From 554fd8c5195424bdbcabf5de30fdc183aba391bd Mon Sep 17 00:00:00 2001 From: upstream source tree Date: Sun, 15 Mar 2015 20:14:05 -0400 Subject: obtained gcc-4.6.4.tar.bz2 from upstream website; verified gcc-4.6.4.tar.bz2.sig; imported gcc-4.6.4 source tree from verified upstream tarball. downloading a git-generated archive based on the 'upstream' tag should provide you with a source tree that is binary identical to the one extracted from the above tarball. if you have obtained the source via the command 'git clone', however, do note that line-endings of files in your working directory might differ from line-endings of the respective files in the upstream repository. --- .../gnu/java/security/jce/prng/VMSecureRandom.java | 129 +++++++++++++++++++++ 1 file changed, 129 insertions(+) create mode 100644 libjava/classpath/vm/reference/gnu/java/security/jce/prng/VMSecureRandom.java (limited to 'libjava/classpath/vm/reference/gnu/java/security/jce/prng') diff --git a/libjava/classpath/vm/reference/gnu/java/security/jce/prng/VMSecureRandom.java b/libjava/classpath/vm/reference/gnu/java/security/jce/prng/VMSecureRandom.java new file mode 100644 index 000000000..86faa097c --- /dev/null +++ b/libjava/classpath/vm/reference/gnu/java/security/jce/prng/VMSecureRandom.java @@ -0,0 +1,129 @@ +/* VMSecureRandom.java -- random seed generator. + Copyright (C) 2006 Free Software Foundation, Inc. + +This file is a part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or (at +your option) any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; if not, write to the Free Software +Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 +USA + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package gnu.java.security.jce.prng; + +/** + * VM-specific methods for generating real (or almost real) random + * seeds. VM implementors should write a version of this class that + * reads random bytes from some system source. + * + *

The default implementation of this class runs eight threads that + * increment counters in a tight loop, and XORs each counter to + * produce one byte of seed data. This is not very efficient, and is + * not guaranteed to be random (the thread scheduler is probably + * deterministic, after all). If possible, VM implementors should + * reimplement this class so it obtains a random seed from a system + * facility, such as a system entropy gathering device or hardware + * random number generator. + */ +final class VMSecureRandom +{ + + /** + * Generate a random seed. Implementations are free to generate + * fewer random bytes than are requested, and leave the remaining + * bytes of the destination buffer as zeros. Implementations SHOULD, + * however, make a best-effort attempt to satisfy the request. + * + * @param buffer The destination buffer. + * @param offset The offset in the buffer to start putting bytes. + * @param length The number of random bytes to generate. + */ + static int generateSeed(byte[] buffer, int offset, int length) + { + if (length < 0) + throw new IllegalArgumentException("length must be nonnegative"); + if (offset < 0 || offset + length > buffer.length) + throw new IndexOutOfBoundsException(); + + Spinner[] spinners = new Spinner[8]; + int n = 0x1; + for (int i = 0; i < spinners.length; i++) + { + spinners[i] = new Spinner((byte) n); + Thread t = new Thread(spinners[i]); + t.start(); + n <<= 1; + } + + // Wait until at least one spinner has started. + while (!(spinners[0].running || spinners[1].running || spinners[2].running + || spinners[3].running || spinners[4].running || spinners[5].running + || spinners[6].running || spinners[7].running)) + { + Thread.yield(); + } + + for (int i = offset; i < length; i++) + { + buffer[i] = (byte) (spinners[0].value ^ spinners[1].value ^ spinners[2].value + ^ spinners[3].value ^ spinners[4].value ^ spinners[5].value + ^ spinners[6].value ^ spinners[7].value); + Thread.yield(); + } + + for (int i = 0; i < spinners.length; i++) + spinners[i].stop(); + + return length; + } + + static class Spinner implements Runnable + { + volatile byte value; + volatile boolean running; + + Spinner(final byte initial) + { + value = initial; + } + + public void run() + { + running = true; + while (running) + value++; + } + + private void stop() + { + running = false; + } + } +} -- cgit v1.2.3