Add IBM i PASE detection

[gsnw-sebast]

Enabling detection of IBM i systems during source compilation
This was requested in issue #465

[gemini-code-assist]

Summary of Changes

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This pull request introduces support for compiling the fping utility on IBM i systems running the Portable Application Solutions Environment (PASE). By adding an automatic detection mechanism to the configure.ac script, the build process can now dynamically adjust compiler and linker flags, ensuring compatibility and simplifying the compilation workflow for this specific platform.

Highlights

• IBM i PASE Detection: Implemented logic in configure.ac to automatically detect the IBM i PASE environment during compilation. This detection enables fping to be built on IBM i systems by setting appropriate CPPFLAGS and LDFLAGS.
• Build Configuration: When IBM i PASE is detected, the build system now includes specific include paths (-I/QOpenSys/pkgs/include), defines (-D_SIGSET_T, -DHAVE_STDLIB_H, -DIP_RECVTOS=0), and library paths (-L/QOpenSys/pkgs/lib) to ensure successful compilation.
• Changelog Update: The CHANGELOG.md file has been updated to reflect the addition of IBM i PASE detection, crediting @acerbis and @gsnw-sebast for their contributions.

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Changelog

• CHANGELOG.md
  • Added an entry for IBM i PASE detection under the 'Next' release section.
• configure.ac
  • Introduced a new AC_COMPILE_IFELSE block to check for the __PASE__ macro, indicating an IBM i PASE environment.
  • Configured CPPFLAGS to include /QOpenSys/pkgs/include and define _SIGSET_T, HAVE_STDLIB_H, and IP_RECVTOS=0 when PASE is detected.
  • Configured LDFLAGS to include /QOpenSys/pkgs/lib when PASE is detected.

Activity

• This change addresses issue compile in PASE IBM i from sources #465, which requested IBM i PASE detection.
• The pull request was authored by gsnw-sebast.

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[gemini-code-assist]

Code Review

This pull request adds detection for the IBM i PASE environment to allow fping to be compiled on that platform. The changes involve updating the changelog and adding a check in configure.ac. While the detection logic is sound, the compiler and linker flags being set can be improved for correctness and robustness. I've left a specific comment with suggestions to refine these flags.

[coveralls]

coverage: 88.091% (+0.05%) from 88.037%
when pulling 3bffcc5 on gsnw:issue/465
into b862609 on schweikert:develop.

[gsnw-sebast]

@acerbis
I've implemented the improvements suggested by gemini-code-assist.
Can you test again to see if this works for IBM i?

[acerbis]

Does NOT work now (was working in the first attempt, just move the var defs before, prepending and not post).

-DHAVE_STDLIB_H is necessary because configure doesn't detect it apparently autonomously so compilation will fail.
-D_SIGSET_T is necessary to avoid double definitions (guard).
-DIP_RECVTOS=0 is necessary because some platforms doesn't have a setsockoptions possible with TOS

yes -DIP_RECVTOS=0 is clearly hackish but doesn't have big impact.

A more elegant way would be to have in fping a conditional to skip TOS releated code stuff for the platforms lacking TOS handling and then use such variable if TOS is present or not (i.e. like you did with PASE try in .ac to compile a source with IP_RECVTOS if the symbol is missing one would disable TOS support it).

my 2c

[gsnw-sebast]

I've put the old code back in, but the workaround using -DIP_RECVTOS=0 has been resolved here in the code.
Please test again.

The test scripts in the ci/ folder fail on IBM i when --print-tos is included in the command.

[acerbis]

Hello!
I confirm working. Thanks.