WaE: C6011 Dereferencing NULL pointer warnings

[LibreOffice.git] / bin / gla11y

#!/usr/bin/env python
# -*- tab-width: 4; indent-tabs-mode: nil; py-indent-offset: 4 -*-
#
# This file is part of the LibreOffice project.
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.
#
# This file incorporates work covered by the following license notice:
#
#   Copyright (c) 2018 Martin Pieuchot
#   Copyright (c) 2018-2020 Samuel Thibault <sthibault@hypra.fr>
#
#   Permission to use, copy, modify, and distribute this software for any
#   purpose with or without fee is hereby granted, provided that the above
#   copyright notice and this permission notice appear in all copies.
#
#   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
#   WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
#   MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
#   ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
#   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
#   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
#   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

# Take LibreOffice (glade) .ui files and check for non accessible widgets

# A white paper documents the rationale of the implementation:
#
# https://inria.hal.science/hal-02957129

from __future__ import print_function

import os
import sys
import getopt
try:
    import lxml.etree as ET
    lxml = True
except ImportError:
    if sys.version_info < (2,7):
        print("gla11y needs lxml or python >= 2.7")
        exit()
    import xml.etree.ElementTree as ET
    lxml = False

howto_url = "https://wiki.documentfoundation.org/Development/Accessibility"

# Toplevel widgets
widgets_toplevel = [
    'GtkWindow',
    'GtkOffscreenWindow',
    'GtkApplicationWindow',
    'GtkDialog',
    'GtkFileChooserDialog',
    'GtkColorChooserDialog',
    'GtkFontChooserDialog',
    'GtkMessageDialog',
    'GtkRecentChooserDialog',
    'GtkAssistant',
    'GtkAppChooserDialog',
    'GtkPrintUnixDialog',
    'GtkShortcutsWindow',
]

widgets_ignored = widgets_toplevel + [
    # Containers
    'GtkBox',
    'GtkGrid',
    'GtkNotebook',
    'GtkFrame',
    'GtkAspectFrame',
    'GtkListBox',
    'GtkFlowBox',
    'GtkOverlay',
    'GtkMenuBar',
    'GtkToolbar',
    'GtkToolpalette',
    'GtkPaned',
    'GtkHPaned',
    'GtkVPaned',
    'GtkButtonBox',
    'GtkHButtonBox',
    'GtkVButtonBox',
    'GtkLayout',
    'GtkFixed',
    'GtkEventBox',
    'GtkExpander',
    'GtkViewport',
    'GtkScrolledWindow',
    'GtkRevealer',
    'GtkSearchBar',
    'GtkHeaderBar',
    'GtkStack',
    'GtkPopover',
    'GtkPopoverMenu',
    'GtkActionBar',
    'GtkHandleBox',
    'GtkShortcutsSection',
    'GtkShortcutsGroup',
    'GtkTable',

    'GtkVBox',
    'GtkHBox',
    'GtkToolItem',
    'GtkMenu',

    # Invisible actions
    'GtkSeparator',
    'GtkHSeparator',
    'GtkVSeparator',
    'GtkAction',
    'GtkToggleAction',
    'GtkActionGroup',
    'GtkCellRendererGraph',
    'GtkCellRendererPixbuf',
    'GtkCellRendererProgress',
    'GtkCellRendererSpin',
    'GtkCellRendererText',
    'GtkCellRendererToggle',
    'GtkSeparatorMenuItem',
    'GtkSeparatorToolItem',

    # Storage objects
    'GtkListStore',
    'GtkTreeStore',
    'GtkTreeModelFilter',
    'GtkTreeModelSort',

    'GtkEntryBuffer',
    'GtkTextBuffer',
    'GtkTextTag',
    'GtkTextTagTable',

    'GtkSizeGroup',
    'GtkWindowGroup',
    'GtkAccelGroup',
    'GtkAdjustment',
    'GtkEntryCompletion',
    'GtkIconFactory',
    'GtkStatusIcon',
    'GtkFileFilter',
    'GtkRecentFilter',
    'GtkRecentManager',
    'GThemedIcon',

    'GtkTreeSelection',

    'GtkListBoxRow',
    'GtkTreeViewColumn',

    # Useless to label
    'GtkScrollbar',
    'GtkHScrollbar',
    'GtkStatusbar',
    'GtkInfoBar',

    # These are actually labels
    'GtkLinkButton',

    # This precisely give a11y information :)
    'AtkObject',
]

widgets_suffixignored = [
]

# These widgets always need a label
widgets_needlabel = [
    'GtkEntry',
    'GtkSearchEntry',
    'GtkScale',
    'GtkHScale',
    'GtkVScale',
    'GtkSpinButton',
    'GtkSwitch',
]

# These widgets normally have their own label
widgets_buttons = [
    'GtkButton',
    'GtkToolButton',
    'GtkToggleButton',
    'GtkToggleToolButton',
    'GtkRadioButton',
    'GtkRadioToolButton',
    'GtkCheckButton',
    'GtkModelButton',
    'GtkLockButton',
    'GtkColorButton',
    'GtkMenuButton',

    'GtkMenuItem',
    'GtkImageMenuItem',
    'GtkMenuToolButton',
    'GtkRadioMenuItem',
    'GtkCheckMenuItem',
]

# These widgets are labels that can label other widgets
widgets_labels = [
    'GtkLabel',
    'GtkAccelLabel',
]

# The rest should probably be labelled if there are orphan labels

# GtkSpinner
# GtkProgressBar
# GtkLevelBar

# GtkComboBox
# GtkComboBoxText
# GtkFileChooserButton
# GtkAppChooserButton
# GtkFontButton
# GtkCalendar
# GtkColorChooserWidget

