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Filename : xdg-settings
back
#!/bin/sh
#---------------------------------------------
#   xdg-settings
#
#   Utility script to get various settings from the desktop environment.
#
#   Refer to the usage() function below for usage.
#
#   Copyright 2009, Google Inc.
#
#   LICENSE:
#
#   Permission is hereby granted, free of charge, to any person obtaining a
#   copy of this software and associated documentation files (the "Software"),
#   to deal in the Software without restriction, including without limitation
#   the rights to use, copy, modify, merge, publish, distribute, sublicense,
#   and/or sell copies of the Software, and to permit persons to whom the
#   Software is furnished to do so, subject to the following conditions:
#
#   The above copyright notice and this permission notice shall be included
#   in all copies or substantial portions of the Software.
#
#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
#   OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
#   THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
#   OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
#   ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
#   OTHER DEALINGS IN THE SOFTWARE.
#
#---------------------------------------------

manualpage()
{
cat << _MANUALPAGE
Name

   xdg-settings - get various settings from the desktop
   environment

Synopsis

   xdg-settings { get | check | set } {property} [subproperty]
   [value]

   xdg-settings { --help | --list | --manual | --version }

Description

   xdg-settings gets various settings from the desktop
   environment. For instance, desktop environments often provide
   proxy configuration and default web browser settings. Using
   xdg-settings these parameters can be extracted for use by
   applications that do not use the desktop environment's
   libraries (which would use the settings natively).

   xdg-settings is for use inside a desktop session only. It is
   not recommended to use xdg-settings as root.

Options

   --help
          Show command synopsis.

   --list
          List all properties xdg-settings knows about.

   --manual
          Show this manual page.

   --version
          Show the xdg-utils version information.

Properties

   When using xdg-settings to get, check or set a desktop setting,
   properties and possibly sub-properties are used to specify the
   setting to be changed.

   Some properties (such as default-web-browser) fully describe
   the setting to be changed. Other properties (such as
   default-url-scheme-handler) require more information (in this
   case the actual scheme to set the default handler for) which
   must be provided in a sub-property.

Exit Codes

   An exit code of 0 indicates success while a non-zero exit code
   indicates failure. The following failure codes can be returned:

   1
          Error in command line syntax.

   2
          One of the files passed on the command line did not
          exist.

   3
          A required tool could not be found.

   4
          The action failed.

See Also

   xdg-mime(1), xdg-open(1), MIME applications associations
   specification

Examples

   Get the desktop file name of the current default web browser
        xdg-settings get default-web-browser

   Check whether the default web browser is firefox.desktop, which
   can be false even if "get default-web-browser" says that is the
   current value (if only some of the underlying settings actually
   reflect that value)
        xdg-settings check default-web-browser firefox.desktop

   Set the default web browser to google-chrome.desktop
        xdg-settings set default-web-browser google-chrome.desktop

   Set the default mailto URL scheme handler to be
   evolution.desktop
        xdg-settings set default-url-scheme-handler mailto evolution.des
ktop
_MANUALPAGE
}

usage()
{
cat << _USAGE
   xdg-settings - get various settings from the desktop
   environment

Synopsis

   xdg-settings { get | check | set } {property} [subproperty]
   [value]

   xdg-settings { --help | --list | --manual | --version }

_USAGE
}

#@xdg-utils-common@

#----------------------------------------------------------------------------
#   Common utility functions included in all XDG wrapper scripts
#----------------------------------------------------------------------------

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 "$dir/applications" ] || [ -d "$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
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" ] && [ -d "$dir/applications" ] || [ -d "$dir/applnk" ] || continue
        # Check if desktop file contains -
        if [ "${desktop#*-}" != "$desktop" ]; then
            vendor=${desktop%-*}
            app=${desktop#*-}
            if [ -r $dir/applications/$vendor/$app ]; then
                file_path=$dir/applications/$vendor/$app
            elif [ -r $dir/applnk/$vendor/$app ]; then
                file_path=$dir/applnk/$vendor/$app
            fi
        fi
        if test -z "$file_path" ; then
            for indir in "$dir"/applications/ "$dir"/applications/*/ "$dir"/applnk/ "$dir"/applnk/*/; do
                file="$indir/$desktop"
                if [ -r "$file" ]; then
                    file_path=$file
                    break
                fi
            done
        fi
        if [ -r "$file_path" ]; then
            # Remove any arguments (%F, %f, %U, %u, etc.).
            command="`grep -E "^Exec(\[[^]=]*])?=" "$file_path" | cut -d= -f 2- | first_word`"
            command="`which "$command"`"
            readlink -f "$command"
            return
        fi
    done
}

