RDKEMW-12824: Propagate signal from DobbyInit to DobbyDaemon

[ks734]

Description

When a container is killed by a signal, DobbyDaemon expects to see a WIFSIGNALED wait status from the container's runc process. However, DobbyInit is PID 1 of the container's PID namespace and the kernel protects it from signals with default disposition - even raise() is silently dropped, making the conventional "reset to SIG_DFL + raise()" approach impossible.

As a result, DobbyInit was exiting with code 0 regardless of the signal received, causing DobbyDaemon to incorrectly treat signal-killed containers as clean exits (WIFEXITED, status 0x0000).

Adopt the POSIX shell convention: record the signal number in a volatile sig_atomic_t from the signal handler, and after all children have been reaped call _exit(128 + signum). On the DobbyDaemon side, detect exit codes in the range 129-192 and synthesise the equivalent WIFSIGNALED wait status.

Test Procedure

Sending a SIGABRT or SIGSEGV or any other fatal message to DobbyInit or another process within the running container results in the app crashing as expected.

Expected:

1. WIFEXITED should return false
2. WIFSIGNALED should return true
3. WCOREDUMP should return true
4. WTERMSIG should return the signal used.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other (doesn't fit into the above categories - e.g. documentation updates)

Requires Bitbake Recipe changes?

• The base Bitbake recipe (meta-rdk-ext/recipes-containers/dobby/dobby.bb) must be modified to support the changes in this PR (beyond updating SRC_REV)

[Copilot]

Pull request overview

This PR aims to correctly propagate “signal-killed” container termination causes from DobbyInit (PID 1 in the container PID namespace) up to DobbyDaemon, by encoding the terminating signal as an exit code (128 + signum) and reconstructing a WIFSIGNALED-style wait status in the daemon.

Changes:

• DobbyInit: record a received/observed terminating signal and _exit(128 + sig) after reaping children.
• DobbyManager: detect WEXITSTATUS in the 128+sig range and synthesize a WIFSIGNALED-compatible wait status (optionally setting WCOREDUMP).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

File	Description
daemon/lib/source/DobbyManager.cpp	Decodes 128+sig exits into synthesized WIFSIGNALED statuses (plus optional WCOREDUMP).
daemon/init/source/InitMain.cpp	Tracks signal receipt/child signal death and exits via the 128+sig convention.

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