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| author | Greg Hazel <ghazel@gmail.com> | 2012-05-29 12:39:12 -0700 |
|---|---|---|
| committer | Nick Mathewson <nickm@torproject.org> | 2012-05-31 00:48:24 -0400 |
| commit | bff5f9407341030c77a29fc1c398083ccdb4e277 (patch) | |
| tree | 794fddf375f71e79800640bc90edceff4e3b8c49 /evutil_rand.c | |
| parent | faa92253e96172a4b2002a6bbc5385a7d710238f (diff) | |
| download | libevent-bff5f9407341030c77a29fc1c398083ccdb4e277.tar.gz | |
check for arc4random_buf at runtime, on OS X
(Tweaked by nickm: Fix up the arcr4andom_buf OSX hack so that the
fallback case isn't compiled into the code when we have
arc4random_buf() and we are not on OSX. Also add a comment
explaining what's up.)
Diffstat (limited to 'evutil_rand.c')
| -rw-r--r-- | evutil_rand.c | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/evutil_rand.c b/evutil_rand.c index 3cc163d3..e2bf605f 100644 --- a/evutil_rand.c +++ b/evutil_rand.c @@ -58,10 +58,22 @@ evutil_secure_rng_global_setup_locks_(const int enable_locks) static void ev_arc4random_buf(void *buf, size_t n) { -#ifdef _EVENT_HAVE_ARC4RANDOM_BUF + unsigned char *b = buf; +#if defined(_EVENT_HAVE_ARC4RANDOM_BUF) && !defined(__APPLE__) return arc4random_buf(buf, n); #else - unsigned char *b = buf; + +#if defined(_EVENT_HAVE_ARC4RANDOM_BUF) + /* OSX 10.7 introducd arc4random_buf, so if you build your program + * there, you'll get surprised when older versions of OSX fail to run. + * To solve this, we can check whether the function pointer is set, + * and fall back otherwise. (OSX does this using some linker + * trickery.) + */ + if (arc4random_buf) { + return arc4random_buf(buf, n); + } +#endif /* Make sure that we start out with b at a 4-byte alignment; plenty * of CPUs care about this for 32-bit access. */ if (n >= 4 && ((ev_uintptr_t)b) & 3) { |