src/librarian/epub.py

   1 # -*- coding: utf-8 -*-
   2 #
   3 # This file is part of Librarian, licensed under GNU Affero GPLv3 or later.
   4 # Copyright © Fundacja Nowoczesna Polska. See NOTICE for more information.
   5 #
   6 from __future__ import print_function, unicode_literals
   7
   8 import os
   9 import os.path
  10 import re
  11 import subprocess
  12 import six
  13 from copy import deepcopy
  14 from mimetypes import guess_type
  15
  16 from ebooklib import epub
  17 from lxml import etree
  18 from tempfile import mkdtemp, NamedTemporaryFile
  19 from shutil import rmtree
  20
  21 from librarian import RDFNS, WLNS, DCNS, OutputFile
  22 from librarian.cover import make_cover
  23
  24 from librarian import functions, get_resource
  25
  26 from librarian.hyphenator import Hyphenator
  27
  28 functions.reg_person_name()
  29
  30
  31 def squeeze_whitespace(s):
  32     return re.sub(b'\\s+', b' ', s)
  33
  34
  35 def set_hyph_language(source_tree):
  36     bibl_lng = etree.XPath('//dc:language//text()',
  37                            namespaces={'dc': str(DCNS)})(source_tree)
  38     short_lng = functions.lang_code_3to2(bibl_lng[0])
  39     try:
  40         return Hyphenator(get_resource('res/hyph-dictionaries/hyph_' +
  41                                        short_lng + '.dic'))
  42     except:
  43         pass
  44
  45
  46 def hyphenate_and_fix_conjunctions(source_tree, hyph):
  47     texts = etree.XPath('/utwor/*[2]//text()')(source_tree)
  48     for t in texts:
  49         parent = t.getparent()
  50         if hyph is not None:
  51             newt = ''
  52             wlist = re.compile(r'\w+|[^\w]', re.UNICODE).findall(t)
  53             for w in wlist:
  54                 newt += hyph.inserted(w, u'\u00AD')
  55         else:
  56             newt = t
  57         newt = re.sub(r'(?<=\s\w)\s+', u'\u00A0', newt)
  58         if t.is_text:
  59             parent.text = newt
  60         elif t.is_tail:
  61             parent.tail = newt
  62
  63
  64 def inner_xml(node):
  65     """ returns node's text and children as a string
  66
  67     >>> print(inner_xml(etree.fromstring('<a>x<b>y</b>z</a>')))
  68     x<b>y</b>z
  69     """
  70
  71     nt = node.text if node.text is not None else ''
  72     return ''.join(
  73         [nt] + [etree.tostring(child, encoding='unicode') for child in node]
  74     )
  75
  76
  77 def set_inner_xml(node, text):
  78     """ sets node's text and children from a string
  79
  80     >>> e = etree.fromstring('<a>b<b>x</b>x</a>')
  81     >>> set_inner_xml(e, 'x<b>y</b>z')
  82     >>> print(etree.tostring(e, encoding='unicode'))
  83     <a>x<b>y</b>z</a>
  84     """
  85
  86     p = etree.fromstring('<x>%s</x>' % text)
  87     node.text = p.text
  88     node[:] = p[:]
  89
  90
  91 def node_name(node):
  92     """ Find out a node's name
  93
  94     >>> print(node_name(etree.fromstring('<a>X<b>Y</b>Z</a>')))
  95     XYZ
  96     """
  97
  98     tempnode = deepcopy(node)
  99
 100     for p in ('pe', 'pa', 'pt', 'pr', 'motyw'):
 101         for e in tempnode.findall('.//%s' % p):
 102             t = e.tail
 103             e.clear()
 104             e.tail = t
 105     etree.strip_tags(tempnode, '*')
 106     return tempnode.text
 107
 108
 109 def xslt(xml, sheet, **kwargs):
 110     if isinstance(xml, etree._Element):
 111         xml = etree.ElementTree(xml)
 112     with open(sheet) as xsltf:
 113         transform = etree.XSLT(etree.parse(xsltf))
