RFR: 8287101: CDS should check for file truncation for all regions

[Ioi Lam]

On Thu, 2 Jun 2022 20:41:15 GMT, Calvin Cheung <ccheung at openjdk.org> wrote:

> Currently, only the `last_valid_region` is checked for file truncation for a CDS archive. If serial GC is used, file truncation is not detected because the `last_valid_region` is empty so `si->file_offset() == 0`. This change is for checking file truncation for all regions.
> 
> Also add a test which truncates at the end of the file to trigger the "The shared archive file has been truncated." error.
> 
> Testing: tiers 1 and 2, also ran the test case with -XX:+UseSerialGC.

Looks good.

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Marked as reviewed by iklam (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/9004