Extract simple integer math into its own module

This commit is contained in:
Nick Mathewson 2018-06-22 09:48:24 -04:00
parent 3883338c81
commit 2cf033f238
19 changed files with 294 additions and 189 deletions

2
.gitignore vendored
View File

@ -173,6 +173,8 @@ uptime-*.json
/src/lib/libtor-ctime-testing.a
/src/lib/libtor-err.a
/src/lib/libtor-err-testing.a
/src/lib/libtor-intmath.a
/src/lib/libtor-intmath-testing.a
/src/lib/libtor-malloc.a
/src/lib/libtor-malloc-testing.a
/src/lib/libtor-string.a

View File

@ -45,6 +45,7 @@ TOR_UTIL_LIBS = \
src/lib/libtor-malloc.a \
src/lib/libtor-wallclock.a \
src/lib/libtor-err.a \
src/lib/libtor-intmath.a \
src/lib/libtor-ctime.a
# Variants of the above for linking the testing variant of tor (for coverage
@ -56,6 +57,7 @@ TOR_UTIL_TESTING_LIBS = \
src/lib/libtor-malloc-testing.a \
src/lib/libtor-wallclock-testing.a \
src/lib/libtor-err-testing.a \
src/lib/libtor-intmath.a \
src/lib/libtor-ctime-testing.a
# Internal crypto libraries used in Tor

View File

@ -166,105 +166,6 @@ tor_llround(double d)
#endif /* defined(HAVE_LLROUND) || ... */
}
/** Returns floor(log2(u64)). If u64 is 0, (incorrectly) returns 0. */
int
tor_log2(uint64_t u64)
{
int r = 0;
if (u64 >= (U64_LITERAL(1)<<32)) {
u64 >>= 32;
r = 32;
}
if (u64 >= (U64_LITERAL(1)<<16)) {
u64 >>= 16;
r += 16;
}
if (u64 >= (U64_LITERAL(1)<<8)) {
u64 >>= 8;
r += 8;
}
if (u64 >= (U64_LITERAL(1)<<4)) {
u64 >>= 4;
r += 4;
}
if (u64 >= (U64_LITERAL(1)<<2)) {
u64 >>= 2;
r += 2;
}
if (u64 >= (U64_LITERAL(1)<<1)) {
// u64 >>= 1; // not using this any more.
r += 1;
}
return r;
}
/** Return the power of 2 in range [1,UINT64_MAX] closest to <b>u64</b>. If
* there are two powers of 2 equally close, round down. */
uint64_t
round_to_power_of_2(uint64_t u64)
{
int lg2;
uint64_t low;
uint64_t high;
if (u64 == 0)
return 1;
lg2 = tor_log2(u64);
low = U64_LITERAL(1) << lg2;
if (lg2 == 63)
return low;
high = U64_LITERAL(1) << (lg2+1);
if (high - u64 < u64 - low)
return high;
else
return low;
}
/** Return the lowest x such that x is at least <b>number</b>, and x modulo
* <b>divisor</b> == 0. If no such x can be expressed as an unsigned, return
* UINT_MAX. Asserts if divisor is zero. */
unsigned
round_to_next_multiple_of(unsigned number, unsigned divisor)
{
tor_assert(divisor > 0);
if (UINT_MAX - divisor + 1 < number)
return UINT_MAX;
number += divisor - 1;
number -= number % divisor;
return number;
}
/** Return the lowest x such that x is at least <b>number</b>, and x modulo
* <b>divisor</b> == 0. If no such x can be expressed as a uint32_t, return
* UINT32_MAX. Asserts if divisor is zero. */
uint32_t
round_uint32_to_next_multiple_of(uint32_t number, uint32_t divisor)
{
tor_assert(divisor > 0);
if (UINT32_MAX - divisor + 1 < number)
return UINT32_MAX;
number += divisor - 1;
number -= number % divisor;
return number;
}
/** Return the lowest x such that x is at least <b>number</b>, and x modulo
* <b>divisor</b> == 0. If no such x can be expressed as a uint64_t, return
* UINT64_MAX. Asserts if divisor is zero. */
uint64_t
round_uint64_to_next_multiple_of(uint64_t number, uint64_t divisor)
{
tor_assert(divisor > 0);
if (UINT64_MAX - divisor + 1 < number)
return UINT64_MAX;
number += divisor - 1;
number -= number % divisor;
return number;
}
/** Transform a random value <b>p</b> from the uniform distribution in
* [0.0, 1.0[ into a Laplace distributed value with location parameter
* <b>mu</b> and scale parameter <b>b</b>. Truncate the final result
@ -319,68 +220,6 @@ add_laplace_noise(int64_t signal_, double random_, double delta_f,
return signal_ + noise;
}
/* Helper: safely add two uint32_t's, capping at UINT32_MAX rather
* than overflow */
uint32_t
tor_add_u32_nowrap(uint32_t a, uint32_t b)
{
/* a+b > UINT32_MAX check, without overflow */
if (PREDICT_UNLIKELY(a > UINT32_MAX - b)) {
return UINT32_MAX;
} else {
return a+b;
}
}
/* Helper: return greatest common divisor of a,b */
static uint64_t
gcd64(uint64_t a, uint64_t b)
{
while (b) {
uint64_t t = b;
b = a % b;
a = t;
}
return a;
}
/* Given a fraction *<b>numer</b> / *<b>denom</b>, simplify it.
* Requires that the denominator is greater than 0. */
void
simplify_fraction64(uint64_t *numer, uint64_t *denom)
{
tor_assert(denom);
uint64_t gcd = gcd64(*numer, *denom);
*numer /= gcd;
*denom /= gcd;
}
/** Return the number of bits set in <b>v</b>. */
int
n_bits_set_u8(uint8_t v)
{
static const int nybble_table[] = {
0, /* 0000 */
1, /* 0001 */
1, /* 0010 */
2, /* 0011 */
1, /* 0100 */
2, /* 0101 */
2, /* 0110 */
3, /* 0111 */
1, /* 1000 */
2, /* 1001 */
2, /* 1010 */
3, /* 1011 */
2, /* 1100 */
3, /* 1101 */
3, /* 1110 */
4, /* 1111 */
};
return nybble_table[v & 15] + nybble_table[v>>4];
}
/* =====
* String manipulation
* ===== */

