only copy icons into repo/ if they changed

This should make things more efficient and reduce the size of the diffs in
the transparency log.  Using shutil.copy2() preserves metadata.

fdroidserver/common.py

@@ -55,6 +55,7 @@ environment variable to include.
 import copy
 import difflib
 from typing import List
+import filecmp
 import git
 import glob
 import io
@@ -812,7 +813,10 @@ def load_localized_config(name, repodir):
                         icons_dir = os.path.join(repodir, 'icons')
                         if not os.path.exists(icons_dir):
                             os.makedirs(icons_dir, exist_ok=True)
-                        shutil.copy(os.path.join("config", value), icons_dir)
+                        src = os.path.join("config", value)
+                        dest = os.path.join(icons_dir, os.path.basename(src))
+                        if not os.path.exists(dest) or not filecmp.cmp(src, dest):
+                            shutil.copy2(src, dest)
                         ret[afname][key][locale] = file_entry(
                             os.path.join(icons_dir, value)
                         )

fdroidserver/update.py

@@ -20,6 +20,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import argparse
+import filecmp
 import sys
 import os
 import shutil
@@ -1460,19 +1461,18 @@ def insert_localized_ios_app_metadata(apps_with_packages):
         fdroidserver.update.copy_ios_screenshots_to_repo(screenshots, package_name)
 
         # lookup icons, copy them and put them into app
-        icon_path = _get_ipa_icon(Path('build') / package_name)
+        icon_src = _get_ipa_icon(Path('build') / package_name)
         icon_dest = Path('repo') / package_name / 'icon.png'  # for now just assume png
-        icon_stat = os.stat(icon_path)
         app['iconv2'] = {
             DEFAULT_LOCALE: {
                 'name': str(icon_dest).lstrip('repo'),
                 'sha256': common.sha256sum(icon_dest),
-                'size': icon_stat.st_size,
+                'size': os.path.getsize(icon_src),
             }
         }
-        if not icon_dest.exists():
+        if not icon_dest.exists() or not filecmp.cmp(icon_src, icon_dest):
             icon_dest.parent.mkdir(parents=True, exist_ok=True)
-            shutil.copy(icon_path, icon_dest)
+            shutil.copy2(icon_src, icon_dest)
 
 
 def scan_repo_files(apkcache, repodir, knownapks, use_date_from_file=False):

tests/test_common.py

@@ -2815,6 +2815,46 @@ class CommonTest(SetUpTearDownMixin, unittest.TestCase):
         )
         self.assertEqual(['en-US'], list(categories['GuardianProject']['name'].keys()))
 
+    def test_load_localized_config_copy_icon(self):
+        os.chdir(self.testdir)
+        os.mkdir('config')
+        Path('config/categories.yml').write_text('System:\n  icon: system.png')
+        source_file = 'config/system.png'
+        Path(source_file).write_text('placeholder')
+        time.sleep(0.01)  # ensure reliable failure if mtime isn't preserved
+        fdroidserver.common.load_localized_config(CATEGORIES_CONFIG_NAME, 'repo')
+        dest_file = f'repo/icons/{os.path.basename(source_file)}'
+        self.assertEqual(os.path.getsize(source_file), os.path.getsize(dest_file))
+        self.assertEqual(os.path.getmtime(source_file), os.path.getmtime(dest_file))
+
+    def test_load_localized_config_copy_unchanged(self):
+        """The destination file should only change if the source file did."""
+        os.chdir(self.testdir)
+        os.mkdir('config')
+        Path('config/categories.yml').write_text('System:\n  icon: system.png')
+        source_file = 'config/system.png'
+        Path(source_file).write_text('placeholder')
+        fdroidserver.common.load_localized_config(CATEGORIES_CONFIG_NAME, 'repo')
+        delta = 0.01
+        time.sleep(delta)  # ensure reliable failure if file isn't preserved
+        fdroidserver.common.load_localized_config(CATEGORIES_CONFIG_NAME, 'repo')
+        dest_file = f'repo/icons/{os.path.basename(source_file)}'
+        self.assertAlmostEqual(
+            os.path.getctime(source_file), os.path.getctime(dest_file), delta=delta
+        )
+
+    def test_load_localized_config_copy_over_dest(self):
+        os.chdir(self.testdir)
+        os.mkdir('config')
+        Path('config/categories.yml').write_text('System:\n  icon: system.png')
+        source_file = Path('config/system.png')
+        dest_file = Path(f'repo/icons/{os.path.basename(source_file)}')
+        source_file.write_text('placeholder')
+        dest_file.parent.mkdir(parents=True)
+        dest_file.write_text('different contents')
+        fdroidserver.common.load_localized_config(CATEGORIES_CONFIG_NAME, 'repo')
+        self.assertEqual(os.path.getsize(source_file), os.path.getsize(dest_file))
+
     def test_load_localized_config_0_file(self):
         os.chdir(self.testdir)
         os.mkdir('config')