Handle exceptions - #807
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This commit fixes crashes that can occur after garbage collection compaction, and adds a test for it (the test fails before the fix, and succeeds afterwards). Without this commit, GC compaction can lead to crashes. Ruby 2.7+ supports GC compaction (GC.compact), which can move objects in memory to reduce fragmentation. The rb_redcarpet_rndr struct stores Ruby VALUE references (link_attributes, self, base_class) as raw C pointers. When compaction moves these objects, the pointers become stale, causing segfaults or "T_IMEMO" errors on next use. This commit fixes this problem in the standard Ruby way. It registers a dcompact callback via Ruby's TypedData API. When GC compaction runs, Ruby calls this callback, allowing us to update each VALUE pointer using rb_gc_location() to its new address. The callback is conditionally compiled only when rb_gc_location is available (Ruby 2.7+), maintaining backward compatibility. Co-authored-by: David A. Wheeler <dwheeler@dwheeler.com> Co-authored-by: Claude <noreply@anthropic.com> Signed-off-by: David A. Wheeler <dwheeler@dwheeler.com>
Ruby callbacks can raise exceptions which use longjmp, bypassing C cleanup
code. This could leave work_bufs in an inconsistent state, causing assertion
failures on subsequent renders.
In addition, it's possible for the internal state to be corrupted
at *least* if there are multiple threads sharing an object
(and possibly other causes), which can quickly lead to an application
crash.
Changes:
- Use rb_ensure() to guarantee cleanup runs even if exception occurs
- Add sd_markdown_cleanup() to free render-time allocations and reset state
- Replace C assertions with detection that raises Ruby exception
- If work_bufs imbalance detected after render, raise informative exception
(indicates threading bug or undiscovered code path) and clean up
so that the problem is visible *but* the caller can keep going
(e.g., log the problem or even try to continue).
- There's a weird formatting of "else nb_p--; i++;" that is misleading.
At this point only the "else" branch can run, but this still triggers
compiler warnings. Change it to the clearer "else { nb_p--; i++; }".
The fix ensures:
1. Exceptions in callbacks propagate to caller properly
2. State is always reset so next render works
3. Work buffer imbalances are reported as Ruby exceptions, not C crashes
Co-Authored-By: David A. Wheeler <dwheeler@dwheeler.com>
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Signed-off-by: David A. Wheeler <dwheeler@dwheeler.com>
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This handles exceptions in the renderer (by raising exceptions), and also raises an exception instead of crashing if there's an internal state problem. |
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