[runtime] Add better control over the random hashing seed #15207
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
- Hash seed randomization can now be disabled by defining the SWIFT_DETERMINISTIC_HASHING environment value with a value of "1". - The random hash seed is now generated using arc4random, where available. On platforms where it isn't, don't construct std::random_device twice. - _Hasher._secretKey is renamed _Hashing._seed, with no setter. - _Hasher._isDeterministic is a new property exposing whether we're running with non-random hashes. (Set/Dictionary will need this information to decide if they're allowed to use per-instance seeding.)
The hash seed is not settable at runtime anymore; update lit config to set the SWIFT_DETERMINISTIC_HASHING environment variable instead.
lorentey
force-pushed
the
seedless-hashes
branch
from
1164b6a to
e5eed66
Compare
|
@swift-ci please test |
milseman
approved these changes
Mar 13, 2018
| // FIXME(hasher): Remove | ||
| @_inlineable // FIXME(sil-serialize-all) | ||
| @_versioned | ||
| @_transparent | ||
| internal static func getExecutionSeed() -> UInt64 { | ||
| // FIXME: This needs to be a per-execution seed. This is just a placeholder | ||
| // implementation. | ||
| let seed: UInt64 = 0xff51afd7ed558ccd | ||
| return _HashingDetail.fixedSeedOverride == 0 ? seed : fixedSeedOverride | ||
| return 0xff51afd7ed558ccd |
There was a problem hiding this comment.
return 0xff51afd7ed558ccd // Chosen by fair dice role. Guaranteed to be random
There was a problem hiding this comment.
0xffffffffffffffff sided die.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This changes the runtime to look for the
SWIFT_DETERMINISTIC_HASHINGenvironment variable, and, if it is set to1during process startup, arrange to disable randomized hashing in the stdlib.This mechanism replaces the old mutable
_Hasher._secretKeyproperty with a read-only_Hasher._seedvar, and adds a new_Hasher._isDeterministicboolean property indicating whetherSetandDictionaryshould ensure repeatable ordering.The seed generator is updated to make better use of the system-provided RNGs.
Swift's lit config is updated to run executable tests with deterministic hashing enabled by default, on all platforms.