# GtkCellView
# GtkTreeView
# GtkTextView
# GtkIconView

# GtkImage
# GtkArrow
# GtkDrawingArea

# GtkScaleButton
# GtkVolumeButton


# TODO:
# GtkColorPlane ?
# GtkColorScale ?
# GtkColorSwatch ?
# GtkFileChooserWidget ?
# GtkFishbowl ?
# GtkFontChooserWidget ?
# GtkIcon ?
# GtkInspector* ?
# GtkMagnifier ?
# GtkPathBar ?
# GtkPlacesSidebar ?
# GtkPlacesView ?
# GtkPrinterOptionWidget ?
# GtkStackCombo ?
# GtkStackSidebar ?
# GtkStackSwitcher ?

progname = os.path.basename(sys.argv[0])

# This dictionary contains the set of suppression lines as read from the
# suppression file(s). It is merely indexed by the text of the suppression line
# and contains whether the suppressions was unused.
suppressions = {}

# This dictionary is indexed like suppressions and returns a "file:line" string
# to report where in the suppression file the suppression was read
suppressions_to_line = {}

# This dictionary is similar to the suppressions dictionary, but for false
# positives rather than suppressions
false_positives = {}

# This dictionary is indexed by the xml id and returns the element object.
ids = {}
# This dictionary is indexed by the xml id and returns whether several objects
# have the same id.
ids_dup = {}

# This dictionary is indexed by the xml id of an element A and returns the list
# of objects which are labelled-by A.
labelled_by_elm = {}

# This dictionary is indexed by the xml id of an element A and returns the list
# of objects which are label-for A.
label_for_elm = {}

# This dictionary is indexed by the xml id of an element A and returns the list
# of objects which have a mnemonic-for A.
mnemonic_for_elm = {}

# Possibly a file name to put generated suppression lines in
gen_suppr = None
# The corresponding opened file
gen_supprfile = None
# A prefix to remove from file names in the generated suppression lines
suppr_prefix = ""

# Possibly an opened file in which our output should also be written to.
outfile = None

# Whether -p option was set, i.e. print XML class path instead of line number in
# the output
pflag = False

# Whether we should warn about labels which are orphan
warn_orphan_labels = True

# Number of errors
errors = 0
# Number of suppressed errors
errexists = 0
# Number of warnings
warnings = 0
# Number of suppressed warnings
warnexists = 0
# Number of fatal errors
fatals = 0
# Number of suppressed fatal errors
fatalexists = 0

# List of warnings and errors which are fatal
#
# Format of each element: (enabled, type, class)
# See the is_enabled function: the list is traversed completely, each element
# can specify whether it enables or disables the warning, possibly the type of
# warning to be enabled/disabled, possibly the class of XML element for which it
# should be enabled.
#
# This mechanism matches the semantic of the parameters on the command line,
# each of which refining the semantic set by the previous parameters
dofatals = [ ]

# List of warnings and errors which are enabled
# Same format as dofatals
enables = [ ]

# buffers all printed output, so it isn't split in parallel builds
output_buffer = ""

#
# XML browsing and printing functions
#

def elm_parent(root, elm):
    """
    Return the parent of the element.
    """
    if lxml:
        return elm.getparent()
    else:
        def find_parent(cur, elm):
            for o in cur:
                if o == elm:
                    return cur
                parent = find_parent(o, elm)
                if parent is not None:
                    return parent
            return None
        return find_parent(root, elm)

def step_elm(elm):
    """
    Return the XML class path step corresponding to elm.
    This can be empty if the elm does not have any class or id.
    """
    step = elm.attrib.get('class')
    if step is None:
        step = ""
    oid = elm.attrib.get('id')
    if oid is not None:
        oid = oid.encode('ascii','ignore').decode('ascii')
        step += "[@id='%s']" % oid
    if len(step) > 0:
        step += '/'
    return step

def find_elm(root, elm):
    """
    Return the XML class path of the element from the given root.
    This is the slow version used when getparent is not available.
    """
    if root == elm:
        return ""
    for o in root:
        path = find_elm(o, elm)
        if path is not None:
            step = step_elm(o)
            return step + path
    return None

def errpath(filename, tree, elm):
    """
    Return the XML class path of the element
    """
    if elm is None:
        return ""
    path = ""
    if 'class' in elm.attrib:
        path += elm.attrib['class']
    oid = elm.attrib.get('id')
    if oid is not None:
        oid = oid.encode('ascii','ignore').decode('ascii')
        path = "//" + path + "[@id='%s']" % oid
    else:
        if lxml:
            elm = elm.getparent()
            while elm is not None:
                step = step_elm(elm)
                path = step + path
                elm = elm.getparent()
        else:
            path = find_elm(tree.getroot(), elm)[:-1]
    path = filename + ':' + path
    return path

#
# Warning/Error printing functions
#

def elm_prefix(filename, elm):
    """
    Return the display prefix of the element
    """
    if elm == None or not lxml:
        return "%s:" % filename
    else:
        return "%s:%u" % (filename, elm.sourceline)

def elm_name(elm):
    """
    Return a display name of the element
    """
    if elm is not None:
        name = ""
        if 'class' in elm.attrib:
            name = "'%s' " % elm.attrib['class']
        if 'id' in elm.attrib:
            id = elm.attrib['id'].encode('ascii','ignore').decode('ascii')
            name += "'%s' " % id
        if not name:
            name = "'" + elm.tag + "'"
            if lxml:
                name += " line " + str(elm.sourceline)
        return name
    return ""

def elm_name_line(elm):
    """
    Return a display name of the element with line number
    """
    if elm is not None:
        name = elm_name(elm)
        if lxml and " line " not in name:
            name += "line " + str(elm.sourceline) + " "
        return name
    return ""

