[sanitizers] Add a blocking boolean to GetRandom prototype

Summary:
On platforms with `getrandom`, the system call defaults to blocking. This
becomes an issue in the very early stage of the boot for Scudo, when the RNG
source is not set-up yet: the syscall will block and we'll stall.

Introduce a parameter to specify that the function should not block, defaulting
to blocking as the underlying syscall does.

Update Scudo to use the non-blocking version.

Reviewers: alekseyshl

Reviewed By: alekseyshl

Subscribers: llvm-commits, kubamracek

Differential Revision: https://reviews.llvm.org/D36399

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@310839 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/sanitizer_common/sanitizer_mac.cc b/lib/sanitizer_common/sanitizer_mac.cc
index 38b418314..6cb75266b 100644
--- a/lib/sanitizer_common/sanitizer_mac.cc
+++ b/lib/sanitizer_common/sanitizer_mac.cc
@@ -992,7 +992,7 @@ void CheckNoDeepBind(const char *filename, int flag) {
 }
 
 // FIXME: implement on this platform.
-bool GetRandom(void *buffer, uptr length) {
+bool GetRandom(void *buffer, uptr length, bool blocking) {
   UNIMPLEMENTED();
 }