#-------------------------------------------------------------
# Exit script on successfully completing the desired operation

exit_success()
{
    if [ $# -gt 0 ]; then
        echo "$@"
        echo
    fi

    exit 0
}


#-----------------------------------------
# Exit script on malformed arguments, not enough arguments
# or missing required option.
# prints usage information

exit_failure_syntax()
{
    if [ $# -gt 0 ]; then
        echo "xdg-settings: $@" >&2
        echo "Try 'xdg-settings --help' for more information." >&2
    else
        usage
        echo "Use 'man xdg-settings' or 'xdg-settings --manual' for additional info."
    fi

    exit 1
}

#-------------------------------------------------------------
# Exit script on missing file specified on command line

exit_failure_file_missing()
{
    if [ $# -gt 0 ]; then
        echo "xdg-settings: $@" >&2
    fi

    exit 2
}

#-------------------------------------------------------------
# Exit script on failure to locate necessary tool applications

exit_failure_operation_impossible()
{
    if [ $# -gt 0 ]; then
        echo "xdg-settings: $@" >&2
    fi

    exit 3
}

#-------------------------------------------------------------
# Exit script on failure returned by a tool application

exit_failure_operation_failed()
{
    if [ $# -gt 0 ]; then
        echo "xdg-settings: $@" >&2
    fi

    exit 4
}

#------------------------------------------------------------
# Exit script on insufficient permission to read a specified file

exit_failure_file_permission_read()
{
    if [ $# -gt 0 ]; then
        echo "xdg-settings: $@" >&2
    fi

    exit 5
}

#------------------------------------------------------------
# Exit script on insufficient permission to write a specified file

exit_failure_file_permission_write()
{
    if [ $# -gt 0 ]; then
        echo "xdg-settings: $@" >&2
    fi

    exit 6
}

check_input_file()
{
    if [ ! -e "$1" ]; then
        exit_failure_file_missing "file '$1' does not exist"
    fi
    if [ ! -r "$1" ]; then
        exit_failure_file_permission_read "no permission to read file '$1'"
    fi
}

check_vendor_prefix()
{
    file_label="$2"
    [ -n "$file_label" ] || file_label="filename"
    file=`basename "$1"`
    case "$file" in
       [[:alpha:]]*-*)
         return
         ;;
    esac

    echo "xdg-settings: $file_label '$file' does not have a proper vendor prefix" >&2
    echo 'A vendor prefix consists of alpha characters ([a-zA-Z]) and is terminated' >&2
    echo 'with a dash ("-"). An example '"$file_label"' is '"'example-$file'" >&2
    echo "Use --novendor to override or 'xdg-settings --manual' for additional info." >&2
    exit 1
}

check_output_file()
{
    # if the file exists, check if it is writeable
    # if it does not exists, check if we are allowed to write on the directory
    if [ -e "$1" ]; then
        if [ ! -w "$1" ]; then
            exit_failure_file_permission_write "no permission to write to file '$1'"
        fi
    else
        DIR=`dirname "$1"`
        if [ ! -w "$DIR" ] || [ ! -x "$DIR" ]; then
            exit_failure_file_permission_write "no permission to create file '$1'"
        fi
    fi
}

#----------------------------------------
# Checks for shared commands, e.g. --help

check_common_commands()
{
    while [ $# -gt 0 ] ; do
        parm="$1"
        shift

        case "$parm" in
            --help)
            usage
            echo "Use 'man xdg-settings' or 'xdg-settings --manual' for additional info."
            exit_success
            ;;

            --manual)
            manualpage
            exit_success
            ;;

            --version)
            echo "xdg-settings 1.1.2+"
            exit_success
            ;;
        esac
    done
}

check_common_commands "$@"

[ -z "${XDG_UTILS_DEBUG_LEVEL}" ] && unset XDG_UTILS_DEBUG_LEVEL;
if [ ${XDG_UTILS_DEBUG_LEVEL-0} -lt 1 ]; then
    # Be silent
    xdg_redirect_output=" > /dev/null 2> /dev/null"
else
    # All output to stderr
    xdg_redirect_output=" >&2"
fi

#--------------------------------------
# Checks for known desktop environments
# set variable DE to the desktop environments name, lowercase

detectDE()
{
    # see https://bugs.freedesktop.org/show_bug.cgi?id=34164
    unset GREP_OPTIONS

    if [ -n "${XDG_CURRENT_DESKTOP}" ]; then
      case "${XDG_CURRENT_DESKTOP}" in
         # only recently added to menu-spec, pre-spec X- still in use
         Cinnamon|X-Cinnamon)
           DE=cinnamon;
           ;;
         ENLIGHTENMENT)
           DE=enlightenment;
           ;;
         # GNOME, GNOME-Classic:GNOME, or GNOME-Flashback:GNOME
         GNOME*)
           DE=gnome;
           ;;
         KDE)
           DE=kde;
           ;;
         LXDE)
           DE=lxde;
           ;;
         LXQt)
           DE=lxqt;
           ;;
         MATE)
           DE=mate;
           ;;
         XFCE)
           DE=xfce
           ;;
         X-Generic)
           DE=generic
           ;;
      esac
    fi