def elm_line(elm):
    """
    Return the line for the given element.
    """
    if lxml:
        return " line " + str(elm.sourceline)
    else:
        return ""

def elms_lines(elms):
    """
    Return the list of lines for the given elements.
    """
    if lxml:
        return " lines " + ', '.join([str(l.sourceline) for l in elms])
    else:
        return ""

def elms_names_lines(elms):
    """
    Return the list of names and lines for the given elements.
    """
    return ', '.join([elm_name_line(elm) for elm in elms])

def elm_suppr(filename, tree, elm, msgtype, dogen):
    """
    Return the prefix to be displayed to the user and the suppression line for
    the warning type "msgtype" for element "elm"
    """
    global gen_suppr, gen_supprfile, suppr_prefix, pflag

    if suppressions or false_positives or gen_suppr is not None or pflag:
        prefix = errpath(filename, tree, elm)
        if prefix[0:len(suppr_prefix)] == suppr_prefix:
            prefix = prefix[len(suppr_prefix):]

    if suppressions or false_positives or gen_suppr is not None:
        suppr = '%s %s' % (prefix, msgtype)

        if gen_suppr is not None and msgtype is not None and dogen:
            if gen_supprfile is None:
                gen_supprfile = open(gen_suppr, 'w')
            print(suppr, file=gen_supprfile)
    else:
        suppr = None

    if not pflag:
        # Use user-friendly line numbers
        prefix = elm_prefix(filename, elm)
        if prefix[0:len(suppr_prefix)] == suppr_prefix:
            prefix = prefix[len(suppr_prefix):]

    return (prefix, suppr)

def is_enabled(elm, msgtype, l, default):
    """
    Test whether warning type msgtype is enabled for elm in l
    """
    enabled = default
    for (enable, thetype, klass) in l:
        # Match warning type
        if thetype is not None:
            if thetype != msgtype:
                continue
        # Match elm class
        if klass is not None and elm is not None:
            if klass != elm.attrib.get('class'):
                continue
        enabled = enable
    return enabled

def err(filename, tree, elm, msgtype, msg, error = True):
    """
    Emit a warning or error for an element
    """
    global errors, errexists, warnings, warnexists, fatals, fatalexists, output_buffer

    # Let user tune whether a warning or error
    fatal = is_enabled(elm, msgtype, dofatals, error)

    # By default warnings and errors are enabled, but let user tune it
    if not is_enabled(elm, msgtype, enables, True):
        return

    (prefix, suppr) = elm_suppr(filename, tree, elm, msgtype, True)
    if suppr in false_positives:
        # That was actually expected
        return
    if suppr in suppressions:
        # Suppressed
        suppressions[suppr] = False
        if fatal:
            fatalexists += 1
        if error:
            errexists += 1
        else:
            warnexists += 1
        return

    if error:
        errors += 1
    else:
        warnings += 1
    if fatal:
        fatals += 1

    msg = "%s %s%s: %s%s" % (prefix,
            "FATAL " if fatal else "",
            "ERROR" if error else "WARNING",
            elm_name(elm), msg)
    output_buffer += msg + "\n"
    if outfile is not None:
        print(msg, file=outfile)

def warn(filename, tree, elm, msgtype, msg):
    """
    Emit a warning for an element
    """
    err(filename, tree, elm, msgtype, msg, False)

#
# Labelling testing functions
#

def find_button_parent(root, elm):
    """
    Find a parent which is a button
    """
    if lxml:
        parent = elm.getparent()
        if parent is not None:
            if parent.attrib.get('class') in widgets_buttons:
                return parent
            return find_button_parent(root, parent)
    else:
        def find_parent(cur, elm):
            for o in cur:
                if o == elm:
                    if cur.attrib.get('class') in widgets_buttons:
                        # we are the button, immediately above the target
                        return cur
                    else:
                        # we aren't the button, but target is over there
                        return True
                parent = find_parent(o, elm)
                if parent == True:
                    # It is over there, but didn't find a button yet
                    if cur.attrib.get('class') in widgets_buttons:
                        # we are the button
                        return cur
                    else:
                        return True
                if parent is not None:
                    # we have the button parent over there
                    return parent
            return None
        parent = find_parent(root, elm)
        if parent == True:
            parent = None
        return parent


def is_labelled_parent(elm):
    """
    Return whether this element is a labelled parent
    """
    klass = elm.attrib.get('class')
    if klass in widgets_toplevel:
        return True
    if klass == 'GtkShortcutsGroup':
        children = elm.findall("property[@name='title']")
        if len(children) >= 1:
            return True
    if klass == 'GtkFrame' or klass == 'GtkNotebook':
        children = elm.findall("child[@type='tab']") + elm.findall("child[@type='label']") 
        if len(children) >= 1:
            return True
    return False

def elm_labelled_parent(root, elm):
    """
    Return the first labelled parent of the element, which can thus be used as
    the root of widgets with common labelled context
    """

    if lxml:
        def find_labelled_parent(elm):
            if is_labelled_parent(elm):
                return elm
            parent = elm.getparent()
            if parent is None:
                return None
            return find_labelled_parent(parent)
        parent = elm.getparent()
        if parent is None:
            return None
        return find_labelled_parent(elm.getparent())
    else:
        def find_labelled_parent(cur, elm):
            if cur == elm:
                # the target element is over there
                return True
            for o in cur:
                parent = find_labelled_parent(o, elm)
                if parent == True:
                    # target element is over there, check ourself
                    if is_labelled_parent(cur):
                        # yes, and we are the first ancestor of the target element
                        return cur
                    else:
                        # no, but target element is over there.
                        return True
                if parent != None:
                    # the first ancestor of the target element was over there
                    return parent
            return None
        parent = find_labelled_parent(root, elm)
        if parent == True:
            parent = None
        return parent

def is_orphan_label(filename, tree, root, obj, orphan_root, doprint = False):
    """
    Check whether this label has no accessibility relation, or doubtful relation
    because another label labels the same target
    """
    global label_for_elm, labelled_by_elm, mnemonic_for_elm, warnexists

