[regression] mirscreencast 0.13 and later gives error and exception (std::exception::what: Failed to mmap buffer 13, "Permission denied")

[Daniel van Vugt]

[regression] mirscreencast 0.13 and later throws an exception:

# bin/mirscreencast -n1
MIR_CLIENT_PLATFORM_PATH=bin/../lib/client-modules/
MIR_SERVER_PLATFORM_PATH=bin/../lib/server-modules/
MIR_SERVER_PLATFORM_INPUT_LIB=bin/../lib/server-modules/input-stub.so
LD_LIBRARY_PATH=bin/../lib
exec=bin/.mirscreencast-uninstalled
[1431419911.659329] <ERROR> MirBufferStreamAPI: Caught exception at client library boundary (in mir_buffer_stream_get_graphics_region): /home/dan/bzr/mir/dev/src/platforms/mesa/client/client_buffer.cpp(63): Throw in function {anonymous}::ShmMemoryRegion::ShmMemoryRegion(const std::shared_ptr<mir::client::mesa::BufferFileOps>&, int, const mir::geometry::Size&, mir::geometry::Stride, MirPixelFormat)
Dynamic exception type: N5boost16exception_detail10clone_implINS0_19error_info_injectorISt13runtime_errorEEEE
std::exception::what: Failed to mmap buffer
13, "Permission denied"

And that's running as root(!)

Workaround: Use the installed version 0.12.1 of mirscreencast on vivid, which works still.

[Daniel van Vugt (vanvugt)]

Same bug exists in the 0.13 branch. But the 0.12 branch works fine.

[Daniel van Vugt (vanvugt)]

Hmm, actually it's still working even with the exception. Dropped importance.

[Alberto Aguirre (albaguirre)]

Yeah it's "benign".

mirscreencast now attempts to use the buffer stream API to map the buffer (which worksaround some android drivers that return bad pixels if you do glReadPixels on a context that was not rendered in that same process).

If it fails (which produces the error log) then it falls back to the EGL/glReadPixels instead.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[dinamic (dinamic6661)]

i also don't get any keyboard events after using mirscreencast, i have to logout/login

[Daniel van Vugt (vanvugt)]

dinamic: That might be bug 1474132 you're talking about. If not, please log a new bug for it.

[Daniel van Vugt (vanvugt)]

I'd like to see this fixed, but we have no definite plans to aim for a particular milestone.

[Andrea Bernabei (faenil)]

any plan yet? still buggy in

mir-utils 0.24.0+16.04.20160815.3-0ubuntu2

I thought the screencasting wasn't working, until I found this thread

[Daniel van Vugt (vanvugt)]

It's a harmless exception and does not mean anything is faulty.

We've just failed to avoid worrying the user into thinking something is broken. The message needs to be hidden from the user.