Implement getentropy for Cygwin

* miscfuncs.cc (getentropy): Move fhandler_dev_random::crypt_gen_random
	here and rename to getentropy.  Fix type and return values to match
	getentropy requirements.
	* miscfuncs.h (getentropy): Add prototype.
	* fhandler.h (fhandler_dev_random::crypt_gen_random): Remove prototype.
	* fhandler_random.cc (fhandler_dev_random::crypt_gen_random): Drop.
	(fhandler_dev_random::write): Use getentropy instead.
	(fhandler_dev_random::read): Ditto.
	* fhandler_socket.cc (fhandler_socket::af_local_set_secret): Ditto.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/fhandler.h

@@ -1731,8 +1731,6 @@ class fhandler_dev_random: public fhandler_base
   void __reg3 read (void *ptr, size_t& len);
   off_t lseek (off_t, int) { return 0; }
 
-  static bool crypt_gen_random (void *ptr, size_t len);
-
   fhandler_dev_random () : fhandler_base () {}
   fhandler_dev_random (void *) {}
 

winsup/cygwin/fhandler_random.cc

@@ -29,23 +29,6 @@ details. */
 #define PSEUDO_MULTIPLIER       (6364136223846793005LL)
 #define PSEUDO_SHIFTVAL		(21)
 
-/* There's a bug in ntsecapi.h (Mingw as well as MSFT).  SystemFunction036
-   is, in fact, a WINAPI function, but it's not defined as such.  Therefore
-   we have to do it correctly here. */
-#define RtlGenRandom SystemFunction036
-extern "C" BOOLEAN WINAPI RtlGenRandom (PVOID, ULONG);
-
-bool
-fhandler_dev_random::crypt_gen_random (void *ptr, size_t len)
-{
-  if (!RtlGenRandom (ptr, len))
-    {
-      debug_printf ("%E = RtlGenRandom()");
-      return false;
-    }
-  return true;
-}
-
 int
 fhandler_dev_random::pseudo_write (const void *ptr, size_t len)
 {
@@ -73,11 +56,8 @@ fhandler_dev_random::write (const void *ptr, size_t len)
   memcpy (buf, ptr, limited_len);
 
   /* Mess up system entropy source. Return error if device is /dev/random. */
-  if (!crypt_gen_random (buf, limited_len) && dev () == FH_RANDOM)
-    {
-      __seterrno ();
-      return -1;
-    }
+  if (getentropy (buf, limited_len) && dev () == FH_RANDOM)
+    return -1;
   /* Mess up the pseudo random number generator. */
   pseudo_write (buf, limited_len);
   return len;
@@ -125,10 +105,9 @@ fhandler_dev_random::read (void *ptr, size_t& len)
 	}
       for (size_t offset = 0; offset < len; offset += 512)
 	{
-	  if (!crypt_gen_random (dummy, RESEED_INTERVAL) ||
-	      !crypt_gen_random ((PBYTE) ptr + offset, len - offset))
+	  if (getentropy (dummy, RESEED_INTERVAL) ||
+	      getentropy ((PBYTE) ptr + offset, len - offset))
 	    {
-	      __seterrno ();
 	      len = (size_t) -1;
 	      break;
 	    }
@@ -138,6 +117,6 @@ fhandler_dev_random::read (void *ptr, size_t& len)
 
   /* If device is /dev/urandom, just use system RNG as is, with our own
      PRNG as fallback. */
-  else if (!crypt_gen_random (ptr, len))
+  else if (getentropy (ptr, len))
     len = pseudo_read (ptr, len);
 }

winsup/cygwin/fhandler_socket.cc

@@ -488,8 +488,7 @@ fhandler_socket::af_local_copy (fhandler_socket *sock)
 void
 fhandler_socket::af_local_set_secret (char *buf)
 {
-  if (!fhandler_dev_random::crypt_gen_random (connect_secret,
-					      sizeof (connect_secret)))
+  if (getentropy (connect_secret, sizeof (connect_secret)))
     bzero ((char*) connect_secret, sizeof (connect_secret));
   __small_sprintf (buf, "%08x-%08x-%08x-%08x",
 		   connect_secret [0], connect_secret [1],

winsup/cygwin/miscfuncs.cc

@@ -236,6 +236,25 @@ check_iovec (const struct iovec *iov, int iovcnt, bool forwrite)
   return -1;
 }
 
+/* There's a bug in ntsecapi.h (Mingw as well as MSFT).  SystemFunction036
+   is, in fact, a WINAPI function, but it's not defined as such.  Therefore
+   we have to do it correctly here. */
+#define RtlGenRandom SystemFunction036
+extern "C" BOOLEAN WINAPI RtlGenRandom (PVOID, ULONG);
+
+/* Used by arc2random, fhandler_socket and fhandler_random. */
+extern "C" int
+getentropy (void *ptr, size_t len)
+{
+  if (!RtlGenRandom (ptr, len))
+    {
+      debug_printf ("%E = RtlGenRandom()");
+      set_errno (EIO);
+      return -1;
+    }
+  return 0;
+}
+
 /* Try hard to schedule another thread.  
    Remember not to call this in a lock condition or you'll potentially
    suffer starvation.  */

winsup/cygwin/miscfuncs.h

@@ -15,6 +15,8 @@ details. */
 #define likely(X) __builtin_expect (!!(X), 1)
 #define unlikely(X) __builtin_expect (!!(X), 0)
 
+extern "C" int getentropy (void *ptr, size_t len);
+
 int __reg1 winprio_to_nice (DWORD);
 DWORD __reg1 nice_to_winprio (int &);