    # label-for
    label_for = obj.findall("accessibility/relation[@type='label-for']")
    for rel in label_for:
        target = rel.attrib['target']
        l = label_for_elm[target]
        if len(l) > 1:
            return True

    # mnemonic_widget
    mnemonic_for = obj.findall("property[@name='mnemonic_widget']") + \
                   obj.findall("property[@name='mnemonic-widget']")
    for rel in mnemonic_for:
        target = rel.text
        l = mnemonic_for_elm[target]
        if len(l) > 1:
            return True

    if len(label_for) > 0:
        # At least one label-for, we are not orphan.
        return False

    if len(mnemonic_for) > 0:
        # At least one mnemonic_widget, we are not orphan.
        return False

    labelled_by = obj.findall("accessibility/relation[@type='labelled-by']")
    if len(labelled_by) > 0:
        # Oh, a labelled label, probably not to be labelling anything
        return False

    # explicit role?
    roles = [x.text for x in obj.findall("child[@internal-child='accessible']/object[@class='AtkObject']/property[@name='AtkObject::accessible-role']")]
    roles += [x.attrib.get("type") for x in obj.findall("accessibility/role")]
    if len(roles) > 1 and doprint:
        err(filename, tree, obj, "multiple-role", "has multiple <child internal-child='accessible'><object class='AtkObject'><property name='AtkBoject::accessible-role'>"
            "%s" % elms_lines(children))
    for role in roles:
        if role == 'static' or role == 'ATK_ROLE_STATIC':
            # This is static text, not meant to label anything
            return False

    parent = elm_parent(root, obj)
    if parent is not None:
        childtype = parent.attrib.get('type')
        if childtype is None:
            childtype = parent.attrib.get('internal-child')
        if parent.tag == 'child' and childtype == 'label' \
                                  or childtype == 'tab':
            # This is a frame or a notebook label, not orphan.
            return False

    if find_button_parent(root, obj) is not None:
        # This label is part of a button
        return False

    oid = obj.attrib.get('id')
    if oid is not None:
        if oid in labelled_by_elm:
            # Some widget is labelled by us, we are not orphan.
            # We should have had a label-for, will warn about it later.
            return False

    # No label-for, no mnemonic-for, no labelled-by, we are orphan.
    (_, suppr) = elm_suppr(filename, tree, obj, "orphan-label", False)
    if suppr in false_positives:
        # That was actually expected
        return False
    if suppr in suppressions:
        # Warning suppressed for this label
        if suppressions[suppr]:
            warnexists += 1
        suppressions[suppr] = False
        return False

    if doprint:
        context = elm_name(orphan_root)
        if context:
            context = " within " + context
        warn(filename, tree, obj, "orphan-label", "does not specify what it labels" + context)
    return True

def is_orphan_widget(filename, tree, root, obj, orphan, orphan_root, doprint = False):
    """
    Check whether this widget has no accessibility relation.
    """
    global warnexists
    if obj.tag != 'object':
        return False

    oid = obj.attrib.get('id')
    klass = obj.attrib.get('class')

    # "Don't care" special case
    if klass in widgets_ignored:
        return False
    for suffix in widgets_suffixignored:
        if klass[-len(suffix):] == suffix:
            return False

    # Widgets usual do not strictly require a label, i.e. a labelled parent
    # is enough for context, but some do always need one.
    requires_label = klass in widgets_needlabel

    labelled_by = obj.findall("accessibility/relation[@type='labelled-by']")

    # Labels special case
    if klass in widgets_labels:
        return False

    # Case 1: has an explicit <child internal-child="accessible"> sub-element
    children = obj.findall("child[@internal-child='accessible']")
    if len(children) > 1 and doprint:
        err(filename, tree, obj, "multiple-accessible", "has multiple <child internal-child='accessible'>"
            "%s" % elms_lines(children))
    if len(children) >= 1:
        return False

    # Case 2: has an <accessibility> sub-element with a "labelled-by"
    # <relation> pointing to an existing element.
    if len(labelled_by) > 0:
        return False

    # Case 3: has a label-for
    if oid in label_for_elm:
        return False

    # Case 4: has a mnemonic
    if oid in mnemonic_for_elm:
        return False

    # Case 5: Has a <property name="tooltip_text">
    tooltips = obj.findall("property[@name='tooltip_text']") + \
               obj.findall("property[@name='tooltip-text']")
    if len(tooltips) > 1 and doprint:
        err(filename, tree, obj, "multiple-tooltip", "has multiple tooltip_text properties")
    if len(tooltips) >= 1 and klass != 'GtkCheckButton':
        return False

    # Case 6: Has a <property name="placeholder_text">
    placeholders = obj.findall("property[@name='placeholder_text']") + \
                   obj.findall("property[@name='placeholder-text']")
    if len(placeholders) > 1 and doprint:
        err(filename, tree, obj, "multiple-placeholder", "has multiple placeholder_text properties")
    if len(placeholders) >= 1:
        return False

    # Buttons usually don't need an external label, their own is enough, (but they do need one)
    if klass in widgets_buttons:

        labels = obj.findall("property[@name='label']")
        if len(labels) > 1 and doprint:
            err(filename, tree, obj, "multiple-label", "has multiple label properties")
        if len(labels) >= 1:
            # Has a <property name="label">
            return False

        actions = obj.findall("property[@name='action_name']")
        if len(actions) > 1 and doprint:
            err(filename, tree, obj, "multiple-action_name", "has multiple action_name properties")
        if len(actions) >= 1:
            # Has a <property name="action_name">
            return False

