bpo-34969: Add --fast, --best on the gzip CLI (GH-9833)
diff --git a/Doc/library/gzip.rst b/Doc/library/gzip.rst
index b52dd1a..a93f377 100644
--- a/Doc/library/gzip.rst
+++ b/Doc/library/gzip.rst
@@ -222,25 +222,26 @@
.. versionchanged:: 3.8
Add a new command line interface with a usage.
+ By default, when you will execute the CLI, the default compression level is 6.
Command line options
^^^^^^^^^^^^^^^^^^^^
.. cmdoption:: file
- .. code-block:: shell-session
-
- $ python -m gzip file
-
If *file* is not specified, read from :attr:`sys.stdin`.
+.. cmdoption:: --fast
+
+ Indicates the fastest compression method (less compression).
+
+.. cmdoption:: --best
+
+ Indicates the slowest compression method (best compression).
+
.. cmdoption:: -d, --decompress
- Decompress the given file
-
- .. code-block:: shell-session
-
- $ python -m gzip -d file.gz
+ Decompress the given file.
.. cmdoption:: -h, --help
diff --git a/Lib/gzip.py b/Lib/gzip.py
index a34d01a..151ff14 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -17,7 +17,12 @@
READ, WRITE = 1, 2
-def open(filename, mode="rb", compresslevel=9,
+_COMPRESS_LEVEL_FAST = 1
+_COMPRESS_LEVEL_TRADEOFF = 6
+_COMPRESS_LEVEL_BEST = 9
+
+
+def open(filename, mode="rb", compresslevel=_COMPRESS_LEVEL_BEST,
encoding=None, errors=None, newline=None):
"""Open a gzip-compressed file in binary or text mode.
@@ -121,7 +126,7 @@
myfileobj = None
def __init__(self, filename=None, mode=None,
- compresslevel=9, fileobj=None, mtime=None):
+ compresslevel=_COMPRESS_LEVEL_BEST, fileobj=None, mtime=None):
"""Constructor for the GzipFile class.
At least one of fileobj and filename must be given a
@@ -515,7 +520,7 @@
super()._rewind()
self._new_member = True
-def compress(data, compresslevel=9):
+def compress(data, compresslevel=_COMPRESS_LEVEL_BEST):
"""Compress data in one shot and return the compressed string.
Optional argument is the compression level, in range of 0-9.
"""
@@ -537,10 +542,21 @@
parser = ArgumentParser(description=
"A simple command line interface for the gzip module: act like gzip, "
"but do not delete the input file.")
- parser.add_argument("-d", "--decompress", action="store_true",
+ group = parser.add_mutually_exclusive_group()
+ group.add_argument('--fast', action='store_true', help='compress faster')
+ group.add_argument('--best', action='store_true', help='compress better')
+ group.add_argument("-d", "--decompress", action="store_true",
help="act like gunzip instead of gzip")
+
parser.add_argument("args", nargs="*", default=["-"], metavar='file')
args = parser.parse_args()
+
+ compresslevel = _COMPRESS_LEVEL_TRADEOFF
+ if args.fast:
+ compresslevel = _COMPRESS_LEVEL_FAST
+ elif args.best:
+ compresslevel = _COMPRESS_LEVEL_BEST
+
for arg in args.args:
if args.decompress:
if arg == "-":
@@ -555,7 +571,8 @@
else:
if arg == "-":
f = sys.stdin.buffer
- g = GzipFile(filename="", mode="wb", fileobj=sys.stdout.buffer)
+ g = GzipFile(filename="", mode="wb", fileobj=sys.stdout.buffer,
+ compresslevel=compresslevel)
else:
f = builtins.open(arg, "rb")
g = open(arg + ".gz", "wb")
diff --git a/Lib/test/test_gzip.py b/Lib/test/test_gzip.py
index b072ce4..1e8b41f 100644
--- a/Lib/test/test_gzip.py
+++ b/Lib/test/test_gzip.py
@@ -12,7 +12,7 @@
from subprocess import PIPE, Popen
from test import support
from test.support import _4G, bigmemtest
-from test.support.script_helper import assert_python_ok
+from test.support.script_helper import assert_python_ok, assert_python_failure
gzip = support.import_module('gzip')
@@ -746,10 +746,38 @@
rc, out, err = assert_python_ok('-m', 'gzip', local_testgzip)
self.assertTrue(os.path.exists(gzipname))
- self.assertEqual(rc, 0)
self.assertEqual(out, b'')
self.assertEqual(err, b'')
+ @create_and_remove_directory(TEMPDIR)
+ def test_compress_infile_outfile(self):
+ for compress_level in ('--fast', '--best'):
+ with self.subTest(compress_level=compress_level):
+ local_testgzip = os.path.join(TEMPDIR, 'testgzip')
+ gzipname = local_testgzip + '.gz'
+ self.assertFalse(os.path.exists(gzipname))
+
+ with open(local_testgzip, 'wb') as fp:
+ fp.write(self.data)
+
+ rc, out, err = assert_python_ok('-m', 'gzip', compress_level, local_testgzip)
+
+ self.assertTrue(os.path.exists(gzipname))
+ self.assertEqual(out, b'')
+ self.assertEqual(err, b'')
+ os.remove(gzipname)
+ self.assertFalse(os.path.exists(gzipname))
+
+ def test_compress_fast_best_are_exclusive(self):
+ rc, out, err = assert_python_failure('-m', 'gzip', '--fast', '--best')
+ self.assertIn(b"error: argument --best: not allowed with argument --fast", err)
+ self.assertEqual(out, b'')
+
+ def test_decompress_cannot_have_flags_compression(self):
+ rc, out, err = assert_python_failure('-m', 'gzip', '--fast', '-d')
+ self.assertIn(b'error: argument -d/--decompress: not allowed with argument --fast', err)
+ self.assertEqual(out, b'')
+
def test_main(verbose=None):
support.run_unittest(TestGzip, TestOpen, TestCommandLine)
diff --git a/Misc/NEWS.d/next/Library/2018-10-13-07-46-50.bpo-34969.Mfnhjb.rst b/Misc/NEWS.d/next/Library/2018-10-13-07-46-50.bpo-34969.Mfnhjb.rst
new file mode 100644
index 0000000..e3b7132
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-10-13-07-46-50.bpo-34969.Mfnhjb.rst
@@ -0,0 +1,3 @@
+gzip: Add --fast, --best on the gzip CLI, these parameters will be used for the
+fast compression method (quick) or the best method compress (slower, but smaller
+file). Also, change the default compression level to 6 (tradeoff).