[Ltrace-devel] Getting prototypes from debug information

[Dima Kogan]

Petr Machata <pmachata at redhat.com> writes:

>>> -e traces PLT calls (i.e. inter-library calls), -x traces symbol entry
>>> points.  -l traces PLT calls done to a symbol defined by a library in
>>> -l.
>>
>> Can we add this to the manpage? I don't feel qualified to do this myself
>> yet.
>
> How about this?
>
> diff --git a/ltrace.1 b/ltrace.1
> index f683844..93032f2 100644
> --- a/ltrace.1
> +++ b/ltrace.1
> @@ -122,11 +122,13 @@ describing which debug messages should be displayed.  Use the option
>  \-Dh to see what can be used, but note that currently the only
>  reliable debugmask is 77, which shows all debug messages.
>  .IP "\-e \fIfilter"
> -A qualifying expression which modifies which library calls to trace.
> -The format of the filter expression is described in the section
> -\fBFILTER EXPRESSIONS\fR.  If more than one \-e option appears on the
> -command line, the library calls that match any of them are traced.  If
> -no \-e is given, \fB at MAIN\fR is assumed as a default.
> +A qualifying expression which modifies which library calls (i.e. calls
> +done through PLT slots, which are typically calls from the main binary
> +to a library, or inter-library calls) to trace.  The format of the
> +filter expression is described in the section \fBFILTER
> +EXPRESSIONS\fR.  If more than one \-e option appears on the command
> +line, the library calls that match any of them are traced.  If no \-e
> +is given, \fB at MAIN\fR is assumed as a default.
>  .IP \-f
>  Trace child processes as they are created by
>  currently traced processes as a result of the fork(2)
> @@ -145,6 +147,9 @@ Print the instruction pointer at the time of the library call.
>  .IP "\-l, \-\-library \fIlibrary_pattern"
>  Display only calls to functions implemented by libraries that match
>  .I library_pattern.
> +This is as if you specified one \-e for every symbol implemented in a
> +library specified by
> +.I library_pattern.
>  Multiple library patters can be specified with several instances of
>  this option.  Syntax of library_pattern is described in section
>  \fBFILTER EXPRESSIONS\fR.
> @@ -200,10 +205,12 @@ option enabled only if elfutils or libunwind support was enabled at compile
>  time.
>  .IP "\-x \fIfilter"
>  A qualifying expression which modifies which symbol table entry points
> -to trace.  The format of the filter expression is described in the
> -section \fBFILTER EXPRESSIONS\fR.  If more than one \-x option appears
> -on the command line, the symbols that match any of them are traced.
> -No entry points are traced if no \-x is given.
> +to trace (those are typically calls inside a library or main binary,
> +though PLT calls, traced by \-e, land on entry points as well).  The
> +format of the filter expression is described in the section \fBFILTER
> +EXPRESSIONS\fR.  If more than one \-x option appears on the command
> +line, the symbols that match any of them are traced.  No entry points
> +are traced if no \-x is given.
>  .IP "\-V, \-\-version"
>  Show the version number of ltrace and exit.

Sure, that's much better than what was there before. I think a little
example would be ideal here. I might add one when I'm done with the
DWARF stuff. Hopefully I'll get to that today...