Added beta update support.

Started work on further appimage support

appimg/CTesting.go

@@ -0,0 +1,78 @@
+package appimg
+
+// Thanks to probono for the majority of this C code: https://discourse.appimage.org/t/accessing-appimage-desktop-file/173/4?u=calebq42
+
+/*
+#cgo CFLAGS: -I/usr/lib
+#cgo LDFLAGS: -L/usr/lib/libappimage.so -lappimage
+#cgo pkg-config: glib-2.0
+
+#include <appimage/appimage.h>
+#include <stdlib.h>
+#include <glib.h>
+#include <strings.h>
+
+bool extract_desktop(char* appimageLoc,char* extractLoc){
+  char** files = appimage_list_files(appimageLoc);
+  g_autofree gchar *desktop_file = NULL;
+  gchar *extracted_desktop_file = extractLoc;
+  int i = 0;
+  for (; files[i] != NULL ; i++) {
+      // g_debug("AppImage file: %s", files[i]);
+      if (g_str_has_suffix (files[i],".desktop")) {
+          desktop_file = files[i];
+          g_debug("AppImage desktop file: %s", desktop_file);
+          break;
+      }
+  }
+  if(desktop_file == NULL) {
+      g_debug("AppImage desktop file not found");
+      appimage_string_list_free(files);
+      return FALSE;
+  }
+  appimage_extract_file_following_symlinks(appimageLoc, desktop_file,extracted_desktop_file);
+  appimage_string_list_free(files);
+	return TRUE;
+}
+
+bool extract_file(char* appimageLoc,char* filename,char* extractLoc){
+  char** files = appimage_list_files(appimageLoc);
+  g_autofree gchar *found_file = NULL;
+  gchar *extracted_file = extractLoc;
+  int i = 0;
+  for (; files[i] != NULL ; i++) {
+      g_debug("AppImage file: %s", files[i]);
+      if (strcmp(files[i],filename)==0) {
+          found_file = files[i];
+          g_debug("FileFound: %s", found_file);
+      }
+  }
+  if(found_file == NULL) {
+      g_debug("filenotfound");
+      appimage_string_list_free(files);
+      return FALSE;
+  }
+  appimage_extract_file_following_symlinks(appimageLoc, found_file,extracted_file);
+  appimage_string_list_free(files);
+	return TRUE;
+}
+*/
+import "C"
+import (
+	"errors"
+	"os"
+	"unsafe"
+)
+
+func GetDesktopFile(loc string) (*os.File, error) {
+	os.Remove("/tmp/my.desktop")
+	var locTmp *C.char = C.CString(loc)
+	defer C.free(unsafe.Pointer(locTmp))
+	var extractLoc *C.char = C.CString("/tmp/my.desktop")
+	defer C.free(unsafe.Pointer(extractLoc))
+	var out C.bool = C.extract_desktop(locTmp, extractLoc)
+	if out == false {
+		return nil, errors.New("Desktop File Not Found!")
+	}
+	return os.Open("/tmp/my.desktop")
+}