    if [ x"$DE" = x"" ]; then
      # classic fallbacks
      if [ x"$KDE_FULL_SESSION" != x"" ]; then DE=kde;
      elif [ x"$GNOME_DESKTOP_SESSION_ID" != x"" ]; then DE=gnome;
      elif [ x"$MATE_DESKTOP_SESSION_ID" != x"" ]; then DE=mate;
      elif `dbus-send --print-reply --dest=org.freedesktop.DBus /org/freedesktop/DBus org.freedesktop.DBus.GetNameOwner string:org.gnome.SessionManager > /dev/null 2>&1` ; then DE=gnome;
      elif xprop -root _DT_SAVE_MODE 2> /dev/null | grep ' = \"xfce4\"$' >/dev/null 2>&1; then DE=xfce;
      elif xprop -root 2> /dev/null | grep -i '^xfce_desktop_window' >/dev/null 2>&1; then DE=xfce
      elif echo $DESKTOP | grep -q '^Enlightenment'; then DE=enlightenment;
      elif [ x"$LXQT_SESSION_CONFIG" != x"" ]; then DE=lxqt;
      fi
    fi

    if [ x"$DE" = x"" ]; then
      # fallback to checking $DESKTOP_SESSION
      case "$DESKTOP_SESSION" in
         gnome)
           DE=gnome;
           ;;
         LXDE|Lubuntu)
           DE=lxde; 
           ;;
         MATE)
           DE=mate;
           ;;
         xfce|xfce4|'Xfce Session')
           DE=xfce;
           ;;
      esac
    fi

    if [ x"$DE" = x"" ]; then
      # fallback to uname output for other platforms
      case "$(uname 2>/dev/null)" in 
        CYGWIN*)
          DE=cygwin;
          ;;
        Darwin)
          DE=darwin;
          ;;
      esac
    fi

    if [ x"$DE" = x"gnome" ]; then
      # gnome-default-applications-properties is only available in GNOME 2.x
      # but not in GNOME 3.x
      which gnome-default-applications-properties > /dev/null 2>&1  || DE="gnome3"
    fi

    if [ -f "$XDG_RUNTIME_DIR/flatpak-info" ]; then
      DE="flatpak"
    fi
}

#----------------------------------------------------------------------------
# kfmclient exec/openURL can give bogus exit value in KDE <= 3.5.4
# It also always returns 1 in KDE 3.4 and earlier
# Simply return 0 in such case

kfmclient_fix_exit_code()
{
    version=`LC_ALL=C.UTF-8 kde-config --version 2>/dev/null | grep '^KDE'`
    major=`echo $version | sed 's/KDE.*: \([0-9]\).*/\1/'`
    minor=`echo $version | sed 's/KDE.*: [0-9]*\.\([0-9]\).*/\1/'`
    release=`echo $version | sed 's/KDE.*: [0-9]*\.[0-9]*\.\([0-9]\).*/\1/'`
    test "$major" -gt 3 && return $1
    test "$minor" -gt 5 && return $1
    test "$release" -gt 4 && return $1
    return 0
}

#----------------------------------------------------------------------------
# Returns true if there is a graphical display attached.

has_display()
{
    if [ -n "$DISPLAY" ] || [ -n "$WAYLAND_DISPLAY" ]; then
        return 0
    else
        return 1
    fi
}

check_desktop_filename()
{
    case "$1" in
      */*)
        exit_failure_syntax "invalid application name"
        ;;
      *.desktop)
        return
        ;;
      *)
        exit_failure_syntax "invalid application name"
        ;;
    esac
}

# {{{ default browser
# {{{ utility functions

# In order to remove an application from the automatically-generated list of
# applications for handling a given MIME type, the desktop environment may copy
# the global .desktop file into the user's .local directory, and remove that
# MIME type from its list. In that case, we must restore the MIME type to the
# application's list of MIME types before we can set it as the default for that
# MIME type. (We can't just delete the local version, since the user may have
# made other changes to it as well. So, tweak the existing file.)
# This function is hard-coded for text/html but it could be adapted if needed.
fix_local_desktop_file()
{
    if test -z "$2" ; then
        MIME="text/html"
    else
        MIME="$2"
    fi
    apps="${XDG_DATA_HOME:-$HOME/.local/share}/applications"
    # No local desktop file?
    [ ! -f "$apps/$1" ] && return
    MIMETYPES="`grep "^MimeType=" "$apps/$1" | cut -d= -f 2-`"
    case "$MIMETYPES" in
      $MIME\;*|*\;$MIME\;*|*\;$MIME\;|*\;$MIME)
        # Already has the mime-type? Great!
        return 0
        ;;
    esac

