Don't crash when printing a recursive structure

[thexa4]

Fixes #1598

local foo to lexicon().
set foo["self"] to foo.

print foo.

Will now print "...recurse..." for the self value instead of crashing KSP. Other serializers will end with an exception instead of a crash.

[Dunbaratu]

@thexa4 I just tested this and still got the stack overflow with this example program:

local aaa is list(1,2,3).
local bbb is list(100,200,aaa,400).
aaa:add(bbb). // this causes recursion since bbb contains aaa at position [2].
print "does this crash?".
print aaa.
print "it never gets here.".

That crashed KSP instantly, with this:

StackOverflowException: The requested operation caused a stack overflow.
  at (wrapper managed-to-native) System.Object.__icall_wrapper_ves_icall_object_new_specific(intptr)
  at kOS.Safe.Serialization.SafeSerializationMgr.Dump (kOS.Safe.Serialization.IDumper dumper, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) [0x00015] in <284f6740e8dd46a481f1ab5fe385b64a>:0 
  at kOS.Safe.Serialization.SafeSerializationMgr.DumpValue (System.Object value, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) [0x00068] in <284f6740e8dd46a481f1ab5fe385b64a>:0 
  at kOS.Safe.Serialization.SafeSerializationMgr+<>c__DisplayClass7_0.<DumpValue>b__0 (System.Object v) [0x00000] in <284f6740e8dd46a481f1ab5fe385b64a>:0 
  at System.Linq.Enumerable+SelectListIterator`2[TSource,TResult].ToList () [0x0002a] in <fbb5ed17eb6e46c680000f8910ebb50c>:0 
  at System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) [0x0001f] in <fbb5ed17eb6e46c680000f8910ebb50c>:0 
  at kOS.Safe.Serialization.SafeSerializationMgr.DumpValue (System.Object value, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) [0x000b7] in <284f6740e8dd46a481f1ab5fe385b64a>:0 
  at kOS.Safe.Serialization.SafeSerializationMgr.Dump (kOS.Safe.Serialization.IDumper dumper, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) [0x00061] in <284f6740e8dd46a481f1ab5fe385b64a>:0 

[ ... Here I truncated the output.  Because it recurses, this repeated a long time. ...]

[thexa4]

Ah, sorry, it seems I only tested the single depth recursion. Will fix.

[thexa4]

While looking at #2894 I noticed that this incorrectly marks all strings as recursive. Fix is in progress.

[mlheur]

I'm trying to test the PR, see if it resolves my issue. It does not.
What I've done:

0. uninstall kOS from my game data.
1. download KOS-bugfix-infinite-recursion-crash.zip from thexa4's fork.
2. extract that.
3. copy [C:\Games\KSP 1.11.1\KSP_x64_Data\Managed\*.*] to [...\KOS-bugfix-infinite-recursion-crash\Resources\].
4. open [...\KOS-bugfix-infinite-recursion-crash\src\kOS.sln] in VS2019 Community Edition.
5. rebuild solution Ctrl-Alt-F7. Fifteen warnings, mostly "somevar isn't used".
6. Check date modified is now for [...\KOS-bugfix-infinite-recursion-crash\Resources\GameData\kOS\Plugins\kOS*.dll].
7. copy [...\KOS-bugfix-infinite-recursion-crash\Resources\GameData\*] to [C:\Games\KSP 1.11.1\GameData\].
8. Open KSP, launch ship, run code listed in my post self-bound delegates CTD. #2918. With the wait removed, CTD on calling print the_object.

