erl_trace.c

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	       && internal_pid_index(*tracer_pid) < erts_max_processes);
	
	tracer = erts_pid2proc(p, ERTS_PROC_LOCK_MAIN,
			       *tracer_pid, ERTS_PROC_LOCK_STATUS);
	if (!tracer)
	    invalid_tracer = 1;
	else {
	    invalid_tracer = (tracer->trace_flags & F_TRACER) == 0;
	    erts_smp_proc_unlock(tracer, ERTS_PROC_LOCK_STATUS);
	}

	if (invalid_tracer) {
#ifdef ERTS_SMP
	    ASSERT(is_nil(tracee) || tracer_pid == &p->tracer_proc);
	    if (is_not_nil(tracee))
		erts_smp_proc_lock(p, ERTS_PROC_LOCKS_ALL_MINOR);
#endif
	    *tracee_flags &= ~TRACEE_FLAGS;
	    *tracer_pid = NIL;
#ifdef ERTS_SMP
	    if (is_not_nil(tracee))
		erts_smp_proc_unlock(p, ERTS_PROC_LOCKS_ALL_MINOR);
#endif
	    return 0;
	}

#ifdef ERTS_SMP
	tpid = *tracer_pid; /* Need to save tracer pid,
			       since *tracer_pid might
			       be reset by erts_match_set_run() */
#endif
	
	/*
	 * If there is a PAM program, run it.  Return if it fails.
	 *
	 * See the rules above in the port trace code.
	 */
	
	/* BEGIN this code should be the same for port and pid trace */
	return_flags = 0;
	arity = mfa[2];
	if (match_spec) {
	    pam_result = erts_match_set_run(p, match_spec, args, arity,
					    &return_flags);
	    if (is_non_value(pam_result)) {
		erts_match_set_release_result(p);
		return 0;
	    }
	}
	if (tracee_flags == &meta_flags) {
	    /* Meta trace */
	    if (pam_result == am_false) {
		erts_match_set_release_result(p);
		return return_flags;
	    }
	} else {
	    /* Non-meta trace */
	    if (*tracee_flags & F_TRACE_SILENT) { 
		erts_match_set_release_result(p);
		return 0;
	    }
	    if (pam_result == am_false) {
		erts_match_set_release_result(p);
		return return_flags;
	    }
	    if (local && (*tracee_flags & F_TRACE_RETURN_TO)) {
		return_flags |= MATCH_SET_RETURN_TO_TRACE;
	    }
	}
	/* END this code should be the same for port and pid trace */
	
	/*
	 * Calculate number of words needed on heap.
	 */
	
	size = 4 + 5;		/* Trace tuple + MFA tuple. */
	if (! (*tracee_flags & F_TRACE_ARITY_ONLY)) {
	    size += 2*arity;
	    for (i = arity-1; i >= 0; i--) {
		sizes[i] = size_object(args[i]);
		size += sizes[i];
	    }
	}
	if (*tracee_flags & F_TIMESTAMP) {
	    size += 1 + 4;
	    /* One element in trace tuple + timestamp tuple. */
	}
	if (pam_result != am_true) {
	    pam_result_size = size_object(pam_result);
	    size += 1 + pam_result_size;
	    /* One element in trace tuple + term size. */
	}
	
#ifdef ERTS_SMP
	bp = new_message_buffer(size);
	hp = bp->mem;
	off_heap = &bp->off_heap;
#else
	hp = erts_alloc_message_heap(size, &bp, &off_heap, tracer, 0);
#endif
#ifdef DEBUG
	limit = hp + size;
#endif

	/*
	 * Build the the {M,F,A} tuple in the message buffer. 
	 * (A is arguments or arity.)
	 */
	
	if (*tracee_flags & F_TRACE_ARITY_ONLY) {
	    mfa_tuple = make_small(arity);
	} else {
	    mfa_tuple = NIL;
	    for (i = arity-1; i >= 0; i--) {
		Eterm term = copy_struct(args[i], sizes[i], &hp,
#ifdef ERTS_SMP
					 &bp->off_heap
#else
					 off_heap
#endif
);
		mfa_tuple = CONS(hp, term, mfa_tuple);
		hp += 2;
	    }
	}
	mfa_tuple = TUPLE3(hp, mfa[0], mfa[1], mfa_tuple);
	hp += 4;
	
