[PATCH] build - use system asn1_compile to cross-compile Samba's bundled Heimdal

[Uri Simchoni]

Two corrections to the account below:

1. For cross-build, it's been necessary to add 
--bundled-libraries='!asn1_compile,!compile_et' regardless of whether or 
not one sets COMPILE_ET / ASN_COMPILE (i.e. there's only one method, and 
setting COMPILE_ET can be used to override the lookup for compile_et 
program in the path).

2. Consequently, cross-building is broken without workaround in 4.11 - 
the patch in this thread can be used until this gets fixed.

Thanks,
Uri.

On 20/10/2019 9:37, Uri Simchoni wrote:
> Hi,
> 
> (Taking discussion from https://bugzilla.samba.org/show_bug.cgi?id=14164 
> to the list)
> 
> Attached is yet another cross-compilation fix which I submitted to 
> bugzilla for test by reporter before MR. The fix works for the reporter, 
>   but has been Nacked by Andrew, and I'd like to discuss this further here.
> 
> Background:
> - Heimdal build requires two tools, asn1_compile and compile_et, which 
> are binary programs.
> - In the native build of Samba with embedded Heimdal, we build them 
> first and use them to build the rest of Heimdal.
> - This fails on cross-build for obvious reasons.
> - One workaround (which I've been using when I was in the embedded Samba 
> business) is to build Samba natively, stash the binaries of asn1_compile 
> and compile_et somewhere, and set environment vars COMPILE_ET and 
> ASN1_COMPILE to point to these binaries.
> - A different workaround which is in common use (buildroot, OpenWRT, 
> LibreELEC to name just a few) is to *somehow* host-build compile_et and 
> asn1_compile and install them in the build's path, then run configure 
> with the flag --bundled-libraries='!asn1_compile,!compile_et'. This 
> would invoke a configuration test which finds the binaries in the path 
> and sets COMPILE_ET / ASN1_COMPILE accordingly. Let's call that "the 
> automatic method".
> - The "somehow" seems to mostly be building of stand-alone Heimdal 
> package. So Samba gets cross-built with asn1_compile that came from 
> stand-alone Heimdal, and compile_et which comes from either Heimdal or, 
> possibly, another package that produces this binary and has been 
> host-built such as e2fsprogs. Both might be overriden by what happens to 
> be installed on the build-host, if the distro doesn't take care to put 
> its built tools in the path before the system tools.
> - commit 8061983d4882f3ba3f12da71443b035d7b672eec broke the automatic 
> method, because it invokes the test to find binaries only if using 
> system Heimdal.
> 
> The attached patch fixes "the automatic method". Andrew Nacked it 
> because using some binary that we don't know where it came from is prone 
> to incompatibility issues. In fact, it appears that embedded vendors 
> routinely use a patch that removes inclusion of <unistd.h> from one of 
> Samba's libreplace files, just because of the automatic method, and this 
> patch works on 4.11 but breaks master. A better fix would be to get 
> Samba's build system to build asn1_compile and compile_et using the host 
> compiler.
> 
> After this long background, my response to the Nack:
> 
> 1. Does waf support this mixed-build method? Are there examples / 
> pointers? (I can try myself but any pointers would be welcome)
> 2. Shouldn't we "get things to the way they were" before supplying "the 
> perfect fix"? I fear of me running out of time and continuing this at a 
> much slower pace.
> 3. If we nack the fix, would it be correct to say that the current 
> situation, where "the automatic method" is invoked in system-heimdal 
> build makes no sense, as there's no need for asn1_compile / et_compile 
> with system Heimdal?
> 
> Thanks,
> Uri.