View File

@ -27,6 +27,10 @@
#include "lib/wallclock/approx_time.h"
#include "lib/string/util_string.h"
#include "lib/string/scanf.h"
#include "lib/intmath/bits.h"
#include "lib/intmath/addsub.h"
#include "lib/intmath/muldiv.h"
#include "lib/intmath/cmp.h"
#include "common/util_bug.h"
#ifndef O_BINARY
@ -66,35 +70,10 @@ void tor_log_mallinfo(int severity);
double tor_mathlog(double d) ATTR_CONST;
long tor_lround(double d) ATTR_CONST;
int64_t tor_llround(double d) ATTR_CONST;
int tor_log2(uint64_t u64) ATTR_CONST;
uint64_t round_to_power_of_2(uint64_t u64);
unsigned round_to_next_multiple_of(unsigned number, unsigned divisor);
uint32_t round_uint32_to_next_multiple_of(uint32_t number, uint32_t divisor);
uint64_t round_uint64_to_next_multiple_of(uint64_t number, uint64_t divisor);
int64_t sample_laplace_distribution(double mu, double b, double p);
int64_t add_laplace_noise(int64_t signal, double random, double delta_f,
double epsilon);
int n_bits_set_u8(uint8_t v);
int64_t clamp_double_to_int64(double number);
void simplify_fraction64(uint64_t *numer, uint64_t *denom);
uint32_t tor_add_u32_nowrap(uint32_t a, uint32_t b);
/* Compute the CEIL of <b>a</b> divided by <b>b</b>, for nonnegative <b>a</b>
* and positive <b>b</b>. Works on integer types only. Not defined if a+(b-1)
* can overflow. */
#define CEIL_DIV(a,b) (((a)+((b)-1))/(b))
/* Return <b>v</b> if it's between <b>min</b> and <b>max</b>. Otherwise
* return <b>min</b> if <b>v</b> is smaller than <b>min</b>, or <b>max</b> if
* <b>b</b> is larger than <b>max</b>.
*
* Requires that <b>min</b> is no more than <b>max</b>. May evaluate any of
* its arguments more than once! */
#define CLAMP(min,v,max) \
( ((v) < (min)) ? (min) : \
((v) > (max)) ? (max) : \
(v) )
/* String manipulation */

