[hangzqcom]

Problem

Several TACDev C API getters trusted the caller's index or left an out-parameter unset:

Function	Input	Before
GetPortData	deviceIndex = -1 / -1000	Host process crashes (negative index into QList::at())
GetCommand	index >= GetCommandCount()	Returns success with a garbage entry ;;18446744073709551615;;;
GetScriptVariable	index >= GetScriptVariableCount()	No range check
GetHelpText	buffer large enough	*actualSize left unset on success

GetCommand relied on commandEntry() returning pin 0 for a bad index. It actually returns a default entry with pin -1, so the existing _pin != 0 check passed.

Change

• GetPortData: also reject deviceIndex < 0, so it returns 0 like any other invalid index.
• GetCommand / GetScriptVariable: check the index against the count explicitly. Out of range now returns TAC_BAD_INDEX with an empty buffer, which is what GetQuickCommand already does.
• GetHelpText: set *actualSize on success too, guarded by the existing null check.

One file, interfaces/C++/TACDev/TACDev.cpp. No header or ABI change.

Valid indexes behave exactly as before. I checked the in-repo callers (C#, Python, Java and MCP examples, TACDump) and they all iterate up to the reported count. None loops until failure, so the new TAC_BAD_INDEX return only affects calls that were already out of range.

Verification

Tested on Windows with a PSoC board (FW 1.4.19.0), using this DLL in the installed tools folder.

• Direct TACDev API:
  • GetPortData(-1) and GetPortData(-1000) return 0 and the process exits cleanly. Before, it crashed.
  • GetCommand(out of range) and GetScriptVariable(out of range) return TAC_BAD_INDEX (4) with an empty buffer.
  • GetHelpText reports actualSize = 1363, matching the returned length.
  • All valid command, quick-command and script-variable entries are unchanged.
  • 20 open/read/close cycles and 80 read sweeps: no errors.
• Through TAC Service, which loads TACDev: the read, idempotent-write, destroy/recreate and kill-recovery sequences all pass.
• Other tools: TAC, TAC Configuration Editor and Device Catalog start normally, and TACDump enumerates the board.

Overall: 165 pass, 0 fail. Before this change the same run had 7 failures, all covered by the table above.