diff options
author | Sybren A. Stüvel <sybren@blender.org> | 2021-09-17 12:53:00 +0300 |
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committer | Sybren A. Stüvel <sybren@blender.org> | 2021-09-17 13:22:00 +0300 |
commit | e1d7ce005f9f9ca84befdd531014d498966f27fc (patch) | |
tree | f518b7fa618a615d4a75f13e983e4f690ee759bd /source/blender/blenlib/intern/uuid.cc | |
parent | 1cd20b0026838c3fb69c0b273db8513f89f31f22 (diff) |
Blenlib: introduce a UUID type
Add `BLI_uuid` and `DNA_uuid_types.h` with a UUID implementation
following RFC4122 (https://datatracker.ietf.org/doc/html/rfc4122.html).
The following features are implemented:
- A struct of 128 bits that can be used in DNA definitions.
- Generation of version 4 UUIDs, that is, purely random ones.
- UUID equality function.
- String to UUID and UUID to string conversion functions that are
compatible with RFC4122.
- C++ stream operator that outputs the UUID as string.
This UUID will be used by the asset system, to uniquely identify asset
catalogs.
Reviewed By: Severin, jacqueslucke
Differential Revision: https://developer.blender.org/D12475
Diffstat (limited to 'source/blender/blenlib/intern/uuid.cc')
-rw-r--r-- | source/blender/blenlib/intern/uuid.cc | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/source/blender/blenlib/intern/uuid.cc b/source/blender/blenlib/intern/uuid.cc new file mode 100644 index 00000000000..a0fbc1a61ff --- /dev/null +++ b/source/blender/blenlib/intern/uuid.cc @@ -0,0 +1,112 @@ +/* + * 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 <random> +#include <string.h> + +/* 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(rng.min() == 0LL); + static_assert(rng.max() == 0xffffffffffffffffLL); + + struct timespec ts; + timespec_get(&ts, TIME_UTC); + rng.seed(ts.tv_nsec); + + 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; +} + +bool BLI_uuid_equal(const UUID uuid1, const UUID uuid2) +{ + return memcmp(&uuid1, &uuid2, sizeof(uuid1)) == 0; +} + +void BLI_uuid_format(char *buffer, const UUID uuid) +{ + 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 = 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; +} |