View File

@ -7,6 +7,7 @@ include src/lib/container/include.am
include src/lib/crypt_ops/include.am
include src/lib/defs/include.am
include src/lib/include.libdonna.am
include src/lib/intmath/include.am
include src/lib/malloc/include.am
include src/lib/string/include.am
include src/lib/testsupport/include.am

View File

@ -7,10 +7,10 @@ lib/malloc/*.h
lib/err/*.h
lib/string/*.h
lib/testsupport/testsupport.h
lib/intmath/*.h
ht.h
siphash.h
# XXX I'd like to remove this.
common/util.h
common/util_bug.h

View File

@ -14,7 +14,7 @@
#include <stdlib.h>
#include "lib/malloc/util_malloc.h"
#include "lib/container/bloomfilt.h"
#include "common/util.h" // For tor_log2
#include "lib/intmath/bits.h"
/** Return a newly allocated digestset_t, optimized to hold a total of
* <b>max_elements</b> digests with a reasonably low false positive weight. */

View File

@ -6,6 +6,7 @@ lib/ctime/*.h
lib/defs/*.h
lib/malloc/*.h
lib/err/*.h
lib/intmath/*.h
lib/string/*.h
lib/testsupport/testsupport.h

View File

@ -15,6 +15,7 @@
#include "lib/crypt_ops/crypto_s2k.h"
#include "lib/crypt_ops/crypto_util.h"
#include "lib/ctime/di_ops.h"
#include "lib/intmath/muldiv.h"
#include "common/util.h"
#include "trunnel/pwbox.h"
@ -212,4 +213,3 @@ crypto_unpwbox(uint8_t **out, size_t *outlen_out,
memwipe(keys, 0, sizeof(keys));
return rv;
}

View File

@ -0,0 +1,4 @@
orconfig.h
lib/cc/*.h
lib/err/*.h
lib/intmath/*.h

20
src/lib/intmath/addsub.c Normal file
View File

@ -0,0 +1,20 @@
/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2018, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#include "lib/intmath/addsub.h"
#include "lib/cc/compat_compiler.h"
/* Helper: safely add two uint32_t's, capping at UINT32_MAX rather
* than overflow */
uint32_t
tor_add_u32_nowrap(uint32_t a, uint32_t b)
{
/* a+b > UINT32_MAX check, without overflow */
if (PREDICT_UNLIKELY(a > UINT32_MAX - b)) {
return UINT32_MAX;
} else {
return a+b;
}
}

13
src/lib/intmath/addsub.h Normal file
View File

@ -0,0 +1,13 @@
/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2018, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#ifndef TOR_INTMATH_ADDSUB_H
#define TOR_INTMATH_ADDSUB_H
#include "lib/cc/torint.h"
uint32_t tor_add_u32_nowrap(uint32_t a, uint32_t b);
#endif /* !defined(TOR_INTMATH_MULDIV_H) */

