From 8865b440d98a158f612f514459e37701805fbece Mon Sep 17 00:00:00 2001
From: Nirbheek Chauhan <nirbheek@centricular.com>
Date: Fri, 5 May 2017 04:30:59 +0530
Subject: [PATCH] decklink: Fix linking on MinGW

MinGW does not provide comsupp.lib, so there's no implementation of
_com_util::ConvertBSTRToString. Use a fallback implementation that
uses wcstombs() instead.

On MinGW we also truncate the name to 100 chars which should be fine.
---
 sys/decklink/gstdecklink.cpp |  4 ++--
 sys/decklink/gstdecklink.h   | 14 ++++++++++----
 sys/decklink/meson.build     | 13 ++++++++-----
 3 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/sys/decklink/gstdecklink.cpp b/sys/decklink/gstdecklink.cpp
index 1c79e3f..f39e2fc 100644
--- a/sys/decklink/gstdecklink.cpp
+++ b/sys/decklink/gstdecklink.cpp
@@ -967,7 +967,7 @@ init_devices (gpointer data)
 
         GST_DEBUG ("Input %d supports:", i);
         while ((ret = mode_iter->Next (&mode)) == S_OK) {
-          const char *name;
+          char *name;
 
           mode->GetName ((COMSTR_T *) & name);
           CONVERT_COM_STRING (name);
@@ -1005,7 +1005,7 @@ init_devices (gpointer data)
 
         GST_DEBUG ("Output %d supports:", i);
         while ((ret = mode_iter->Next (&mode)) == S_OK) {
-          const char *name;
+          char *name;
 
           mode->GetName ((COMSTR_T *) & name);
           CONVERT_COM_STRING (name);
diff --git a/sys/decklink/gstdecklink.h b/sys/decklink/gstdecklink.h
index 052f099..820fa44 100644
--- a/sys/decklink/gstdecklink.h
+++ b/sys/decklink/gstdecklink.h
@@ -39,13 +39,19 @@
 #define bool BOOL
 
 #define COMSTR_T BSTR
-#define FREE_COM_STRING(s) delete[] s;
-#define CONVERT_COM_STRING(s) BSTR _s = (BSTR)s; s = _com_util::ConvertBSTRToString(_s); ::SysFreeString(_s);
+/* MinGW does not have comsuppw.lib, so no _com_util::ConvertBSTRToString */
+# ifdef __MINGW32__
+#  define CONVERT_COM_STRING(s) BSTR _s = (BSTR)s; s = (char*) malloc(100); wcstombs(s, _s, 100); ::SysFreeString(_s);
+#  define FREE_COM_STRING(s) free(s);
+# else
+#  define CONVERT_COM_STRING(s) BSTR _s = (BSTR)s; s = _com_util::ConvertBSTRToString(_s); ::SysFreeString(_s);
+#  define FREE_COM_STRING(s) delete[] s;
+# endif
 #else
 #define COMSTR_T const char*
-#define FREE_COM_STRING(s)
 #define CONVERT_COM_STRING(s)
-#endif /* _MSC_VER */
+#define FREE_COM_STRING(s)
+#endif /* G_OS_WIN32 */
 
 typedef enum {
   GST_DECKLINK_MODE_AUTO,
diff --git a/sys/decklink/meson.build b/sys/decklink/meson.build
index 12e086e..a7e094f 100644
--- a/sys/decklink/meson.build
+++ b/sys/decklink/meson.build
@@ -12,12 +12,15 @@ decklink_libs = []
 
 if host_machine.system() == 'windows'
   decklink_sources += ['win/DeckLinkAPIDispatch.cpp', 'win/DeckLinkAPI_i.c']
-  # Only used by MSVC. On MinGW, this is all inlined.
-  # FIXME: Use commsuppwd.lib for debug builds?
-  comutil_dep = cxx.find_library('comsuppw', required : false)
-  if comutil_dep.found()
+  if cxx.get_id() == 'msvc'
+    # FIXME: Use commsuppwd.lib for debug builds?
+    comutil_dep = cxx.find_library('comsuppw')
+    if comutil_dep.found()
+      build_decklink = true
+      decklink_libs = [comutil_dep]
+    endif
+  else
     build_decklink = true
-    decklink_libs = [comutil_dep]
   endif
 else
   libdl = cc.find_library('dl', required: false)
-- 
2.7.4