Issue #4756: zipfile.is_zipfile() now supports file-like objects.
Patch by Gabriel Genellina.
diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index 5e99382..9cc5860 100644
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -634,20 +634,49 @@
def testIsZipErroneousFile(self):
# This test checks that the is_zipfile function correctly identifies
# a file that is not a zip file
- fp = open(TESTFN, "w")
- fp.write("this is not a legal zip file\n")
- fp.close()
+
+ # - passing a filename
+ with open(TESTFN, "w") as fp:
+ fp.write("this is not a legal zip file\n")
chk = zipfile.is_zipfile(TESTFN)
- self.assert_(chk is False)
+ self.assert_(not chk)
+ # - passing a file object
+ with open(TESTFN, "rb") as fp:
+ chk = zipfile.is_zipfile(fp)
+ self.assert_(not chk)
+ # - passing a file-like object
+ fp = StringIO()
+ fp.write("this is not a legal zip file\n")
+ chk = zipfile.is_zipfile(fp)
+ self.assert_(not chk)
+ fp.seek(0,0)
+ chk = zipfile.is_zipfile(fp)
+ self.assert_(not chk)
def testIsZipValidFile(self):
# This test checks that the is_zipfile function correctly identifies
# a file that is a zip file
+
+ # - passing a filename
zipf = zipfile.ZipFile(TESTFN, mode="w")
zipf.writestr("foo.txt", "O, for a Muse of Fire!")
zipf.close()
chk = zipfile.is_zipfile(TESTFN)
- self.assert_(chk is True)
+ self.assert_(chk)
+ # - passing a file object
+ with open(TESTFN, "rb") as fp:
+ chk = zipfile.is_zipfile(fp)
+ self.assert_(chk)
+ fp.seek(0,0)
+ zip_contents = fp.read()
+ # - passing a file-like object
+ fp = StringIO()
+ fp.write(zip_contents)
+ chk = zipfile.is_zipfile(fp)
+ self.assert_(chk)
+ fp.seek(0,0)
+ chk = zipfile.is_zipfile(fp)
+ self.assert_(chk)
def testNonExistentFileRaisesIOError(self):
# make sure we don't raise an AttributeError when a partially-constructed
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index bb8fc53..66fe078 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -128,18 +128,30 @@
_CD64_DIRECTORY_SIZE = 8
_CD64_OFFSET_START_CENTDIR = 9
-def is_zipfile(filename):
- """Quickly see if file is a ZIP file by checking the magic number."""
+def _check_zipfile(fp):
try:
- fpin = open(filename, "rb")
- endrec = _EndRecData(fpin)
- fpin.close()
- if endrec:
- return True # file has correct magic number
+ if _EndRecData(fp):
+ return True # file has correct magic number
except IOError:
pass
return False
+def is_zipfile(filename):
+ """Quickly see if a file is a ZIP file by checking the magic number.
+
+ The filename argument may be a file or file-like object too.
+ """
+ result = False
+ try:
+ if hasattr(filename, "read"):
+ result = _check_zipfile(fp=filename)
+ else:
+ with open(filename, "rb") as fp:
+ result = _check_zipfile(fp)
+ except IOError:
+ pass
+ return result
+
def _EndRecData64(fpin, offset, endrec):
"""
Read the ZIP64 end-of-archive records and use that to update endrec