Issue #26293: Fixed writing ZIP files that starts not from the start of the

file.  Offsets in ZIP file now are relative to the start of the archive in
conforming to the specification.

diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index d278e06a453be3afd2a4a26e431170fb45ef7b60..d18a77017fa8081f6c5f99a8ac27b965edc5dd82 100644 (file)
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -415,6 +415,49 @@ class StoredTestsWithSourceFile(AbstractTestsWithSourceFile,
             f.seek(len(data))
             with zipfile.ZipFile(f, "r") as zipfp:
                 self.assertEqual(zipfp.namelist(), [TESTFN])
+                self.assertEqual(zipfp.read(TESTFN), self.data)
+        with open(TESTFN2, 'rb') as f:
+            self.assertEqual(f.read(len(data)), data)
+            zipfiledata = f.read()
+        with io.BytesIO(zipfiledata) as bio, zipfile.ZipFile(bio) as zipfp:
+            self.assertEqual(zipfp.namelist(), [TESTFN])
+            self.assertEqual(zipfp.read(TESTFN), self.data)
+
+    def test_read_concatenated_zip_file(self):
+        with io.BytesIO() as bio:
+            with zipfile.ZipFile(bio, 'w', zipfile.ZIP_STORED) as zipfp:
+                zipfp.write(TESTFN, TESTFN)
+            zipfiledata = bio.getvalue()
+        data = b'I am not a ZipFile!'*10
+        with open(TESTFN2, 'wb') as f:
+            f.write(data)
+            f.write(zipfiledata)
+
+        with zipfile.ZipFile(TESTFN2) as zipfp:
+            self.assertEqual(zipfp.namelist(), [TESTFN])
+            self.assertEqual(zipfp.read(TESTFN), self.data)
+
+    def test_append_to_concatenated_zip_file(self):
+        with io.BytesIO() as bio:
+            with zipfile.ZipFile(bio, 'w', zipfile.ZIP_STORED) as zipfp:
+                zipfp.write(TESTFN, TESTFN)
+            zipfiledata = bio.getvalue()
+        data = b'I am not a ZipFile!'*1000000
+        with open(TESTFN2, 'wb') as f:
+            f.write(data)
+            f.write(zipfiledata)
+
+        with zipfile.ZipFile(TESTFN2, 'a') as zipfp:
+            self.assertEqual(zipfp.namelist(), [TESTFN])
+            zipfp.writestr('strfile', self.data)
+
+        with open(TESTFN2, 'rb') as f:
+            self.assertEqual(f.read(len(data)), data)
+            zipfiledata = f.read()
+        with io.BytesIO(zipfiledata) as bio, zipfile.ZipFile(bio) as zipfp:
+            self.assertEqual(zipfp.namelist(), [TESTFN, 'strfile'])
+            self.assertEqual(zipfp.read(TESTFN), self.data)
+            self.assertEqual(zipfp.read('strfile'), self.data)
 
     def test_ignores_newline_at_end(self):
         with zipfile.ZipFile(TESTFN2, "w", zipfile.ZIP_STORED) as zipfp:

diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index 56a2479fb3850a4e4dac10da15b3eebb1c17614f..2476717c963a8314133b3c38c9c5e35ef3c0648d 100644 (file)
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -1029,10 +1029,10 @@ class ZipFile:
                 # even if no files are added to the archive
                 self._didModify = True
                 try:
-                    self.start_dir = self.fp.tell()
+                    self.start_dir = self._start_disk = self.fp.tell()
                 except (AttributeError, OSError):
                     self.fp = _Tellable(self.fp)
-                    self.start_dir = 0
+                    self.start_dir = self._start_disk = 0
                     self._seekable = False
                 else:
                     # Some file-like objects can provide tell() but not seek()
@@ -1053,7 +1053,7 @@ class ZipFile:
                     # set the modified flag so central directory gets written
                     # even if no files are added to the archive
                     self._didModify = True
-                    self.start_dir = self.fp.tell()
+                    self.start_dir = self._start_disk = self.fp.tell()
             else:
                 raise RuntimeError("Mode must be 'r', 'w', 'x', or 'a'")
         except:
@@ -1097,17 +1097,18 @@ class ZipFile:
         offset_cd = endrec[_ECD_OFFSET]         # offset of central directory
         self._comment = endrec[_ECD_COMMENT]    # archive comment
 
-        # "concat" is zero, unless zip was concatenated to another file
-        concat = endrec[_ECD_LOCATION] - size_cd - offset_cd
+        # self._start_disk:  Position of the start of ZIP archive
+        # It is zero, unless ZIP was concatenated to another file
+        self._start_disk = endrec[_ECD_LOCATION] - size_cd - offset_cd
         if endrec[_ECD_SIGNATURE] == stringEndArchive64:
             # If Zip64 extension structures are present, account for them
-            concat -= (sizeEndCentDir64 + sizeEndCentDir64Locator)
+            self._start_disk -= (sizeEndCentDir64 + sizeEndCentDir64Locator)
 
         if self.debug > 2:
-            inferred = concat + offset_cd
-            print("given, inferred, offset", offset_cd, inferred, concat)
+            inferred = self._start_disk + offset_cd
+            print("given, inferred, offset", offset_cd, inferred, self._start_disk)
         # self.start_dir:  Position of start of central directory
-        self.start_dir = offset_cd + concat
+        self.start_dir = offset_cd + self._start_disk
         fp.seek(self.start_dir, 0)
         data = fp.read(size_cd)
         fp = io.BytesIO(data)
@@ -1147,7 +1148,7 @@ class ZipFile:
                             t>>11, (t>>5)&0x3F, (t&0x1F) * 2 )
 
             x._decodeExtra()
-            x.header_offset = x.header_offset + concat
+            x.header_offset = x.header_offset + self._start_disk
             self.filelist.append(x)
             self.NameToInfo[x.filename] = x
 
@@ -1627,11 +1628,10 @@ class ZipFile:
                 file_size = zinfo.file_size
                 compress_size = zinfo.compress_size
 
-            if zinfo.header_offset > ZIP64_LIMIT:
-                extra.append(zinfo.header_offset)
+            header_offset = zinfo.header_offset - self._start_disk
+            if header_offset > ZIP64_LIMIT:
+                extra.append(header_offset)
                 header_offset = 0xffffffff
-            else:
-                header_offset = zinfo.header_offset
 
             extra_data = zinfo.extra
             min_version = 0
@@ -1678,7 +1678,7 @@ class ZipFile:
         # Write end-of-zip-archive record
         centDirCount = len(self.filelist)
         centDirSize = pos2 - self.start_dir
-        centDirOffset = self.start_dir
+        centDirOffset = self.start_dir - self._start_disk
         requires_zip64 = None
         if centDirCount > ZIP_FILECOUNT_LIMIT:
             requires_zip64 = "Files count"

diff --git a/Misc/NEWS b/Misc/NEWS
index 369aa8b03f6f008a3d40f77c822741dde43e314c..36a7f30a436cdb773deaa59e4cafe1303488535d 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -92,6 +92,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #26293: Fixed writing ZIP files that starts not from the start of the
+  file.  Offsets in ZIP file now are relative to the start of the archive in
+  conforming to the specification.
+
 - Issue #28321: Fixed writing non-BMP characters with binary format in plistlib.
 
 - Issue #28322: Fixed possible crashes when unpickle itertools objects from