88
src/lib/intmath/bits.c Normal file
View File

@ -0,0 +1,88 @@
/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2018, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#include "lib/intmath/bits.h"
/** Returns floor(log2(u64)). If u64 is 0, (incorrectly) returns 0. */
int
tor_log2(uint64_t u64)
{
int r = 0;
if (u64 >= (U64_LITERAL(1)<<32)) {
u64 >>= 32;
r = 32;
}
if (u64 >= (U64_LITERAL(1)<<16)) {
u64 >>= 16;
r += 16;
}
if (u64 >= (U64_LITERAL(1)<<8)) {
u64 >>= 8;
r += 8;
}
if (u64 >= (U64_LITERAL(1)<<4)) {
u64 >>= 4;
r += 4;
}
if (u64 >= (U64_LITERAL(1)<<2)) {
u64 >>= 2;
r += 2;
}
if (u64 >= (U64_LITERAL(1)<<1)) {
// u64 >>= 1; // not using this any more.
r += 1;
}
return r;
}
/** Return the power of 2 in range [1,UINT64_MAX] closest to <b>u64</b>. If
* there are two powers of 2 equally close, round down. */
uint64_t
round_to_power_of_2(uint64_t u64)
{
int lg2;
uint64_t low;
uint64_t high;
if (u64 == 0)
return 1;
lg2 = tor_log2(u64);
low = U64_LITERAL(1) << lg2;
if (lg2 == 63)
return low;
high = U64_LITERAL(1) << (lg2+1);
if (high - u64 < u64 - low)
return high;
else
return low;
}
/** Return the number of bits set in <b>v</b>. */
int
n_bits_set_u8(uint8_t v)
{
static const int nybble_table[] = {
0, /* 0000 */
1, /* 0001 */
1, /* 0010 */
2, /* 0011 */
1, /* 0100 */
2, /* 0101 */
2, /* 0110 */
3, /* 0111 */
1, /* 1000 */
2, /* 1001 */
2, /* 1010 */
3, /* 1011 */
2, /* 1100 */
3, /* 1101 */
3, /* 1110 */
4, /* 1111 */
};
return nybble_table[v & 15] + nybble_table[v>>4];
}

16
src/lib/intmath/bits.h Normal file
View File

@ -0,0 +1,16 @@
/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2018, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#ifndef TOR_INTMATH_BITS_H
#define TOR_INTMATH_BITS_H
#include "lib/cc/torint.h"
#include "lib/cc/compat_compiler.h"
int tor_log2(uint64_t u64) ATTR_CONST;
uint64_t round_to_power_of_2(uint64_t u64);
int n_bits_set_u8(uint8_t v);
#endif /* !defined(TOR_INTMATH_BITS_H) */

20
src/lib/intmath/cmp.h Normal file
View File

@ -0,0 +1,20 @@
/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2018, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#ifndef TOR_INTMATH_CMP_H
#define TOR_INTMATH_CMP_H
/* Return <b>v</b> if it's between <b>min</b> and <b>max</b>. Otherwise
* return <b>min</b> if <b>v</b> is smaller than <b>min</b>, or <b>max</b> if
* <b>b</b> is larger than <b>max</b>.
*
* Requires that <b>min</b> is no more than <b>max</b>. May evaluate any of
* its arguments more than once! */
#define CLAMP(min,v,max) \
( ((v) < (min)) ? (min) : \
((v) > (max)) ? (max) : \
(v) )
#endif /* !defined(TOR_INTMATH_CMP_H) */

View File

@ -0,0 +1,22 @@
noinst_LIBRARIES += src/lib/libtor-intmath.a
if UNITTESTS_ENABLED
noinst_LIBRARIES += src/lib/libtor-intmath-testing.a
endif
src_lib_libtor_intmath_a_SOURCES = \
src/lib/intmath/addsub.c \
src/lib/intmath/bits.c \
src/lib/intmath/muldiv.c
src_lib_libtor_intmath_testing_a_SOURCES = \
$(src_lib_libtor_intmath_a_SOURCES)
src_lib_libtor_intmath_testing_a_CPPFLAGS = $(AM_CPPFLAGS) $(TEST_CPPFLAGS)
src_lib_libtor_intmath_testing_a_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
noinst_HEADERS += \
src/lib/intmath/addsub.h \
src/lib/intmath/cmp.h \
src/lib/intmath/bits.h \
src/lib/intmath/muldiv.h