[EXC 12:11:28.756] StackOverflowException: The requested operation caused a stack overflow.
	kOS.Safe.Encapsulation.StringValue.Dump () (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.Dump (kOS.Safe.Serialization.IDumper dumper, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.DumpValue (System.Object value, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr+<>c__DisplayClass7_1.<DumpValue>b__0 (System.Object v) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	System.Linq.Enumerable+SelectListIterator`2[TSource,TResult].ToList () (at <fbb5ed17eb6e46c680000f8910ebb50c>:0)
	System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) (at <fbb5ed17eb6e46c680000f8910ebb50c>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.DumpValue (System.Object value, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.Dump (kOS.Safe.Serialization.IDumper dumper, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.Serialize (kOS.Safe.Serialization.IDumper serialized, kOS.Safe.Serialization.IFormatWriter formatter, System.Boolean includeType, System.Boolean allowTruncatedRecursion) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.ToString (kOS.Safe.Serialization.IDumper dumper) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Encapsulation.Lexicon.ToString () (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Encapsulation.KOSDelegate.ToString () (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Encapsulation.UserDelegate.ToString () (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.DumpValue (System.Object value, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr+<>c__DisplayClass7_1.<DumpValue>b__0 (System.Object v) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	System.Linq.Enumerable+SelectListIterator`2[TSource,TResult].ToList () (at <fbb5ed17eb6e46c680000f8910ebb50c>:0)
	System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) (at <fbb5ed17eb6e46c680000f8910ebb50c>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.DumpValue (System.Object value, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.Dump (kOS.Safe.Serialization.IDumper dumper, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.Serialize (kOS.Safe.Serialization.IDumper serialized, kOS.Safe.Serialization.IFormatWriter formatter, System.Boolean includeType, System.Boolean allowTruncatedRecursion) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.ToString (kOS.Safe.Serialization.IDumper dumper) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Encapsulation.Lexicon.ToString () (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Encapsulation.KOSDelegate.ToString () (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Encapsulation.UserDelegate.ToString () (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.DumpValue (System.Object value, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr+<>c__DisplayClass7_1.<DumpValue>b__0 (System.Object v) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	System.Linq.Enumerable+SelectListIterator`2[TSource,TResult].ToList () (at <fbb5ed17eb6e46c680000f8910ebb50c>:0)
	System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) (at <fbb5ed17eb6e46c680000f8910ebb50c>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.DumpValue (System.Object value, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.Dump (kOS.Safe.Serialization.IDumper dumper, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.Serialize (kOS.Safe.Serialization.IDumper serialized, kOS.Safe.Serialization.IFormatWriter formatter, System.Boolean includeType, System.Boolean allowTruncatedRecursion) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.ToString (kOS.Safe.Serialization.IDumper dumper) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Encapsulation.Lexicon.ToString () (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Encapsulation.KOSDelegate.ToString () (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Encapsulation.UserDelegate.ToString () (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.DumpValue (System.Object value, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr+<>c__DisplayClass7_1.<DumpValue>b__0 (System.Object v) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	System.Linq.Enumerable+SelectListIterator`2[TSource,TResult].ToList () (at <fbb5ed17eb6e46c680000f8910ebb50c>:0)
	System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) (at <fbb5ed17eb6e46c680000f8910ebb50c>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.DumpValue (System.Object value, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.Dump (kOS.Safe.Serialization.IDumper dumper, System.Boolean includeType, System.Boolean allowTruncatedRecursion, System.Collections.Generic.List`1[T] seenList) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.Serialize (kOS.Safe.Serialization.IDumper serialized, kOS.Safe.Serialization.IFormatWriter formatter, System.Boolean includeType, System.Boolean allowTruncatedRecursion) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)
	kOS.Safe.Serialization.SafeSerializationMgr.ToString (kOS.Safe.Serialization.IDumper dumper) (at <1c1a8b3318a64b7787b45fc960c254ee>:0)

[thexa4]

Thanks for testing it, I'll try to reproduce and fix it somewhere this week / next weekend.

[mlheur]

Thank you for working on the patch. I looked at the diff, that's pretty much what I would've tried but have no experience with C#. With the insight I've gained from you I was able to make my code work, after eliminating all attempts to print and run haskey on my 'object'. Thanks again and let me know if there's more I can do to help.

[thexa4]

Closed in favor of #2910