fix aliasing-based undefined behavior in string functions

[musl] / src / string / stpcpy.c

diff --git a/src/string/stpcpy.c b/src/string/stpcpy.c
index 06623c4..4db46a9 100644 (file)
--- a/src/string/stpcpy.c
+++ b/src/string/stpcpy.c
@@ -1,7 +1,6 @@
 #include <string.h>
 #include <stdint.h>
 #include <limits.h>
-#include "libc.h"
 
 #define ALIGN (sizeof(size_t))
 #define ONES ((size_t)-1/UCHAR_MAX)
@@ -10,9 +9,10 @@
 
 char *__stpcpy(char *restrict d, const char *restrict s)
 {
-       size_t *wd;
-       const size_t *ws;
-
+#ifdef __GNUC__
+       typedef size_t __attribute__((__may_alias__)) word;
+       word *wd;
+       const word *ws;
        if ((uintptr_t)s % ALIGN == (uintptr_t)d % ALIGN) {
                for (; (uintptr_t)s % ALIGN; s++, d++)
                        if (!(*d=*s)) return d;
@@ -20,6 +20,7 @@ char *__stpcpy(char *restrict d, const char *restrict s)
                for (; !HASZERO(*ws); *wd++ = *ws++);
                d=(void *)wd; s=(const void *)ws;
        }
+#endif
        for (; (*d=*s); s++, d++);
 
        return d;