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| author | Rich Felker <dalias@aerifal.cx> | 2018-09-26 14:39:10 -0400 |
|---|---|---|
| committer | Rich Felker <dalias@aerifal.cx> | 2018-09-26 14:39:10 -0400 |
| commit | 4d0a82170a25464c39522d7190b9fe302045ddb2 (patch) | |
| tree | b3a469567ed3a995300c9751b824ef20b84f154d /src/string/stpncpy.c | |
| parent | 8cd738bbee3b4e60a99b71599c338bf444070f18 (diff) | |
| download | musl-4d0a82170a25464c39522d7190b9fe302045ddb2.tar.gz | |
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.
Diffstat (limited to 'src/string/stpncpy.c')
| -rw-r--r-- | src/string/stpncpy.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/src/string/stpncpy.c b/src/string/stpncpy.c index d6d92ffc..f57fa6b7 100644 --- a/src/string/stpncpy.c +++ b/src/string/stpncpy.c @@ -9,9 +9,10 @@ char *__stpncpy(char *restrict d, const char *restrict s, size_t n) { - 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) && n && (*d=*s); n--, s++, d++); if (!n || !*s) goto tail; @@ -20,6 +21,7 @@ char *__stpncpy(char *restrict d, const char *restrict s, size_t n) n-=sizeof(size_t), ws++, wd++) *wd = *ws; d=(void *)wd; s=(const void *)ws; } +#endif for (; n && (*d=*s); n--, s++, d++); tail: memset(d, 0, n); |