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Unix/Process.inc: Give more useful random seed to srand. Workaround for PR12743. 

llvm-svn: 156252
This commit is contained in:
NAKAMURA Takumi 2012-05-06 08:24:24 +00:00
parent 54acb28882
commit 7bec74112d
1 changed files with 14 additions and 1 deletions
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15
llvm/lib/Support/Unix/Process.inc
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@ -298,11 +298,24 @@ const char *Process::ResetColor() {
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
}