[DeepClone] Fix round-tripping objects whose __serialize() nests another object#629
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…her object A needsFullUnserialize object (a final internal class with __unserialize that rejects an empty payload, e.g. Random\Randomizer) whose __serialize() nests another object carries an object-ref mask on its state. Such an object cannot be built as an early empty shell, and the eager-finalize pass skipped masked states, leaving a null placeholder; when another object referenced it, the properties loop threw "unknown object id" before the states loop could reconstruct it. These objects are now finalized to a fixpoint after the refs pass, once the objects their mask references exist. Round-tripping Random\Randomizer as an object property (or deeper) now works, matching the extension. A shared object nested inside such a state is still reconstructed as an independent copy (pure PHP cannot inject a live shared object into an internal final class's __unserialize); the extension preserves identity there.
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… instances on PHP 8.2 (nicolas-grekas) This PR was merged into the 1.x branch. Discussion ---------- [DeepClone] Fix round-tripping short-lived Random\Randomizer instances on PHP 8.2 | Q | A | ------------- | --- | Branch? | 1.x | Bug fix? | yes | New feature? | no | Deprecations? | no | Issues | - | License | MIT This is what has been segfaulting the PHP 8.2 CI jobs since the Randomizer round-trip tests landed in #629 (and what #630 inherits). Minimal reproducer, no polyfill involved, on PHP 8.2.31: ```php $state = (new Random\Randomizer(new Random\Engine\Mt19937(7)))->__serialize(); serialize($state); // SIGSEGV ``` Before PHP 8.3, `Random\Randomizer::__serialize()` returns the object's raw property table with only the table itself addref'd. Its `engine` entry is an `IS_INDIRECT` slot pointing into the object, so once the Randomizer is released the retained state dangles. php-src fixed this for 8.3 by duplicating the table (php/php-src@c5fa7696e64), but 8.2 was already security-only and the fix was never backported; 8.2.31 still crashes. `deepclone_to_array()` retains exactly such a state in its payload, so round-tripping a Randomizer that does not outlive the payload segfaulted on 8.2. There is no copy-based userland fix: plain array reads copy `IS_INDIRECT` slots verbatim instead of resolving them (`gettype()` reports `unknown type`), which is also how the contamination is detected. The serializer is the one userland-reachable code path that resolves these slots, so when a `__serialize()` result is contaminated (checked while the source object is still alive, and only on PHP < 8.3), it is passed through a `serialize()`/`unserialize()` round trip to materialize real values. No new tests: the #629 Randomizer tests are the regression tests; they segfault on PHP 8.2 before this change and pass after (suite verified green on 8.1, 8.2, 8.3 and 8.5). The nested engine becomes a fresh copy rather than a shared instance on the affected versions, matching the already-documented identity behavior of nested `__serialize()` states. Companion extension fix (the with-extensions 8.2 CI legs run the tagged ext via PIE and stay red until it ships in a release): symfony/php-ext-deepclone#23 Perf note: `Random\Randomizer` is special-cased instead of scanned for, after auditing PHP 8.2 core for the pattern: of the internal classes whose `__serialize()` retains the un-duplicated property table (Randomizer, `HashContext`, the Random engines), only Randomizer declares a property, and only declared properties create `IS_INDIRECT` slots (GMP uses the legacy serialize handler, consumed while the object is alive; the date classes already duplicate). Measured on 8.2: no overhead for any other class; Randomizer itself pays one serialize round trip (~190 us for a Mt19937 state), the price of not crashing. On PHP 8.3+ the version guard makes the branch dead code. The trade-off versus scanning every internal state: a hypothetical third-party extension class combining the same pattern with declared properties would keep crashing, as it does today. Companion extension fix (the with-extensions 8.2 CI legs run the tagged ext via PIE, fixed in v0.7.2): symfony/php-ext-deepclone#23 Commits ------- ae1778e [DeepClone] Fix round-tripping short-lived Random\Randomizer instances on PHP 8.2
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Builds on #628 (which adds the states-loop guard this relies on).
A
needsFullUnserializeobject (afinalinternal class whose__unserialize()rejects an empty payload, so it has no empty-shell prototype) whose__serialize()nests another object carries an object-ref mask on its reconstruction state.Random\Randomizer, which wraps aRandom\Engine\*, is the common case.reconstruct()defers these to the states loop, but the eager-finalize pass that turns deferred objects into real instances (so the properties loop can resolve references to them) skipped any state with an object-ref mask. The placeholder stayednull, and as soon as another object referenced it the properties loop threwdeepclone_from_array(): ... unknown object id. The extension does not have this problem: it instantiates every object shell up front viaobject_init_ex()and calls__unserialize()later.Reproducer (works with the extension, threw with the polyfill):
These objects are now finalized to a fixpoint after the refs pass, once the objects their mask references exist (a remaining cycle, which pure PHP cannot reconstruct, is still reported by the existing loops).
Random\Randomizernow round-trips as an object property, top-level, in arrays and nested.Known limitation: a shared object nested inside such a state is reconstructed as an independent copy, because pure PHP cannot inject a live shared object into an internal
finalclass's__unserialize(). The extension preserves identity in that case. This only affects an object shared between aneedsFullUnserializeobject's serialized state and the rest of the graph.