[Buildroot] [PATCH] package/dbus-cpp: new patch to fix dbus c++ threading issue

[Buildroot] [PATCH] package/dbus-cpp: new patch to fix dbus c++ threading issue

[Kamel Bouhara]

From: https://sourceforge.net/p/dbus-cplusplus/patches/18/

dispatcher.h has invalid template code. When DBUS_HAS_RECURSIVE_MUTEX is
MutexFreeFn and MutexLockFn become of type void and the code is valid.
See lines 232-235.
However, when a user #includes dispatcher.h directly or indirectly the
macro DBUS_HAS_RECURSIVE_MUTEX is undefined. This makes the above
function pointers defined of type bool and but then _init_threading
function call in line 259 becomes invalid, as it passes function
pointers to mutex_free and mutex_lock which or of type void.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
---
 .../dbus-cpp/0004-dbus-c++-threading.patch    | 45 +++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 package/dbus-cpp/0004-dbus-c++-threading.patch

diff --git a/package/dbus-cpp/0004-dbus-c++-threading.patch b/package/dbus-cpp/0004-dbus-c++-threading.patch
new file mode 100644
index 0000000000..502320ad09
--- /dev/null
+++ b/package/dbus-cpp/0004-dbus-c++-threading.patch
@@ -0,0 +1,45 @@
+--- libdbus-c++-0.9.0/include/dbus-c++/dispatcher.h.threading	2017-02-15 13:40:53.796004263 +0000
++++ libdbus-c++-0.9.0/include/dbus-c++/dispatcher.h	2017-02-15 13:40:46.907000493 +0000
+@@ -188,6 +188,7 @@
+ /* classes for multithreading support
+ */
+
++#if 0
+ class DXXAPI Mutex
+ {
+ public:
+@@ -243,9 +244,11 @@
+ typedef bool (*CondVarWaitTimeoutFn)(CondVar *cv, Mutex *mx, int timeout);
+ typedef void (*CondVarWakeOneFn)(CondVar *cv);
+ typedef void (*CondVarWakeAllFn)(CondVar *cv);
++#endif
+
+ void DXXAPI _init_threading();
+
++#if 0
+ void DXXAPI _init_threading(
+   MutexNewFn, MutexFreeFn, MutexLockFn, MutexUnlockFn,
+   CondVarNewFn, CondVarFreeFn, CondVarWaitFn, CondVarWaitTimeoutFn, CondVarWakeOneFn, CondVarWakeAllFn
+@@ -312,6 +315,7 @@
+     cv->wake_all();
+   }
+ };
++#endif
+
+ } /* namespace DBus */
+
+--- libdbus-c++-0.9.0/src/dispatcher.cpp.threading	2017-02-15 13:48:22.627249868 +0000
++++ libdbus-c++-0.9.0/src/dispatcher.cpp	2017-02-15 13:48:29.164253445 +0000
+@@ -253,6 +253,7 @@
+ #endif//DBUS_HAS_THREADS_INIT_DEFAULT
+ }
+
++#if 0
+ void DBus::_init_threading(
+   MutexNewFn m1,
+   MutexFreeFn m2,
+@@ -318,3 +319,4 @@
+ #endif//DBUS_HAS_RECURSIVE_MUTEX
+   dbus_threads_init(&functions);
+ }
++#endif
-- 
2.26.2

[Buildroot] [PATCH] package/dbus-cpp: new patch to fix dbus c++ threading issue

[Thomas Petazzoni]

Hello Kamel,

On Mon,  6 Jul 2020 17:33:55 +0200
Kamel Bouhara <kamel.bouhara@bootlin.com> wrote:

> From: https://sourceforge.net/p/dbus-cplusplus/patches/18/
> 
> dispatcher.h has invalid template code. When DBUS_HAS_RECURSIVE_MUTEX is
> MutexFreeFn and MutexLockFn become of type void and the code is valid.
> See lines 232-235.
> However, when a user #includes dispatcher.h directly or indirectly the
> macro DBUS_HAS_RECURSIVE_MUTEX is undefined. This makes the above
> function pointers defined of type bool and but then _init_threading
> function call in line 259 becomes invalid, as it passes function
> pointers to mutex_free and mutex_lock which or of type void.
> 
> Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> ---
>  .../dbus-cpp/0004-dbus-c++-threading.patch    | 45 +++++++++++++++++++
>  1 file changed, 45 insertions(+)
>  create mode 100644 package/dbus-cpp/0004-dbus-c++-threading.patch
> 
> diff --git a/package/dbus-cpp/0004-dbus-c++-threading.patch b/package/dbus-cpp/0004-dbus-c++-threading.patch
> new file mode 100644
> index 0000000000..502320ad09
> --- /dev/null
> +++ b/package/dbus-cpp/0004-dbus-c++-threading.patch
> @@ -0,0 +1,45 @@

Thanks for your patch, but the patch itself needs a proper commit
title, commit description and Signed-off-by. See
https://buildroot.org/downloads/manual/manual.html#_format_and_licensing_of_the_package_patches.

Also, under what conditions does this build failure occurs ? We don't
have any build failures for the dbus-cpp package in our autobuilders.

Finally, it looks like Ubuntu or Debian have a 5.0.x version of
dbus-cpp, and we're at 0.9.0. It's really unclear what site really is
the official upstream for this project.

The SourceForge project points to a Gitorious Git repository, but
Gitorious has been shut down a few years ago. Then there is
https://github.com/lib-cpp/dbus-cpp, but is that the same project ?