 114         params = dict(
 115             (key, transform.strparam(value))
 116             for key, value in kwargs.items()
 117         )
 118         return transform(xml, **params)
 119
 120
 121 def replace_characters(node):
 122     def replace_chars(text):
 123         if text is None:
 124             return None
 125         return text.replace(u"\ufeff", u"")\
 126                    .replace("---", u"\u2014")\
 127                    .replace("--", u"\u2013")\
 128                    .replace(",,", u"\u201E")\
 129                    .replace('"', u"\u201D")\
 130                    .replace("'", u"\u2019")
 131     if node.tag in ('uwaga', 'extra'):
 132         t = node.tail
 133         node.clear()
 134         node.tail = t
 135     node.text = replace_chars(node.text)
 136     node.tail = replace_chars(node.tail)
 137     for child in node:
 138         replace_characters(child)
 139
 140
 141 def find_annotations(annotations, source, part_no):
 142     for child in source:
 143         if child.tag in ('pe', 'pa', 'pt', 'pr'):
 144             annotation = deepcopy(child)
 145             number = str(len(annotations) + 1)
 146             annotation.set('number', number)
 147             annotation.set('part', str(part_no))
 148             annotation.tail = ''
 149             annotations.append(annotation)
 150             tail = child.tail
 151             child.clear()
 152             child.tail = tail
 153             child.text = number
 154         if child.tag not in ('extra', 'uwaga'):
 155             find_annotations(annotations, child, part_no)
 156
 157
 158 class Stanza(object):
 159     """
 160     Converts / verse endings into verse elements in a stanza.
 161
 162     Slashes may only occur directly in the stanza. Any slashes in subelements
 163     will be ignored, and the subelements will be put inside verse elements.
 164
 165     >>> s = etree.fromstring(
 166     ...         "<strofa>a <b>c</b> <b>c</b>/\\nb<x>x/\\ny</x>c/ \\nd</strofa>"
 167     ...     )
 168     >>> Stanza(s).versify()
 169     >>> print(etree.tostring(s, encoding='unicode', pretty_print=True).strip())
 170     <strofa>
 171       <wers_normalny>a <b>c</b><b>c</b></wers_normalny>
 172       <wers_normalny>b<x>x/
 173     y</x>c</wers_normalny>
 174       <wers_normalny>d</wers_normalny>
 175     </strofa>
 176
 177     """
 178     def __init__(self, stanza_elem):
 179         self.stanza = stanza_elem
 180         self.verses = []
 181         self.open_verse = None
 182
 183     def versify(self):
 184         self.push_text(self.stanza.text)
 185         for elem in self.stanza:
 186             self.push_elem(elem)
 187             self.push_text(elem.tail)
 188         tail = self.stanza.tail
 189         self.stanza.clear()
 190         self.stanza.tail = tail
 191         self.stanza.extend(
 192             verse for verse in self.verses
 193             if verse.text or len(verse) > 0
 194         )
 195
 196     def open_normal_verse(self):
 197         self.open_verse = self.stanza.makeelement("wers_normalny")
 198         self.verses.append(self.open_verse)
 199
 200     def get_open_verse(self):
 201         if self.open_verse is None:
 202             self.open_normal_verse()
 203         return self.open_verse
 204
 205     def push_text(self, text):
 206         if not text:
 207             return
 208         for i, verse_text in enumerate(re.split(r"/\s*\n", text)):
 209             if i:
