[Python-checkins] bpo-8978: improve tarfile.open error message when lzma / bz2 are missing (GH-24850)
miss-islington
webhook-mailer at python.org
Tue Apr 27 13:39:07 EDT 2021
https://github.com/python/cpython/commit/9aea31deddf7458be3546f72185740f3cd06687f
commit: 9aea31deddf7458be3546f72185740f3cd06687f
branch: master
author: Anthony Sottile <asottile at umich.edu>
committer: miss-islington <31488909+miss-islington at users.noreply.github.com>
date: 2021-04-27T10:39:01-07:00
summary:
bpo-8978: improve tarfile.open error message when lzma / bz2 are missing (GH-24850)
Automerge-Triggered-By: GH:pablogsal
files:
A Lib/test/testtar.tar.xz
A Misc/NEWS.d/next/Library/2021-03-13-14-02-07.bpo-8978.CRxG-O.rst
M Lib/tarfile.py
M Lib/test/test_tarfile.py
diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 395c0f1d30040..18d415adf5441 100755
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -1604,17 +1604,20 @@ def open(cls, name=None, mode="r", fileobj=None, bufsize=RECORDSIZE, **kwargs):
# Find out which *open() is appropriate for opening the file.
def not_compressed(comptype):
return cls.OPEN_METH[comptype] == 'taropen'
+ error_msgs = []
for comptype in sorted(cls.OPEN_METH, key=not_compressed):
func = getattr(cls, cls.OPEN_METH[comptype])
if fileobj is not None:
saved_pos = fileobj.tell()
try:
return func(name, "r", fileobj, **kwargs)
- except (ReadError, CompressionError):
+ except (ReadError, CompressionError) as e:
+ error_msgs.append(f'- method {comptype}: {e!r}')
if fileobj is not None:
fileobj.seek(saved_pos)
continue
- raise ReadError("file could not be opened successfully")
+ error_msgs_summary = '\n'.join(error_msgs)
+ raise ReadError(f"file could not be opened successfully:\n{error_msgs_summary}")
elif ":" in mode:
filemode, comptype = mode.split(":", 1)
diff --git a/Lib/test/test_tarfile.py b/Lib/test/test_tarfile.py
index 77ad8305c3107..817e6f1799712 100644
--- a/Lib/test/test_tarfile.py
+++ b/Lib/test/test_tarfile.py
@@ -2283,6 +2283,18 @@ def test__all__(self):
'SubsequentHeaderError', 'ExFileObject', 'main'}
support.check__all__(self, tarfile, not_exported=not_exported)
+ def test_useful_error_message_when_modules_missing(self):
+ fname = os.path.join(os.path.dirname(__file__), 'testtar.tar.xz')
+ with self.assertRaises(tarfile.ReadError) as excinfo:
+ error = tarfile.CompressionError('lzma module is not available'),
+ with unittest.mock.patch.object(tarfile.TarFile, 'xzopen', side_effect=error):
+ tarfile.open(fname)
+
+ self.assertIn(
+ "\n- method xz: CompressionError('lzma module is not available')\n",
+ str(excinfo.exception),
+ )
+
class CommandLineTest(unittest.TestCase):
diff --git a/Lib/test/testtar.tar.xz b/Lib/test/testtar.tar.xz
new file mode 100644
index 0000000000000..512fa149e6cfd
Binary files /dev/null and b/Lib/test/testtar.tar.xz differ
diff --git a/Misc/NEWS.d/next/Library/2021-03-13-14-02-07.bpo-8978.CRxG-O.rst b/Misc/NEWS.d/next/Library/2021-03-13-14-02-07.bpo-8978.CRxG-O.rst
new file mode 100644
index 0000000000000..2da8874dc7f34
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-03-13-14-02-07.bpo-8978.CRxG-O.rst
@@ -0,0 +1,2 @@
+Improve error message for :func:`tarfile.open` when :mod:`lzma` / :mod:`bz2`
+are unavailable. Patch by Anthony Sottile.
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