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libroot: Synchronize random() implementation with upstream FreeBSD.

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Specifically, FreeBSD 12 (newer versions refactored this API into
more than just one file.)

Fixes #18346.
This commit is contained in:
Augustin Cavalier
2023-04-08 13:49:03 -04:00
parent 6d3d196648
commit 05a0671dde
1 changed files with 95 additions and 134 deletions
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src/system/libroot/posix/stdlib/random.c
+95 -134
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@@ -1,4 +1,6 @@
/*
/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1983, 1993
* The Regents of the University of California. All rights reserved.
*
@@ -10,11 +12,7 @@
* 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
* 3. 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.
*
@@ -29,16 +27,15 @@
* 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.
*
* $FreeBSD: src/lib/libc/stdlib/random.c,v 1.13 2000/01/27 23:06:49 jasone Exp $
*
*/
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
/* An improved random number generation package. In addition to the standard
/*
* random.c:
*
* An improved random number generation package. In addition to the standard
* rand()/srand() like interface, this package also has a special state info
* interface. The initstate() routine is called with a seed, an array of
* bytes, and a count of how many bytes are being passed in; this array is
@@ -51,10 +48,10 @@
* congruential generator. If the amount of state information is less than
* 32 bytes, a simple linear congruential R.N.G. is used.
*
* Internally, the state information is treated as an array of longs; the
* Internally, the state information is treated as an array of uint32_t's; the
* zeroeth element of the array is the type of R.N.G. being used (small
* integer); the remainder of the array is the state information for the
* R.N.G. Thus, 32 bytes of state information will give 7 longs worth of
* R.N.G. Thus, 32 bytes of state information will give 7 ints worth of
* state information, which will allow a degree seven polynomial. (Note:
* the zeroeth word of state information also has some other information
* stored in it -- see setstate() for details).
@@ -70,7 +67,7 @@
* period of the generator is approximately deg*(2**deg - 1); thus doubling
* the amount of state information has a vast influence on the period of the
* generator. Note: the deg*(2**deg - 1) is an approximation only good for
* large deg, when the period of the shift register is the dominant factor.
* large deg, when the period of the shift is the dominant factor.
* With deg equal to seven, the period is actually much longer than the
* 7*(2**7 - 1) predicted by this formula.
*
@@ -132,8 +129,10 @@
*/
#define MAX_TYPES 5 /* max number of types above */
static long degrees[MAX_TYPES] = { DEG_0, DEG_1, DEG_2, DEG_3, DEG_4 };
static long seps [MAX_TYPES] = { SEP_0, SEP_1, SEP_2, SEP_3, SEP_4 };
#define NSHUFF 50 /* to drop some "seed -> 1st value" linearity */
static const int degrees[MAX_TYPES] = { DEG_0, DEG_1, DEG_2, DEG_3, DEG_4 };
static const int seps [MAX_TYPES] = { SEP_0, SEP_1, SEP_2, SEP_3, SEP_4 };
/*
* Initially, everything is set up as if from:
@@ -149,25 +148,14 @@ static long seps [MAX_TYPES] = { SEP_0, SEP_1, SEP_2, SEP_3, SEP_4 };
* MAX_TYPES * (rptr - state) + TYPE_3 == TYPE_3.
*/
static long randtbl[DEG_3 + 1] = {
static uint32_t randtbl[DEG_3 + 1] = {
TYPE_3,
#ifdef USE_WEAK_SEEDING
/* Historic implementation compatibility */
/* The random sequences do not vary much with the seed */
0x9a319039, 0x32d9c024, 0x9b663182, 0x5da1f342, 0xde3b81e0, 0xdf0a6fb5,
0xf103bc02, 0x48f340fb, 0x7449e56b, 0xbeb1dbb0, 0xab5c5918, 0x946554fd,
0x8c2e680f, 0xeb3d799f, 0xb11ee0b7, 0x2d436b86, 0xda672e2a, 0x1588ca88,
0xe369735d, 0x904f35f7, 0xd7158fd6, 0x6fa6f051, 0x616e6b96, 0xac94efdc,
0x36413f93, 0xc622c298, 0xf5a42ab8, 0x8a88d77b, 0xf5ad9d0e, 0x8999220b,
0x27fb47b9,
#else /* !USE_WEAK_SEEDING */
0x991539b1, 0x16a5bce3, 0x6774a4cd, 0x3e01511e, 0x4e508aaa, 0x61048c05,
0xf5500617, 0x846b7115, 0x6a19892c, 0x896a97af, 0xdb48f936, 0x14898454,
0x37ffd106, 0xb58bff9c, 0x59e17104, 0xcf918a49, 0x09378c83, 0x52c7a471,
0x8d293ea9, 0x1f4fc301, 0xc3db71be, 0x39b44e1c, 0xf8a44ef9, 0x4c8b80b1,
0x19edc328, 0x87bf4bdd, 0xc9b240e5, 0xe9ee4b1b, 0x4382aee7, 0x535b6b41,
0xf3bec5da
#endif /* !USE_WEAK_SEEDING */
0x2cf41758, 0x27bb3711, 0x4916d4d1, 0x7b02f59f, 0x9b8e28eb, 0xc0e80269,
0x696f5c16, 0x878f1ff5, 0x52d9c07f, 0x916a06cd, 0xb50b3a20, 0x2776970a,
0xee4eb2a6, 0xe94640ec, 0xb1d65612, 0x9d1ed968, 0x1043f6b7, 0xa3432a76,
0x17eacbb9, 0x3c09e2eb, 0x4f8c2b3, 0x708a1f57, 0xee341814, 0x95d0e4d2,
0xb06f216c, 0x8bd2e72e, 0x8f7c38d7, 0xcfc6a8fc, 0x2a59495, 0xa20d2a69,
0xe29d12d1
};
/*
@@ -184,8 +172,8 @@ static long randtbl[DEG_3 + 1] = {
* in the initialization of randtbl) because the state table pointer is set
* to point to randtbl[1] (as explained below).
