--- /dev/null
+/*-
+ * Copyright (c) 1990, 1993
+ * The Regents of the University of California. 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.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ *
+ * Posix rand_r function added May 1999 by Wes Peters <wes@softweyr.com>.
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)rand.c 8.1 (Berkeley) 6/14/93";
+#endif /* LIBC_SCCS and not lint */
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD: src/lib/libc/stdlib/rand.c,v 1.15 2003/02/17 03:52:35 ache Exp $");
+
+#include "namespace.h"
+#include <sys/time.h> /* for sranddev() */
+#include <sys/types.h>
+#include <fcntl.h> /* for sranddev() */
+#include <stdlib.h>
+#include <unistd.h> /* for sranddev() */
+#include "un-namespace.h"
+
+#ifdef TEST
+#include <stdio.h>
+#endif /* TEST */
+
+static int
+do_rand(unsigned long *ctx)
+{
+#ifdef USE_WEAK_SEEDING
+/*
+ * Historic implementation compatibility.
+ * The random sequences do not vary much with the seed,
+ * even with overflowing.
+ */
+ return ((*ctx = *ctx * 1103515245 + 12345) % ((u_long)RAND_MAX + 1));
+#else /* !USE_WEAK_SEEDING */
+/*
+ * Compute x = (7^5 * x) mod (2^31 - 1)
+ * wihout overflowing 31 bits:
+ * (2^31 - 1) = 127773 * (7^5) + 2836
+ * 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.
+ */
+ long hi, lo, x;
+
+ /* Can't be initialized with 0, so use another value. */
+ if (*ctx == 0)
+ *ctx = 123459876;
+ hi = *ctx / 127773;
+ lo = *ctx % 127773;
+ x = 16807 * lo - 2836 * hi;
+ if (x < 0)
+ x += 0x7fffffff;
+ return ((*ctx = x) % ((u_long)RAND_MAX + 1));
+#endif /* !USE_WEAK_SEEDING */
+}
+
+
+int
+rand_r(unsigned int *ctx)
+{
+ u_long val = (u_long) *ctx;
+ int r = do_rand(&val);
+
+ *ctx = (unsigned int) val;
+ return (r);
+}
+
+
+static u_long next = 1;
+
+int
+rand()
+{
+ return (do_rand(&next));
+}
+
+void
+srand(seed)
+u_int seed;
+{
+ next = seed;
+}
+
+
+/*
+ * sranddev:
+ *
+ * Many programs choose the seed value in a totally predictable manner.
+ * This often causes problems. We seed the generator using the much more
+ * secure random(4) interface.
+ */
+void
+sranddev()
+{
+ int fd, done;
+
+ done = 0;
+ fd = _open("/dev/random", O_RDONLY, 0);
+ if (fd >= 0) {
+ if (_read(fd, (void *) &next, sizeof(next)) == sizeof(next))
+ done = 1;
+ _close(fd);
+ }
+
+ if (!done) {
+ struct timeval tv;
+ unsigned long junk;
+
+ gettimeofday(&tv, NULL);
+ srand((getpid() << 16) ^ tv.tv_sec ^ tv.tv_usec ^ junk);
+ }
+}
+
+
+#ifdef TEST
+
+main()
+{
+ int i;
+ unsigned myseed;
+
+ printf("seeding rand with 0x19610910: \n");
+ srand(0x19610910);
+
+ printf("generating three pseudo-random numbers:\n");
+ for (i = 0; i < 3; i++)
+ {
+ printf("next random number = %d\n", rand());
+ }
+
+ printf("generating the same sequence with rand_r:\n");
+ myseed = 0x19610910;
+ for (i = 0; i < 3; i++)
+ {
+ printf("next random number = %d\n", rand_r(&myseed));
+ }
+
+ return 0;
+}
+
+#endif /* TEST */
+
projects / apple / libc.git / blobdiff