 210                 self.open_normal_verse()
 211             if not verse_text.strip():
 212                 continue
 213             verse = self.get_open_verse()
 214             if len(verse):
 215                 verse[-1].tail = (verse[-1].tail or "") + verse_text
 216             else:
 217                 verse.text = (verse.text or "") + verse_text
 218
 219     def push_elem(self, elem):
 220         if elem.tag.startswith("wers"):
 221             verse = deepcopy(elem)
 222             verse.tail = None
 223             self.verses.append(verse)
 224             self.open_verse = verse
 225         else:
 226             appended = deepcopy(elem)
 227             appended.tail = None
 228             self.get_open_verse().append(appended)
 229
 230
 231 def replace_by_verse(tree):
 232     """ Find stanzas and create new verses in place of a '/' character """
 233
 234     stanzas = tree.findall('.//' + WLNS('strofa'))
 235     for stanza in stanzas:
 236         Stanza(stanza).versify()
 237
 238
 239 def used_chars(element):
 240     """ Lists characters used in an ETree Element """
 241     chars = set((element.text or '') + (element.tail or ''))
 242     for child in element:
 243         chars = chars.union(used_chars(child))
 244     return chars
 245
 246
 247 def chop(main_text):
 248     """ divide main content of the XML file into chunks """
 249
 250     # prepare a container for each chunk
 251     part_xml = etree.Element('utwor')
 252     etree.SubElement(part_xml, 'master')
 253     main_xml_part = part_xml[0]  # master
 254
 255     last_node_part = False
 256
 257     # The below loop are workaround for a problem with epubs
 258     # in drama ebooks without acts.
 259     is_scene = False
 260     is_act = False
 261     for one_part in main_text:
 262         name = one_part.tag
 263         if name == 'naglowek_scena':
 264             is_scene = True
 265         elif name == 'naglowek_akt':
 266             is_act = True
 267
 268     for one_part in main_text:
 269         name = one_part.tag
 270         if is_act is False and is_scene is True:
 271             if name == 'naglowek_czesc':
 272                 yield part_xml
 273                 last_node_part = True
 274                 main_xml_part[:] = [deepcopy(one_part)]
 275             elif not last_node_part and name == "naglowek_scena":
 276                 yield part_xml
 277                 main_xml_part[:] = [deepcopy(one_part)]
 278             else:
 279                 main_xml_part.append(deepcopy(one_part))
 280                 last_node_part = False
 281         else:
 282             if name == 'naglowek_czesc':
 283                 yield part_xml
 284                 last_node_part = True
 285                 main_xml_part[:] = [deepcopy(one_part)]
 286             elif (not last_node_part
 287                   and name in (
 288                       "naglowek_rozdzial", "naglowek_akt", "srodtytul"
 289                   )):
 290                 yield part_xml
 291                 main_xml_part[:] = [deepcopy(one_part)]
 292             else:
 293                 main_xml_part.append(deepcopy(one_part))
 294                 last_node_part = False
 295     yield part_xml
 296
 297
 298 def transform_chunk(chunk_xml, chunk_no, annotations, empty=False,
 299                     _empty_html_static=[]):
 300     """
 301     Transforms one chunk, returns a HTML string, a TOC object
 302     and a set of used characters.