*/
static long *fptr = &randtbl[SEP_3 + 1];
static long *rptr = &randtbl[1];
static uint32_t *fptr = &randtbl[SEP_3 + 1];
static uint32_t *rptr = &randtbl[1];
/*
* The following things are the pointer to the state information table, the
@@ -197,24 +185,15 @@ static long *rptr = &randtbl[1];
* this is more efficient than indexing every time to find the address of
* the last element to see if the front and rear pointers have wrapped.
*/
static long *state = &randtbl[1];
static long rand_type = TYPE_3;
static long rand_deg = DEG_3;
static long rand_sep = SEP_3;
static long *end_ptr = &randtbl[DEG_3 + 1];
static uint32_t *state = &randtbl[1];
static int rand_type = TYPE_3;
static int rand_deg = DEG_3;
static int rand_sep = SEP_3;
static uint32_t *end_ptr = &randtbl[DEG_3 + 1];
static inline long good_rand(long);
static inline long good_rand(long x)
static inline uint32_t
good_rand(uint32_t ctx)
{
#ifdef USE_WEAK_SEEDING
/*
* Historic implementation compatibility.
* The random sequences do not vary much with the seed,
* even with overflowing.
*/
return (1103515245 * x + 12345);
#else /* !USE_WEAK_SEEDING */
/*
* Compute x = (7^5 * x) mod (2^31 - 1)
* wihout overflowing 31 bits:
@@ -223,15 +202,17 @@ static inline long good_rand(long x)
* Park and Miller, Communications of the ACM, vol. 31, no. 10,
* October 1988, p. 1195.
*/
register long hi, lo;
int32_t hi, lo, x;
/* Transform to [1, 0x7ffffffe] range. */
x = (ctx % 0x7ffffffe) + 1;
hi = x / 127773;
lo = x % 127773;
x = 16807 * lo - 2836 * hi;
if (x <= 0)
if (x < 0)
x += 0x7fffffff;
return (x);
#endif /* !USE_WEAK_SEEDING */
/* Transform to [0, 0x7ffffffd] range. */
return (x - 1);
}
/*
@@ -249,61 +230,56 @@ static inline long good_rand(long x)
void
srandom(unsigned int x)
{
long i;
int i, lim;
if (rand_type == TYPE_0) {
state[0] = x;
} else {
state[0] = x;
for (i = 1; i < rand_deg; i++) {
state[0] = (uint32_t)x;
if (rand_type == TYPE_0)
lim = NSHUFF;
else {
for (i = 1; i < rand_deg; i++)
state[i] = good_rand(state[i - 1]);
}
fptr = &state[rand_sep];
rptr = &state[0];
for (i = 0; i < 10 * rand_deg; i++) {
(void)random();
}
lim = 10 * rand_deg;
}
for (i = 0; i < lim; i++)
(void)random();
}
/*
* srandomdev:
*
* Many programs choose the seed value in a totally predictable manner.
* This often causes problems. We seed the generator using the much more
* secure urandom(4) interface. Note that this particular seeding
* procedure can generate states which are impossible to reproduce by
* calling srandom() with any value, since the succeeding terms in the
* state buffer are no longer derived from the LC algorithm applied to
* a fixed seed.
* This often causes problems. We seed the generator using pseudo-random
* data from the kernel.
*
* Note that this particular seeding procedure can generate states
* which are impossible to reproduce by calling srandom() with any
* value, since the succeeding terms in the state buffer are no longer
* derived from the LC algorithm applied to a fixed seed.
