gkeyfile: Fix group comment management

This removes the `comment` member of the GKeyFileGroup structure, which
seemed intended to distinguish comments just above a group from comments
above them, separated by one or more blank lines. Indeed:
* This does not seem to match any specification in the documentation,
  where blank lines and lines starting with `#` are indiscriminately
  considered comments. In particular, no distinction is made between the
  comment above the first group and the comment at the beginning of the
  file.
* This distinction was only half implemented, resulting in confusion
  between comment above a group and comment at the end of the preceding
  group.

Instead, the same logic is used for groups as for keys: the comment
above a group is simply the sequence of key-value pairs of the preceding
group where the key is null, starting from the bottom.

The addition of a blank line above groups when writing, involved in
bugs #104 and #2927, is kept, but:
* It is now added as a comment as soon as the group is added (since a
  blank line is considered a comment), so that
  `g_key_file_get_comment()` returns the correct result right away.
* It is always added if comments are not kept.
* Otherwise it is only added if the group is newly created (not present
  in the original data), in order to really keep comments (existing and
  not existing).

Closes: #104, #2927

1 files changed, 73 insertions, 2 deletions

diff --git a/glib/tests/keyfile.c b/glib/tests/keyfile.c
index 3d72d9670..d3eed2984 100644
--- a/glib/tests/keyfile.c
+++ b/glib/tests/keyfile.c
@@ -382,7 +382,9 @@ test_comments (void)
     "key4 = value4\n"
     "# group comment\n"
     "# group comment, continued\n"
-    "[group2]\n";
+    "[group2]\n\n"
+    "[group3]\n"
+    "[group4]\n";
 
   const gchar *top_comment = " top comment\n top comment, continued";
   const gchar *group_comment = " group comment\n group comment, continued";
@@ -427,6 +429,12 @@ test_comments (void)
   check_name ("top comment", comment, top_comment, 0);
   g_free (comment);
 
+  g_key_file_remove_comment (keyfile, NULL, NULL, &error);
+  check_no_error (&error);
+  comment = g_key_file_get_comment (keyfile, NULL, NULL, &error);
+  check_no_error (&error);
+  g_assert_null (comment);
+
   comment = g_key_file_get_comment (keyfile, "group1", "key2", &error);
   check_no_error (&error);
   check_name ("key comment", comment, key_comment, 0);
@@ -448,7 +456,25 @@ test_comments (void)
   check_name ("group comment", comment, group_comment, 0);
   g_free (comment);
 
+  g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/issues/104");
+
+  /* check if comments above another group than the first one are properly removed */
+  g_key_file_remove_comment (keyfile, "group2", NULL, &error);
+  check_no_error (&error);
+  comment = g_key_file_get_comment (keyfile, "group2", NULL, &error);
+  check_no_error (&error);
+  g_assert_null (comment);
+
   comment = g_key_file_get_comment (keyfile, "group3", NULL, &error);
+  check_no_error (&error);
+  check_name ("group comment", comment, "", 0);
+  g_free (comment);
+
+  comment = g_key_file_get_comment (keyfile, "group4", NULL, &error);
+  check_no_error (&error);
+  g_assert_null (comment);
+
+  comment = g_key_file_get_comment (keyfile, "group5", NULL, &error);
   check_error (&error,
                G_KEY_FILE_ERROR,
                G_KEY_FILE_ERROR_GROUP_NOT_FOUND);
@@ -1321,9 +1347,16 @@ test_reload_idempotency (void)
     "[fifth]\n";
   GKeyFile *keyfile;
   GError *error = NULL;
-  gchar *data1, *data2;
+  gchar *data1, *data2, *comment;
   gsize len1, len2;
 
+  const gchar *key_comment = " A random comment in the first group";
+  const gchar *top_comment = " Top comment\n\n First comment";
+  const gchar *group_comment_1 = top_comment;
+  const gchar *group_comment_2 = " Second comment - one line";
+  const gchar *group_comment_3 = " Third comment - two lines\n Third comment - two lines";
+  const gchar *group_comment_4 = "\n";
+
   g_test_bug ("https://bugzilla.gnome.org/show_bug.cgi?id=420686");
 
   /* check that we only insert a single new line between groups */
@@ -1347,6 +1380,44 @@ test_reload_idempotency (void)
 
   data2 = g_key_file_to_data (keyfile, &len2, &error);
   g_assert_nonnull (data2);
+
+  g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/issues/2927");
+
+  /* check if comments are preserved on reload */
+  comment = g_key_file_get_comment (keyfile, "first", "anotherkey", &error);
+  check_no_error (&error);
+  g_assert_cmpstr (comment, ==, key_comment);
+  g_free (comment);
+
+  comment = g_key_file_get_comment (keyfile, NULL, NULL, &error);
+  check_no_error (&error);
+  g_assert_cmpstr (comment, ==, top_comment);
+  g_free (comment);
+
+  comment = g_key_file_get_comment (keyfile, "first", NULL, &error);
+  check_no_error (&error);
+  g_assert_cmpstr (comment, ==, group_comment_1);
+  g_free (comment);
+
+  comment = g_key_file_get_comment (keyfile, "second", NULL, &error);
+  check_no_error (&error);
+  g_assert_cmpstr (comment, ==, group_comment_2);
+  g_free (comment);
+
+  comment = g_key_file_get_comment (keyfile, "third", NULL, &error);
+  check_no_error (&error);
+  g_assert_cmpstr (comment, ==, group_comment_3);
+  g_free (comment);
+
+  comment = g_key_file_get_comment (keyfile, "fourth", NULL, &error);
+  check_no_error (&error);
+  g_assert_cmpstr (comment, ==, group_comment_4);
+  g_free (comment);
+
+  comment = g_key_file_get_comment (keyfile, "fifth", NULL, &error);
+  check_no_error (&error);
+  g_assert_null (comment);
+
   g_key_file_free (keyfile);
 
   g_assert_cmpstr (data1, ==, data2);