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/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/** \file
* \ingroup bli
*/
#include "BLI_uuid.h"
#include <cstdio>
#include <cstring>
#include <ctime>
#include <random>
#include <string>
/* Ensure the UUID struct doesn't have any padding, to be compatible with memcmp(). */
static_assert(sizeof(UUID) == 16, "expect UUIDs to be 128 bit exactly");
UUID BLI_uuid_generate_random()
{
static std::mt19937_64 rng = []() {
std::mt19937_64 rng;
/* Ensure the RNG really can output 64-bit values. */
static_assert(std::mt19937_64::min() == 0LL);
static_assert(std::mt19937_64::max() == 0xffffffffffffffffLL);
struct timespec ts;
#ifdef __APPLE__
/* `timespec_get()` is only available on macOS 10.15+, so until that's the minimum version
* supported by Blender, use another function to get the timespec.
*
* `clock_gettime()` is only available on POSIX, so not on Windows; Linux uses the newer C++11
* function `timespec_get()` as well. */
clock_gettime(CLOCK_REALTIME, &ts);
#else
timespec_get(&ts, TIME_UTC);
#endif
/* XOR the nanosecond and second fields, just in case the clock only has seconds resolution. */
uint64_t seed = ts.tv_nsec;
seed ^= ts.tv_sec;
rng.seed(seed);
return rng;
}();
UUID uuid;
/* RFC4122 suggests setting certain bits to a fixed value, and then randomizing the remaining
* bits. The opposite is easier to implement, though, so that's what's done here. */
/* Read two 64-bit numbers to randomize all 128 bits of the UUID. */
uint64_t *uuid_as_int64 = reinterpret_cast<uint64_t *>(&uuid);
uuid_as_int64[0] = rng();
uuid_as_int64[1] = rng();
/* Set the most significant four bits to 0b0100 to indicate version 4 (random UUID). */
uuid.time_hi_and_version &= ~0xF000;
uuid.time_hi_and_version |= 0x4000;
/* Set the most significant two bits to 0b10 to indicate compatibility with RFC4122. */
uuid.clock_seq_hi_and_reserved &= ~0x40;
uuid.clock_seq_hi_and_reserved |= 0x80;
return uuid;
}
UUID BLI_uuid_nil(void)
{
const UUID nil = {0, 0, 0, 0, 0, 0};
return nil;
}
bool BLI_uuid_is_nil(UUID uuid)
{
return BLI_uuid_equal(BLI_uuid_nil(), uuid);
}
bool BLI_uuid_equal(const UUID uuid1, const UUID uuid2)
{
return std::memcmp(&uuid1, &uuid2, sizeof(uuid1)) == 0;
}
void BLI_uuid_format(char *buffer, const UUID uuid)
{
std::sprintf(buffer,
"%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
uuid.time_low,
uuid.time_mid,
uuid.time_hi_and_version,
uuid.clock_seq_hi_and_reserved,
uuid.clock_seq_low,
uuid.node[0],
uuid.node[1],
uuid.node[2],
uuid.node[3],
uuid.node[4],
uuid.node[5]);
}
bool BLI_uuid_parse_string(UUID *uuid, const char *buffer)
{
const int num_fields_parsed = std::sscanf(
buffer,
"%8x-%4hx-%4hx-%2hhx%2hhx-%2hhx%2hhx%2hhx%2hhx%2hhx%2hhx",
&uuid->time_low,
&uuid->time_mid,
&uuid->time_hi_and_version,
&uuid->clock_seq_hi_and_reserved,
&uuid->clock_seq_low,
&uuid->node[0],
&uuid->node[1],
&uuid->node[2],
&uuid->node[3],
&uuid->node[4],
&uuid->node[5]);
return num_fields_parsed == 11;
}
std::ostream &operator<<(std::ostream &stream, UUID uuid)
{
std::string buffer(36, '\0');
BLI_uuid_format(buffer.data(), uuid);
stream << buffer;
return stream;
}
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