Deprecate sranddev(3) API

It serves no useful purpose and wasn't as popular as its equally meritless
cousin, srandomdev(3).

Setting aside the problems with rand(3) in general, the problem with this
interface is that the seed isn't shared with the caller (other than by
attacking the output of the generator, which is trivial, but not a hallmark of
pleasant API design).  The (arguable) utility of rand(3) or random(3) is as a
semi-fast simulation generator which produces consistent results from a given
seed.  These are mutually at odd.  Furthermore, sometimes people got the
mistaken impression that a high quality random seed meant a weak generator like
rand(3) or random(3) could be used for things like cryptographic key
generation.  This is absolutely not so.

The API was never part of a standard and was not widely used in tree.  Existing
in-tree uses have all been removed.

Possible replacement in out of tree codebases:

	char buf[3];
	time_t t;

	time(t);
	strftime(buf, sizeof(buf), "%S", gmtime(&t));
	srand(atoi(buf));

Relnotes:	yes

ObsoleteFiles.inc

@@ -36,6 +36,8 @@
 #   xargs -n1 | sort | uniq -d;
 # done
 
+# 20191214: Removal of sranddev(3)
+OLD_FILES+=usr/share/man/man3/sranddev.3.gz
 # 20191213: remove timeout(9)
 OLD_FILES+=usr/share/man/man9/timeout.9.gz
 OLD_FILES+=usr/share/man/man9/untimeout.9.gz

include/stdlib.h

@@ -309,12 +309,17 @@ int	 rpmatch(const char *);
 void	 setprogname(const char *);
 int	 sradixsort(const unsigned char **, int, const unsigned char *,
 	    unsigned);
-void	 sranddev(void);
 void	 srandomdev(void);
 long long
 	strtonum(const char *, long long, long long, const char **);
 
 /* Deprecated interfaces, to be removed. */
+static inline void
+__attribute__((__deprecated__("sranddev to be removed in FreeBSD 13")))
+sranddev(void)
+{
+}
+
 __int64_t
 	 strtoq(const char *, char **, int);
 __uint64_t

lib/libc/stdlib/Makefile.inc

@@ -52,7 +52,7 @@ MLINKS+=insque.3 remque.3
 MLINKS+=lsearch.3 lfind.3
 MLINKS+=ptsname.3 grantpt.3 ptsname.3 unlockpt.3
 MLINKS+=qsort.3 heapsort.3 qsort.3 mergesort.3 qsort.3 qsort_r.3
-MLINKS+=rand.3 rand_r.3 rand.3 srand.3 rand.3 sranddev.3
+MLINKS+=rand.3 rand_r.3 rand.3 srand.3
 MLINKS+=random.3 initstate.3 random.3 setstate.3 random.3 srandom.3 \
 	random.3 srandomdev.3
 MLINKS+=radixsort.3 sradixsort.3

lib/libc/stdlib/Symbol.map

@@ -56,7 +56,6 @@ FBSD_1.0 {
 	rand_r;
 	rand;
 	srand;
-	sranddev;
 	srandom;
 	srandomdev;
 	initstate;

lib/libc/stdlib/rand.3

@@ -32,13 +32,12 @@
 .\"     @(#)rand.3	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\"
-.Dd April 22, 2019
+.Dd December 14, 2019
 .Dt RAND 3
 .Os
 .Sh NAME
 .Nm rand ,
 .Nm srand ,
-.Nm sranddev ,
 .Nm rand_r
 .Nd bad random number generator
 .Sh LIBRARY
@@ -47,8 +46,6 @@
 .In stdlib.h
 .Ft void
 .Fn srand "unsigned seed"
-.Ft void
-.Fn sranddev void
 .Ft int
 .Fn rand void
 .Ft int
@@ -90,10 +87,6 @@ value is provided, the functions are automatically
 seeded with a value of 1.
 .Pp
 The
-.Fn sranddev
-function initializes a seed using pseudo-random numbers obtained from the kernel.
-.Pp
-The
 .Fn rand_r
 function
 provides the same functionality as
@@ -122,4 +115,5 @@ conform to
 .Pp
 The
 .Fn rand_r
-function is as proposed in the POSIX.4a Draft #6 document.
+function is marked as obsolescent in POSIX and may be removed in a future
+revision of the standard.

lib/libc/stdlib/rand.c

@@ -40,7 +40,9 @@ __FBSDID("$FreeBSD$");
 #include "namespace.h"
 #include <sys/param.h>
 #include <sys/sysctl.h>
+#include <stdbool.h>
 #include <stdlib.h>
+#include <syslog.h>
 #include "un-namespace.h"
 
 #ifdef TEST
@@ -102,25 +104,18 @@ srand(unsigned seed)
 }
 
 
-/*
- * sranddev:
- *
- * Many programs choose the seed value in a totally predictable manner.
- * This often causes problems.  We seed the generator using pseudo-random
- * data from the kernel.
- */
+void __sranddev_fbsd12(void);
 void
-sranddev(void)
+__sranddev_fbsd12(void)
 {
-	int mib[2];
-	size_t len;
+	static bool warned = false;
 
-	len = sizeof(next);
-
-	mib[0] = CTL_KERN;
-	mib[1] = KERN_ARND;
-	sysctl(mib, 2, (void *)&next, &len, NULL, 0);
+	if (!warned) {
+		syslog(LOG_DEBUG, "Deprecated function sranddev() called");
+		warned = true;
+	}
 }
+__sym_compat(sranddev, __sranddev_fbsd12, FBSD_1.0);
 
 
 #ifdef TEST

lib/libxo/xo_config.h

@@ -102,7 +102,7 @@
 #define HAVE_SRAND 1
 
 /* Define to 1 if you have the `sranddev' function. */
-#define HAVE_SRANDDEV 1
+/* #undef HAVE_SRANDDEV */
 
 /* Define to 1 if you have the <stdint.h> header file. */
 #define HAVE_STDINT_H 1