Update ReadZipFS.openbin handler to use native Python zipfile code

CHANGELOG.md

@@ -12,6 +12,11 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Replaced `appdirs` with `platformdirs` dependency 
  ([#489](https://github.com/PyFilesystem/pyfilesystem2/pull/489)).
+- Make `fs.zipfs._ZipExtFile` use the seeking mechanism implemented
+ in the Python standard library in Python version 3.7 and later
+ ([#527](https://github.com/PyFilesystem/pyfilesystem2/pull/527)).
+- Mark `fs.zipfs.ReadZipFS` as a case-sensitive filesystem
+ ([#527](https://github.com/PyFilesystem/pyfilesystem2/pull/527)). 
 
 
 ## [2.4.15] - 2022-02-07

fs/zipfs.py

@@ -4,6 +4,7 @@
 from __future__ import print_function
 from __future__ import unicode_literals
 
+import sys
 import typing
 import zipfile
 from datetime import datetime
@@ -51,74 +52,126 @@ def __init__(self, fs, name): # noqa: D107
  self._pos = 0
  super(_ZipExtFile, self).__init__(_zip.open(name), "r", name)
 
- def read(self, size=-1):
- # type: (int) -> bytes
- buf = self._f.read(-1 if size is None else size)
- self._pos += len(buf)
- return buf
-
- def read1(self, size=-1):
- # type: (int) -> bytes
- buf = self._f.read1(-1 if size is None else size) # type: ignore
- self._pos += len(buf)
- return buf
-
- def seek(self, offset, whence=Seek.set):
- # type: (int, SupportsInt) -> int
- """Change stream position.
-
- Change the stream position to the given byte offset. The
- offset is interpreted relative to the position indicated by
- ``whence``.
-
- Arguments:
- offset (int): the offset to the new position, in bytes.
- whence (int): the position reference. Possible values are:
- * `Seek.set`: start of stream (the default).
- * `Seek.current`: current position; offset may be negative.
- * `Seek.end`: end of stream; offset must be negative.
-
- Returns:
- int: the new absolute position.
-
- Raises:
- ValueError: when ``whence`` is not known, or ``offset``
- is invalid.
-
- Note:
- Zip compression does not support seeking, so the seeking
- is emulated. Seeking somewhere else than the current position
- will need to either:
- * reopen the file and restart decompression
- * read and discard data to advance in the file
-
- """
- _whence = int(whence)
- if _whence == Seek.current:
- offset += self._pos
- if _whence == Seek.current or _whence == Seek.set:
- if offset < 0:
- raise ValueError("Negative seek position {}".format(offset))
- elif _whence == Seek.end:
- if offset > 0:
- raise ValueError("Positive seek position {}".format(offset))
- offset += self._end
- else:
- raise ValueError(
- "Invalid whence ({}, should be {}, {} or {})".format(
- _whence, Seek.set, Seek.current, Seek.end
+ # NOTE(@althonos): Starting from Python 3.7, files inside a Zip archive are
+ # seekable provided they were opened from a seekable file
+ # handle. Before that, we can emulate a seek using the
+ # read method, although it adds a ton of overhead and is
+ # way less efficient than extracting once to a BytesIO.
+ if sys.version_info < (3, 7):
+
+ def read(self, size=-1):
+ # type: (int) -> bytes
+ buf = self._f.read(-1 if size is None else size)
+ self._pos += len(buf)
+ return buf
+
+ def read1(self, size=-1):
+ # type: (int) -> bytes
+ buf = self._f.read1(-1 if size is None else size) # type: ignore
+ self._pos += len(buf)
+ return buf
+
+ def tell(self):
+ # type: () -> int
+ return self._pos
+
+ def seekable(self):
+ return True
+
+ def seek(self, offset, whence=Seek.set):
+ # type: (int, SupportsInt) -> int
+ """Change stream position.
+
+ Change the stream position to the given byte offset. The
+ offset is interpreted relative to the position indicated by
+ ``whence``.
+
+ Arguments:
+ offset (int): the offset to the new position, in bytes.
+ whence (int): the position reference. Possible values are:
+ * `Seek.set`: start of stream (the default).
+ * `Seek.current`: current position; offset may be negative.
+ * `Seek.end`: end of stream; offset must be negative.
+
+ Returns:
+ int: the new absolute position.
+
+ Raises:
+ ValueError: when ``whence`` is not known, or ``offset``
+ is invalid.
+
+ Note:
+ Zip compression does not support seeking, so the seeking
+ is emulated. Seeking somewhere else than the current position
+ will need to either:
+ * reopen the file and restart decompression
+ * read and discard data to advance in the file
+
+ """
+ _whence = int(whence)
+ if _whence == Seek.current:
+ offset += self._pos
+ if _whence == Seek.current or _whence == Seek.set:
+ if offset < 0:
+ raise ValueError("Negative seek position {}".format(offset))
+ elif _whence == Seek.end:
+ if offset > 0:
+ raise ValueError("Positive seek position {}".format(offset))
+ offset += self._end
+ else:
+ raise ValueError(
+ "Invalid whence ({}, should be {}, {} or {})".format(
+ _whence, Seek.set, Seek.current, Seek.end
+ )
  )
- )
 
- if offset < self._pos:
- self._f = self._zip.open(self.name) # type: ignore
- self._pos = 0
- self.read(offset - self._pos)
- return self._pos
+ if offset < self._pos:
+ self._f = self._zip.open(self.name) # type: ignore
+ self._pos = 0
+ self.read(offset - self._pos)
+ return self._pos
+
+ else:
+
+ def seek(self, offset, whence=Seek.set):
+ # type: (int, SupportsInt) -> int
+ """Change stream position.
+
+ Change the stream position to the given byte offset. The
+ offset is interpreted relative to the position indicated by
+ ``whence``.
+
+ Arguments:
+ offset (int): the offset to the new position, in bytes.
+ whence (int): the position reference. Possible values are:
+ * `Seek.set`: start of stream (the default).
+ * `Seek.current`: current position; offset may be negative.
+ * `Seek.end`: end of stream; offset must be negative.
+
+ Returns:
+ int: the new absolute position.
+
+ Raises:
+ ValueError: when ``whence`` is not known, or ``offset``
+ is invalid.
+
+ """
+ _whence = int(whence)
+ _pos = self.tell()
+ if _whence == Seek.current or _whence == Seek.set:
+ if _pos + offset < 0:
+ raise ValueError("Negative seek position {}".format(offset))
+ elif _whence == Seek.end:
+ if _pos + offset > 0:
+ raise ValueError("Positive seek position {}".format(offset))
+ else:
+ raise ValueError(
+ "Invalid whence ({}, should be {}, {} or {})".format(
+ _whence, Seek.set, Seek.current, Seek.end
+ )
+ )
 
- def tell(self):
- # type: () -> int
- return self._pos
+ return self._f.seek(offset, _whence)
 
 
 class ZipFS(WrapFS):
@@ -279,7 +332,7 @@ class ReadZipFS(FS):
  """A readable zip file."""
 
  _meta = {
- "case_insensitive": True,
+ "case_insensitive": False,
  "network": False,
  "read_only": True,
  "supports_rename": False,