Even in that tree/version (which is from 9 years ago), packet-xml.c doesn't call the function itself. I don't see any out-of-tree commits to packet-xml.c in the history of that tree. The only file that includes packet-xml.h is packet-xmpp-utils.h (which is included by various XMPP dissectors), but they didn't even exist in the repo/snapshot you pointed to.
Looking with 'git annotate', the lines of these 3 functions were re-formatted by Bill Meier in a cleanup change in 2011, and I'm not going to dig further back than that.
I think I'd best just leave those 3 functions in, and will add them to an exemption list in my script. But this does show that investigating these symbols can be time-consuming and inconclusive.
Hi,
Did some googling out of curiosity and found https://jelmer.uk/klaus/wireshark/blob/e738b556d72d4db5d7df85969c15117dedd0d063/epan/dissectors/packet-xml.c
Search for “xml_get_attrib" So it seems it was part of packet-xml.c at some point so perhaps safe to remove…
/Anders
Hi João,
I agree that every function / variable needs to be looked at carefully, but more so if they have WS_DLL_PUBLIC in a header file.
I will reinstate the XML functions in my change. Hopefully, in other places I will find clear comments saying that they are provided for calling from private code or plugins, etc.
The few occasions I've added to debian/libwireshark0.symbols have been to unbreak the pipeline when linking between dissectors and GUI code. My pdcp key-setting functions don't even appear there, but I don't build Windows plugins.
Hi Martin,
As you said some functions may only be used by third party plugins so indiscriminately removing every exported but not used function would be a bad policy. Even if they're not actually being used right now, who knows, they may be part of some public API for plugins, so for use as needed. The considerate way to remove them would be to have a deprecation period.
Unfortunately debian symbols doesn't help here. It does not say anything interesting not already said by the static/exported C keywords, because functions that may be internal, for example exported from epan to the wireshark GUI application (not intended to be part of a public API), must also be included in debian symbols.
So really IMO the analysis must be done case by case for each function. And of course the risk of breaking someone elses plugin is always there, however small, so I think it needs to proceed with some caution.
On 27/01/21 11:06, Martin Mathieson via Wireshark-dev wrote:
dpkg-gensymbols: error: some symbols or patterns disappeared in the symbols file: see diff output below
4934dpkg-gensymbols: warning: debian/libwireshark0/DEBIAN/symbols doesn't match completely debian/libwireshark0.symbols
4935--- debian/libwireshark0.symbols (libwireshark0_3.5.0_amd64)
4936+++ dpkg-gensymbolsUhOwDI 2021-01-27 10:38:17.000000000 +0000
4937@@ -2124,7 +2124,7 @@
4938 wsp_vals_pdu_type_ext@Base 1.9.1
4939 wsp_vals_status_ext@Base 1.9.1
4940 xml_escape@Base 1.9.1
4941- xml_get_attrib@Base 1.9.1
4942- xml_get_cdata@Base 1.9.1
4943- xml_get_tag@Base 1.9.1
4944+#MISSING: 3.5.0# xml_get_attrib@Base 1.9.1
4945+#MISSING: 3.5.0# xml_get_cdata@Base 1.9.1
4946+#MISSING: 3.5.0# xml_get_tag@Base 1.9.1
4947 zbee_zcl_init_cluster@Base 2.5.2
It may be possible that someone has a private dissector that uses these xml accessor functions to try to pick out some interesting fields.
I am guessing that I should have my script read debian/libwireshark0.symbols to realise that these functions need to be non-static, even if there it can't find any actual references?
I have done a bit more on this - I started picking off the ones at the end of the (alphabetical) list - 2nd one is https://gitlab.com/wireshark/wireshark/-/merge_requests/1817. Please feel free if anyone feels motivated to tackle some of the earlier ones. The script is much tidier now, and also checks for references from the ui folder (this removed around 20 from the list), will take another pass through it before creating an MR with it.
Sometimes I see that header files are being used as a way to untangle the order or functions, but just doing some static forward-declarations at the top of the C module would be better if they are not shared. I am leery of deleting functions that are not being called, but if they've been that way for years they probably don't matter.
Hi,
I checked the code I know:
> epan/dissectors/packet-rtp-events.c (00000000000001a0 D> rtp_event_type_values_ext) is not referred to so could be static? (in>
header)
It is used in UI, outside of dissectors. Therefore it should be exported.
Yes, I can have the script also check for references from the object files in ui to avoid reporting cases like this.
> epan/dissectors/packet-rtp.c (00000000000006d0 T rtp_dyn_payload_remove)
> is not referred to so could be static? (in header)
> epan/dissectors/packet-rtp.c (0000000000000660 T
> rtp_dyn_payload_replace) is not referred to so could be static? (in header)
I think these 2 functions can be removed.
> epan/dissectors/packet-rtps.c (0000000000000e20 D class_id_enum_names)
> is not referred to so could be static?
This variable is able to become static.
That two functions are not used at all. Can we remove them?
Best regards,
Jirka Novak
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