 303     """
 304
 305     toc = []
 306     for element in chunk_xml[0]:
 307         if element.tag == "naglowek_czesc":
 308             toc.append(
 309                 (
 310                     epub.Link(
 311                         "part%d.xhtml#book-text" % chunk_no,
 312                         node_name(element),
 313                         "part%d-text" % chunk_no
 314                     ),
 315                     []
 316                 )
 317             )
 318         elif element.tag in ("naglowek_rozdzial", "naglowek_akt", "srodtytul"):
 319             toc.append(
 320                 (
 321                     epub.Link(
 322                         "part%d.xhtml" % chunk_no,
 323                         node_name(element),
 324                         "part%d" % chunk_no
 325                     ),
 326                     []
 327                 )
 328             )
 329         elif element.tag in ('naglowek_podrozdzial', 'naglowek_scena'):
 330             subnumber = len(toc[-1][1])
 331             toc[-1][1].append(
 332                 epub.Link(
 333                     "part%d.xhtml#sub%d" % (chunk_no, subnumber),
 334                     node_name(element),
 335                     "part%d-sub%d" % (chunk_no, subnumber)
 336                 )
 337             )
 338             element.set('sub', six.text_type(subnumber))
 339     if empty:
 340         if not _empty_html_static:
 341             with open(get_resource('epub/emptyChunk.xhtml')) as f:
 342                 _empty_html_static.append(f.read())
 343         chars = set()
 344         output_html = _empty_html_static[0]
 345     else:
 346         find_annotations(annotations, chunk_xml, chunk_no)
 347         replace_by_verse(chunk_xml)
 348         html_tree = xslt(chunk_xml, get_resource('epub/xsltScheme.xsl'))
 349         chars = used_chars(html_tree.getroot())
 350         output_html = etree.tostring(
 351             html_tree, pretty_print=True, xml_declaration=True,
 352             encoding="utf-8",
 353             doctype='<!DOCTYPE html>'
 354         )
 355     return output_html, toc, chars
 356
 357
 358 def remove_empty_lists_from_toc(toc):
 359     for i, e in enumerate(toc):
 360         if isinstance(e, tuple):
 361             if e[1]:
 362                 remove_empty_lists_from_toc(e[1])
 363             else:
 364                 toc[i] = e[0]
 365
 366
 367 def transform(wldoc, verbose=False, style=None,
 368               sample=None, cover=None, flags=None, hyphenate=False,
 369               ilustr_path='', output_type='epub'):
 370     """ produces a EPUB file
 371
 372     sample=n: generate sample e-book (with at least n paragraphs)
 373     cover: a cover.Cover factory or True for default
 374     flags: less-advertising, without-fonts, working-copy
 375     """
 376
 377     def transform_file(wldoc, chunk_counter=1, first=True, sample=None):
 378         """ processes one input file and proceeds to its children """
 379
 380         replace_characters(wldoc.edoc.getroot())
 381
 382         hyphenator = set_hyph_language(
 383             wldoc.edoc.getroot()
 384         ) if hyphenate else None
 385         hyphenate_and_fix_conjunctions(wldoc.edoc.getroot(), hyphenator)
 386
 387         # every input file will have a TOC entry,
 388         # pointing to starting chunk
 389         toc = [
 390             (
 391                 epub.Link(
 392                     "part%d.xhtml" % chunk_counter,
 393                     wldoc.book_info.title,
 394                     "path%d-start" % chunk_counter
 395                 ),
 396                 []
 397             )
 398         ]
 399         chars = set()
 400         if first:
 401             # write book title page
 402             html_tree = xslt(wldoc.edoc, get_resource('epub/xsltTitle.xsl'),
 403                              outputtype=output_type)
 404             chars = used_chars(html_tree.getroot())
 405             html_string = etree.tostring(
 406                 html_tree, pretty_print=True, xml_declaration=True,
 407                 encoding="utf-8",
 408                 doctype='<!DOCTYPE html>'
 409             )
 410             item = epub.EpubItem(
 411                 uid="titlePage",
 412                 file_name="title.xhtml",
 413                 media_type="application/xhtml+xml",
 414                 content=squeeze_whitespace(html_string)
 415             )
