Fix FlexRadio meter-list parse crash on frame without "meter " keyword

[patrickrb]

Summary

FlexMeterInfos.setMeterInfos() can throw an uncaught StringIndexOutOfBoundsException and crash the entire app when a FlexRadio METER_LIST response frame is corrupt or truncated.

Root cause

The parser sliced the meter-definition list with:

temp = content.substring(content.indexOf("meter ") + "meter ".length()).split("#");

with no guard on the indexOf() result. When content does not contain "meter ", indexOf() returns -1, so the offset becomes -1 + 6 = 5, and substring(5) throws StringIndexOutOfBoundsException for any frame shorter than 5 characters (e.g. "0").

This parse runs on the FlexRadio TCP read thread (RadioTcpClient.SocketThread.run()), whose read loop catches only SocketException/IOException:

} catch (SocketException e){ ...
} catch (IOException e) { ...

A RuntimeException therefore propagates out of the read thread uncaught → Android's default handler terminates the process. Same failure class as the previously fixed Xiegu handle (PR #488) and Icom/Kenwood/Yaesu CAT parser crashes (PRs #487/#489): a rig-response parser that trusts the shape of untrusted serial/network input.

Fix

Validate that the "meter " keyword is present before slicing; if it is not, return early (a non-meter frame carries no meter definitions to parse). This is the smallest safe change and additionally prevents a long non-meter frame from being mis-parsed as garbage meter definitions.

int meterIndex = content.indexOf("meter ");
if (meterIndex < 0) return;
temp = content.substring(meterIndex + "meter ".length()).split("#");

No protocol behavior changes for well-formed meter lists.

Testing

• New FlexMeterInfosTest (pure JVM, no Robolectric — FlexMeterInfos touches no Android types):
  • shortFrameWithoutMeterKeyword_doesNotCrash — the crash regression; fails with StringIndexOutOfBoundsException on the pre-fix code, passes after.
  • parsesWellFormedMeterList — confirms ids (sMeterId/swrId/pwrId/alcId/tempCId), unit mapping, and numeric fields still parse correctly.
  • emptyContent_isNoOp, frameWithoutMeterKeyword_isIgnored, meterKeywordAtEnd_doesNotCrash, reparseUpdatesExistingDefinitions.
• Verified the regression by reverting the fix and re-running: the buggy code fails exactly shortFrameWithoutMeterKeyword_doesNotCrash.
• ./gradlew :app:testDebugUnitTest — full suite BUILD SUCCESSFUL.
• ./gradlew :app:assembleDebug (native/cmake included) — BUILD SUCCESSFUL.

Risk assessment

Very low. One-file guard on a single parse path; no DSP, encoder/decoder, waterfall, or audio code touched. Well-formed frames are unaffected; the only behavior change is that malformed/non-meter frames are now ignored instead of crashing (or being parsed as junk).

Affected platforms

All (FlexRadio 6xxx TCP CAT path).

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 23.35%. Comparing base (54b5b13) to head (ea5bde8).

Additional details and impacted files

@@            Coverage Diff            @@
##                dev     #491   +/-   ##
=========================================
  Coverage     23.35%   23.35%           
  Complexity      162      162           
=========================================
  Files           167      167           
  Lines         21450    21450           
  Branches       3154     3154           
=========================================
  Hits           5009     5009           
  Misses        16248    16248           
  Partials        193      193           

Flag	Coverage Δ
android	13.26% <ø> (ø)
native	9.93% <ø> (ø)

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[Copilot]

Pull request overview

This PR hardens the FlexRadio METER_LIST parser to avoid an app-crashing StringIndexOutOfBoundsException when a response frame is corrupt/truncated and lacks the "meter " keyword, and adds JVM unit tests to prevent regressions.

Changes:

• Add a guard in FlexMeterInfos.setMeterInfos() to return early when "meter " is missing before slicing/parsing.
• Add a new pure-JVM FlexMeterInfosTest covering the crash regression and validating well-formed parsing behavior.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
ft8af/app/src/main/java/com/k1af/ft8af/flex/FlexMeterInfos.java	Adds a safe "meter " presence check to prevent substring-based crashes on malformed frames.
ft8af/app/src/test/java/com/k1af/ft8af/flex/FlexMeterInfosTest.java	Adds unit tests for malformed/non-meter frames and for correct parsing of a representative meter list.

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