bpo-34898: Add mtime parameter to gzip.compress(). (GH-9704)

Without setting mtime, time.time() will be used as the timestamp which will
end up in the compressed data and each invocation of the compress() function
will vary over time.

2 files changed, 13 insertions, 2 deletions

diff --git a/Lib/gzip.py b/Lib/gzip.py
index 151ff1405b..948fec293e 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -520,12 +520,12 @@ class _GzipReader(_compression.DecompressReader):
         super()._rewind()
         self._new_member = True
 
-def compress(data, compresslevel=_COMPRESS_LEVEL_BEST):
+def compress(data, compresslevel=_COMPRESS_LEVEL_BEST, *, mtime=None):
     """Compress data in one shot and return the compressed string.
     Optional argument is the compression level, in range of 0-9.
     """
     buf = io.BytesIO()
-    with GzipFile(fileobj=buf, mode='wb', compresslevel=compresslevel) as f:
+    with GzipFile(fileobj=buf, mode='wb', compresslevel=compresslevel, mtime=mtime) as f:
         f.write(data)
     return buf.getvalue()
 
diff --git a/Lib/test/test_gzip.py b/Lib/test/test_gzip.py
index 1e8b41f07b..2c8f854c64 100644
--- a/Lib/test/test_gzip.py
+++ b/Lib/test/test_gzip.py
@@ -499,6 +499,17 @@ class TestGzip(BaseTest):
                 with gzip.GzipFile(fileobj=io.BytesIO(datac), mode="rb") as f:
                     self.assertEqual(f.read(), data)
 
+    def test_compress_mtime(self):
+        mtime = 123456789
+        for data in [data1, data2]:
+            for args in [(), (1,), (6,), (9,)]:
+                with self.subTest(data=data, args=args):
+                    datac = gzip.compress(data, *args, mtime=mtime)
+                    self.assertEqual(type(datac), bytes)
+                    with gzip.GzipFile(fileobj=io.BytesIO(datac), mode="rb") as f:
+                        f.read(1) # to set mtime attribute
+                        self.assertEqual(f.mtime, mtime)
+
     def test_decompress(self):
         for data in (data1, data2):
             buf = io.BytesIO()