 416             spine.append(item)
 417             output.add_item(item)
 418             # add a title page TOC entry
 419             toc[-1][1].append(
 420                 epub.Link(
 421                     "title.xhtml",
 422                     "Strona tytułowa",
 423                     "title",
 424                 )
 425             )
 426
 427             item = epub.EpubNav()
 428             toc[-1][1].append(
 429                 epub.Link(
 430                     "nav.xhtml",
 431                     "Spis treści",
 432                     "nav"
 433                 )
 434             )
 435             output.add_item(item)
 436             spine.append(item)
 437
 438         elif wldoc.book_info.parts:
 439             # write title page for every parent
 440             if sample is not None and sample <= 0:
 441                 chars = set()
 442                 html_string = open(
 443                     get_resource('epub/emptyChunk.xhtml')).read()
 444             else:
 445                 html_tree = xslt(wldoc.edoc,
 446                                  get_resource('epub/xsltChunkTitle.xsl'))
 447                 chars = used_chars(html_tree.getroot())
 448                 html_string = etree.tostring(
 449                     html_tree, pretty_print=True, xml_declaration=True,
 450                     encoding="utf-8",
 451                     doctype='<!DOCTYPE html>'
 452                 )
 453             item = epub.EpubItem(
 454                 uid="part%d" % chunk_counter,
 455                 file_name="part%d.xhtml" % chunk_counter,
 456                 media_type="application/xhtml+xml",
 457                 content=squeeze_whitespace(html_string)
 458             )
 459             output.add_item(item)
 460             spine.append(item)
 461
 462             chunk_counter += 1
 463
 464         if len(wldoc.edoc.getroot()) > 1:
 465             # rdf before style master
 466             main_text = wldoc.edoc.getroot()[1]
 467         else:
 468             # rdf in style master
 469             main_text = wldoc.edoc.getroot()[0]
 470             if main_text.tag == RDFNS('RDF'):
 471                 main_text = None
 472
 473         if main_text is not None:
 474             for chunk_xml in chop(main_text):
 475                 empty = False
 476                 if sample is not None:
 477                     if sample <= 0:
 478                         empty = True
 479                     else:
 480                         sample -= len(chunk_xml.xpath(
 481                             '//strofa|//akap|//akap_cd|//akap_dialog'
 482                         ))
 483                 chunk_html, chunk_toc, chunk_chars = transform_chunk(
 484                     chunk_xml, chunk_counter, annotations, empty)
 485
 486                 toc[-1][1].extend(chunk_toc)
 487                 chars = chars.union(chunk_chars)
 488                 item = epub.EpubItem(
 489                     uid="part%d" % chunk_counter,
 490                     file_name="part%d.xhtml" % chunk_counter,
 491                     media_type="application/xhtml+xml",
 492                     content=squeeze_whitespace(chunk_html)
 493                 )
 494                 output.add_item(item)
 495                 spine.append(item)
 496                 chunk_counter += 1
 497
 498         for child in wldoc.parts():
 499             child_toc, chunk_counter, chunk_chars, sample = transform_file(
 500                 child, chunk_counter, first=False, sample=sample)
 501             toc[-1][1].extend(child_toc)
 502             chars = chars.union(chunk_chars)
 503
 504         return toc, chunk_counter, chars, sample
 505
 506     document = deepcopy(wldoc)
 507     del wldoc
 508
 509     if flags:
 510         for flag in flags:
 511             document.edoc.getroot().set(flag, 'yes')
 512
 513     document.clean_ed_note()
 514     document.clean_ed_note('abstrakt')
 515
 516     # add editors info
 517     editors = document.editors()
 518     if editors:
 519         document.edoc.getroot().set('editors', u', '.join(sorted(
 520             editor.readable() for editor in editors)))
 521     if document.book_info.funders:
 522         document.edoc.getroot().set('funders', u', '.join(
 523             document.book_info.funders))
 524     if document.book_info.thanks:
 525         document.edoc.getroot().set('thanks', document.book_info.thanks)
 526
 527     output = epub.EpubBook()
