From 4d0a82170a25464c39522d7190b9fe302045ddb2 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Wed, 26 Sep 2018 14:39:10 -0400 Subject: fix aliasing-based undefined behavior in string functions use the GNU C may_alias attribute if available, and fallback to naive byte-by-byte loops if __GNUC__ is not defined. this patch has been written to minimize changes so that history remains reviewable; it does not attempt to bring the affected code into a more consistent or elegant form. --- src/string/stpcpy.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'src/string/stpcpy.c') diff --git a/src/string/stpcpy.c b/src/string/stpcpy.c index 54cf9ca5..4db46a9e 100644 --- a/src/string/stpcpy.c +++ b/src/string/stpcpy.c @@ -9,9 +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; @@ -19,6 +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; -- cgit v1.2.1