*/
#if 0
void
srandomdev()
srandomdev(void)
{
int fd, done;
size_t len;
int mib[2];
size_t expected, len;
if (rand_type == TYPE_0)
len = sizeof state[0];
expected = len = sizeof(state[0]);
else
len = rand_deg * sizeof state[0];
expected = len = rand_deg * sizeof(state[0]);
done = 0;
fd = _open("/dev/urandom", O_RDONLY, 0);
if (fd >= 0) {
if (_read(fd, (void *) state, len) == (ssize_t) len)
done = 1;
_close(fd);
}
if (!done) {
struct timeval tv;
unsigned long junk;
gettimeofday(&tv, NULL);
srandom(getpid() ^ tv.tv_sec ^ tv.tv_usec ^ junk);
return;
mib[0] = CTL_KERN;
mib[1] = KERN_ARND;
if (sysctl(mib, 2, state, &len, NULL, 0) == -1 || len != expected) {
/*
* The sysctl cannot fail. If it does fail on some FreeBSD
* derivative or after some future change, just abort so that
* the problem will be found and fixed. abort is not normally
* suitable for a library but makes sense here.
*/
abort();
}
if (rand_type != TYPE_0) {
@@ -332,25 +308,22 @@ srandomdev()
*
* Returns a pointer to the old state.
*
* Note: The Sparc platform requires that arg_state begin on a long
* Note: The Sparc platform requires that arg_state begin on an int
* word boundary; otherwise a bus error will occur. Even so, lint will
* complain about mis-alignment, but you should disregard these messages.
*/
char *
initstate(unsigned int seed, char *arg_state, size_t n)
{
register char *ostate = (char *)(&state[-1]);
register long *long_arg_state = (long *) arg_state;
char *ostate = (char *)(&state[-1]);
uint32_t *int_arg_state = (uint32_t *)arg_state;
if (n < BREAK_0)
return (NULL);
if (rand_type == TYPE_0)
state[-1] = rand_type;
else
state[-1] = MAX_TYPES * (rptr - state) + rand_type;
if (n < BREAK_0) {
(void)fprintf(stderr,
"random: not enough state (%ld bytes); ignored.\n", n);
return(0);
}
if (n < BREAK_1) {
rand_type = TYPE_0;
rand_deg = DEG_0;
@@ -372,14 +345,14 @@ initstate(unsigned int seed, char *arg_state, size_t n)
rand_deg = DEG_4;
rand_sep = SEP_4;
}
state = (long *) (long_arg_state + 1); /* first location */
state = int_arg_state + 1; /* first location */
end_ptr = &state[rand_deg]; /* must set end_ptr before srandom */
srandom(seed);
if (rand_type == TYPE_0)
long_arg_state[0] = rand_type;
int_arg_state[0] = rand_type;
else
long_arg_state[0] = MAX_TYPES * (rptr - state) + rand_type;
return(ostate);
int_arg_state[0] = MAX_TYPES * (rptr - state) + rand_type;
return (ostate);
}
/*
@@ -397,47 +370,36 @@ initstate(unsigned int seed, char *arg_state, size_t n)
*
* Returns a pointer to the old state information.
*
* Note: The Sparc platform requires that arg_state begin on a long
* Note: The Sparc platform requires that arg_state begin on an int
* word boundary; otherwise a bus error will occur. Even so, lint will
* complain about mis-alignment, but you should disregard these messages.
*/
char *
setstate(arg_state)
char *arg_state; /* pointer to state array */
setstate(char *arg_state)
{
register long *new_state = (long *) arg_state;
register long type = new_state[0] % MAX_TYPES;
register long rear = new_state[0] / MAX_TYPES;
uint32_t *new_state = (uint32_t *)arg_state;
uint32_t type = new_state[0] % MAX_TYPES;
uint32_t rear = new_state[0] / MAX_TYPES;
char *ostate = (char *)(&state[-1]);
if (type != TYPE_0 && rear >= degrees[type])
return (NULL);
if (rand_type == TYPE_0)
state[-1] = rand_type;
else
state[-1] = MAX_TYPES * (rptr - state) + rand_type;
switch(type) {
case TYPE_0:
case TYPE_1:
case TYPE_2:
case TYPE_3:
case TYPE_4:
rand_type = type;
rand_deg = degrees[type];
rand_sep = seps[type];
break;
default:
(void)fprintf(stderr,
"random: state info corrupted; not changed.\n");
}
state = (long *) (new_state + 1);
rand_type = type;
rand_deg = degrees[type];
rand_sep = seps[type];
state = new_state + 1;
if (rand_type != TYPE_0) {
rptr = &state[rear];
fptr = &state[(rear + rand_sep) % rand_deg];
}
end_ptr = &state[rand_deg]; /* set end_ptr too */
return(ostate);
return (ostate);
}
/*
* random:
*
@@ -458,20 +420,19 @@ setstate(arg_state)
int
random(void)
{
long i;
long *f;
long *r;
uint32_t i;
uint32_t *f, *r;
if (rand_type == TYPE_0) {
i = state[0];
state[0] = i = (good_rand(i)) & 0x7fffffff;
state[0] = i = good_rand(i);
} else {
/*
* Use local variables rather than static variables for speed.
*/
f = fptr; r = rptr;
*f += *r;
i = (*f >> 1) & 0x7fffffff; /* chucking least random bit */
i = *f >> 1; /* chucking least random bit */
if (++f >= end_ptr) {
f = state;
++r;
@@ -482,5 +443,5 @@ random(void)
fptr = f; rptr = r;
}
return(i);
return ((long)i);
}