        # Uses id as an action_name
        if 'id' in obj.attrib:
            if obj.attrib['id'].startswith(".uno:"):
                return False

        gtklabels = obj.findall(".//object[@class='GtkLabel']") + obj.findall(".//object[@class='GtkAccelLabel']")
        if len(gtklabels) >= 1:
            # Has a custom label
            return False

        # no label for a button, warn
        if doprint:
            warn(filename, tree, obj, "button-no-label", "does not have its own label")
        if not is_enabled(obj, "button-no-label", enables, True):
            # Warnings disabled
            return False
        (_, suppr) = elm_suppr(filename, tree, obj, "button-no-label", False)
        if suppr in false_positives:
            # That was actually expected
            return False
        if suppr in suppressions:
            # Warning suppressed for this widget
            if suppressions[suppr]:
                warnexists += 1
            suppressions[suppr] = False
            return False
        return True

    # GtkImages special case
    if klass == "GtkImage":
        uses = [u for u in tree.iterfind(".//object/property[@name='image']") if u.text == oid]
        if len(uses) > 0:
            # This image is just used by another element, don't warn
            # about the image itself, we probably want the warning on
            # the element instead.
            return False

        if find_button_parent(root, obj) is not None:
            # This image is part of a button, we want the warning on the button
            # instead, if any.
            return False

    # GtkEntry special case
    if klass == 'GtkEntry' or klass == 'GtkSearchEntry':
        parent = elm_parent(root, obj)
        if parent is not None:
            if parent.tag == 'child' and \
                parent.attrib.get('internal-child') == "entry":
                # This is an internal entry of another widget. Relations
                # will be handled by that widget.
                return False

    # GtkShortcutsShortcut special case
    if klass == 'GtkShortcutsShortcut':
        children = obj.findall("property[@name='title']")
        if len(children) >= 1:
            return False

    # Really no label, perhaps emit a warning
    if not is_enabled(obj, "no-labelled-by", enables, True):
        # Warnings disabled for this class of widgets
        return False
    (_, suppr) = elm_suppr(filename, tree, obj, "no-labelled-by", False)
    if suppr in false_positives:
        # That was actually expected
        return False
    if suppr in suppressions:
        # Warning suppressed for this widget
        if suppressions[suppr]:
            warnexists += 1
        suppressions[suppr] = False
        return False

    if not orphan:
        # No orphan label, so probably the labelled parent provides enough
        # context.
        if requires_label:
            # But these always need a label.
            if doprint:
                warn(filename, tree, obj, "no-labelled-by", "has no accessibility label")
            return True
        return False

    if doprint:
        context = elm_name(orphan_root)
        if context:
            context = " within " + context
        warn(filename, tree, obj, "no-labelled-by", "has no accessibility label while there are orphan labels" + context)
    return True

def orphan_items(filename, tree, root, elm):
    """
    Check whether from some element there exists orphan labels and orphan widgets
    """
    orphan_labels = False
    orphan_widgets = False
    if elm.attrib.get('class') in widgets_labels:
        orphan_labels = is_orphan_label(filename, tree, root, elm, None)
    else:
        orphan_widgets = is_orphan_widget(filename, tree, root, elm, True, None)
    for obj in elm:
        # We are not interested in orphan labels under another labelled
        # parent.  This also allows to keep linear complexity.
        if not is_labelled_parent(obj):
            label, widget = orphan_items(filename, tree, root, obj)
            if label:
                orphan_labels = True
            if widget:
                orphan_widgets = True
            if orphan_labels and orphan_widgets:
                # No need to look up more
                break
    return orphan_labels, orphan_widgets

#
# UI accessibility checks
#

def check_props(filename, tree, root, elm, forward):
    """
    Check the given list of relation properties
    """
    props = elm.findall("property[@name='" + forward + "']")
    for prop in props:
        if prop.text not in ids:
            err(filename, tree, elm, "undeclared-target", forward + " uses undeclared target '%s'" % prop.text)
    return props

def is_visible(obj):
    visible = False
    visible_prop = obj.findall("property[@name='visible']")
    visible_len = len(visible_prop)
    if visible_len:
        visible_txt = visible_prop[visible_len - 1].text
        if visible_txt.lower() == "true":
            visible = True
        elif visible_txt.lower() == "false":
            visible = False
    return visible

def check_rels(filename, tree, root, elm, forward, backward = None):
    """
    Check the relations given by forward
    """
    oid = elm.attrib.get('id')
    rels = elm.findall("accessibility/relation[@type='" + forward + "']")
    for rel in rels:
        target = rel.attrib['target']
        if target not in ids:
            err(filename, tree, elm, "undeclared-target", forward + " uses undeclared target '%s'" % target)
        elif backward is not None:
            widget = ids[target]
            backrels = widget.findall("accessibility/relation[@type='" + backward + "']")
            if len([x for x in backrels if x.attrib['target'] == oid]) == 0:
                err(filename, tree, elm, "missing-" + backward, "has " + forward + \
                    ", but is not " + backward + " by " + elm_name_line(widget))
    return rels

def check_a11y_relation(filename, tree):
    """
    Emit an error message if any of the 'object' elements of the XML
    document represented by `root' doesn't comply with Accessibility
    rules.
    """
    global widgets_ignored, ids, label_for_elm, labelled_by_elm, mnemonic_for_elm

    def check_elm(orphan_root, obj, orphan_labels, orphan_widgets):
        """
        Check one element, knowing that orphan_labels/widgets tell whether
        there are orphan labels and widgets within orphan_root
        """

        oid = obj.attrib.get('id')
        klass = obj.attrib.get('class')

