Linux: update xdg-utils to the latest git version and include a one-line fix in xdg-mime.

scripts/xdg-email

 #!/bin/sh
 #---------------------------------------------
 #   xdg-email
 #
 #   Utility script to open the users favorite email program, using the
 #       RFC 2368 mailto: URI spec
 #
 #   Refer to the usage() function below for usage.
 #
 #   Copyright 2009-2010, Fathi Boudra <fabo@freedesktop.org>
@@ skipping 156 matching lines @@
 #----------------------------------------------------------------------------
 
 DEBUG()
 {
   [ -z "${XDG_UTILS_DEBUG_LEVEL}" ] && return 0;
   [ ${XDG_UTILS_DEBUG_LEVEL} -lt $1 ] && return 0;
   shift
   echo "$@" >&2
 }
 
+# This handles backslashes but not quote marks.
+first_word()
+{
+    read first rest
+    echo "$first"
+}
+
+#-------------------------------------------------------------
+# map a binary to a .desktop file
+binary_to_desktop_file()
+{
+    search="${XDG_DATA_HOME:-$HOME/.local/share}:${XDG_DATA_DIRS:-/usr/local/share:/usr/share}"
+    binary="`which "$1"`"
+    binary="`readlink -f "$binary"`"
+    base="`basename "$binary"`"
+    IFS=:
+    for dir in $search; do
+        unset IFS
+        [ "$dir" ] || continue
+        [ -d "$dir/applications" -o -d "$dir/applnk" ] || continue
+        for file in "$dir"/applications/*.desktop "$dir"/applications/*/*.desktop "$dir"/applnk/*.desktop "$dir"/applnk/*/*.desktop; do
+            [ -r "$file" ] || continue
+            # Check to make sure it's worth the processing.
+            grep -q "^Exec.*$base" "$file" || continue
+            # Make sure it's a visible desktop file (e.g. not "preferred-web-browser.desktop").
+            grep -Eq "^(NoDisplay|Hidden)=true" "$file" && continue
+            command="`grep -E "^Exec(\[[^]=]*])?=" "$file" | cut -d= -f 2- | first_word`"
+            command="`which "$command"`"
+            if [ x"`readlink -f "$command"`" = x"$binary" ]; then
+                # Fix any double slashes that got added path composition
+                echo "$file" | sed -e 's,//*,/,g'
+                return
+            fi
+        done
+    done
+}
+
+#-------------------------------------------------------------
+# map a .desktop file to a binary
+## FIXME: handle vendor dir case
+desktop_file_to_binary()
+{
+    search="${XDG_DATA_HOME:-$HOME/.local/share}:${XDG_DATA_DIRS:-/usr/local/share:/usr/share}"
+    desktop="`basename "$1"`"
+    IFS=:
+    for dir in $search; do
+        unset IFS
+        [ "$dir" -a -d "$dir/applications" ] || continue
+        file="$dir/applications/$desktop"
+        [ -r "$file" ] || continue
+        # Remove any arguments (%F, %f, %U, %u, etc.).
+        command="`grep -E "^Exec(\[[^]=]*])?=" "$file" | cut -d= -f 2- | first_word`"
+        command="`which "$command"`"
+        readlink -f "$command"
+        return
+    done
+}
+
 #-------------------------------------------------------------
 # Exit script on successfully completing the desired operation
 
 exit_success()
 {
     if [ $# -gt 0 ]; then
         echo "$@"
         echo
     fi
 
@@ skipping 592 matching lines @@
     ;;
 
     generic|lxde)
     open_generic "${mailto}"
     ;;
 
     *)
     exit_failure_operation_impossible "no method available for opening '${mailto}'"
     ;;
 esac