RFR: JDK-8320005 : Allow loading of shared objects with .a extension on AIX [v23]

[Joachim Kern]

On Mon, 19 Feb 2024 11:11:23 GMT, Suchismith Roy <sroy at openjdk.org> wrote:

>> src/hotspot/os/aix/os_aix.cpp line 1181:
>> 
>>> 1179:   // First try to load the existing file.
>>> 1180:   result = dll_load_library(filename, ebuf, ebuflen);
>>> 1181:   int error_code = errno;
>> 
>> this might not necessarily be the `errno` of the underlying `dlopen()`, because there is to much code in-between and branches without a `dlopen()` call.
>
>> this might not necessarily be the `errno` of the underlying `dlopen()`, because there is to much code in-between and branches without a `dlopen()` call.
> 
> As i see the code in Aix_dlopen , there is no additional functional call after the dlopen which might change the errno . Could you tell me the how the errno would get overriden ?

Suchi, errno is a global static variable. If some runtime API sets it, it will continue to have this value until the next runtime call updates it. If you call dll_load_library, there are many execution paths not passing dlopen(). So you receive an errno from some unknown runtime API called before. The correct errno handling is:

errno = 0;
runtime_API_which_might_set_errno_in_error_case();
error_code = errno;

But what you really need is the result of the `search_file_in_LIBPATH(...)` call in `Aix_dlopen()`. If it is false, then the error_report starts with the string "Could not load module . ....."
This is called in any case. A `dlopen()` is not called in any case.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16604#discussion_r1494459722