Unix/Process.inc: Give more useful random seed to srand. Workaround for PR12743.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156252 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/Unix/Process.inc b/lib/Support/Unix/Process.inc
index de98262..dd855b0 100644
--- a/lib/Support/Unix/Process.inc
+++ b/lib/Support/Unix/Process.inc
@@ -298,11 +298,24 @@
return "\033[0m";
}
+#if !defined(HAVE_ARC4RANDOM)
+static unsigned GetRandomNumberSeed() {
+ unsigned seed = ::time(NULL); // FIXME: It might not provide unique seed.
+ FILE *RandomSource = ::fopen("/dev/urandom", "r");
+ if (RandomSource) {
+ ::fread((void *)&seed, sizeof(seed), 1, RandomSource);
+ ::fclose(RandomSource);
+ }
+ return seed;
+}
+#endif
+
unsigned llvm::sys::Process::GetRandomNumber() {
#if defined(HAVE_ARC4RANDOM)
return arc4random();
#else
- static int x = (::srand(::time(NULL)), 0);
+ static int x = (::srand(GetRandomNumberSeed()), 0);
+ (void)x;
return ::rand();
#endif
}