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diff --git a/lib/sh/random.c b/lib/sh/random.c
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+/* random.c -- Functions for managing 16-bit and 32-bit random numbers. */
+
+/* Copyright (C) 2020 Free Software Foundation, Inc.
+
+ This file is part of GNU Bash, the Bourne Again SHell.
+
+ Bash 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 3 of the License, or
+ (at your option) any later version.
+
+ Bash 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 Bash. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "config.h"
+
+#include "bashtypes.h"
+
+#if defined (HAVE_SYS_RANDOM_H)
+# include <sys/random.h>
+#endif
+
+#if defined (HAVE_UNISTD_H)
+# include <unistd.h>
+#endif
+#include "filecntl.h"
+
+#include <stdio.h>
+#include "bashansi.h"
+
+#include "shell.h"
+
+extern time_t shell_start_time;
+
+extern int last_random_value;
+
+static u_bits32_t intrand32 PARAMS((u_bits32_t));
+static u_bits32_t genseed PARAMS((void));
+
+static u_bits32_t brand32 PARAMS((void));
+static void sbrand32 PARAMS((u_bits32_t));
+static void perturb_rand32 PARAMS((void));
+
+/* The random number seed. You can change this by setting RANDOM. */
+static u_bits32_t rseed = 1;
+
+/* Returns a 32-bit pseudo-random number. */
+static u_bits32_t
+intrand32 (last)
+ u_bits32_t last;
+{
+ /* Minimal Standard generator from
+ "Random number generators: good ones are hard to find",
+ Park and Miller, Communications of the ACM, vol. 31, no. 10,
+ October 1988, p. 1195. Filtered through FreeBSD.
+
+ x(n+1) = 16807 * x(n) mod (m).
+
+ We split up the calculations to avoid overflow.
+
+ h = last / q; l = x - h * q; t = a * l - h * r
+ m = 2147483647, a = 16807, q = 127773, r = 2836
+
+ There are lots of other combinations of constants to use; look at
+ https://www.gnu.org/software/gsl/manual/html_node/Other-random-number-generators.html#Other-random-number-generators */
+
+ bits32_t h, l, t;
+ u_bits32_t ret;
+
+ /* Can't seed with 0. */
+ ret = (last == 0) ? 123459876 : last;
+ h = ret / 127773;
+ l = ret - (127773 * h);
+ t = 16807 * l - 2836 * h;
+ ret = (t < 0) ? t + 0x7fffffff : t;
+
+ return (ret);
+}
+
+static u_bits32_t
+genseed ()
+{
+ struct timeval tv;
+ u_bits32_t iv;
+
+ gettimeofday (&tv, NULL);
+ iv = (u_bits32_t)seedrand; /* let the compiler truncate */
+ iv = tv.tv_sec ^ tv.tv_usec ^ getpid () ^ getppid () ^ current_user.uid ^ iv;
+ return (iv);
+}
+
+#define BASH_RAND_MAX 32767 /* 0x7fff - 16 bits */
+
+/* Returns a pseudo-random number between 0 and 32767. */
+int
+brand ()
+{
+ unsigned int ret;
+
+ rseed = intrand32 (rseed);
+ if (shell_compatibility_level > 50)
+ ret = (rseed >> 16) ^ (rseed & 65535);
+ else
+ ret = rseed;
+ return (ret & BASH_RAND_MAX);
+}
+
+/* Set the random number generator seed to SEED. */
+void
+sbrand (seed)
+ unsigned long seed;
+{
+ rseed = seed;
+ last_random_value = 0;
+}
+
+void
+seedrand ()
+{
+ u_bits32_t iv;
+
+ iv = genseed ();
+ sbrand (iv);
+}
+
+static u_bits32_t rseed32 = 1073741823;
+static int last_rand32;
+
+static int urandfd = -1;
+
+#define BASH_RAND32_MAX 0x7fffffff /* 32 bits */
+
+/* Returns a 32-bit pseudo-random number between 0 and 4294967295. */
+static u_bits32_t
+brand32 ()
+{
+ u_bits32_t ret;
+
+ rseed32 = intrand32 (rseed32);
+ return (rseed32 & BASH_RAND32_MAX);
+}
+
+static void
+sbrand32 (seed)
+ u_bits32_t seed;
+{
+ last_rand32 = rseed32 = seed;
+}
+
+void
+seedrand32 ()
+{
+ u_bits32_t iv;
+
+ iv = genseed ();
+ sbrand32 (iv);
+}
+
+static void
+perturb_rand32 ()
+{
+ rseed32 ^= genseed ();
+}
+
+/* Force another attempt to open /dev/urandom on the next call to get_urandom32 */
+void
+urandom_close ()
+{
+ if (urandfd >= 0)
+ close (urandfd);
+ urandfd = -1;
+}
+
+#if !defined (HAVE_GETRANDOM)
+/* Imperfect emulation of getrandom(2). */
+#ifndef GRND_NONBLOCK
+# define GRND_NONBLOCK 1
+# define GRND_RANDOM 2
+#endif
+
+static ssize_t
+getrandom (buf, len, flags)
+ void *buf;
+ size_t len;
+ unsigned int flags;
+{
+ int oflags;
+ ssize_t r;
+ static int urand_unavail = 0;
+
+#if HAVE_GETENTROPY
+ r = getentropy (buf, len);
+ return (r == 0) ? len : -1;
+#endif
+
+ if (urandfd == -1 && urand_unavail == 0)
+ {
+ oflags = O_RDONLY;
+ if (flags & GRND_NONBLOCK)
+ oflags |= O_NONBLOCK;
+ urandfd = open ("/dev/urandom", oflags, 0);
+ if (urandfd >= 0)
+ SET_CLOSE_ON_EXEC (urandfd);
+ else
+ {
+ urand_unavail = 1;
+ return -1;
+ }
+ }
+ if (urandfd >= 0 && (r = read (urandfd, buf, len)) == len)
+ return (r);
+ return -1;
+}
+#endif
+
+u_bits32_t
+get_urandom32 ()
+{
+ u_bits32_t ret;
+
+ if (getrandom ((void *)&ret, sizeof (ret), GRND_NONBLOCK) == sizeof (ret))
+ return (last_rand32 = ret);
+
+#if defined (HAVE_ARC4RANDOM)
+ ret = arc4random ();
+#else
+ if (subshell_environment)
+ perturb_rand32 ();
+ do
+ ret = brand32 ();
+ while (ret == last_rand32);
+#endif
+ return (last_rand32 = ret);
+}