160 lines
4.2 KiB
Python
160 lines
4.2 KiB
Python
# encoding: utf-8
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"""
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Provides a general interface to a *physical* OPC package, such as a zip file.
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"""
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from __future__ import absolute_import
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import os
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from zipfile import ZipFile, is_zipfile, ZIP_DEFLATED
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from ..compat import is_string
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from ..exceptions import PackageNotFoundError
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from .packuri import CONTENT_TYPES_URI
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class PhysPkgReader(object):
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"""
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Factory for physical package reader objects.
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"""
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def __new__(cls, pkg_file):
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# if *pkg_file* is a string, treat it as a path
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if is_string(pkg_file):
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if os.path.isdir(pkg_file):
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reader_cls = _DirPkgReader
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elif is_zipfile(pkg_file):
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reader_cls = _ZipPkgReader
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else:
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raise PackageNotFoundError("Package not found at '%s'" % pkg_file)
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else: # assume it's a stream and pass it to Zip reader to sort out
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reader_cls = _ZipPkgReader
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return super(PhysPkgReader, cls).__new__(reader_cls)
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class PhysPkgWriter(object):
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"""
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Factory for physical package writer objects.
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"""
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def __new__(cls, pkg_file):
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return super(PhysPkgWriter, cls).__new__(_ZipPkgWriter)
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class _DirPkgReader(PhysPkgReader):
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"""
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Implements |PhysPkgReader| interface for an OPC package extracted into a
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directory.
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"""
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def __init__(self, path):
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"""
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*path* is the path to a directory containing an expanded package.
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"""
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super(_DirPkgReader, self).__init__()
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self._path = os.path.abspath(path)
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def blob_for(self, pack_uri):
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"""
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Return contents of file corresponding to *pack_uri* in package
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directory.
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"""
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path = os.path.join(self._path, pack_uri.membername)
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with open(path, "rb") as f:
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blob = f.read()
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return blob
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def close(self):
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"""
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Provides interface consistency with |ZipFileSystem|, but does
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nothing, a directory file system doesn't need closing.
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"""
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pass
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@property
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def content_types_xml(self):
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"""
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Return the `[Content_Types].xml` blob from the package.
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"""
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return self.blob_for(CONTENT_TYPES_URI)
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def rels_xml_for(self, source_uri):
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"""
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Return rels item XML for source with *source_uri*, or None if the
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item has no rels item.
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"""
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try:
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rels_xml = self.blob_for(source_uri.rels_uri)
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except IOError:
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rels_xml = None
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return rels_xml
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class _ZipPkgReader(PhysPkgReader):
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"""
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Implements |PhysPkgReader| interface for a zip file OPC package.
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"""
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def __init__(self, pkg_file):
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super(_ZipPkgReader, self).__init__()
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self._zipf = ZipFile(pkg_file, "r")
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def blob_for(self, pack_uri):
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"""
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Return blob corresponding to *pack_uri*. Raises |ValueError| if no
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matching member is present in zip archive.
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"""
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return self._zipf.read(pack_uri.membername)
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def close(self):
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"""
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Close the zip archive, releasing any resources it is using.
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"""
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self._zipf.close()
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@property
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def content_types_xml(self):
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"""
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Return the `[Content_Types].xml` blob from the zip package.
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"""
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return self.blob_for(CONTENT_TYPES_URI)
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def rels_xml_for(self, source_uri):
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"""
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Return rels item XML for source with *source_uri* or None if no rels
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item is present.
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"""
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try:
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rels_xml = self.blob_for(source_uri.rels_uri)
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except KeyError:
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rels_xml = None
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return rels_xml
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class _ZipPkgWriter(PhysPkgWriter):
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"""
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Implements |PhysPkgWriter| interface for a zip file OPC package.
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"""
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def __init__(self, pkg_file):
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super(_ZipPkgWriter, self).__init__()
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self._zipf = ZipFile(pkg_file, "w", compression=ZIP_DEFLATED)
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def close(self):
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"""
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Close the zip archive, flushing any pending physical writes and
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releasing any resources it's using.
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"""
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self._zipf.close()
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def write(self, pack_uri, blob):
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"""
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Write *blob* to this zip package with the membername corresponding to
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*pack_uri*.
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"""
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self._zipf.writestr(pack_uri.membername, blob)
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