    # Add the mime-type to the list
    temp="`mktemp "$apps/$1.XXXXXX"`" || return
    grep -v "^MimeType=" "$apps/$1" >> "$temp"
    echo "MimeType=$MIME;$MIMETYPES" >> "$temp"

    oldlines="`wc -l < "$apps/$1"`"
    newlines="`wc -l < "$temp"`"
    # The new file should have at least as many lines as the old.
    if [ $oldlines -le $newlines ]; then
        mv "$temp" "$apps/$1"
        # This can take a little bit to get noticed.
        sleep 4
    else
        rm -f "$temp"
        return 1
    fi
}

# }}} utility functions
# {{{ MIME utilities

xdg_mime_fixup()
{
    # xdg-mime may use ktradertest, which will fork off a copy of kdeinit if
    # one does not already exist. It will exit after about 15 seconds if no
    # further processes need it around. But since it does not close its stdout,
    # the shell (via grep) will wait around for kdeinit to exit. If we start a
    # copy here, that copy will be used in xdg-mime and we will avoid waiting.
    if [ "$DE" = kde -a -z "$XDG_MIME_FIXED" ]; then
        ktradertest text/html Application > /dev/null 2>&1
        # Only do this once, as we only need it once.
        XDG_MIME_FIXED=yes
    fi
}

get_browser_mime()
{
    if test -z "$1" ; then
        MIME="text/html"
    else
        MIME="$1"
    fi
    xdg_mime_fixup
    xdg-mime query default "$MIME"
}

set_browser_mime()
{
    xdg_mime_fixup
    if test -z "$2" ; then
        MIME="text/html"
    else
        MIME="$2"
    fi
    orig="`get_browser_mime $MIME`"
    # Fixing the local desktop file can actually change the default browser all
    # by itself, so we fix it only after querying to find the current default.
    fix_local_desktop_file "$1" "$MIME" || return
    mkdir -p "${XDG_DATA_HOME:-$HOME/.local/share}/applications"
    xdg-mime default "$1" "$MIME" || return
    if [ x"`get_browser_mime`" != x"$1" ]; then
        # Put back the original value
        xdg-mime default "$orig" "$MIME"
        exit_failure_operation_failed
    fi
}

# }}} MIME utilities
# {{{ KDE utilities

# Reads the KDE configuration setting, compensating for a bug in some versions of kreadconfig.
read_kde_config()
{
    configfile="$1"
    configsection="$2"
    configkey="$3"
    if [ x"${KDE_SESSION_VERSION}" = x"5" ]; then
        application="`kreadconfig5 --file $configfile --group $configsection --key $configkey`"
    else
        application="`kreadconfig --file $configfile --group $configsection --key $configkey`"
    fi
    if [ x"$application" != x ]; then
        echo "$application"
    else
      if [ x"${KDE_SESSION_VERSION}" = x"4" ]; then
        # kreadconfig in KDE 4 may not notice Key[$*]=... localized settings, so
        # check by hand if it didn't find anything (oddly kwriteconfig works
        # fine though).
        configfile_dir=`kde${KDE_SESSION_VERSION}-config --path config  | cut -d ':' -f 1`
        configfile_path="$configfile_dir/$configfile"
        [ ! -f "$configfile_path" ] && return
        # This will only take the first value if there is more than one.
        grep "^$configkey"'\[$[^]=]*\]=' "$configfile_path" | head -n 1 | cut -d= -f 2-
      fi
    fi
}

# }}} KDE utilities
# {{{ KDE

# Resolves the KDE browser setting to a binary: if prefixed with !, simply removes it;
# otherwise, uses desktop_file_to_binary to get the binary out of the desktop file.
resolve_kde_browser()
{
    [ -z "$browser" ] && return
    case "$browser" in
      !*)
        echo "${browser#!}"
        ;;
      *)
        desktop_file_to_binary "$browser"
        ;;
    esac
}

# Does the opposite of resolve_kde_browser: if prefixed with !, tries to find a desktop
# file corresponding to the binary, otherwise just returns the desktop file name.
resolve_kde_browser_desktop()
{
    [ -z "$browser" ] && return
    case "$browser" in
      !*)
        desktop="`binary_to_desktop_file "${browser#!}"`"
        basename "$desktop"
        ;;
      *)
        echo "$browser"
        ;;
    esac
}

read_kde_browser()
{
    read_kde_config kdeglobals General BrowserApplication
}

get_browser_kde()
{
    browser="`read_kde_browser`"
    if [ x"$browser" = x ]; then
        # No explicit default browser; KDE will use the MIME type text/html.
        get_browser_mime
    else
        resolve_kde_browser_desktop
    fi
}

