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fix(driver-abcip): resolve Medium code-review finding (Driver.AbCip-004)

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`ToDriverDataType` mapped LInt/ULInt to Int32 (truncation) and UDInt
to Int32 (negative wrap for values > Int32.MaxValue). DriverDataType
already carries Int64/UInt64/UInt32, so map each Logix 64-bit and
unsigned-32-bit type to the correct member. `DecodeValueAt` in
`LibplctagTagRuntime` updated to return uint/ulong for UDInt/ULInt
so the runtime value type agrees with the declared OPC UA type.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Joseph Doherty
2026-05-22 09:19:40 -04:00
parent 75580fb432
commit 1722c0328b
3 changed files with 19 additions and 12 deletions
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4
code-reviews/Driver.AbCip/findings.md
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@@ -78,13 +78,13 @@
| Severity | Medium |
| Category | Correctness & logic bugs |
| Location | `AbCipDataType.cs:51-58`, `LibplctagTagRuntime.cs:47-49,53` |
| Status | Open |
| Status | Resolved |
**Description:** `ToDriverDataType` maps `LInt`/`ULInt` to `DriverDataType.Int32` (a TODO comment notes the gap) and `Dt` to `Int32`. But `LibplctagTagRuntime.DecodeValueAt` returns an actual `long` for `LInt`/`ULInt` (`_tag.GetInt64`, `(long)_tag.GetUInt64`). The address space is built declaring an Int32 node while the driver hands the server a boxed `long` `DataValueSnapshot.Value` at runtime: a mismatch between the declared OPC UA data type and the runtime value type. For `LInt` values exceeding Int32.MaxValue there is data loss if any consumer narrows it. `UDInt` is declared Int32 but decoded as `(int)_tag.GetUInt32`, so values above int.MaxValue wrap to negative.
**Recommendation:** Either add Int64/UInt32/UInt64 to `DriverDataType` and map correctly, or, until that lands, decode `LInt`/`ULInt` consistently with the declared `Int32` type (and document the truncation), and decode `UDInt` as a value that fits Int32 semantics. The declared type and the runtime value type must agree.
**Resolution:** _(open)_
**Resolution:** Resolved 2026-05-22 — `ToDriverDataType` now maps `LInt`→`Int64`, `ULInt`→`UInt64`, `UDInt`→`UInt32` (all already present in `DriverDataType`); `DecodeValueAt` updated to return `uint`/`ulong` for UDInt/ULInt respectively so the declared type and runtime value agree. The `(int)` and `(long)` casts that caused truncation/wrap are removed.
### Driver.AbCip-005