On Fri, 4 Feb 2022, Andrii Nakryiko wrote:
> On Mon, Jan 31, 2022 at 8:13 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote:
> >
> > Now that u[ret]probes can use name-based specification, it makes
> > sense to add support for auto-attach based on SEC() definition.
> > The format proposed is
> >
> > SEC("u[ret]probe//path/to/prog:[raw_offset|[function_name[+offset]]")
> >
> > For example, to trace malloc() in libc:
> >
> > SEC("uprobe//usr/lib64/libc.so.6:malloc")
>
> I assume that path to library can be relative path as well, right?
>
> Also, should be look at trying to locate library in the system if it's
> specified as "libc"? Or if the binary is "bash", for example. Just
> bringing this up, because I think it came up before in the context of
> one of libbpf-tools.
>
This is a great suggestion for usability, but I'm trying to puzzle
out how to carry out the location search for cases where the path
specified is not a relative or absolute path.
A few things we can can do - use search paths from PATH and
LD_LIBRARY_PATH, with an appended set of standard locations
such as /usr/bin, /usr/sbin for cases where those environment
variables are missing or incomplete.
However, when it comes to libraries, do we search in /usr/lib64 or
/usr/lib? We could use whether the version of libbpf is 64-bit or not I
suppose, but it's at least conceivable that the user might want to
instrument a 32-bit library from a 64-bit libbpf. Do you think that
approach is sufficient, or are there other things we should do? Thanks!
Alan