        # "Don't care" special case
        if klass in widgets_ignored:
            return
        for suffix in widgets_suffixignored:
            if klass[-len(suffix):] == suffix:
                return

        # Widgets usual do not strictly require a label, i.e. a labelled parent
        # is enough for context, but some do always need one.
        requires_label = klass in widgets_needlabel

        if oid is not None:
            # Check that ids are unique
            if oid in ids_dup:
                if ids[oid] == obj:
                    # We are the first, warn
                    duplicates = tree.findall(".//object[@id='" + oid + "']")
                    err(filename, tree, obj, "duplicate-id", "has the same id as other elements " + elms_names_lines(duplicates))

        # Check label-for and their dual labelled-by
        label_for = check_rels(filename, tree, root, obj, "label-for", "labelled-by")

        # Check labelled-by and its dual label-for
        labelled_by = check_rels(filename, tree, root, obj, "labelled-by", "label-for")

        visible = is_visible(obj)

        # warning message type "syntax" used:
        #
        # multiple-*  => 2+ XML tags of the inspected element itself
        # duplicate-* => 2+ XML tags of other elements referencing this element

        # Should have only one label
        if len(labelled_by) >= 1:
            if oid in mnemonic_for_elm:
                warn(filename, tree, obj, "labelled-by-and-mnemonic",
                     "has both a mnemonic " + elm_name_line(mnemonic_for_elm[oid][0]) + "and labelled-by relation")
            if len(labelled_by) > 1:
                warn(filename, tree, obj, "multiple-labelled-by", "has multiple labelled-by relations")

        if oid in labelled_by_elm:
            if len(labelled_by_elm[oid]) == 1:
                paired = labelled_by_elm[oid][0]
                if paired != None and visible != is_visible(paired):
                    warn(filename, tree, obj, "visibility-conflict", "visibility conflicts with paired " + elm_name_line(paired))

        if oid in label_for_elm:
            if len(label_for_elm[oid]) > 1:
                warn(filename, tree, obj, "duplicate-label-for", "is referenced by multiple label-for " + elms_names_lines(label_for_elm[oid]))
            elif len(label_for_elm[oid]) == 1:
                paired = label_for_elm[oid][0]
                if visible != is_visible(paired):
                    warn(filename, tree, obj, "visibility-conflict", "visibility conflicts with paired " + elm_name_line(paired))

        if oid in mnemonic_for_elm:
            if len(mnemonic_for_elm[oid]) > 1:
                warn(filename, tree, obj, "duplicate-mnemonic", "is referenced by multiple mnemonic_widget " + elms_names_lines(mnemonic_for_elm[oid]))

        # Check controlled-by/controller-for
        controlled_by = check_rels(filename, tree, root, obj, "controlled-by", "controller-for")
        controller_for = check_rels(filename, tree, root, obj, "controlled-for", "controlled-by")

        # Labels special case
        if klass in widgets_labels:
            properties = check_props(filename, tree, root, obj, "mnemonic_widget") + \
                         check_props(filename, tree, root, obj, "mnemonic-widget")
            if len(properties) > 1:
                err(filename, tree, obj, "multiple-mnemonic", "has multiple mnemonic_widgets properties"
                    "%s" % elms_lines(properties))

            # Emit orphaning warnings
            if warn_orphan_labels or orphan_widgets:
                is_orphan_label(filename, tree, root, obj, orphan_root, True)

            # We are done with the label
            return

        # Not a label, will perhaps need one

        # Emit orphaning warnings
        is_orphan_widget(filename, tree, root, obj, orphan_labels, orphan_root, True)

    root = tree.getroot()

    # Flush ids and relations from previous files
    ids = {}
    ids_dup = {}
    labelled_by_elm = {}
    label_for_elm = {}
    mnemonic_for_elm = {}

    # First pass to get links into hash tables, no warning, just record duplicates
    for obj in root.iter('object'):
        oid = obj.attrib.get('id')
        if oid is not None:
            if oid not in ids:
                ids[oid] = obj
            else:
                ids_dup[oid] = True

        labelled_by = obj.findall("accessibility/relation[@type='labelled-by']")
        for rel in labelled_by:
            target = rel.attrib.get('target')
            if target is not None:
                if target not in labelled_by_elm:
                    labelled_by_elm[target] = [ obj ]
                else:
                    labelled_by_elm[target].append(obj)

        label_for = obj.findall("accessibility/relation[@type='label-for']")
        for rel in label_for:
            target = rel.attrib.get('target')
            if target is not None:
                if target not in label_for_elm:
                    label_for_elm[target] = [ obj ]
                else:
                    label_for_elm[target].append(obj)

        mnemonic_for = obj.findall("property[@name='mnemonic_widget']") + \
                       obj.findall("property[@name='mnemonic-widget']")
        for rel in mnemonic_for:
            target = rel.text
            if target is not None:
                if target not in mnemonic_for_elm:
                    mnemonic_for_elm[target] = [ obj ]
                else:
                    mnemonic_for_elm[target].append(obj)

    # Second pass, recursive depth-first, to be able to efficiently know whether
    # there are orphan labels within a part of the tree.
    def recurse(orphan_root, obj, orphan_labels, orphan_widgets):
        if obj == root or is_labelled_parent(obj):
            orphan_root = obj
            orphan_labels, orphan_widgets = orphan_items(filename, tree, root, obj)

        if obj.tag == 'object':
            check_elm(orphan_root, obj, orphan_labels, orphan_widgets)

        for o in obj:
            recurse(orphan_root, o, orphan_labels, orphan_widgets)

    recurse(root, root, False, False)

