Update 7zip wrapper code for removal of read method

src/calibre/utils/seven_zip.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python
 # License: GPL v3 Copyright: 2021, Kovid Goyal <kovid at kovidgoyal.net>
 
+import io
 import os
 import re
 
@@ -17,6 +18,27 @@ def names(path_or_stream):
         return tuple(zf.getnames())
 
 
+class Writer:
+
+    def __init__(self):
+        self.outputs = {}
+
+    def create(self, filename):
+        b = self.outputs[filename] = io.BytesIO()
+        return b
+
+    def asdatadict(self):
+        return {k: v.getvalue() for k, v in self.outputs.items()}
+
+
+def read_file(archive, name):
+    w = Writer()
+    archive.extract(targets=[name], factory=w)
+    for v in w.outputs.values():
+        return v.getvalue()
+    raise KeyError(f'No file named {name} in archive')
+
+
 def extract_member(path_or_stream, match=None, name=None):
     if iswindows and name is not None:
         name = name.replace(os.sep, '/')
@@ -32,7 +54,7 @@ def extract_member(path_or_stream, match=None, name=None):
     with open_archive(path_or_stream) as ar:
         all_names = list(filter(is_match, ar.getnames()))
         if all_names:
-            return all_names[0], ar.read(all_names[:1])[all_names[0]].read()
+            return all_names[0], read_file(ar, all_names[0])
 
 
 def extract_cover_image(stream):
@@ -79,15 +101,21 @@ def test_basic():
         with open_archive(os.path.join('a.7z')) as zf:
             if set(zf.getnames()) != set(tdata):
                 raise ValueError('names not equal')
-            read_data = {name:af.read() for name, af in zf.readall().items()}
+            w = Writer()
+            zf.extractall(factory=w)
+            read_data = w.asdatadict()
             if read_data != tdata:
                 raise ValueError('data not equal')
 
+        os.mkdir('ex')
+        extract('a.7z', 'ex')
         for name in tdata:
             if name not in '1 2 symlink'.split():
-                with open(os.path.join(tdir, name), 'rb') as s:
+                with open(os.path.join(tdir, 'ex', name), 'rb') as s:
                     if s.read() != tdata[name]:
                         raise ValueError(f'Did not extract {name} properly')
+        if extract_member('a.7z', name='one.txt')[1] != tdata['one.txt']:
+            raise ValueError('extract_member failed')
 
     with TemporaryDirectory('test-7z') as tdir, CurrentDir(tdir):
         do_test()