| #include "libc.h" |
| #include <limits.h> |
| #include <stdint.h> |
| #include <string.h> |
| |
| #define ALIGN (sizeof(size_t) - 1) |
| #define ONES ((size_t)-1 / UCHAR_MAX) |
| #define HIGHS (ONES * (UCHAR_MAX / 2 + 1)) |
| #define HASZERO(x) (((x)-ONES) & ~(x)&HIGHS) |
| |
| char* __stpncpy(char* restrict d, const char* restrict s, size_t n) { |
| // This reads past the end of the string, which is usually OK since |
| // it won't cross a page boundary. But under ASan, even one byte |
| // past the actual end is diagnosed. |
| if (!__has_feature(address_sanitizer) && |
| ((uintptr_t)s & ALIGN) == ((uintptr_t)d & ALIGN)) { |
| for (; ((uintptr_t)s & ALIGN) && n && (*d = *s); n--, s++, d++) |
| ; |
| if (!n || !*s) |
| goto tail; |
| size_t* wd = (void*)d; |
| const size_t* ws = (const void*)s; |
| for (; n >= sizeof(size_t) && !HASZERO(*ws); n -= sizeof(size_t), ws++, wd++) |
| *wd = *ws; |
| d = (void*)wd; |
| s = (const void*)ws; |
| } |
| for (; n && (*d = *s); n--, s++, d++) |
| ; |
| tail: |
| memset(d, 0, n); |
| return d; |
| } |
| |
| weak_alias(__stpncpy, stpncpy); |