#
# Main
#

def usage(fatal = True):
    print("`%s' checks accessibility of glade .ui files" % progname)
    print("")
    print("Usage: %s [-p] [-g SUPPR_FILE] [-s SUPPR_FILE] [-f SUPPR_FILE] [-P PREFIX] [-o LOG_FILE] [file ...]" % progname)
    print("")
    print("  -p Print XML class path instead of line number")
    print("  -g Generate suppression file SUPPR_FILE")
    print("  -s Suppress warnings given by file SUPPR_FILE, but count them")
    print("  -f Suppress warnings given by file SUPPR_FILE completely")
    print("  -P Remove PREFIX from file names in warnings")
    print("  -o Also prints errors and warnings to given file")
    print("")
    print("  --widgets-FOO [+][CLASS1[,CLASS2[,...]]]")
    print("    Give or extend one of the lists of widget classes, where FOO can be:")
    print("    - toplevel      : widgets to be considered toplevel windows")
    print("    - ignored       : widgets which do not need labelling (e.g. GtkBox)")
    print("    - suffixignored : suffixes of widget classes which do not need labelling")
    print("    - needlabel     : widgets which always need labelling (e.g. GtkEntry)")
    print("    - buttons       : widgets which need their own label but not more")
    print("                      (e.g. GtkButton)")
    print("    - labels        : widgets which provide labels (e.g. GtkLabel)")
    print("  --widgets-print print default widgets lists")
    print("")
    print("  --enable-all         enable all warnings/dofatals (default)")
    print("  --disable-all        disable all warnings/dofatals")
    print("  --fatal-all          make all warnings dofatals")
    print("  --not-fatal-all      do not make all warnings dofatals (default)")
    print("")
    print("  --enable-type=TYPE    enable warning/fatal type TYPE")
    print("  --disable-type=TYPE   disable warning/fatal type TYPE")
    print("  --fatal-type=TYPE     make warning type TYPE a fatal")
    print("  --not-fatal-type=TYPE make warning type TYPE not a fatal")
    print("")
    print("  --enable-widgets=CLASS    enable warning/fatal type CLASS")
    print("  --disable-widgets=CLASS   disable warning/fatal type CLASS")
    print("  --fatal-widgets=CLASS     make warning type CLASS a fatal")
    print("  --not-fatal-widgets=CLASS make warning type CLASS not a fatal")
    print("")
    print("  --enable-specific=TYPE.CLASS    enable warning/fatal type TYPE for widget")
    print("                                  class CLASS")
    print("  --disable-specific=TYPE.CLASS   disable warning/fatal type TYPE for widget")
    print("                                  class CLASS")
    print("  --fatal-specific=TYPE.CLASS     make warning type TYPE a fatal for widget")
    print("                                  class CLASS")
    print("  --not-fatal-specific=TYPE.CLASS make warning type TYPE not a fatal for widget")
    print("                                  class CLASS")
    print("")
    print("  --disable-orphan-labels         only warn about orphan labels when there are")
    print("                                  orphan widgets in the same context")
    print("")
    print("Report bugs to <bugs@hypra.fr>")
    sys.exit(2 if fatal else 0)

def widgets_opt(widgets_list, arg):
    """
    Replace or extend `widgets_list' with the list of classes contained in `arg'
    """
    append = arg and arg[0] == '+'
    if append:
        arg = arg[1:]

    if arg:
        widgets = arg.split(',')
    else:
        widgets = []

    if not append:
        del widgets_list[:]

    widgets_list.extend(widgets)


def main():
    global pflag, gen_suppr, gen_supprfile, suppressions, suppr_prefix, false_positives, dofatals, enables, dofatals, warn_orphan_labels
    global widgets_toplevel, widgets_ignored, widgets_suffixignored, widgets_needlabel, widgets_buttons, widgets_labels
    global outfile, output_buffer

    try:
        opts, args = getopt.getopt(sys.argv[1:], "hpiIg:s:f:P:o:L:", [
                "help",
                "version",

                "widgets-toplevel=",
                "widgets-ignored=",
                "widgets-suffixignored=",
                "widgets-needlabel=",
                "widgets-buttons=",
                "widgets-labels=",
                "widgets-print",

                "enable-all",
                "disable-all",
                "fatal-all",
                "not-fatal-all",

                "enable-type=",
                "disable-type=",
                "fatal-type=",
                "not-fatal-type=",

                "enable-widgets=",
                "disable-widgets=",
                "fatal-widgets=",
                "not-fatal-widgets=",

                "enable-specific=",
                "disable-specific=",
                "fatal-specific=",
                "not-fatal-specific=",

                "disable-orphan-labels",
            ] )
    except getopt.GetoptError:
        usage()

    suppr = None
    false = None
    out = None
    filelist = None

    for o, a in opts:
        if o == "--help" or o == "-h":
            usage(False)
        if o == "--version":
            print("0.1")
            sys.exit(0)
        elif o == "-p":
            pflag = True
        elif o == "-g":
            gen_suppr = a
        elif o == "-s":
            suppr = a
        elif o == "-f":
            false = a
        elif o == "-P":
            suppr_prefix = a
        elif o == "-o":
            out = a
        elif o == "-L":
            filelist = a

