From d64a7a34166a470e6fa93a9f93e49c6ab23a7e62 Mon Sep 17 00:00:00 2001
From: Nikias Bassen
Date: Mon, 13 Sep 2021 18:50:01 +0200
Subject: Check availability of constructor attribute and use it on Windows in
 favor of DllMain

---
 configure.ac  | 18 ++++++++++++++++++
 src/idevice.c | 28 ++++++++++++++++++----------
 2 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/configure.ac b/configure.ac
index ed9270c..cdd388b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -83,6 +83,24 @@ case ${host_os} in
 esac
 AM_CONDITIONAL(WIN32, test x$win32 = xtrue)
 
+# Check if the C compiler supports __attribute__((constructor))
+AC_CACHE_CHECK([wether the C compiler supports constructor/destructor attributes],
+  ac_cv_attribute_constructor, [
+  ac_cv_attribute_constructor=no
+  AC_COMPILE_IFELSE([AC_LANG_PROGRAM(
+    [[
+      static void __attribute__((constructor)) test_constructor(void) {
+      }
+      static void __attribute__((destructor)) test_destructor(void) {
+      }
+    ]], [])],
+    [ac_cv_attribute_constructor=yes]
+  )]
+)
+if test "$ac_cv_attribute_constructor" = "yes"; then
+  AC_DEFINE(HAVE_ATTRIBUTE_CONSTRUCTOR, 1, [Define if the C compiler supports constructor/destructor attributes])
+fi
+
 AC_CHECK_MEMBER(struct dirent.d_type, AC_DEFINE(HAVE_DIRENT_D_TYPE, 1, [define if struct dirent has member d_type]),, [#include <dirent.h>])
 
 # Cython Python Bindings
diff --git a/src/idevice.c b/src/idevice.c
index 4545bfa..6a03c5e 100644
--- a/src/idevice.c
+++ b/src/idevice.c
@@ -174,7 +174,23 @@ static void internal_idevice_deinit(void)
 static thread_once_t init_once = THREAD_ONCE_INIT;
 static thread_once_t deinit_once = THREAD_ONCE_INIT;
 
-#ifdef WIN32
+#ifndef HAVE_ATTRIBUTE_CONSTRUCTOR
+  #if defined(__llvm__) || defined(__GNUC__)
+    #define HAVE_ATTRIBUTE_CONSTRUCTOR
+  #endif
+#endif
+
+#ifdef HAVE_ATTRIBUTE_CONSTRUCTOR
+static void __attribute__((constructor)) libimobiledevice_initialize(void)
+{
+	thread_once(&init_once, internal_idevice_init);
+}
+
+static void __attribute__((destructor)) libimobiledevice_deinitialize(void)
+{
+	thread_once(&deinit_once, internal_idevice_deinit);
+}
+#elif defined(WIN32)
 BOOL WINAPI DllMain(HINSTANCE hModule, DWORD dwReason, LPVOID lpReserved)
 {
 	switch (dwReason) {
@@ -190,15 +206,7 @@ BOOL WINAPI DllMain(HINSTANCE hModule, DWORD dwReason, LPVOID lpReserved)
 	return 1;
 }
 #else
-static void __attribute__((constructor)) libimobiledevice_initialize(void)
-{
-	thread_once(&init_once, internal_idevice_init);
-}
-
-static void __attribute__((destructor)) libimobiledevice_deinitialize(void)
-{
-	thread_once(&deinit_once, internal_idevice_deinit);
-}
+#warning No compiler support for constructor/destructor attributes, some features might not be available.
 #endif
 
 static idevice_event_cb_t event_cb = NULL;
-- 
cgit v1.1-32-gdbae