fix(libacron/acronc): complete cross-platform build

This patch made several changes to correctly build libac on Windows:

1. Deprecated PkgConfig on Unix. On both platforms, libac requires the JSON-C CMake module to locate libraries (whether is dynamic or static) and headers. On Windows, the common practice is to statically link the library, so libac now provides setup.bat to automatically clone JSON-C and build it. In CMakeLists.txt, libac will automatically pick up the in-tree JSON-C build if it presents. Otherwise, it will use the system default's. Users can override the CMAKE_PREFIX_PATH to supply a custom JSON-C library if it is not found in-tree.
2. Switched from #include <json-c/xxx.h> to <xxx.h>, as the former (current) approach is non-standard and depends on the system header locations. The later (new) approach relies on CMake to supply header search paths, which works on Windows as well.
3. Deprecated --version-script on Unix linkers. Instead, libac now uses -fvisibility (https://gcc.gnu.org/wiki/Visibility) on GCC or LLVM, as well as __declspec(dllexport) on MSVC to export selected symbols. A new macro, LIBAC_EXPORT, is defined in incl.h (new), and all functions needed to export are marked with that macro.
4. Changed several codes (mostly socket-related) to work on Windows.
5. Massive rewrite of CMake in preparation of further installation and static library support.

Signed-off-by: Trumeet <yuuta@yuuta.moe>

5 files changed, 27 insertions, 8 deletions

diff --git a/client/libacron/include/ids.h b/client/libacron/include/ids.h
index 80e7448..34d312e 100644
--- a/client/libacron/include/ids.h
+++ b/client/libacron/include/ids.h
@@ -5,6 +5,8 @@
 #ifndef LIBAC_IDS_H
 #define LIBAC_IDS_H
 
+#include "incl.h"
+
 #define AC_TYPE_EVENT       0   /* 0b00000000 */
 #define AC_TYPE_REQUEST     64  /* 0b01000000 */
 #define AC_TYPE_RESPONSE    128 /* 0b10000000 */
@@ -26,6 +28,6 @@ typedef struct ac_obj {
  * @param obj Object to free. Must be a valid object.
  * @return AC_E_OK or an error code. When succeeds, obj is freed and no longer valid.
  */
-int ac_object_free(ac_obj_t *obj);
+LIBAC_EXPORT int ac_object_free(ac_obj_t *obj);
 
 #endif /* LIBAC_IDS_H */
diff --git a/client/libacron/include/incl.h b/client/libacron/include/incl.h
new file mode 100644
index 0000000..4ac00ab
--- /dev/null
+++ b/client/libacron/include/incl.h
@@ -0,0 +1,14 @@
+/*
+ * Created by yuuta on 7/21/22.
+ */
+
+#ifndef LIBAC_INCL_H
+#define LIBAC_INCL_H
+
+#ifdef _MSC_VER
+#define LIBAC_EXPORT __declspec(dllexport)
+#else
+#define LIBAC_EXPORT __attribute__ ((visibility ("default"))) extern
+#endif
+
+#endif /* LIBAC_INCL_H */
diff --git a/client/libacron/include/libac.h b/client/libacron/include/libac.h
index 542adcb..adf0310 100644
--- a/client/libacron/include/libac.h
+++ b/client/libacron/include/libac.h
@@ -5,13 +5,14 @@
 #ifndef LIBAC_LIBAC_H
 #define LIBAC_LIBAC_H
 
+#include "incl.h"
 #include "common.h"
 #include "events.h"
 #include "net.h"
 #include "requests.h"
 #include "ids.h"
 
-#include <json-c/json_tokener.h>
+#include <json_tokener.h>
 #include <stdio.h>
 
 typedef struct libac_config {
@@ -23,12 +24,12 @@ typedef struct libac_config {
  * Initialize libac for the calling thread.
  * @return AC_E_OK on success.
  */
-int ac_init(const libac_config_t *config);
+LIBAC_EXPORT int ac_init(const libac_config_t *config);
 
 /**
  * Destroy libac configuration for the calling thread.
  * @return AC_E_OK on success.
  */
-int ac_free(void);
+LIBAC_EXPORT int ac_free(void);
 
 #endif /* LIBAC_LIBAC_H */
diff --git a/client/libacron/include/net.h b/client/libacron/include/net.h
index 8fb33f8..6d8d9e7 100644
--- a/client/libacron/include/net.h
+++ b/client/libacron/include/net.h
@@ -5,6 +5,7 @@
 #ifndef LIBAC_NET_H
 #define LIBAC_NET_H
 
+#include "incl.h"
 #include "common.h"
 #include "events.h"
 #include "requests.h"
@@ -27,7 +28,7 @@ typedef struct ac_connection_parameters {
  * @return AC_E_OK or an error code. When failed, *out will be untouched.
  * MT-Safe
  */
-int ac_connect(ac_connection_parameters_t parameters, void **out);
+LIBAC_EXPORT int ac_connect(ac_connection_parameters_t parameters, void **out);
 
 /**
  * Disconnect the connection.
@@ -35,7 +36,7 @@ int ac_connect(ac_connection_parameters_t parameters, void **out);
  * @return AC_E_OK or an error code. When failed, connection is undefined. When succeeds, connection is freed and invalid.
  * MT-Unsafe
  */
-int ac_disconnect(void *connection);
+LIBAC_EXPORT int ac_disconnect(void *connection);
 
 /**
  * Blocks the current thread until a new response or event arrives.
@@ -43,6 +44,6 @@ int ac_disconnect(void *connection);
  * @param response Output response of either an event or a response. May be NULL even if it succeeds.
  * @return AC_E_OK or an error code. When failed, *response is NULL.
  */
-int ac_receive(void *connection, ac_obj_t **response);
+LIBAC_EXPORT int ac_receive(void *connection, ac_obj_t **response);
 
 #endif /* LIBAC_NET_H */
diff --git a/client/libacron/include/requests.h b/client/libacron/include/requests.h
index 590bb2e..54c414b 100644
--- a/client/libacron/include/requests.h
+++ b/client/libacron/include/requests.h
@@ -5,6 +5,7 @@
 #ifndef LIBAC_REQUESTS_H
 #define LIBAC_REQUESTS_H
 
+#include "incl.h"
 #include "common.h"
 #include "ids.h"
 #include <stdbool.h>
@@ -74,6 +75,6 @@ typedef struct ac_request_set_config {
  * @return AC_E_OK or an error code.
  * MT-Unsafe: Must be called on the same thread calling ac_receive().
  */
-int ac_request(void *connection, const ac_request_t *request);
+LIBAC_EXPORT int ac_request(void *connection, const ac_request_t *request);
 
 #endif /* LIBAC_REQUESTS_H */