fix(rocdbgapi): exit early if accessing nullptr

[aktemur]

Motivation

Check for nullptr access and do not attempt to access memory. Give a proper error.

Technical Details

When accessing the memory, check if accessing the nullptr and if so, exit early with an error, so that we don't go into lower layers.

Issue Tracking

Bug: AIROCGDB-645

Test Plan

A new test to be included in ROCgdb.

Test Result

Passes with this patch, fails without.

[therock-pr-bot]

❌ PR Check — Action Required

Check	Status	Details
📝 PR Description	❌ Fail	Error: PR description must reference a JIRA ID, ISSUE ID, or a GitHub closing keyword. Expected: include a JIRA ID / ISSUE ID line (separator : or -, or omitted; value may be a JIRA key, a number with/without #, or a link), OR a closing keyword + issue reference. Accepted examples: • JIRA ID : TESTAUTO-6039 • JIRA ID - #330 • JIRA ID #330 • JIRA ID (on separate line) ROCM-25757 • ISSUE ID : TESTUTO-3334 • ISSUE ID #3334 • ISSUE ID - TESTAUTO-3433 • ISSUE ID (on separate line) AIRUNTIME-2352 • ISSUE ID : https://github.com/<org_name>/<repo_name>/issues/1234 • Closes #10 • Fixes octo-org/octo-repo#100 • Resolves: #123 • #123 • https://github.com/<org_name>/<repo_name>/issues/123 Current: no valid JIRA/ISSUE/closing-keyword reference found
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🧪 Unit Test	⚠️ Warning	Error: Source/code files changed without an accompanying unit test. Expected: add at least one test file named like test_<name>.py / test_<name>.cpp (or <name>_test.*). Current: code file(s) changed: projects/rocdbgapi/src/memory.cpp; no test file found
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🚩 Feature Flag	🔜 To Be Enabled	—
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[aktemur]

ROCgdb companion PR: ROCm/ROCgdb#250

[lancesix]

LGTM, thanks.

[lumachad]

OK. Windows failures unrelated.

[aktemur]

The ASAN failures are unrelated.