check_browser_kde()
{
    check="`desktop_file_to_binary "$1"`"
    if [ -z "$check" ]; then
        echo no
        exit_success
    fi
    browser="`read_kde_browser`"
    binary="`resolve_kde_browser`"
    # Because KDE will use the handler for MIME type text/html if this value
    # is empty, we allow either the empty string or a match to $check here.
    if [ x"$binary" != x -a x"$binary" != x"$check" ]; then
        echo no
        exit_success
    fi
    browser="`get_browser_mime`"
    binary="`desktop_file_to_binary "$browser"`"
    if [ x"$binary" != x"$check" ]; then
        echo no
        exit_success
    fi
    echo yes
    exit_success
}

set_browser_kde()
{
    set_browser_mime "$1" || return
    if [ x"${KDE_SESSION_VERSION}" = x"5" ]; then
        kwriteconfig5 --file kdeglobals --group General --key BrowserApplication "$1"
    else
        kwriteconfig --file kdeglobals --group General --key BrowserApplication "$1"
    fi
}

# }}} KDE
# {{{ GNOME

get_browser_gnome()
{
    binary="`gconftool-2 --get /desktop/gnome/applications/browser/exec | first_word`"
    if [ x"$binary" = x ]; then
        # No default browser; GNOME might use the MIME type text/html.
        get_browser_mime
    else
        # gconftool gives the binary (maybe with %s etc. afterward),
        # but we want the desktop file name, not the binary. So, we
        # have to find the desktop file to which it corresponds.
        desktop="`binary_to_desktop_file "$binary"`"
        basename "$desktop"
    fi
}

check_browser_gnome()
{
    check="`desktop_file_to_binary "$1"`"
    if [ -z "$check" ]; then
        echo no
        exit_success
    fi
    binary="`gconftool-2 --get /desktop/gnome/applications/browser/exec | first_word`"
    if [ x"$binary" != x"$check" ]; then
        echo no
        exit_success
    fi
    # Check HTTP and HTTPS, but not about: and unknown:.
    for protocol in http https; do
        binary="`gconftool-2 --get /desktop/gnome/url-handlers/$protocol/command | first_word`"
        if [ x"$binary" != x"$check" ]; then
            echo no
            exit_success
        fi
    done
    browser="`get_browser_mime`"
    binary="`desktop_file_to_binary "$browser"`"
    if [ x"$binary" != x"$check" ]; then
        echo no
        exit_success
    fi
    echo yes
    exit_success
}

set_browser_gnome()
{
    binary="`desktop_file_to_binary "$1"`"
    [ "$binary" ] || exit_failure_file_missing
    set_browser_mime "$1" || return

    # Set the default browser.
    gconftool-2 --type string --set /desktop/gnome/applications/browser/exec "$binary"
    gconftool-2 --type bool --set /desktop/gnome/applications/browser/needs_term false
    gconftool-2 --type bool --set /desktop/gnome/applications/browser/nremote true
    # Set the handler for HTTP and HTTPS.
    for protocol in http https; do
        gconftool-2 --type string --set /desktop/gnome/url-handlers/$protocol/command "$binary %s"
        gconftool-2 --type bool --set /desktop/gnome/url-handlers/$protocol/needs_terminal false
        gconftool-2 --type bool --set /desktop/gnome/url-handlers/$protocol/enabled true
    done
    # Set the handler for about: and unknown URL types.
    for protocol in about unknown; do
        gconftool-2 --type string --set /desktop/gnome/url-handlers/$protocol/command "$binary %s"
    done
}

# }}} GNOME
# {{{ GNOME 3.x

get_browser_gnome3()
{
    get_browser_mime "x-scheme-handler/http"
}

check_browser_gnome3()
{
    desktop="$1"
    check="`desktop_file_to_binary "$1"`"
    if [ -z "$check" ]; then
        echo no
        exit_success
    fi
    # Check HTTP and HTTPS, but not about: and unknown:.
    for protocol in http https; do
        browser="`get_browser_mime "x-scheme-handler/$protocol"`"
        if [ x"$browser" != x"$desktop" ]; then
            echo no
            exit_success
        fi
    done
    echo yes
    exit_success
}

set_browser_gnome3()
{
    binary="`desktop_file_to_binary "$1"`"
    [ "$binary" ] || exit_failure_file_missing
    set_browser_mime "$1" || return