Hm according to
https://www.freedesktop.org/wiki/Software/DBusBindings/, dbus-c++
(which we call dbus-cpp in Buildroot) is different from dbus-cpp. They
also say that dbus-c++ has been inactive since 2011, and shouldn't be
used.

Perhaps we should instead remove this package entirely ? Do you have
the possibility of moving to a properly maintained D-Bus C++ binding ?

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

[Buildroot] [PATCH] package/dbus-cpp: new patch to fix dbus c++ threading issue

[Kamel Bouhara]

On Sun, Jul 12, 2020 at 11:12:47AM +0200, Thomas Petazzoni wrote:
> Hello Kamel,
>

Hello Thomas,

> On Mon,  6 Jul 2020 17:33:55 +0200
> Kamel Bouhara <kamel.bouhara@bootlin.com> wrote:
>
> > From: https://sourceforge.net/p/dbus-cplusplus/patches/18/
> >
> > dispatcher.h has invalid template code. When DBUS_HAS_RECURSIVE_MUTEX is
> > MutexFreeFn and MutexLockFn become of type void and the code is valid.
> > See lines 232-235.
> > However, when a user #includes dispatcher.h directly or indirectly the
> > macro DBUS_HAS_RECURSIVE_MUTEX is undefined. This makes the above
> > function pointers defined of type bool and but then _init_threading
> > function call in line 259 becomes invalid, as it passes function
> > pointers to mutex_free and mutex_lock which or of type void.
> >
> > Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> > ---
> >  .../dbus-cpp/0004-dbus-c++-threading.patch    | 45 +++++++++++++++++++
> >  1 file changed, 45 insertions(+)
> >  create mode 100644 package/dbus-cpp/0004-dbus-c++-threading.patch
> >
> > diff --git a/package/dbus-cpp/0004-dbus-c++-threading.patch b/package/dbus-cpp/0004-dbus-c++-threading.patch
> > new file mode 100644
> > index 0000000000..502320ad09
> > --- /dev/null
> > +++ b/package/dbus-cpp/0004-dbus-c++-threading.patch
> > @@ -0,0 +1,45 @@
>
> Thanks for your patch, but the patch itself needs a proper commit
> title, commit description and Signed-off-by. See
> https://buildroot.org/downloads/manual/manual.html#_format_and_licensing_of_the_package_patches.
>

Ok.

> Also, under what conditions does this build failure occurs ? We don't
> have any build failures for the dbus-cpp package in our autobuilders.
>

Actually, I have an application that depends on dbus-c++ and fails with
the following errors:

...
In file included from .../buildroot/output/host/aarch64-buildroot-linux-gnu/sysroot/usr/include/dbus-c++-1/dbus-c++/server.h:34,
                 from .../buildroot/output/host/aarch64-buildroot-linux-gnu/sysroot/usr/include/dbus-c++-1/dbus-c++/dbus.h:33,
                 from src/DbusComm/DBusGlobal.h:3,
                 from src/DbusComm/DBusGlobal.cpp:1:
 .../buildroot/output/host/aarch64-buildroot-linux-gnu/sysroot/usr/include/dbus-c++-1/dbus-c++/dispatcher.h: In static member function ?static void DBus::Threading<Mx, Cv>::init()?:
 .../buildroot/output/host/aarch64-buildroot-linux-gnu/sysroot/usr/include/dbus-c++-1/dbus-c++/dispatcher.h:262:5: error: no matching function for call to ?_init_threading(DBus::Mutex* (&)(), void (&)(DBus::Mutex*), void (&)(DBus::Mutex*), void (&)(DBus::Mutex*), DBus::CondVar* (&)(), void (&)(DBus::CondVar*), void (&)(DBus::CondVar*, DBus::Mutex*), bool (&)(DBus::CondVar*, DBus::Mutex*, int), void (&)(DBus::CondVar*), void (&)(DBus::CondVar*))?
     );
     ^
 .../buildroot/output/host/aarch64-buildroot-linux-gnu/sysroot/usr/include/dbus-c++-1/dbus-c++/dispatcher.h:247:13: note: candidate: ?void DBus::_init_threading()?
 void DXXAPI _init_threading();
             ^~~~~~~~~~~~~~~
...

Which after some googling points me to the following thread:

https://sourceforge.net/p/dbus-cplusplus/patches/18/

The proposed patch applies to libdbus-c++ which is part of the dbus-cpp
package here. Applying this patch also fixed my application build issue.

> Finally, it looks like Ubuntu or Debian have a 5.0.x version of
> dbus-cpp, and we're at 0.9.0. It's really unclear what site really is
> the official upstream for this project.
>
> The SourceForge project points to a Gitorious Git repository, but
> Gitorious has been shut down a few years ago. Then there is
> https://github.com/lib-cpp/dbus-cpp, but is that the same project ?
>

Im completely agree but the sf project seems the more relevant.

> Hm according to
> https://www.freedesktop.org/wiki/Software/DBusBindings/, dbus-c++
> (which we call dbus-cpp in Buildroot) is different from dbus-cpp. They
> also say that dbus-c++ has been inactive since 2011, and shouldn't be
> used.
>
> Perhaps we should instead remove this package entirely ? Do you have
> the possibility of moving to a properly maintained D-Bus C++ binding ?
>

I have several modules of my application dependending on it yet.

Thanks.

> Thanks!
>
> Thomas
> --
> Thomas Petazzoni, CTO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

--
Kamel Bouhara, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com