bpo-39039: tarfile raises descriptive exception from zlib.error (GH-27766)

* during tarfile parsing, a zlib error indicates invalid data
* tarfile.open now raises a descriptive exception from the zlib error
* this makes it clear to the user that they may be trying to open a
  corrupted tar file

1 files changed, 9 insertions, 0 deletions

diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 18d415a..c1ee122 100755
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -2349,6 +2349,15 @@ class TarFile(object):
                     raise ReadError(str(e)) from None
             except SubsequentHeaderError as e:
                 raise ReadError(str(e)) from None
+            except Exception as e:
+                try:
+                    import zlib
+                    if isinstance(e, zlib.error):
+                        raise ReadError(f'zlib error: {e}') from None
+                    else:
+                        raise e
+                except ImportError:
+                    raise e
             break
 
         if tarinfo is not None: