random(6): produce random results

This program is trash and there's no reason to keep it in base.  But as long as
we're shipping a silly program named 'random', let's actually make it random.

usr.bin/random/random.6

@@ -28,7 +28,7 @@
 .\"     @(#)random.6	8.2 (Berkeley) 3/31/94
 .\" $FreeBSD$
 .\"
-.Dd February 8, 2003
+.Dd December 12, 2019
 .Dt RANDOM 6
 .Os
 .Sh NAME
@@ -62,9 +62,7 @@ space characters as determined by
 The default
 .Ar denominator
 for this mode of operation is 1, which gives each line a chance to be
-displayed, but in a
-.Xr random 3
-order.
+displayed, but in a random order.
 .Pp
 The options are as follows:
 .Bl -tag -width Ds
@@ -112,7 +110,6 @@ Randomize words separated by
 instead of newlines.
 .El
 .Sh SEE ALSO
-.Xr random 3 ,
 .Xr fortune 6
 .Sh HISTORY
 The

usr.bin/random/random.c

@@ -51,6 +51,7 @@ __FBSDID("$FreeBSD$");
 #include <fcntl.h>
 #include <limits.h>
 #include <locale.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -135,8 +136,6 @@ main(int argc, char *argv[])
 		/* NOTREACHED */
 	}
 
-	srandomdev();
-
 	/*
 	 * Act as a filter, randomly choosing lines of the standard input
 	 * to write to the standard output.
@@ -158,7 +157,7 @@ main(int argc, char *argv[])
 
 	/* Compute a random exit status between 0 and denom - 1. */
 	if (random_exit)
-		return (int)(denom * random() / RANDOM_MAX_PLUS1);
+		return (arc4random_uniform(denom));
 
 	/*
 	 * Select whether to print the first line.  (Prime the pump.)
@@ -166,7 +165,7 @@ main(int argc, char *argv[])
 	 * 0 (which has a 1 / denom chance of being true), we select the
 	 * line.
 	 */
-	selected = (int)(denom * random() / RANDOM_MAX_PLUS1) == 0;
+	selected = (arc4random_uniform(denom) == 0);
 	while ((ch = getchar()) != EOF) {
 		if (selected)
 			(void)putchar(ch);
@@ -176,8 +175,7 @@ main(int argc, char *argv[])
 				err(2, "stdout");
 
 			/* Now see if the next line is to be printed. */
-			selected = (int)(denom * random() /
-				RANDOM_MAX_PLUS1) == 0;
+			selected = (arc4random_uniform(denom) == 0);
 		}
 	}
 	if (ferror(stdin))

usr.bin/random/randomize_fd.c

@@ -34,6 +34,7 @@ __FBSDID("$FreeBSD$");
 #include <err.h>
 #include <errno.h>
 #include <stdlib.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
@@ -175,7 +176,7 @@ randomize_fd(int fd, int type, int unique, double denom)
 			    (type == RANDOM_TYPE_WORDS && isspace(buf[i])) ||
 			    (eof && i == buflen - 1)) {
 make_token:
-				if (numnode == RANDOM_MAX_PLUS1) {
+				if (numnode == UINT32_MAX - 1) {
 					errno = EFBIG;
 					err(1, "too many delimiters");
 				}
@@ -210,15 +211,14 @@ randomize_fd(int fd, int type, int unique, double denom)
 	free(buf);
 
 	for (i = numnode; i > 0; i--) {
-		selected = random() % numnode;
+		selected = arc4random_uniform(numnode + 1);
 
 		for (j = 0, prev = n = rand_root; n != NULL; j++, prev = n, n = n->next) {
 			if (j == selected) {
 				if (n->cp == NULL)
 					break;
 
-				if ((int)(denom * random() /
-					RANDOM_MAX_PLUS1) == 0) {
+				if (arc4random_uniform(denom) == 0) {
 					ret = printf("%.*s",
 						(int)n->len - 1, n->cp);
 					if (ret < 0)

usr.bin/random/randomize_fd.h

@@ -29,12 +29,6 @@
 #ifndef __RANDOMIZE_FD__
 #define __RANDOMIZE_FD__
 
-/*
- * The random() function is defined to return values between 0 and
- * 2^31 - 1 inclusive in random(3).
- */
-#define	RANDOM_MAX_PLUS1	0x80000000UL
-
 #define RANDOM_TYPE_UNSET 0
 #define RANDOM_TYPE_LINES 1
 #define RANDOM_TYPE_WORDS 2