 528     output.set_identifier(six.text_type(document.book_info.url))
 529     output.set_language(functions.lang_code_3to2(document.book_info.language))
 530     output.set_title(document.book_info.title)
 531     for author in document.book_info.authors:
 532         output.add_author(
 533             author.readable(),
 534             file_as=six.text_type(author)
 535         )
 536     for translator in document.book_info.translators:
 537         output.add_author(
 538             translator.readable(),
 539             file_as=six.text_type(translator),
 540             role='translator'
 541         )
 542     for publisher in document.book_info.publisher:
 543         output.add_metadata("DC", "publisher", publisher)
 544     output.add_metadata("DC", "date", document.book_info.created_at)
 545
 546     output.guide.append({
 547         "type": "text",
 548         "title": "Początek",
 549         "href": "part1.xhtml"
 550     })
 551
 552     output.add_item(epub.EpubNcx())
 553
 554     spine = output.spine
 555
 556     functions.reg_mathml_epub(zip)
 557
 558     if os.path.isdir(ilustr_path):
 559         ilustr_elements = set(ilustr.get('src')
 560                               for ilustr in document.edoc.findall('//ilustr'))
 561         for i, filename in enumerate(os.listdir(ilustr_path)):
 562             if filename not in ilustr_elements:
 563                 continue
 564             file_path = os.path.join(ilustr_path, filename)
 565             with open(file_path, 'rb') as f:
 566                 output.add_item(
 567                     epub.EpubItem(
 568                         uid='image%s' % i,
 569                         file_name=filename,
 570                         media_type=guess_type(file_path)[0],
 571                         content=f.read()
 572                     )
 573                 )
 574
 575     # write static elements
 576
 577     with open(get_resource('res/wl-logo-small.png'), 'rb') as f:
 578         output.add_item(
 579             epub.EpubItem(
 580                 uid="logo_wolnelektury.png",
 581                 file_name="logo_wolnelektury.png",
 582                 media_type="image/png",
 583                 content=f.read()
 584             )
 585         )
 586     with open(get_resource('res/jedenprocent.png'), 'rb') as f:
 587         output.add_item(
 588             epub.EpubItem(
 589                 uid="jedenprocent",
 590                 file_name="jedenprocent.png",
 591                 media_type="image/png",
 592                 content=f.read()
 593             )
 594         )
 595
 596     if not style:
 597         style = get_resource('epub/style.css')
 598     with open(style, 'rb') as f:
 599         output.add_item(
 600             epub.EpubItem(
 601                 uid="style",
 602                 file_name="style.css",
 603                 media_type="text/css",
 604                 content=f.read()
 605             )
 606         )
 607
 608     if cover:
 609         if cover is True:
 610             cover = make_cover
 611
 612         cover_file = six.BytesIO()
 613         bound_cover = cover(document.book_info)
 614         bound_cover.save(cover_file)
 615         cover_name = 'cover.%s' % bound_cover.ext()
 616
 617         output.set_cover(
 618             file_name=cover_name,
 619             content=cover_file.getvalue(),
 620         )
 621         spine.append('cover')
 622         output.guide.append({
 623             "type": "cover",
 624             "href": "cover.xhtml",
 625             "title": "Okładka",
 626         })
 627
 628         del cover_file
 629
 630         if bound_cover.uses_dc_cover:
 631             if document.book_info.cover_by:
 632                 document.edoc.getroot().set('data-cover-by',
 633                                             document.book_info.cover_by)
 634             if document.book_info.cover_source:
 635                 document.edoc.getroot().set('data-cover-source',
 636                                             document.book_info.cover_source)
 637
 638     annotations = etree.Element('annotations')
 639
 640     toc, chunk_counter, chars, sample = transform_file(document, sample=sample)
 641     output.toc = toc[0][1]
 642
 643     if len(toc) < 2:
 644         toc.append(
 645             epub.Link(
 646                 "part1.xhtml",
 647                 "Początek utworu",
 648                 "part1"
