jpeg-utils: Unify media libraries initialization

Both MagickWand and exiv2 needs some initialization and cleanup, move
it to jpeg-utils for clean includes in cgg.c.

Also add explicit exiv2 XMP initialization as stated on
http://dev.exiv2.org/projects/exiv2/wiki/Thread_safety:

"The XMP SDK initialization function is not mutex protected, thus
Exiv2::XmpParser::initialize is not thread-safe. Therefore, multi-threaded
applications need to ensure that this XMP function is serialized, e.g.,
by calling them from an initialization section which is run before any
threads are started."

See also https://bugs.kde.org/show_bug.cgi?id=166424

3 files changed, 30 insertions, 6 deletions

diff --git a/src/cgg.c b/src/cgg.c
index be882b1..e13ffbb 100644
--- a/src/cgg.c
+++ b/src/cgg.c
@@ -26,8 +26,6 @@
 
 #include <libxml/xmlmemory.h>
 
-#include <wand/magick-wand.h>
-
 #include <config.h>
 
 #include "setup.h"
@@ -35,6 +33,7 @@
 #include "stats.h"
 #include "atom-writer.h"
 #include "gallery-utils.h"
+#include "jpeg-utils.h"
 
 
 
@@ -129,8 +128,8 @@ main (int argc, char* argv[])
   g_thread_init (NULL);
 #endif
 
-  /*  Initialize ImageMagick at this point, for multithreading safety  */
-  MagickWandGenesis();
+  /*  Initialize imaging libraries  */
+  init_jpeg_utils ();
 
   /*  Parse commandline  */
   if (! parse_cmd (argc, argv))
@@ -261,8 +260,7 @@ main (int argc, char* argv[])
       printf ("%d errors occured.\n", stats_errors);
   }
 
-
-  MagickWandTerminus();
+  destroy_jpeg_utils ();
 
   /*  Cleanup function for the XML library. */
   xmlCleanupParser();
diff --git a/src/jpeg-utils.cpp b/src/jpeg-utils.cpp
index 965d751..2d85d3b 100644
--- a/src/jpeg-utils.cpp
+++ b/src/jpeg-utils.cpp
@@ -35,6 +35,26 @@ struct ExifDataPrivate {
 };
 
 
+/*
+ *   Thread-safe ImageMagick and exiv2 libraries initialization and cleanup
+ */
+void
+init_jpeg_utils (void)
+{
+  MagickWandGenesis();
+  /*  http://dev.exiv2.org/projects/exiv2/wiki/Thread_safety  */
+  /*  https://bugs.kde.org/show_bug.cgi?id=166424  */
+  Exiv2::XmpParser::initialize();
+}
+
+void
+destroy_jpeg_utils (void)
+{
+  Exiv2::XmpParser::terminate();
+  MagickWandTerminus();
+}
+
+
 static void
 shift_time (struct tm *tm, int offset_min)
 {
diff --git a/src/jpeg-utils.h b/src/jpeg-utils.h
index 9e4c729..bddb096 100644
--- a/src/jpeg-utils.h
+++ b/src/jpeg-utils.h
@@ -63,6 +63,12 @@ typedef struct {
 
 
 /*
+ *   Thread-safe ImageMagick and exiv2 libraries initialization and cleanup
+ */
+void init_jpeg_utils (void);
+void destroy_jpeg_utils (void);
+
+/*
  *   EXIF and IPTC info retrieval, keeps the source file open until freed
  */
 ExifData * read_exif (const gchar *filename);