Implement Embedding To Make Signatures Always Available

Situation..

PySide works fine with normal applications. But when installers
are used to pack the application together, then the signature
extension cannot be loaded.

This is a problem that exists since the signature extension was
written. But starting with PySide 5.12.1, the signature extension
is very visible, because it is used to support the __doc__ attribute.

There have beed successful attempts to solve the problem for
PyInstaller and Py2App. But there are more packers available,
and they all need a change both in PySide and in the packer.

Solution..

To solve this problem once and for all, we embed the Python
support files in the binary shiboken package. When the Python
files are not normally accessible, they are unpacked from a ZIP
file.

Details..

- The embedded files shall only be used when the normal files
  are not available,

- The signature extension should no longer be lazily loaded.
  When the application starts, all files should be present.

- We drop support for shiboken2.support.signature and
  use a single, independen folder 'shibokensupport' (proposal).
  This avoids problems with multiple existence of the shiboken2
  folder. PySide2.support.signature remains the official interface,
  but it's only an alias when PySide2 exists.

- The embedding is used when the normal files cannot be
  loaded for some reason. It can be enforced by a sys variable
  "pyside_uses_embedding".

- Testcase is included.

- Tested with PyInstaller on macOS

Fixes: PYSIDE-932
Fixes: PYSIDE-942
Change-Id: Iaa62dc0623503a2e0943eedd10d2b2484c65cc2d
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 241 insertions, 0 deletions

