homepage

The proposed patch fixes the problem:
* f_lineno cannot be set now from an exception trace function or from a return
 trace function.
* The broken arithmetic involving a null pointer (f->f_stacktop, at the end of
 frame_setlineno when popping blocks that are being jumped from and the
 function is invoked from an exception trace function or a return trace
 function), is fixed now.
* Blocks cannot be popped now in frame_setlineno (the cause of the crash) when
 tracing a yield.
To summarize the proposed fixes on f_lineno accessors:
* setter: f_lineno can only be set in the frame that is being traced (issue
 17277) and from within a line trace function (current issue).
* getter: f_lineno is valid in the frame being traced (issue 17277) and:
 + not from within a call trace function (i.e. when f->f_trace == NULL)
 + from within a line trace function
 + and from within an exception or return trace function. There is a corner
 case here when returning to a frame that was not being traced previously
 (its f_lineno is not valid) and that has had its local trace function
 f_trace set from within a trace function in one of its callees (the fix of
 issue 13183 does that) and when the first trace function invoked on
 returning to that frame is an exception or a return trace function: this is
 correctly handled by the f_trace setter that makes sure that f_lineno is
 accurate when setting f_trace (and an extension module implementing tracing,
 must ensure that f_lineno is accurate when setting f_trace).