 649             )
 650         )
 651
 652     # Last modifications in container files and EPUB creation
 653     if len(annotations) > 0:
 654         toc.append(
 655             epub.Link(
 656                 "annotations.xhtml",
 657                 "Przypisy",
 658                 "annotations"
 659             )
 660         )
 661         replace_by_verse(annotations)
 662         html_tree = xslt(annotations, get_resource('epub/xsltAnnotations.xsl'))
 663         chars = chars.union(used_chars(html_tree.getroot()))
 664
 665         item = epub.EpubItem(
 666             uid="annotations",
 667             file_name="annotations.xhtml",
 668             media_type="application/xhtml+xml",
 669             content=etree.tostring(
 670                 html_tree, pretty_print=True, xml_declaration=True,
 671                 encoding="utf-8",
 672                 doctype='<!DOCTYPE html>'
 673             )
 674         )
 675         output.add_item(item)
 676         spine.append(item)
 677
 678     toc.append(
 679         epub.Link(
 680             "support.xhtml",
 681             "Wesprzyj Wolne Lektury",
 682             "support"
 683         )
 684     )
 685     with open(get_resource('epub/support.xhtml'), 'rb') as f:
 686         html_string = f.read()
 687     chars.update(used_chars(etree.fromstring(html_string)))
 688     item = epub.EpubItem(
 689         uid="support",
 690         file_name="support.xhtml",
 691         media_type="application/xhtml+xml",
 692         content=squeeze_whitespace(html_string)
 693     )
 694     output.add_item(item)
 695     spine.append(item)
 696
 697     toc.append(
 698         epub.Link(
 699             "last.xhtml",
 700             "Strona redakcyjna",
 701             "last"
 702         )
 703     )
 704     html_tree = xslt(document.edoc, get_resource('epub/xsltLast.xsl'),
 705                      outputtype=output_type)
 706     chars.update(used_chars(html_tree.getroot()))
 707     item = epub.EpubItem(
 708         uid="last",
 709         file_name="last.xhtml",
 710         media_type="application/xhtml+xml",
 711         content=squeeze_whitespace(etree.tostring(
 712             html_tree, pretty_print=True, xml_declaration=True,
 713             encoding="utf-8",
 714             doctype='<!DOCTYPE html>'
 715         ))
 716     )
 717     output.add_item(item)
 718     spine.append(item)
 719
 720     if not flags or 'without-fonts' not in flags:
 721         # strip fonts
 722         tmpdir = mkdtemp('-librarian-epub')
 723         try:
 724             cwd = os.getcwd()
 725         except OSError:
 726             cwd = None
 727
 728         os.chdir(os.path.join(os.path.dirname(os.path.realpath(__file__)),
 729                               'font-optimizer'))
 730         for fname in ('DejaVuSerif.ttf', 'DejaVuSerif-Bold.ttf',
 731                       'DejaVuSerif-Italic.ttf', 'DejaVuSerif-BoldItalic.ttf'):
 732             optimizer_call = ['perl', 'subset.pl', '--chars',
 733                               ''.join(chars).encode('utf-8'),
 734                               get_resource('fonts/' + fname),
 735                               os.path.join(tmpdir, fname)]
 736             env = {"PERL_USE_UNSAFE_INC": "1"}
 737             if verbose:
 738                 print("Running font-optimizer")
 739                 subprocess.check_call(optimizer_call, env=env)
 740             else:
 741                 dev_null = open(os.devnull, 'w')
 742                 subprocess.check_call(optimizer_call, stdout=dev_null,
 743                                       stderr=dev_null, env=env)
 744             with open(os.path.join(tmpdir, fname), 'rb') as f:
 745                 output.add_item(
 746                     epub.EpubItem(
 747                         uid=fname,
 748                         file_name=fname,
 749                         media_type="font/ttf",
 750                         content=f.read()
 751                     )
 752                 )
 753         rmtree(tmpdir)
 754         if cwd is not None:
 755             os.chdir(cwd)
 756
 757     remove_empty_lists_from_toc(output.toc)
 758
 759     output_file = NamedTemporaryFile(prefix='librarian', suffix='.epub',
 760                                      delete=False)
 761     output_file.close()
 762     epub.write_epub(output_file.name, output, {'epub3_landmark': False})
 763     return OutputFile.from_filename(output_file.name)