Issue #27194: superfluous truncate calls in tarfile.py slow down extraction

Patch by Jason Fried.

2 files changed, 3 insertions, 2 deletions

diff --git a/Lib/tarfile.py b/Lib/tarfile.py
index 86e1cf9b89..721f9d7f91 100755
--- a/Lib/tarfile.py
+++ b/Lib/tarfile.py
@@ -2150,10 +2150,10 @@ class TarFile(object):
                 for offset, size in tarinfo.sparse:
                     target.seek(offset)
                     copyfileobj(source, target, size, ReadError)
+                target.seek(tarinfo.size)
+                target.truncate()
             else:
                 copyfileobj(source, target, tarinfo.size, ReadError)
-            target.seek(tarinfo.size)
-            target.truncate()
 
     def makeunknown(self, tarinfo, targetpath):
         """Make a file from a TarInfo object with an unknown type
diff --git a/Misc/ACKS b/Misc/ACKS
index 001373b940..be303e0e50 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -458,6 +458,7 @@ Stefan Franke
 Martin Franklin
 Kent Frazier
 Bruce Frederiksen
+Jason Fried
 Robin Friedrich
 Bradley Froehle
 Ivan Frohne