    # Set the default browser.
    for protocol in http https about unknown; do
        set_browser_mime "$1" "x-scheme-handler/$protocol" || return
    done
}
# }}} GNOME 3.x
# {{{ xfce

get_browser_xfce()
{
    search="${XDG_CONFIG_HOME:-$HOME/.config}:${XDG_CONFIG_DIRS:-/etc/xdg}"
    IFS=:
    for dir in $search; do
        unset IFS
        [ "$dir" ] && [ -d "$dir/xfce4" ] || continue
        file="$dir/xfce4/helpers.rc"
        [ -r "$file" ] || continue
        grep -q "^WebBrowser=" "$file" || continue
        desktop="`grep "^WebBrowser=" "$file" | cut -d= -f 2-`"
        echo "$desktop.desktop"
        return
    done
    exit_failure_operation_failed
}

check_browser_xfce()
{
    browser="`get_browser_xfce`"
    if [ x"$browser" != x"$1" ]; then
        echo no
        exit_success
    fi
    echo yes
    exit_success
}

check_xfce_desktop_file()
{
    # Annoyingly, xfce wants its .desktop files in a separate directory instead
    # of the standard locations, and requires a few custom tweaks to them:
    # "Type" must be "X-XFCE-Helper"
    # "X-XFCE-Category" must be "WebBrowser" (for web browsers, anyway)
    # "X-XFCE-Commands" and "X-XFCE-CommandsWithParameter" must be set
    search="${XDG_DATA_HOME:-$HOME/.local/share}:${XDG_DATA_DIRS:-/usr/local/share:/usr/share}"
    IFS=:
    for dir in $search; do
        unset IFS
        [ "$dir" ] && [ -d "$dir/xfce4/helpers" ] || continue
        file="$dir/xfce4/helpers/$1"
        # We have the file, no need to create it.
        [ -r "$file" ] && return
    done
    IFS=:
    for dir in $search; do
        unset IFS
        [ "$dir" ] && [ -d "$dir/applications" ] || continue
        file="$dir/applications/$1"
        if [ -r "$file" ]; then
            # Found a file to convert.
            target="${XDG_DATA_HOME:-$HOME/.local/share}/xfce4/helpers"
            mkdir -p "$target"
            # Copy file up to first "Exec=" line.
            sed -e 's/^Type=.*/Type=X-XFCE-Helper/' -e '/^Exec[=[]/,$d' "$file" > "$target/$1"
            echo "X-XFCE-Category=WebBrowser" >> "$target/$1"
            # Change %F, %f, %U, and %u to "%s".
            command=$(grep -E '^Exec(\[[^]=]*])?=' "$file" | cut -d= -f 2- | sed -e 's/%[FfUu]/"%s"/g' | head -1)
            echo "X-XFCE-Commands=`echo "$command" | first_word`" >> "$target/$1"
            echo "X-XFCE-CommandsWithParameter=$command" >> "$target/$1"
            # Copy rest of file (from first "Exec=" line to end-of-file).
            sed -n -e 's/^Type=.*/Type=X-XFCE-Helper/' -e '/^Exec[=[]/,$p' "$file" >> "$target/$1"
            return
        fi
    done
    return 1
}

set_browser_xfce()
{
    check_xfce_desktop_file "$1" || exit_failure_operation_failed

    helper_dir="${XDG_CONFIG_HOME:-$HOME/.config}/xfce4"
    if [ ! -d "$helper_dir" ]; then
        mkdir -p "$helper_dir" || exit_failure_operation_failed
    fi

    helpers_rc="$helper_dir/helpers.rc"
    # Create the file if it does not exist to avoid special cases below.
    if [ ! -r "$helpers_rc" ]; then
        touch "$helpers_rc" || exit_failure_operation_failed
    fi

    temp="`mktemp "$helpers_rc.XXXXXX"`" || return
    grep -v "^WebBrowser=" "$helpers_rc" >> "$temp"
    echo "WebBrowser=${1%.desktop}" >> "$temp"

    oldlines="`wc -l < "$helpers_rc"`"
    newlines="`wc -l < "$temp"`"
    # The new file should have at least as many lines as the old.
    if [ $oldlines -le $newlines ]; then
        mv "$temp" "$helpers_rc"
    else
        rm -f "$temp"
        return 1
    fi
}

# }}} xfce
# {{{ generic

get_browser_generic()
{
    if [ -n "$BROWSER" ]; then
        local browser=$(binary_to_desktop_file "${BROWSER%%:*}")
        if [ -n "$browser" ]; then
            echo "$(basename "$browser")"
            return 0
        fi
    fi

    if get_browser_mime x-scheme-handler/http; then
        return 0
    fi

    # Debian and derivatives have x-www-browser
    local browser=$(binary_to_desktop_file x-www-browser)
    if [ -n "$browser" ]; then
        echo "$(basename "$browser")"
        return 0
    fi

    return 4
}

check_browser_generic()
{
    local desktop="$1"