diff --git a/sources/shiboken2/libshiboken/embed/embedding_generator.py b/sources/shiboken2/libshiboken/embed/embedding_generator.py
new file mode 100644
index 000000000..3ee96a1a5
--- /dev/null
+++ b/sources/shiboken2/libshiboken/embed/embedding_generator.py
@@ -0,0 +1,241 @@
+#############################################################################
+##
+## Copyright (C) 2019 The Qt Company Ltd.
+## Contact: https://www.qt.io/licensing/
+##
+## This file is part of PySide2.
+##
+## $QT_BEGIN_LICENSE:LGPL$
+## Commercial License Usage
+## Licensees holding valid commercial Qt licenses may use this file in
+## accordance with the commercial license agreement provided with the
+## Software or, alternatively, in accordance with the terms contained in
+## a written agreement between you and The Qt Company. For licensing terms
+## and conditions see https://www.qt.io/terms-conditions. For further
+## information use the contact form at https://www.qt.io/contact-us.
+##
+## GNU Lesser General Public License Usage
+## Alternatively, this file may be used under the terms of the GNU Lesser
+## General Public License version 3 as published by the Free Software
+## Foundation and appearing in the file LICENSE.LGPL3 included in the
+## packaging of this file. Please review the following information to
+## ensure the GNU Lesser General Public License version 3 requirements
+## will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+##
+## GNU General Public License Usage
+## Alternatively, this file may be used under the terms of the GNU
+## General Public License version 2.0 or (at your option) the GNU General
+## Public license version 3 or any later version approved by the KDE Free
+## Qt Foundation. The licenses are as published by the Free Software
+## Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+## included in the packaging of this file. Please review the following
+## information to ensure the GNU General Public License requirements will
+## be met: https://www.gnu.org/licenses/gpl-2.0.html and
+## https://www.gnu.org/licenses/gpl-3.0.html.
+##
+## $QT_END_LICENSE$
+##
+#############################################################################
+
+"""
+embedding_generator.py
+
+This file takes the content of the two supported directories and inserts
+it into a zip file. The zip file is then converted into a C++ source
+file that can easily be unpacked again with Python (see signature.cpp,
+constant 'PySide_PythonCode').
+
+Note that this _is_ a zipfile, but since it is embedded into the shiboken
+binary, we cannot use the zipimport module from Python.
+But a similar solution is possible that allows for normal imports.
+
+See signature_bootstrap.py for details.
+"""
+
+from __future__ import print_function, absolute_import
+
+import sys
+import os
+import subprocess
+import textwrap
+import tempfile
+import argparse
+import marshal
+import traceback
+
+# work_dir is set to the source for testing, onl.
+# It can be overridden in the command line.
+work_dir = os.path.abspath(os.path.dirname(__file__))
+embed_dir = work_dir
+cur_dir = os.getcwd()
+source_dir = os.path.normpath(os.path.join(work_dir, "..", "..", ".."))
+assert os.path.basename(source_dir) == "sources"
+build_script_dir = os.path.normpath(os.path.join(work_dir, "..", "..", "..", ".."))
+assert os.path.exists(os.path.join(build_script_dir, "build_scripts"))
+
+sys.path.insert(0, build_script_dir)
+
+from build_scripts import utils
+
+
+def runpy(cmd, **kw):
+    subprocess.call([sys.executable, '-E'] + cmd.split(), **kw)
+
+
+def create_zipfile(limited_api):
+    """
+    Collect all Python files, compile them, create a zip file
+    and make a chunked base64 encoded file from it.
+    """
+    zip_name = "signature.zip"
+    inc_name = "signature.inc"
+    flag = '-b' if sys.version_info >= (3,) else ''
+    os.chdir(work_dir)
+
+    # Limited API: Remove all left-over py[co] files first, in case we use '--reuse-build'.
+    # Note that we could improve that with the PyZipfile function to use .pyc files
+    # in different folders, but that makes only sense when COIN allows us to have
+    # multiple Python versions in parallel.
+    from os.path import join, getsize
+    for root, dirs, files in os.walk(work_dir):
+        for name in files:
+            fpath = os.path.join(root, name)
+            if name.endswith(".pyc") or name.endswith(".pyo"):
+                os.remove(fpath)
+
+    # We copy every Python file into this dir, but only for the right version.
+    # For testing in the source dir, we need to filter.
+    if sys.version_info[0] == 3:
+        ignore = "backport_inspect.py typing27.py".split()
+    else:
+        ignore = "".split()
+    utils.copydir(os.path.join(source_dir, "shiboken2", "shibokenmodule", "files.dir", "shibokensupport"),
+                  os.path.join(work_dir, "shibokensupport"),
+                  ignore=ignore, file_filter_function=lambda name, n2: name.endswith(".py"))
+    if embed_dir != work_dir:
+        utils.copyfile(os.path.join(embed_dir, "signature_bootstrap.py"), work_dir)
+
+    if limited_api:
+        pass   # We cannot compile, unless we have folders per Python version
+    else:
+        files = ' '.join(fn for fn in os.listdir('.'))
+        runpy('-m compileall -q {flag} {files}'.format(**locals()))
+    files = ' '.join(fn for fn in os.listdir('.') if not fn == zip_name)
+    runpy('-m zipfile -c {zip_name} {files}'.format(**locals()))
+    tmp = tempfile.TemporaryFile(mode="w+")
+    runpy('-m base64 {zip_name}'.format(**locals()), stdout=tmp)
+    # now generate the include file
+    tmp.seek(0)
+    with open(inc_name, "w") as inc:
+        _embed_file(tmp, inc)
+    # also generate a simple embeddable .pyc file for signature_bootstrap.pyc
+    boot_name = "signature_bootstrap.py" if limited_api else "signature_bootstrap.pyc"
+    with open(boot_name, "rb") as ldr, open("signature_bootstrap.inc", "w") as inc:
+        _embed_bytefile(ldr, inc, limited_api)
+    os.chdir(cur_dir)
+
+
+def _embed_file(fin, fout):
+    """
+    Format a text file for embedding in a C++ source file.
+    """
+    # MSVC has a 64k string limitation. In C, it would be easy to create an
+    # array of 64 byte strings and use them as one big array. In C++ this does
+    # not work, since C++ insists in having the terminating nullbyte.
+    # Therefore, we split the string after an arbitrary number of lines
+    # (chunked file).
+    limit = 50
+    text = fin.readlines()
+    print(textwrap.dedent("""
+        /*
+         * This is a ZIP archive of all Python files in the directory
+         *         "shiboken2/shibokenmodule/files.dir/shibokensupport/signature"
+         * There is also a toplevel file "signature_bootstrap.py[c]" that will be
+         * directly executed from C++ as a bootstrap loader.
+         */
+         """).strip(), file=fout)
+    block, blocks = 0, len(text) // limit + 1
+    for idx, line in enumerate(text):
+        if idx % limit == 0:
+            comma = "," if block else ""
+            block += 1
+            print(file=fout)
+            print('/* Block {block} of {blocks} */{comma}'.format(**locals()), file=fout)
+        print('\"{}\"'.format(line.strip()), file=fout)
+    print('/* Sentinel */, \"\"', file=fout)
+
+
+def _embed_bytefile(fin, fout, is_text):
+    """
+    Format a binary file for embedding in a C++ source file.
+    This version works directly with a single .pyc file.
+    """
+    fname = fin.name
+    remark = ("No .pyc file because '--LIMITED-API=yes'" if is_text else
+              "The .pyc header is stripped away")
+    print(textwrap.dedent("""
+        /*
+         * This is the file "{fname}" as a simple byte array.
+         * It can be directly embedded without any further processing.
+         * {remark}.
+         */
+         """).format(**locals()).strip(), file=fout)
+    headsize = ( 0 if is_text else
+                16 if sys.version_info >= (3, 7) else 12 if sys.version_info >= (3, 3) else 8)
+    binstr = fin.read()[headsize:]
+    if is_text:
+        try:
+            compile(binstr, fin.name, "exec")
+        except SyntaxError as e:
+            print(e)
+            traceback.print_exc(file=sys.stdout)
+            print(textwrap.dedent("""
+                *************************************************************************
+                ***
+                *** Could not compile the boot loader '{fname}'!
+                ***
+                *************************************************************************
+                """).format(version=sys.version_info[:3], **locals()))
+            raise SystemError
+    else:
+        try:
+            marshal.loads(binstr)
+        except ValueError as e:
+            print(e)
+            traceback.print_exc(file=sys.stdout)
+            print(textwrap.dedent("""
+                *************************************************************************
+                ***
+                *** This Python version {version} seems to have a new .pyc header size.
+                *** Please correct the 'headsize' constant ({headsize}).
+                ***
+                *************************************************************************
+                """).format(version=sys.version_info[:3], **locals()))
+            raise SystemError
+
+    print(file=fout)
+    use_ord = sys.version_info[0] == 2
+    for i in range(0, len(binstr), 16):
+        for c in bytes(binstr[i : i + 16]):
+            print("{:#4},".format(ord(c) if use_ord else c), file=fout, end="")
+        print(file=fout)
+    print("/* End Of File */", file=fout)
+
+
+def str2bool(v):
+    if v.lower() in ('yes', 'true', 't', 'y', '1'):
+        return True
+    elif v.lower() in ('no', 'false', 'f', 'n', '0'):
+        return False
+    else:
+        raise argparse.ArgumentTypeError('Boolean value expected.')
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--cmake-dir', nargs="?")
+    parser.add_argument('--limited-api', type=str2bool)
+    args = parser.parse_args()
+    if args.cmake_dir:
+        work_dir = os.path.abspath(args.cmake_dir)
+    create_zipfile(args.limited_api)