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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/memchr.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/memchr.c')
| -rw-r--r-- | src/string/memchr.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/src/string/memchr.c b/src/string/memchr.c index 4daff7bb..65f0d789 100644 --- a/src/string/memchr.c +++ b/src/string/memchr.c @@ -12,12 +12,16 @@ void *memchr(const void *src, int c, size_t n) { const unsigned char *s = src; c = (unsigned char)c; +#ifdef __GNUC__ for (; ((uintptr_t)s & ALIGN) && n && *s != c; s++, n--); if (n && *s != c) { - const size_t *w; + typedef size_t __attribute__((__may_alias__)) word; + const word *w; size_t k = ONES * c; for (w = (const void *)s; n>=SS && !HASZERO(*w^k); w++, n-=SS); - for (s = (const void *)w; n && *s != c; s++, n--); + s = (const void *)w; } +#endif + for (; n && *s != c; s++, n--); return n ? (void *)s : 0; } |