372036854775807L |
/* Nonzero if X (a long int) contains a NULL byte. */ |
#define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080) |
#else |
#error long int is not a 32bit or 64bit type. |
#endif |
#endif |
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#ifndef DETECTNULL |
#error long int is not a 32bit or 64bit byte |
#endif |
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#define TOO_SMALL(LEN) ((LEN) < sizeof (long)) |
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char * |
_DEFUN (strncpy, (dst0, src0), |
char *dst0 _AND |
_CONST char *src0 _AND |
size_t count) |
{ |
#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) |
char *dscan; |
_CONST char *sscan; |
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dscan = dst0; |
sscan = src0; |
while (count > 0) |
{ |
--count; |
if ((*dscan++ = *sscan++) == '\0') |
break; |
} |
while (count-- > 0) |
*dscan++ = '\0'; |
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return dst0; |
#else |
char *dst = dst0; |
_CONST char *src = src0; |
long *aligned_dst; |
_CONST long *aligned_src; |
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/* If SRC and DEST is aligned and count large enough, then copy words. */ |
if (!UNALIGNED (src, dst) && !TOO_SMALL (count)) |
{ |
aligned_dst = (long*)dst; |
aligned_src = (long*)src; |
|
/* SRC and DEST are both "long int" aligned, try to do "long int" |
sized copies. */ |
while (count >= sizeof (long int) && !DETECTNULL(*aligned_src)) |
{ |
count -= sizeof (long int); |
*aligned_dst++ = *aligned_src++; |
} |
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dst = (char*)aligned_dst; |
src = (char*)aligned_src; |
} |
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while (count > 0) |
{ |
--count; |
if ((*dst++ = *src++) == '\0') |
break; |
} |
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while (count-- > 0) |
*dst++ = '\0'; |
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return dst0; |
#endif /* not PREFER_SIZE_OVER_SPEED */ |
} |