MDEV-23893: Apply Sergei’s patch to validate numeric suffix parsing

[Adityacode-hub]

Summary

This patch applies Sergei’s proposed fix for MDEV-23893, ensuring that invalid suffixes for numeric configuration options (like expire_logs_days) are properly rejected.

In previous MariaDB versions (10.3–10.5), the server incorrectly accepted values such as:

expire_logs_days=abc
expire_logs_days=5garbage

This patch adds stricter validation during numeric suffix parsing.

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✅ Changes

• Added validation in eval_num_suffix() to reject suffixes longer than one character (ab, hjh, etc.).
• Improved numeric parsing in eval_num_suffix_ll() to handle empty or invalid numeric values.
• Aligns MariaDB 10.5 behavior with later fixed versions (10.6, 10.11, 11.4).

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🧠 Technical Details

if (suffix[0] && suffix[1]) {
    *error = 1;
    return 0ULL;
}

This prevents multi-character suffixes from being accepted.
Also, additional range and parsing checks were added for safer numeric handling.

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🧑‍💻 Credits

• Original idea / discussion: Sergei Golubchik
• Contributor: Aditya Kumar (@Adityacode-hub)
• Fixes: MDEV-23893

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🔧 Testing

Verified that invalid values such as expire_logs_days=abc or expire_logs_days=pq now trigger an error during startup.

[CLAassistant]

All committers have signed the CLA.

[Adityacode-hub]

Thanks @serg and @danblack for guidance.
This PR implements the validation check discussed in MDEV-23893 for invalid numeric suffix parsing.

[grooverdan]

On the Commit message. "MDEV-23893: Reject invalid numerical suffixes" is closer as a function description.

git commit --amend --author "Sergei Golubchik <[email protected]>" is a right way to attribute an author. Credit yourself in the body of the message if you want.

With these done, make this a single corrected commit and git push --force tot he same branch will update this PR.

[grooverdan]

remove above bit of comment and just leave as a comment on the text below, aligned to the indentation level. Correct the indentation level of if too`.

[grooverdan]

Spaces on either side of ||.