bpo-24538: Fix bug in shutil involving the copying of xattrs to read-only files. (PR-13212)
Extended attributes can only be set on user-writeable files, but shutil previously
first chmod()ed the destination file to the source's permissions and then tried to
copy xattrs. This will cause failures if attempting to copy read-only files with
xattrs, as occurs with Git clones on Lustre FS.
diff --git a/Lib/shutil.py b/Lib/shutil.py
index 6cfe373..b2e8f5f 100644
--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -359,6 +359,9 @@
mode = stat.S_IMODE(st.st_mode)
lookup("utime")(dst, ns=(st.st_atime_ns, st.st_mtime_ns),
follow_symlinks=follow)
+ # We must copy extended attributes before the file is (potentially)
+ # chmod()'ed read-only, otherwise setxattr() will error with -EACCES.
+ _copyxattr(src, dst, follow_symlinks=follow)
try:
lookup("chmod")(dst, mode, follow_symlinks=follow)
except NotImplementedError:
@@ -382,7 +385,6 @@
break
else:
raise
- _copyxattr(src, dst, follow_symlinks=follow)
def copy(src, dst, *, follow_symlinks=True):
"""Copy data and mode bits ("cp src dst"). Return the file's destination.
diff --git a/Lib/test/test_shutil.py b/Lib/test/test_shutil.py
index e709a56..eeebb97 100644
--- a/Lib/test/test_shutil.py
+++ b/Lib/test/test_shutil.py
@@ -531,12 +531,20 @@
# test that shutil.copystat copies xattrs
src = os.path.join(tmp_dir, 'the_original')
+ srcro = os.path.join(tmp_dir, 'the_original_ro')
write_file(src, src)
+ write_file(srcro, srcro)
os.setxattr(src, 'user.the_value', b'fiddly')
+ os.setxattr(srcro, 'user.the_value', b'fiddly')
+ os.chmod(srcro, 0o444)
dst = os.path.join(tmp_dir, 'the_copy')
+ dstro = os.path.join(tmp_dir, 'the_copy_ro')
write_file(dst, dst)
+ write_file(dstro, dstro)
shutil.copystat(src, dst)
+ shutil.copystat(srcro, dstro)
self.assertEqual(os.getxattr(dst, 'user.the_value'), b'fiddly')
+ self.assertEqual(os.getxattr(dstro, 'user.the_value'), b'fiddly')
@support.skip_unless_symlink
@support.skip_unless_xattr
diff --git a/Misc/ACKS b/Misc/ACKS
index 300e788..dfb9637 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -149,6 +149,7 @@
Ron Bickers
Natalia B. Bidart
Adrian von Bidder
+Olexa Bilaniuk
David Binger
Dominic Binks
Philippe Biondi
diff --git a/Misc/NEWS.d/next/Library/2019-05-09-08-35-18.bpo-24538.WK8Y-k.rst b/Misc/NEWS.d/next/Library/2019-05-09-08-35-18.bpo-24538.WK8Y-k.rst
new file mode 100644
index 0000000..e799f93
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-05-09-08-35-18.bpo-24538.WK8Y-k.rst
@@ -0,0 +1,3 @@
+In `shutil.copystat()`, first copy extended file attributes and then file
+permissions, since extended attributes can only be set on the destination
+while it is still writeable.