[build] _WIN32 shared dll build (autotools, cmake)

There are likely better and cleaner ways to do this; patches welcome.

_WIN32 symbol imports and exports

MS Visual Studio (_MSC_VER) does not appear to export global data
symbols even when exporting all functions.

Annotating any symbols with __declspec(dllexport) in any translation
unit appears to change default dll symbol implict export behavior.

Currently, src/Makefile.am and CMakeLists.txt take different approaches
(implib versus linking against executable which has exported symbols)

x-ref:
  (improved solutions might possibly be constructed using these docs)
  https://sourceware.org/binutils/docs/ld/WIN32.html
  https://cmake.org/cmake/help/latest/prop_tgt/WINDOWS_EXPORT_ALL_SYMBOLS.html
  https://stackoverflow.com/questions/225432/export-all-symbols-when-creating-a-dll

1 files changed, 6 insertions, 0 deletions

diff --git a/src/log.c b/src/log.c
index fe49433a..841d38a4 100644
--- a/src/log.c
+++ b/src/log.c
@@ -5,6 +5,9 @@
 
 #include "first.h"
 
+#undef __declspec_dllimport__
+#define __declspec_dllimport__  __declspec_dllexport__
+
 #include "log.h"
 
 #include <sys/types.h>
@@ -31,9 +34,12 @@ static uint32_t tlen;
 static char tstr[24]; /* 20 "%F %T" incl '\0' +2 ": " */
 
 /* log_con_jqueue instance here to be defined in shared object (see base.h) */
+__declspec_dllexport__
 connection *log_con_jqueue;
 
+__declspec_dllexport__
 unix_time64_t log_epoch_secs = 0;
+__declspec_dllexport__
 unix_time64_t log_monotonic_secs = 0;
 
 #if !defined(HAVE_CLOCK_GETTIME) || !HAS_TIME_BITS64