Merge branch 'upstream' into debian

1 files changed, 213 insertions, 0 deletions

diff --git a/Src/Modules/random_real.c b/Src/Modules/random_real.c
new file mode 100644
index 000000000..4a8fcae19
--- /dev/null
+++ b/Src/Modules/random_real.c
@@ -0,0 +1,213 @@
+/*  This file contains code under different copyrights separated by */
+/* ====@@@@@=== */
+
+/*
+ * random_real.c - module to access kernel random sources.
+ *
+ * This file is part of zsh, the Z shell.
+ *
+ * Copyright (c) 2022 Clinton Bunch
+ * All rights reserved.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and to distribute modified versions of this software for any
+ * purpose, provided that the above copyright notice and the following
+ * two paragraphs appear in all copies of this software.
+ *
+ * In no event shall Clinton Bunch or the Zsh Development Group be liable
+ * to any party for direct, indirect, special, incidental, or consequential
+ * damages arising out of the use of this software and its documentation,
+ * even if Clinton Bunch and the Zsh Development Group have been advised of
+ * the possibility of such damage.
+ *
+ * Clinton Bunch and the Zsh Development Group specifically disclaim any
+ * warranties, including, but not limited to, the implied warranties of
+ * merchantability and fitness for a particular purpose.  The software
+ * provided hereunder is on an "as is" basis, and Clinton Bunch and the
+ * Zsh Development Group have no obligation to provide maintenance,
+ * support, updates, enhancements, or modifications.
+ *
+ */
+
+#include "random.mdh"
+
+#include <math.h>
+#include <stdint.h>
+#include <errno.h>
+
+
+/* Count the number of leading zeros, hopefully in gcc/clang by HW
+ * instruction */
+#if defined(__GNUC__) || defined(__clang__)
+#define clz64(x) __builtin_clzll(x)
+#else
+#define clz64(x) _zclz64(x)
+
+/**/
+int
+_zclz64(uint64_t x) {
+    int n = 0;
+
+    if (x == 0)
+	return 64;
+
+    if (!(x & 0xFFFFFFFF00000000ull)) {
+	n+=32;
+	x<<=32;
+    }
+    if (!(x & 0xFFFF000000000000ull)) {
+	n+=16;
+	x<<=16;
+    }
+    if (!(x & 0xFF00000000000000ull)) {
+	n+=8;
+	x<<=8;
+    }
+    if (!(x & 0xF000000000000000ull)) {
+	n+=4;
+	x<<=4;
+    }
+    if (!(x & 0xC000000000000000ull)) {
+	n+=2;
+	x<<=1;
+    }
+    if (!(x & 0x8000000000000000ull)) {
+	n+=1;
+    }
+    return n;
+}
+#endif /* __GNU_C__ or __clang__ */
+
+/**/
+uint64_t
+random_64bit(void) {
+    uint64_t r;
+
+    if(getrandom_buffer(&r,sizeof(r)) < 0) {
+	zwarn("zsh/random: Can't get sufficient random data.");
+	return 1; /* 0 will cause loop */
+    }
+
+    return r;
+}
+
+/* ====@@@@@=== */
+/* Following code is under the below copyright, despite changes for error
+ * handling and removing GCCisms */
+
+/*-
+ * Copyright (c) 2014 Taylor R. Campbell
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * Uniform random floats: How to generate a double-precision
+ * floating-point numbers in [0, 1] uniformly at random given a uniform
+ * random source of bits.
+ *
+ * See<http://mumble.net/~campbell/2014/04/28/uniform-random-float>
+ * for explanation.
+ *
+ * Updated 2015-02-22 to replace ldexp(x, <constant>) by x * ldexp(1,
+ * <constant>), since glibc and NetBSD libm both have slow software
+ * bit-twiddling implementations of ldexp, but GCC can constant-fold
+ * the latter.
+ */
+
+/*
+ * random_real: Generate a stream of bits uniformly at random and
+ * interpret it as the fractional part of the binary expansion of a
+ * number in [0, 1], 0.00001010011111010100...; then round it.
+ */
+
+/**/
+double
+random_real(void)
+{
+	int exponent = 0;
+	uint64_t significand = 0;
+	uint64_t r = 0;
+	unsigned shift;
+
+	/*
+	 * Read zeros into the exponent until we hit a one; the rest
+	 * will go into the significand.
+	 */
+	while (significand == 0) {
+		exponent -= 64;
+
+		/* Get random_64bit and check for error */
+		errno = 0;
+		significand = random_64bit();
+		if (errno)
+		    return -1;
+		/*
+		 * If the exponent falls below -1074 = emin + 1 - p,
+		 * the exponent of the smallest subnormal, we are
+		 * guaranteed the result will be rounded to zero.  This
+		 * case is so unlikely it will happen in realistic
+		 * terms only if random_64bit is broken.
+		 */
+		if (exponent < -1074)
+			return 0;
+	}
+
+	/*
+	 * There is a 1 somewhere in significand, not necessarily in
+	 * the most significant position.  If there are leading zeros,
+	 * shift them into the exponent and refill the less-significant
+	 * bits of the significand.  Can't predict one way or another
+	 * whether there are leading zeros: there's a fifty-fifty
+	 * chance, if random_64bit is uniformly distributed.
+	 */
+	shift = clz64(significand);
+	if (shift != 0) {
+
+		errno = 0;
+		r = random_64bit();
+		if (errno)
+		    return -1;
+
+		exponent -= shift;
+		significand <<= shift;
+		significand |= (r >> (64 - shift));
+	}
+
+	/*
+	 * Set the sticky bit, since there is almost surely another 1
+	 * in the bit stream.  Otherwise, we might round what looks
+	 * like a tie to even when, almost surely, were we to look
+	 * further in the bit stream, there would be a 1 breaking the
+	 * tie.
+	 */
+	significand |= 1;
+
+	/*
+	 * Finally, convert to double (rounding) and scale by
+	 * 2^exponent.
+	 */
+	return ldexp((double)significand, exponent);
+}
+/* ====@@@@@=== */