Porting/Tor Browser

Early efforts to port Tor Browser to POWER are underway. The primary challenge is that Tor Browser uses an unusual build system (rbm) in order to ensure reproducible builds. While Tor's configuration of rbm can cross-compile for Windows and macOS targets, it is not configured out of the box to cross-compile for GNU/Linux targets. As a result, our early efforts are focused on modifying Tor's rbm configuration to support cross-compiling for non-x86 GNU/Linux targets; it is expected that this will be useful not only for POWER but also for targets like ARM.

Current source code is at https://notabug.org/JeremyRand/tor-browser-build/src/armhf . If you're interested in joining the effort, talk to Jeremy_Rand or Jeremy_Rand_Talos in #talos-workstation.

Build instructions

./rbm/rbm build firefox --target release --target torbrowser-linux-arm

Errors / Troubleshooting

Unfixed

• ./firefox: error while loading shared libraries: libssp.so.0: cannot open shared object file: No such file or directory
  • Workaround: copy libssp.so* from the gcc-cross output tar into the Browser directory of the firefox output.
  • Also note that you need to add the Browser directory to your LD_LIBRARY_PATH in order for Tor Browser to find the library.
  • This should be fixable by editing the Firefox rbm build script to copy libssp.so*, and by porting the non-Firefox projects (one of which is responsible for setting the LD_LIBRARY_PATH).

Fixed

• /var/tmp/build/firefox-f8f42fea2af3/js/src/jsnativestack.cpp:69:31: error: 'syscall' was not declared in this scope
  • This is because jsnativestack.cpp forgot to #include <unistd.h>. This is fixed in all releases of Tor Browser based on ESR 60. Since we're still using ESR 52 for now, I fixed it by applying a short patch to add the missing include.
• /var/tmp/build/firefox-f8f42fea2af3/js/src/jsnativestack.cpp:77:27: error: 'getpid' was not declared in this scope
  • Also caused by missing #include <unistd.h> in jsnativestack.cpp; same fixes as above.

Task list

• Port this to newer versions of Tor Browser that use Firefox ESR 60. This will require making Rust work.
• Build the projects besides Firefox.
• Generalize the GNU/Linux cross-compiling changes so that they work on target arches besides armhf. (ppc64be, ppc64le, and aarch64 are all likely to be useful.)

Upstream Tickets

• http://ea5faa5po25cf7fb.onion/projects/tor/ticket/12631