[lttng-dev] [RFC PATCH lttng-ust 2/2] dl instrumentation: add dlmopen event, trace dlopen flags

[Mathieu Desnoyers]

----- On Feb 21, 2017, at 4:03 AM, Thomas Petazzoni thomas.petazzoni at free-electrons.com wrote:

> Hello,
> 
> On Mon,  4 Jul 2016 18:53:48 -0400, Mathieu Desnoyers wrote:
>> Add missing dlmopen(3) instrumentation, and add the "flags" field to
>> dlopen instrumentation.
>> 
>> Link: http://man7.org/linux/man-pages/man3/dlopen.3.html
>> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
> 
> FYI, this commit (7b0fdd83c137bea1d7302df1a45252dfdccd8172) breaks the
> build with the musl C library, because it doesn't implement the
> dlmopen() extension.
> 
> Perhaps there should be an autoconf test to check if the C library
> provides dlmopen() functionality or not?

My expectation is that the dlmopen override symbol gets generated,
but it is never invoked in builds where the libc does not implement
it, so we never have to look it up dynamically through dlsym().

How does the build fail with musl ? Can you provide the build
output ?

Thanks,

Mathieu

> 
> Best regards,
> 
> Thomas Petazzoni
> --
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com