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1#!/usr/bin/env python
2# Copyright 2014 The PDFium Authors. All rights reserved.
3# Use of this source code is governed by a BSD-style license that can be
4# found in the LICENSE file.
5"""Expands a hand-written PDF testcase (template) into a valid PDF file.
6
7There are several places in a PDF file where byte-offsets are required. This
8script replaces {{name}}-style variables in the input with calculated results
9
10  {{include path/to/file}} - inserts file's contents into stream.
11  {{header}} - expands to the header comment required for PDF files.
12  {{xref}} - expands to a generated xref table, noting the offset.
13  {{trailer}} - expands to a standard trailer with "1 0 R" as the /Root.
14  {{startxref} - expands to a startxref directive followed by correct offset.
15  {{object x y}} - expands to |x y obj| declaration, noting the offset.
16  {{streamlen}} - expands to |/Length n|.
17"""
18
19import cStringIO
20import optparse
21import os
22import re
23import sys
24
25
26class StreamLenState:
27  START = 1
28  FIND_STREAM = 2
29  FIND_ENDSTREAM = 3
30
31
32class TemplateProcessor:
33  HEADER_TOKEN = '{{header}}'
34  HEADER_REPLACEMENT = '%PDF-1.7\n%\xa0\xf2\xa4\xf4'
35
36  XREF_TOKEN = '{{xref}}'
37  XREF_REPLACEMENT = 'xref\n%d %d\n'
38
39  XREF_REPLACEMENT_N = '%010d %05d n \n'
40  XREF_REPLACEMENT_F = '0000000000 65535 f \n'
41  # XREF rows must be exactly 20 bytes - space required.
42  assert len(XREF_REPLACEMENT_F) == 20
43
44  TRAILER_TOKEN = '{{trailer}}'
45  TRAILER_REPLACEMENT = 'trailer <<\n  /Root 1 0 R\n  /Size %d\n>>'
46
47  STARTXREF_TOKEN = '{{startxref}}'
48  STARTXREF_REPLACEMENT = 'startxref\n%d'
49
50  OBJECT_PATTERN = r'\{\{object\s+(\d+)\s+(\d+)\}\}'
51  OBJECT_REPLACEMENT = r'\1 \2 obj'
52
53  STREAMLEN_TOKEN = '{{streamlen}}'
54  STREAMLEN_REPLACEMENT = '/Length %d'
55
56  def __init__(self):
57    self.streamlen_state = StreamLenState.START
58    self.streamlens = []
59    self.offset = 0
60    self.xref_offset = 0
61    self.max_object_number = 0
62    self.objects = {}
63
64  def insert_xref_entry(self, object_number, generation_number):
65    self.objects[object_number] = (self.offset, generation_number)
66    self.max_object_number = max(self.max_object_number, object_number)
67
68  def generate_xref_table(self):
69    result = self.XREF_REPLACEMENT % (0, self.max_object_number + 1)
70    for i in range(0, self.max_object_number + 1):
71      if i in self.objects:
72        result += self.XREF_REPLACEMENT_N % self.objects[i]
73      else:
74        result += self.XREF_REPLACEMENT_F
75    return result
76
77  def preprocess_line(self, line):
78    if self.STREAMLEN_TOKEN in line:
79      assert self.streamlen_state == StreamLenState.START
80      self.streamlen_state = StreamLenState.FIND_STREAM
81      self.streamlens.append(0)
82      return
83
84    if (self.streamlen_state == StreamLenState.FIND_STREAM and
85        line.rstrip() == 'stream'):
86      self.streamlen_state = StreamLenState.FIND_ENDSTREAM
87      return
88
89    if self.streamlen_state == StreamLenState.FIND_ENDSTREAM:
90      if line.rstrip() == 'endstream':
91        self.streamlen_state = StreamLenState.START
92      else:
93        self.streamlens[-1] += len(line)
94
95  def process_line(self, line):
96    if self.HEADER_TOKEN in line:
97      line = line.replace(self.HEADER_TOKEN, self.HEADER_REPLACEMENT)
98    if self.STREAMLEN_TOKEN in line:
99      sub = self.STREAMLEN_REPLACEMENT % self.streamlens.pop(0)
100      line = re.sub(self.STREAMLEN_TOKEN, sub, line)
101    if self.XREF_TOKEN in line:
102      self.xref_offset = self.offset
103      line = self.generate_xref_table()
104    if self.TRAILER_TOKEN in line:
105      replacement = self.TRAILER_REPLACEMENT % (self.max_object_number + 1)
106      line = line.replace(self.TRAILER_TOKEN, replacement)
107    if self.STARTXREF_TOKEN in line:
108      replacement = self.STARTXREF_REPLACEMENT % self.xref_offset
109      line = line.replace(self.STARTXREF_TOKEN, replacement)
110    match = re.match(self.OBJECT_PATTERN, line)
111    if match:
112      self.insert_xref_entry(int(match.group(1)), int(match.group(2)))
113      line = re.sub(self.OBJECT_PATTERN, self.OBJECT_REPLACEMENT, line)
114    self.offset += len(line)
115    return line
116
117
118def expand_file(infile, output_path):
119  processor = TemplateProcessor()
120  try:
121    with open(output_path, 'wb') as outfile:
122      preprocessed = cStringIO.StringIO()
123      for line in infile:
124        preprocessed.write(line)
125        processor.preprocess_line(line)
126      preprocessed.seek(0)
127      for line in preprocessed:
128        outfile.write(processor.process_line(line))
129  except IOError:
130    print >> sys.stderr, 'failed to process %s' % input_path
131
132
133def insert_includes(input_path, output_file, visited_set):
134  input_path = os.path.normpath(input_path)
135  if input_path in visited_set:
136    print >> sys.stderr, 'Circular inclusion %s, ignoring' % input_path
137    return
138  visited_set.add(input_path)
139  try:
140    with open(input_path, 'rb') as infile:
141      for line in infile:
142        match = re.match(r'\s*\{\{include\s+(.+)\}\}', line)
143        if match:
144          insert_includes(
145              os.path.join(os.path.dirname(input_path), match.group(1)),
146              output_file, visited_set)
147        else:
148          output_file.write(line)
149  except IOError:
150    print >> sys.stderr, 'failed to include %s' % input_path
151    raise
152  visited_set.discard(input_path)
153
154
155def main():
156  parser = optparse.OptionParser()
157  parser.add_option('--output-dir', default='')
158  options, args = parser.parse_args()
159  for testcase_path in args:
160    testcase_filename = os.path.basename(testcase_path)
161    testcase_root, _ = os.path.splitext(testcase_filename)
162    output_dir = os.path.dirname(testcase_path)
163    if options.output_dir:
164      output_dir = options.output_dir
165    intermediate_stream = cStringIO.StringIO()
166    insert_includes(testcase_path, intermediate_stream, set())
167    intermediate_stream.seek(0)
168    output_path = os.path.join(output_dir, testcase_root + '.pdf')
169    expand_file(intermediate_stream, output_path)
170  return 0
171
172
173if __name__ == '__main__':
174  sys.exit(main())
175