[dtrace-discuss] Accessing variables in shared libraries

[Nicolas Williams]

On Mon, Jul 02, 2007 at 12:40:58PM -0700, Seth Goldberg wrote:
> dtrace: failed to compile script ./tt.d: line 6: floating-point constants are not permitted

IIRC DTrace doesn't support floating point types.

> dtrace: failed to compile script ./tt.d: line 6: failed to resolve set_lock_count: Unknown variable name
> 
>   What am I doing wrong?  Can libraries (with dots) not be used as
>   scope-resolution entities?

DTrace has no knowledge of variables and types in user-land.  Instead
you have to use copyin() and friends and casts.  The result isn't very
pretty, but it works.  I think one could add a function or operator that
interprets simple expressions in the context of the user-land process to
which the given pid provider probe refers; the expression would have to
be compiled in user-land when the provider is opened and translated into
a corresponding set of D expressions that copyin stuff as needed and
which get shoved into the actul probe body.  But that sounds like a
non-trivial project.

Nico
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