1 files changed, 240 insertions, 0 deletions
diff --git a/lib/sh/random.c b/lib/sh/random.c
new file mode 100644
index 0000000..1eaa71a
--- /dev/null
+++ b/lib/sh/random.c
@@ -0,0 +1,240 @@
+/* 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);
+}