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Bluetooth file transfer for all file types

Disable filter for supported MIME types when receiving files via OBEX with bluez

SailfishOS and MeeGo use bluez, obexd and the RPM obexd-contentfilter-helper. This package provides a single file, obexd-contentfilter-helperapp, which is usually installed in /usr/libexec/. obexd-contentfilter-helperapp is a shell script (as of v0.0.2), which checks per lca-tool if the MIME type of a file is registered (i.e., has a handler), when called as /usr/libexec/obexd-contentfilter-helperapp --receive-file <filepath> (as usual, it exits with 0 for success and 1 if any failure occurred).

Unfortunately this RPM is marked as proprietary, see rpm -q --info obexd-contentfilter-helper | fgrep License. Hence it cannot be found as part of either mer-core, the mer-mw (middleware) or anywhere at the mer-obs, and is consequently filed in the section "Non OSS packages" on the list of SailfishOS OSS components.
But luckily what triggers the installation of the obexd-contentfilter-helper RPM can be found (as that is FLOSS) in the spec file of the droid-hal-configs of mer-hybris, providing a bit of context.

As adapting or altering the obexd-contentfilter-helper RPM or its contents (specifically the obexd-contentfilter-helperapp script) is out of scope due to their licensing, the obexd-contentfilter-off RPM simply replaces its counterpart and provides a dummy obexd-contentfilter-helperapp script, which always returns success.

Hence obexd-contentfilter-off provides a simple way to disable the filter for only registered MIME types, when receiving files via Bluetooth with its OBEX profile.

Notes

  • For easy installation, RPMs are available in the release section and at OpenRepos.
  • obexd-contentfilter-off should install and work fine on all SailfishOS and even MeeGo releases.
  • To restore the original behaviour and state of the OS, simply remove ("uninstall") this package. Then also remove or disable its repository, if you have enabled it, in order to prevent automatic reinstallation of obexd-contentfilter-off when upgrading the OS.
    Mind that, while pkcon, zypper / libzypp and consequently all tools using them (Jolla's system updater, Warehouse, Storeman etc.) satisfy all package dependencies fine when removing obexd-contentfilter-off (by reinstalling obexd-contentfilter-helper automatically), the basic rpm utility does not! If one really wants to use rpm for removing (not recommended, anyway), one must execute rpm -e --nodeps obexd-contentfilter-off && rpm -i obexd-contentfilter-helper in order to restore the original behaviour and state without breaking the OS installation by doing so. Also note that you need a local download of obexd-contentfilter-helper for that to succeed (e.g., per pkcon download obexd-contentfilter-helper).
    TL;DR: Do not use rpm for removing obexd-contentfilter-off !
  • A coarse changelog is provided per release comments.

Background

  • The purpose of the original obexd-contentfilter-helper(app) is to strictly adhere to the OBEX specification in MeeGo and subsequently in SailfishOS. The idea is to never let users receive files per Bluetooth, which cannot be processed on the device.
    But this behaviour is contrary to most other file transfer methods and falls short, as e.g., TUI (textual user interface, "shell") programs usually do not register MIME types of files they can process and apparently the MIME type registrations of Android apps installed in an Android runtime environment (e.g., Alien Dalvik aka "Android App Support", Anbox → Waydroid) are not being passed through to the underlying GNU/Linux distribution.
    The main argument from the manufacturers perspective was, "BT SIG qualification for Obex push requires that unsupported content is rejected, regardless of whether we want to let everything through or not." (2014-09-25). Actually the OBEX aka IrDA Interoperability (IrOBEX) (v2.0, 26 Aug 2010) and Generic Object Exchange Profile (GOEP) (v2.1.1, 15 Dec 2015) specifications do not require this, but the Object Push Profile (OPP) (v1.2.1, 15 Dec 2015) specification may (the latter does not seem to be publicly available, only the aspects essential for implementing the OPP are).
  • The deliberate filtering for supported MIME types has sparked heated dicussions at TJC (e.g., [1], [2]), because users expect arbitrary files to be easily transferred as on their PCs.
    Obviously the current behaviour does not fit well for this user group.
  • obexd-contentfilter-off evolved from this (kudos to @hmallat for the original suggestion).