npth requires unnamed semaphores; provide those for Darwin 9 and earlier

[ccorn]

npthis used by gpg-agent which is now part of the gnupg2 port.

Both ports compile on darwin9-powerpc, but trying to start gpg-agent triggers an assertion error by npth:

$ gpg-agent --homedir=~/.gnupg --daemon
Assertion failed: (!res), function leave_npth, file npth.c, line 200.

Since gnupg2 now requires a running gpg-agent for everything that requires passphrases, this error makes gnupg2 essentially unusable for signing as well as decryption.

Digging a bit, I have found that leave_npthuses sem_wait to wait for an unnamed, statically allocated semaphore. sem_wait then returns -1 and sets errno = EBADF. I conclude that Darwin 9 does not support such use. (I suppose that this issue is OS version specific but not dependent on architecture.)

Other projects in need of support for unnamed semaphores have provided an implementation for Darwin, e.g. ​here. I have added those files to the npth sources and done a little patching to ensure that those files are used. The result is that gpg-agent now runs fine.

The added files darwin_compat.{h,c} have comments indicating that they are based on code from glibc which is under GPL-2+. This matches the npth license and should therefore be unproblematic. However, I have no judgement about the code itself except that it solves my problem. Which is what keeps me from opening a direct pull request.

I have a working MacPorts patch for npth ​on my Darwin9-PPC64 branch. If you are in pressing need for a working MacPorts gnupg2on Darwin < 10, you can use that.

I have chosen a MacPorts-based patch for convenience: Portfiles have easy-to-use commands for platform-specific actions. However, the proper approach would be to modify npths configure.ac to test for Darwin < 10 and set an autoconf variable and config.h macro that is used in src/Makefile.amand src/npth.c respectively. Such a patch should then be offered upstream. I have not come to that yet, and I do not know the chances of success.

For the time being, I just want to let you know that there is a problem with current npth (and therefore gnupg2) on Darwin < 10 which indirectly prevents users from accessing or signing their mails, and that there is a solution that seems to work. No need to panic!

[ballapete (Peter "Pete" Dyballa)]

I tried your additions on Tiger, MacOS X 10.4.11, Darwin8. It runs on a 32 bit PPC 7447A. And it works! I can use gpg2.

The next try on Leopard, Mac OS X 10.5.8, Darwin9, same hardware is just starting.

[ballapete (Peter "Pete" Dyballa)]

On PPC Leopard success as well!

[ballapete (Peter "Pete" Dyballa)]

I created a new ticket, #61115, that requests an enhancement of npth (and potentially gnupg2 because it builds but is useless and does not work and since it substitutes gnupg the user has no working GnuPG implementation installed, except when from a third party).

[ryandesign (Ryan Carsten Schmidt)]

Should this be added to our legacy support library instead?

[ballapete (Peter "Pete" Dyballa)]

Replying to ryandesign:

Should this be added to our legacy support library instead?

The C files, that might be a splendid idea. This way a few ports could use a uniform legacy support instead of individual solutions for unnamed (therefore safer?) semaphores. My wish is that npth is enhanced soon that GnuPG 2 can be used on older systems. As I mention in #61115 there can be a number of users that have installed GnuPG 2 and have now an unusable software. I found this by trying to use GnuPG 2 – and it failed completely and I did not understand why. It took a long time until I found this explanatory ticket…

[barracuda156]

What happened to this? gnupg2 is still unusable, as of now.

[kencu (Ken)]

basically, nobody was motivated to move it along. I never used npth or gpu-agent, so didn't come across it.

Looking at the header and the source file, it would seem to be a trivial addition to legacysupport. But someone would need to figure out how this made it's way into Darwin, what systems need it, and (ideally) how to make a simple test for it.

[barracuda156]

In c811f064de5dab620de65f44effd081ac91c97d4/macports-ports (master):

npth: fix for old systems
Fixes: #56185
Fixes: #61115