Archive for March, 2011

Handling unit test with C++ visibility=hidden

Recently I started working on the libbash project. I will write several articles talking about it in future. Now I’d just like to write something about the problem we encountered during development.

Our project will be a shared library. The C++ visibility support could improve the overall performance. Put simply, it hides most of the ELF symbols which would have previously (and unnecessarily) been public. Well it’s good for the library, it’s not good for unit tests(namely gtest) because they need to know the symbols.

Of course we don’t want  the unit tests to be part of our library. So we need to find some way to let the unit test know the symbols and separate them into different automake targets. Our first solution is to use hidden visibility for the library and create an internal target with default visibility for the unit test. However, that requires compiling the source code twice. Finally Petteri Räty come with a solution (He is too busy to write a post :P):

libcppbash_la_SOURCES = blah
libcppbash_la_CXXFLAGS = $(AM_CXXFLAGS) -fvisibility=hidden -fvisibility-inlines-hidden

cppunittests_SOURCES = blah
cppunittests_LDADD = $(GTEST_LIBS)
cppunittests_LDFLAGS = -static

Here’s his explanation:
libtool by default builds both a shared and a static library for our project. This is why you see it building things twice (with PIC and without). Giving -static to libtool is just telling it to use the static version. Using the static version means everything ends up in the unit test binaries.


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Gentoo NetworkManager Plug-in now supports non-alnum SSID

For a long time, we can’t use non-alnum SSID for system connections when ifnet is enabled. For example, when you have an SSID named “foo bar”, ifnet plug-in will write this into /etc/conf.d/net:
config_foo bar=(…)
And this will break baselayout or openrc because space is not allowed in variable name.

But now you can specify any SSID you want, the plug-in will handle it transparently. Here’s how it works:
When an non-alnum SSID is specified, ifnet plug-in will transform it to the equivalent hex format. For example, you have the SSID “foo bar”, the following will be written to /etc/conf.dnet:
config_0x666F6F20626172=( “dhcp” )
Meanwhile, the name displayed in nm-applet will be transformed to printable characters.

Thanks to  William L. Thomson Jr’s help in Bug #356337.

PS: What is non-alnum? man isalnum