    # Check HTTP
    if [ "$desktop" != "$(get_browser_generic)" ]; then
        echo no
        exit_success
    fi

    # Check text/html
    if [ "$desktop" != "$(get_browser_mime)" ]; then
        echo no
        exit_success
    fi

    # Check HTTPS
    if [ "$desktop" != "$(get_url_scheme_handler_generic https)" ]; then
        echo no
        exit_success
    fi

    echo yes
    exit_success
}

set_browser_generic()
{
    if [ -n "$BROWSER" ]; then
        exit_failure_operation_failed \
            "\$BROWSER is set and can't be changed with xdg-settings"
    fi

    binary=$(desktop_file_to_binary "$1")
    [ -n "$binary" ] || exit_failure_file_missing

    set_browser_mime "$1" text/html || return

    for protocol in http https about unknown; do
        set_browser_mime "$1" "x-scheme-handler/$protocol" || return
    done
}
# }}} generic
# }}} default browser

# {{{ default url scheme handler

exit_unimplemented_default_handler()
{
    exit_failure_operation_impossible "default-url-scheme-handler not implemented for $DE"
}

# {{{ KDE

# Recent versions of KDE support default scheme handler applications using the
# mime type of x-scheme-handler/scheme. Older versions will not support this
# but do have support for setting a default mail handler. There is also a
# system in KDE where .protocol files can be used, however this is not
# supported by this script. When reading a scheme handler we will use the
# default mail handler for the mailto scheme, otherwise we will use the mime
# type x-scheme-handler/scheme.

get_url_scheme_handler_kde()
{
    if [ "$1" = "mailto" ]; then
        handler="`read_kde_config emaildefaults PROFILE_Default EmailClient | first_word`"
        echo "handler is $handler"
        if [ x"$handler" != x ]; then
            binary_to_desktop_file "$handler"
        else
            get_browser_mime "x-scheme-handler/$1"
        fi
    else 
        get_browser_mime "x-scheme-handler/$1"
    fi
}

check_url_scheme_handler_kde()
{
    check="`desktop_file_to_binary "$2"`"
    if [ -z "$check" ]; then
        echo no
        exit_success
    fi
    if [ x"$1" = "mailto" ]; then
        binary="`read_kde_config emaildefaults PROFILE_Default EmailClient`"
        if [ x"$binary" != x"$check" ]; then
            echo no
            exit_success
        fi
    fi
    handler="`get_browser_mime x-scheme-handler/$1`"
    binary="`desktop_file_to_binary "$handler"`"
    if [ x"$binary" != x"$check" ]; then
        echo no
        exit_success
    fi
    echo yes
    exit_success
}

set_url_scheme_handler_kde()
{
    set_browser_mime "$2" "x-scheme-handler/$1" || return
    if [ "$1" = "mailto" ]; then
        binary="`desktop_file_to_binary "$2"`"
        if [ x"${KDE_SESSION_VERSION}" = x"5" ]; then
            kwriteconfig5 --file emaildefaults --group PROFILE_Default --key EmailClient "$binary"
        else
            kwriteconfig --file emaildefaults --group PROFILE_Default --key EmailClient "$binary"
        fi
    fi
}

# }}} KDE
# {{{ GNOME

get_url_scheme_handler_gnome()
{
    binary="`gconftool-2 --get /desktop/gnome/url-handlers/$1/command | first_word`"
    if [ x"$binary" != x"" ]; then
        # gconftool gives the binary (maybe with %s etc. afterward),
        # but we want the desktop file name, not the binary. So, we
        # have to find the desktop file to which it corresponds.
        desktop="`binary_to_desktop_file "$binary"`"
        basename "$desktop"
    fi
}

check_url_scheme_handler_gnome()
{
    check="`desktop_file_to_binary "$2"`"
    if [ -z "$check" ]; then
        echo no
        exit_success
    fi
    binary="`gconftool-2 --get /desktop/gnome/url-handlers/$1/command | first_word`"
    if [ x"$binary" != x"$check" ]; then
        echo no
        exit_success
    fi
    echo yes
    exit_success
}

set_url_scheme_handler_gnome()
{
    binary="`desktop_file_to_binary "$2"`"
    [ "$binary" ] || exit_failure_file_missing

    gconftool-2 --type string --set /desktop/gnome/url-handlers/$1/command "$binary %s"
    gconftool-2 --type bool --set /desktop/gnome/url-handlers/$1/needs_terminal false
    gconftool-2 --type bool --set /desktop/gnome/url-handlers/$1/enabled true
}

# }}} GNOME
# {{{ GNOME 3.x

get_url_scheme_handler_gnome3()
{
    get_browser_mime "x-scheme-handler/$1"
}

check_url_scheme_handler_gnome3()
{
    desktop="$2"
    check="`desktop_file_to_binary "$2"`"
    if [ -z "$check" ]; then
        echo no
        exit_success
    fi
    browser="`get_browser_mime "x-scheme-handler/$1"`"
    if [ x"$browser" != x"$desktop" ]; then
        echo no
        exit_success
    fi
    echo yes
    exit_success
}

set_url_scheme_handler_gnome3()
{
    binary="`desktop_file_to_binary "$2"`"
    [ "$binary" ] || exit_failure_file_missing
    set_browser_mime "$2" || return