75
src/lib/intmath/muldiv.c Normal file
View File

@ -0,0 +1,75 @@
/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2018, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#include "lib/intmath/muldiv.h"
#include "lib/err/torerr.h"
#include <stdlib.h>
/** Return the lowest x such that x is at least <b>number</b>, and x modulo
* <b>divisor</b> == 0. If no such x can be expressed as an unsigned, return
* UINT_MAX. Asserts if divisor is zero. */
unsigned
round_to_next_multiple_of(unsigned number, unsigned divisor)
{
raw_assert(divisor > 0);
if (UINT_MAX - divisor + 1 < number)
return UINT_MAX;
number += divisor - 1;
number -= number % divisor;
return number;
}
/** Return the lowest x such that x is at least <b>number</b>, and x modulo
* <b>divisor</b> == 0. If no such x can be expressed as a uint32_t, return
* UINT32_MAX. Asserts if divisor is zero. */
uint32_t
round_uint32_to_next_multiple_of(uint32_t number, uint32_t divisor)
{
raw_assert(divisor > 0);
if (UINT32_MAX - divisor + 1 < number)
return UINT32_MAX;
number += divisor - 1;
number -= number % divisor;
return number;
}
/** Return the lowest x such that x is at least <b>number</b>, and x modulo
* <b>divisor</b> == 0. If no such x can be expressed as a uint64_t, return
* UINT64_MAX. Asserts if divisor is zero. */
uint64_t
round_uint64_to_next_multiple_of(uint64_t number, uint64_t divisor)
{
raw_assert(divisor > 0);
if (UINT64_MAX - divisor + 1 < number)
return UINT64_MAX;
number += divisor - 1;
number -= number % divisor;
return number;
}
/* Helper: return greatest common divisor of a,b */
static uint64_t
gcd64(uint64_t a, uint64_t b)
{
while (b) {
uint64_t t = b;
b = a % b;
a = t;
}
return a;
}
/* Given a fraction *<b>numer</b> / *<b>denom</b>, simplify it.
* Requires that the denominator is greater than 0. */
void
simplify_fraction64(uint64_t *numer, uint64_t *denom)
{
raw_assert(denom);
uint64_t gcd = gcd64(*numer, *denom);
*numer /= gcd;
*denom /= gcd;
}

22
src/lib/intmath/muldiv.h Normal file
View File

@ -0,0 +1,22 @@
/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2018, The Tor Project, Inc. */
/* See LICENSE for licensing information */
#ifndef TOR_INTMATH_MULDIV_H
#define TOR_INTMATH_MULDIV_H
#include "lib/cc/torint.h"
unsigned round_to_next_multiple_of(unsigned number, unsigned divisor);
uint32_t round_uint32_to_next_multiple_of(uint32_t number, uint32_t divisor);
uint64_t round_uint64_to_next_multiple_of(uint64_t number, uint64_t divisor);
void simplify_fraction64(uint64_t *numer, uint64_t *denom);
/* Compute the CEIL of <b>a</b> divided by <b>b</b>, for nonnegative <b>a</b>
* and positive <b>b</b>. Works on integer types only. Not defined if a+(b-1)
* can overflow. */
#define CEIL_DIV(a,b) (((a)+((b)-1))/(b))
#endif /* !defined(TOR_INTMATH_MULDIV_H) */

View File

@ -156,6 +156,7 @@ pub fn main() {
cfg.component("tor-malloc");
cfg.component("tor-err-testing");
cfg.component("or-event-testing");
cfg.component("tor-intmath-testing");
cfg.component("tor-ctime-testing");
cfg.component("curve25519_donna");
cfg.component("keccak-tiny");