        elif o == "--widgets-toplevel":
            widgets_opt(widgets_toplevel, a)
        elif o == "--widgets-ignored":
            widgets_opt(widgets_ignored, a)
        elif o == "--widgets-suffixignored":
            widgets_opt(widgets_suffixignored, a)
        elif o == "--widgets-needlabel":
            widgets_opt(widgets_needlabel, a)
        elif o == "--widgets-buttons":
            widgets_opt(widgets_buttons, a)
        elif o == "--widgets-labels":
            widgets_opt(widgets_labels, a)
        elif o == "--widgets-print":
            print("--widgets-toplevel '" + ','.join(widgets_toplevel) + "'")
            print("--widgets-ignored '" + ','.join(widgets_ignored) + "'")
            print("--widgets-suffixignored '" + ','.join(widgets_suffixignored) + "'")
            print("--widgets-needlabel '" + ','.join(widgets_needlabel) + "'")
            print("--widgets-buttons '" + ','.join(widgets_buttons) + "'")
            print("--widgets-labels '" + ','.join(widgets_labels) + "'")
            sys.exit(0)

        elif o == '--enable-all':
            enables.append( (True, None, None) )
        elif o == '--disable-all':
            enables.append( (False, None, None) )
        elif o == '--fatal-all':
            dofatals.append( (True, None, None) )
        elif o == '--not-fatal-all':
            dofatals.append( (False, None, None) )

        elif o == '--enable-type':
            enables.append( (True, a, None) )
        elif o == '--disable-type':
            enables.append( (False, a, None) )
        elif o == '--fatal-type':
            dofatals.append( (True, a, None) )
        elif o == '--not-fatal-type':
            dofatals.append( (False, a, None) )

        elif o == '--enable-widgets':
            enables.append( (True, None, a) )
        elif o == '--disable-widgets':
            enables.append( (False, None, a) )
        elif o == '--fatal-widgets':
            dofatals.append( (True, None, a) )
        elif o == '--not-fatal-widgets':
            dofatals.append( (False, None, a) )

        elif o == '--enable-specific':
            (thetype, klass) = a.split('.', 1)
            enables.append( (True, thetype, klass) )
        elif o == '--disable-specific':
            (thetype, klass) = a.split('.', 1)
            enables.append( (False, thetype, klass) )
        elif o == '--fatal-specific':
            (thetype, klass) = a.split('.', 1)
            dofatals.append( (True, thetype, klass) )
        elif o == '--not-fatal-specific':
            (thetype, klass) = a.split('.', 1)
            dofatals.append( (False, thetype, klass) )

        elif o == '--disable-orphan-labels':
            warn_orphan_labels = False

    output_header = ""

    # Read suppression file before overwriting it
    if suppr is not None:
        try:
            output_header += "Suppression file: " + suppr + "\n"
            supprfile = open(suppr, 'r')
            line_no = 0
            for line in supprfile.readlines():
                line_no = line_no + 1
                if line.startswith('#'):
                    continue
                prefix = line.rstrip()
                suppressions[prefix] = True
                suppressions_to_line[prefix] = "%s:%u" % (suppr, line_no)
            supprfile.close()
        except IOError:
            pass

    # Read false positives file
    if false is not None:
        try:
            output_header += "False positive file: " + false + "\n"
            falsefile = open(false, 'r')
            for line in falsefile.readlines():
                if line.startswith('#'):
                    continue
                prefix = line.rstrip()
                false_positives[prefix] = True
            falsefile.close()
        except IOError:
            pass

    if out is not None:
        outfile = open(out, 'w')

    if filelist is not None:
        try:
            filelistfile = open(filelist, 'r')
            for line in filelistfile.readlines():
                line = line.strip()
                if line:
                    args += line.split(' ')
            filelistfile.close()
        except IOError:
            err(filelist, None, None, "unable to read file list file")

    for filename in args:
        try:
            tree = ET.parse(filename)
        except ET.ParseError:
            err(filename, None, None, "parse", "malformatted xml file")
            continue
        except IOError:
            err(filename, None, None, None, "unable to read file")
            continue

        try:
            check_a11y_relation(filename, tree)
        except Exception as error:
            import traceback
            output_buffer += traceback.format_exc()
            err(filename, None, None, "parse", "error parsing file")

    if errors > 0 or errexists > 0:
        output_buffer += "%s new error%s" % (errors, 's' if errors != 1 else '')
        if errexists > 0:
            output_buffer += " (%s suppressed by %s, please fix %s)" % (errexists, suppr, 'them' if errexists > 1 else 'it')
        output_buffer += "\n"

    if warnings > 0 or warnexists > 0:
        output_buffer += "%s new warning%s" % (warnings, 's' if warnings != 1 else '')
        if warnexists > 0:
            output_buffer += " (%s suppressed by %s, please fix %s)" % (warnexists, suppr, 'them' if warnexists > 1 else 'it')
        output_buffer += "\n"

    if fatals > 0 or fatalexists > 0:
        output_buffer += "%s new fatal%s" % (fatals, 's' if fatals != 1 else '')
        if fatalexists > 0:
            output_buffer += " (%s suppressed by %s, please fix %s)" % (fatalexists, suppr, 'them' if fatalexists > 1 else 'it')
        output_buffer += "\n"

    n = 0
    for (suppr,unused) in suppressions.items():
        if unused:
            n += 1

    if n > 0:
        output_buffer += "%s suppression%s unused:\n" % (n, 's' if n != 1 else '')
        for (suppr,unused) in suppressions.items():
            if unused:
                output_buffer += "    %s:%s\n" % (suppressions_to_line[suppr], suppr)

    if gen_supprfile is not None:
        gen_supprfile.close()
    if outfile is not None:
        outfile.close()

    if gen_suppr is None:
        if output_buffer != "":
            output_buffer += "Explanations are available on " + howto_url + "\n"

        if fatals > 0:
            print(output_header.rstrip() + "\n" + output_buffer)
            sys.exit(1)

    if len(output_buffer) > 0:
        print(output_header.rstrip() + "\n" + output_buffer)

if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt:
        pass

# vim: set shiftwidth=4 softtabstop=4 expandtab: