RFR: 8354920: SA core file support on Linux only prints error messages when debug logging is enabled

[Chris Plummer]

On Thu, 17 Apr 2025 12:27:55 GMT, Daniel Jeliński <djelinski at openjdk.org> wrote:

> Currently if loading a core file fails, the diagnostic information provided on different systems is different; on MacOS we produce an error message, while on Linux we only print information if debug logging is enabled.
> 
> This PR adds some new messages on Linux to match MacOSX, and changes some of the diagnostic output to error level instead of debug. Additionally, if opening the core or the exe file fails, the system error message (strerror) is printed.
> 
> Tier1-3 testing clean.

This is a good start for getting a reasonable error message without having to first enable LIBSAPROC_DEBUG. A couple of suggestions for additional improvements below:

You've covered the top level error message in Pgrab_core(), but there are many other print_debug messages that are for errors that are closer to the root cause of the error. For example, look in core_handle_note() and read_lib_info(). Also, Pgrab() needs updating, although it only has one debug message, but it also is missing detecting when add_thread_info() or read_lib_info() fails.

add_map_info() and core_handle_prstatus() are lacking a print_error message when they fail.

-------------

Changes requested by cjplummer (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24722#pullrequestreview-2776146648