    # Set the default browser.
    set_browser_mime "$2" "x-scheme-handler/$1" || return
}

# }}} GNOME 3.x
# {{{ xfce

get_url_scheme_handler_xfce()
{
    exit_unimplemented_default_handler "$1"
}

check_url_scheme_handler_xfce()
{
    exit_unimplemented_default_handler "$1"
}

set_url_scheme_handler_xfce()
{
    exit_unimplemented_default_handler "$1"
}

# }}} xfce
# {{{ generic

get_url_scheme_handler_generic()
{
    if [ -n "$BROWSER" ] && ([ "$1" = http ] || [ "$1" = https ]); then
        get_browser_generic
    else
        get_browser_mime "x-scheme-handler/$1"
    fi
}

check_url_scheme_handler_generic()
{
    local scheme="$1" desktop="$2"

    if [ -z "$(desktop_file_to_binary "$desktop")" ]; then
        echo no
        exit_success
    fi

    local browser=$(get_url_scheme_handler_generic "$scheme")
    if [ "$browser" != "$desktop" ]; then
        echo no
        exit_success
    fi
    echo yes
    exit_success
}

set_url_scheme_handler_generic()
{
    local scheme="$1" desktop="$2"

    if [ -n "$BROWSER" ] && \
           ([ "$scheme" = http ] || [ "$scheme" = https ]); then
        exit_failure_operation_failed \
            "\$BROWSER is set and can't be changed with xdg-settings"
    fi

    if [ -z "$(desktop_file_to_binary "$desktop")" ]; then
        exit_failure_file_missing
    fi

    set_browser_mime "$desktop" "x-scheme-handler/$scheme"
}

# }}} generic
# }}} default protocol handler

dispatch_specific()
{
    local handler=$1; shift
    # The PROP comments in this function are used to generate the output of
    # the --list option. The formatting is important. Make sure to line up the
    # property descriptions with spaces so that it will look nice.
    if [ x"$op" = x"get" ]; then
        case "$parm" in
          default-web-browser) # PROP:           Default web browser
            get_browser_$handler
            ;;

          default-url-scheme-handler) # PROP:    Default handler for URL scheme
            get_url_scheme_handler_$handler "$1"
            ;;

          *)
            exit_failure_syntax
            ;;
        esac
    elif [ x"$op" = x"check" ]; then
        case "$parm" in
          default-web-browser)
            check_desktop_filename "$1"
            check_browser_$handler "$1"
            ;;

          default-url-scheme-handler)
            check_desktop_filename "$2"
            check_url_scheme_handler_$handler "$1" "$2"
            ;;

          *)
            exit_failure_syntax
            ;;
        esac
    else # set
        case "$parm" in
          default-web-browser)
	    [ $# -eq 1 ] || exit_failure_syntax "unexpected/missing argument"
            check_desktop_filename "$1"
            set_browser_$handler "$1"
            ;;

          default-url-scheme-handler)
	    [ $# -eq 2 ] || exit_failure_syntax "unexpected/missing argument"
            check_desktop_filename "$2"
            set_url_scheme_handler_$handler "$1" "$2"
            ;;

          *)
            exit_failure_syntax
            ;;
        esac
    fi

    if [ $? -eq 0 ]; then
        exit_success
    else
        exit_failure_operation_failed
    fi
}

if [ x"$1" = x"--list" ]; then
    echo "Known properties:"
    # Extract the property names from dispatch_specific() above.
    grep "^[ 	]*[^)]*) # PROP:" "$0" | sed -e 's/^[ 	]*\([^)]*\)) # PROP: \(.*\)$/  \1 \2/' | sort
    exit_success
fi

[ x"$1" != x ] || exit_failure_syntax "no operation given"
[ x"$2" != x ] || exit_failure_syntax "no parameter name given"
[ x"$1" = x"get" -o x"$3" != x ] || exit_failure_syntax "no parameter value given"

op="$1"
parm="$2"
shift 2

if [ x"$op" != x"get" -a x"$op" != x"check" -a x"$op" != x"set" ]; then
  exit_failure_syntax "invalid operation"
fi

detectDE

if [ -z "$DE" ]; then
    DE=generic
fi

case "$DE" in
    kde)
    dispatch_specific kde "$@"
    ;;

    gnome)
    dispatch_specific gnome "$@"
    ;;

    gnome3|cinnamon|lxde|mate)
    dispatch_specific gnome3 "$@"
    ;;

    xfce)
    dispatch_specific xfce "$@"
    ;;

    generic|lxqt|enlightenment)
    dispatch_specific generic "$@"
    ;;

    *)
    exit_failure_operation_impossible "unknown desktop environment"
    ;;
esac