Improve build system

[lahwaacz]

These changes make building with system flags and libs more straightforward or actually possible. I had to patch the build system a lot while making a package for Arch Linux.

[lahwaacz]

@elezar Can you look at this please? 🙏

[elezar]

@lahwaacz sorry for the delay. I will have a look.

[elezar]

Thanks for the changes.

I think they look good. The one thing missing is ensuring that the defaults for all major platforms are the same given the WITH_TIRPC changes.

[lahwaacz]

@elezar Any progress with merging this? It's been almost half a year...

[lahwaacz]

@elezar It has been a year, can you merge this please?

[lahwaacz]

@elezar ping

It would also be good to know which license applies to the changed files (#193)

[ssalagam]

@cdesiniotis , please review this.

[myeolenv]

@henry118 Please review this.

[henry118]

This flips the existing behavior.

Currently we will build the library from source when this flag is yes, but after this change it behaves the opposite.

This might break some platforms that package this repo.

[lahwaacz]

As I wrote before:

Well, the meaning of WITH_TIRPC was not flipped:

• before: "yes" means building libtirpc from source, "no" means don't use libtirpc at all (I think)
  (@klueska explained that "Previously no meant -- use the native sunrpc library that is bundled in the OS (instead of tirpc).")
• after: "yes" means linking to system libtirpc, "no" means building libtirpc from source

Which other approach enabling linking to system libtirpc would you propose?

[henry118]

imho we should keep the existing semantics.

• yes - build from source
• no - use system library

My concern is that many downstream users might already depend on the current behavior and silently flipping the meaning would cause unexpected breaks.

[lahwaacz]

WITH_TIRPC=no does not use a system libtirpc - it uses something else for RPC.

AFAICT, there is currently no way to build with system libtirpc without patching or passing custom compiler flags. IMHO this is a good enough reason for a breaking change.

[henry118]

That's the SunRPC implementation that used to be shipped as part of glibc. Like Ubuntu 18.04 and older, they often still had the glibc SunRPC headers. But modern distros would require libtirpc-dev to compile code using RPC.

To avoid changing the meaning of WITH_TIRPC, perhaps we can introduce a 3 state selector instead:

TIRPC_MODE ?= sunrpc
# sunrpc - use the platform-provided SunRPC implementation# bundled - build and statically link the bundled libtirpc# system - use the system libtirpc discovered through pkg-config

Then preserve the existing flag as a compatibility shim:

ifdefWITH_TIRPC
ifeq ($(WITH_TIRPC),yes)
TIRPC_MODE := bundled
else
TIRPC_MODE := sunrpc
endif
endif

This keeps existing build scripts working as they do today:

make WITH_TIRPC=yes # still means bundled libtirpc
make WITH_TIRPC=no # still means SunRPC

while allowing the new behavior explicitly:

make TIRPC_MODE=system