Bug 181433 – [GTK] Missing symbols exported in 2.19.4

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Carlos Garcia Campos]

Berto has just reported that some symbols are no longer exported in 2.19.4, see:

- webkit_authentication_dialog_get_type@Base 2.5.3
+#MISSING: 2.19.4-1# webkit_authentication_dialog_get_type@Base 2.5.3

- webkit_dom_dom_window_webkit_message_handlers_post_message@Base 2.8.1
+#MISSING: 2.19.4-1# webkit_dom_dom_window_webkit_message_handlers_post_message@Base 2.8.1

- webkit_inspector_window_get_type@Base 2.17.3
+#MISSING: 2.19.4-1# webkit_inspector_window_get_type@Base 2.17.3

- webkit_web_view_base_accessible_get_type@Base 2.5.3
+#MISSING: 2.19.4-1# webkit_web_view_base_accessible_get_type@Base 2.5.3

These are symbols were we forgot to add WEBKIT_API macros, but were always exported before by the filter script (webkit_*)

There are others affected by this, but because we never wanted to expose them:

- webkit_media_src_get_type@Base 2.19.3-2~
+#MISSING: 2.19.4-1# webkit_media_src_get_type@Base 2.19.3-2~

- webkit_mse_debug@Base 2.19.3-2~
+#MISSING: 2.19.4-1# webkit_mse_debug@Base 2.19.3-2~

- (optional)webkit_soup_request_generic_get_type@Base 2.5.3
- (optional)webkit_soup_request_input_stream_get_type@Base 2.5.3
+#MISSING: 2.19.4-1# (optional)webkit_soup_request_generic_get_type@Base 2.5.3
+#MISSING: 2.19.4-1# (optional)webkit_soup_request_input_stream_get_type@Base 2.5.3

- webkit_web_src_get_type@Base 2.5.3
+#MISSING: 2.19.4-1# webkit_web_view_base_accessible_get_type@Base 2.5.3

So, we should make the filter script work again, add the missing WEBKIT_API and stop exposing private symbols even when using the filter script.

[Carlos Garcia Campos]

Michael, could it be that when using hidden visibility the filter is script is not used?

[Carlos Garcia Campos]

I've checked that using hidden visiblity takes precedence. This is actually a good thing, because it means that only webkit_ symbols will be exported thanks to the filter script, but also that webkit_ symbols not marked as public will not be exported either. So, we only need to add the missing WEBKIT_API macros.

[Carlos Garcia Campos]

Just in case you are curious, this is my experiment:

test.c

int __attribute__((visibility("default"))) p_foo() { return 1; }
int bar() { return 2; }
int __attribute__((visibility("default"))) exported() { return 3; }
int __attribute__((visibility("default"))) p_bar() { return 4; }
int p_baz() { return 5; }

filter

{
  global: p_*;
  local: *;
};

$ gcc test.c -Wl,--version-script=filter -fPIC -shared -o libtest.so

0000000000000555 l     F .text	000000000000000b              bar
0000000000000560 l     F .text	000000000000000b              exported
000000000000054a g     F .text	000000000000000b              p_foo
000000000000056b g     F .text	000000000000000b              p_bar
0000000000000576 g     F .text	000000000000000b              p_baz

Only p_ symbols are exported, as set in the version script, no matter what mark they have in the code.

$ gcc test.c -fvisibility=hidden -fPIC -shared -o libtest.so

0000000000000615 l     F .text	000000000000000b              bar
0000000000000636 l     F .text	000000000000000b              p_baz
000000000000060a g     F .text	000000000000000b              p_foo
0000000000000620 g     F .text	000000000000000b              exported
000000000000062b g     F .text	000000000000000b              p_bar

Only symbols marked as public in the code are exported.

$ gcc test.c -Wl,--version-script=filter -fvisibility=hidden -fPIC -shared -o libtest.so

0000000000000535 l     F .text	000000000000000b              bar
0000000000000540 l     F .text	000000000000000b              exported
0000000000000556 l     F .text	000000000000000b              p_baz
000000000000052a g     F .text	000000000000000b              p_foo
000000000000054b g     F .text	000000000000000b              p_bar

Only symbols with p_ prefix and marked as public in the code are exported. Which is exactly what we want in WebKit :-)

[Carlos Garcia Campos]

Only webkit_dom_dom_window_webkit_message_handlers_post_message() is meant to be public and is missing the WEBKIT_API, not exposing all others now is actually and improvement, not a bug. It shouldn't break any application, and it's not an ABI break because those have always been private even exported.

[Carlos Garcia Campos]

Created attachment 330816 [details]
Patch

[Carlos Garcia Campos]

webkit_dom_dom_window_webkit_message_handlers_post_message(9 is used by ephy, so I'll have to make another release when this patch lands.

[EWS Watchlist]

Thanks for the patch. If this patch contains new public API please make sure it follows the guidelines for new WebKit2 GTK+ API. See http://trac.webkit.org/wiki/WebKitGTK/AddingNewWebKit2API

[Michael Catanzaro]

Comment on attachment 330816 [details]
Patch

Yes, this is caused by -fvisibility=hidden.

[Michael Catanzaro]

Carlos, in the linker version script, Source/WebKit/webkitglib-symbols.map, please remove line 13:

  webkit_media_player_debug;

There's no point in having it anymore since it is not marked with WEBKIT_API. I didn't consider that when modifying the script.

[Carlos Garcia Campos]

Committed r226633: <https://trac.webkit.org/changeset/226633>