6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-08-07 12:28:24 +00:00
Code Issues Projects Releases Wiki Activity

[Support] Fix sys::GetRandomNumber() to always use a high quality seed.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156414 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Daniel Dunbar
2012-05-08 20:38:00 +00:00
parent ab3a7fb244
commit 2b8f3ba843
1 changed files with 15 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
lib/Support/Unix/Process.inc
View File

@@ -12,6 +12,8 @@
//===----------------------------------------------------------------------===// //===----------------------------------------------------------------------===//
#include "Unix.h" #include "Unix.h"
#include "llvm/ADT/Hashing.h"
#include "llvm/Support/TimeValue.h"
#ifdef HAVE_SYS_TIME_H #ifdef HAVE_SYS_TIME_H
#include <sys/time.h> #include <sys/time.h>
#endif #endif
@@ -300,13 +302,21 @@ const char *Process::ResetColor() {
#if !defined(HAVE_ARC4RANDOM) #if !defined(HAVE_ARC4RANDOM)
static unsigned GetRandomNumberSeed() { static unsigned GetRandomNumberSeed() {
unsigned seed = ::time(NULL); // FIXME: It might not provide unique seed. // Attempt to get the initial seed from /dev/urandom, if possible.
FILE *RandomSource = ::fopen("/dev/urandom", "r"); if (FILE *RandomSource = ::fopen("/dev/urandom", "r")) {
if (RandomSource) { unsigned seed;
::fread((void *)&seed, sizeof(seed), 1, RandomSource); int count = ::fread((void *)&seed, sizeof(seed), 1, RandomSource);
::fclose(RandomSource); ::fclose(RandomSource);
// Return the seed if the read was successful.
if (count == 1)
return seed;
} }
return seed;
// Otherwise, swizzle the current time and the process ID to form a reasonable
// seed.
TimeValue Now = llvm::TimeValue::now();
return hash_combine(Now.seconds(), Now.nanoseconds(), ::getpid());
} }
#endif #endif