build failures due to 64-bit time_t on 32-bit systems (seen on Ubuntu 24.04 32bit)

[mwinter-osr]

FRR master @ 65c2593 (and most likely earlier versions)

Compiling fails with some errors:

In file included from lib/log.h:17,
                 from lib/vty.h:22,
                 from lib/command.h:11,
                 from lib/debug.h:11,
                 from lib/northbound_oper.c:13:
lib/northbound_oper.c: In function 'nb_op_yield':
./lib/zlog.h:109:34: error: format '%lu' expects argument of type 'long unsigned int', but argument 4 has type '__suseconds64_t' {aka 'long long int'} [-Werror=format=]
  109 |                 zlog_ref(&_xref, (msg), ##__VA_ARGS__);                        \
      |                                  ^~~~~
./lib/zlog.h:116:26: note: in expansion of macro '_zlog_ecref'
  116 | #define zlog_debug(...)  _zlog_ecref(0, LOG_DEBUG, __VA_ARGS__)
      |                          ^~~~~~~~~~~
lib/debug.h:210:25: note: in expansion of macro 'zlog_debug'
  210 |                         zlog_##level(fmt, ##__VA_ARGS__);                      \
      |                         ^~~~~
lib/debug.h:218:32: note: in expansion of macro 'DEBUG'
  218 | #define DEBUGD(name, fmt, ...) DEBUG(debug, name, fmt, ##__VA_ARGS__)
      |                                ^~~~~
lib/northbound_oper.c:1559:9: note: in expansion of macro 'DEBUGD'
 1559 |         DEBUGD(&nb_dbg_events, "NB oper-state: yielding %s for %lus (should_batch %d)",
      |         ^~~~~~

and

bgpd/rfapi/rfapi_rib.c: In function ‘rfapiRibFTDFilterRecentPrefix’:
bgpd/rfapi/rfapi_rib.c:1797:23: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
 1797 |         prefix_time = (time_t)trn->info;
      |   
cc1: all warnings being treated as errors
make[1]: *** [Makefile:10730: bgpd/rfapi/rfapi_rib.o] Error 1

Configure used:

./configure --enable-vtysh --enable-isisd --enable-ospfclient=yes --enable-ospfapi=yes --enable-multipath=0 \
--enable-rtadv --enable-user=root --enable-sharpd --enable-rpki --enable-fpm --enable-scripting --enable-pimd \
--enable-pim6d --enable-bfdd --enable-vrrpd --enable-werror --with-pkg-extra-version=-20240429-git.65c2593 \
--enable-watchfrr --prefix=/home/ci/cibuild.7624/frr-source/usr_local

Full compile log can be seen at https://ci1.netdef.org/download/FRR-FRR-U2404ARM7/build_logs/FRR-FRR-U2404ARM7-7624.log

[eqvinox]

All of these are due to Debian/Ubuntu changing time_t from 32bit to 64bit on all platforms. This means two things:

• time_t cannot be stored in a pointer, because it is larger than that
• atomic operations on time_t need libatomic because several 32bit platforms do not support 64bit atomic ops in the CPU
• time_t can never be printed directly with printf, because there is no format specifier for it. Both %ld and %lld are wrong. We could define a PRItime_t (like PRIu64) but honestly casting to (long long) and using %lld is simpler.

[eqvinox]

• atomic operations on time_t need libatomic because several 32bit platforms do not support 64bit atomic ops in the CPU

NB: this also means these operations will be slow as f*ck because they're emulated with a global lock for all atomic ops across the entire process