	/*
	 * Copy the PAM result (if any) onto the heap.
	 */
	
	if (pam_result != am_true) {
	    pam_result = copy_struct(pam_result, pam_result_size, &hp, off_heap);
	}

	erts_match_set_release_result(p);

	/*
	 * Build the trace tuple and enqueue it.
	 */
	
	mess = TUPLE4(hp, am_trace, p->id/* Local pid */, am_call, mfa_tuple);
	hp += 5;
	if (pam_result != am_true) {
	    hp[-5] = make_arityval(5);
	    *hp++ = pam_result;
	}

	erts_smp_mtx_lock(&smq_mtx);

	if (*tracee_flags & F_TIMESTAMP) {
	    hp = patch_ts(mess, hp);
	}

	ASSERT(hp == limit);
#ifdef ERTS_SMP
	enqueue_sys_msg_unlocked(SYS_MSG_TYPE_TRACE, tracee, tpid, mess, bp);
	erts_smp_mtx_unlock(&smq_mtx);
#else
	erts_queue_message(tracer, 0, bp, mess, NIL);
#endif
	return return_flags;
    }
}

/* Sends trace message:
 *    {trace_ts, ProcessPid, What, Data, Timestamp}
 * or {trace, ProcessPid, What, Data}
 *
 * 'what' must be atomic, 'data' may be a deep term.
 * 'c_p' is the currently executing process, may be NULL.
 * 't_p' is the traced process.
 */
void
trace_proc(Process *c_p, Process *t_p, Eterm what, Eterm data)
{
    Eterm mess;
    Eterm* hp;
    int need;

    if (is_internal_port(t_p->tracer_proc)) {
	Eterm local_heap[5+5];
	hp = local_heap;
	mess = TUPLE4(hp, am_trace, t_p->id, what, data);
	hp += 5;
	erts_smp_mtx_lock(&smq_mtx);
	if (t_p->trace_flags & F_TIMESTAMP) {
	    hp = patch_ts(mess, hp);
	}
	send_to_port(
#ifndef ERTS_SMP
	    /* No fake schedule out and in again after an exit */
	    what == am_exit ? NULL : c_p,
#else
	    /* Fake schedule out and in are never sent when smp enabled */
	    c_p,
#endif
	    mess, &t_p->tracer_proc, &t_p->trace_flags);
	erts_smp_mtx_unlock(&smq_mtx);
    } else {
	Eterm tmp;
	ErlHeapFragment *bp;
	ErlOffHeap *off_heap;
#ifndef ERTS_SMP
	Process *tracer;
#endif
	size_t sz_data;

	ASSERT(is_internal_pid(t_p->tracer_proc)
	       && internal_pid_index(t_p->tracer_proc) < erts_max_processes);

#ifndef ERTS_SMP
	tracer = process_tab[internal_pid_index(t_p->tracer_proc)];
	if (INVALID_PID(tracer, t_p->tracer_proc)
	    || (tracer->trace_flags & F_TRACER) == 0) {
	    t_p->trace_flags &= ~TRACEE_FLAGS;
	    t_p->tracer_proc = NIL;
	    return;
	}
#endif

	sz_data = size_object(data);

	need = sz_data + 5 + TS_SIZE(t_p);

#ifdef ERTS_SMP
	bp = new_message_buffer(need);
	hp = bp->mem;
	off_heap = &bp->off_heap;
#else
	hp = erts_alloc_message_heap(need, &bp, &off_heap, tracer, 0);
#endif

	tmp = copy_struct(data, sz_data, &hp, off_heap);
	mess = TUPLE4(hp, am_trace, t_p->id/* Local pid */, what, tmp);
	hp += 5;

	erts_smp_mtx_lock(&smq_mtx);

	if (t_p->trace_flags & F_TIMESTAMP) {
	    hp = patch_ts(mess, hp);
	}

#ifdef ERTS_SMP
	enqueue_sys_msg_unlocked(SYS_MSG_TYPE_TRACE,
				 t_p->id, t_p->tracer_proc, mess, bp);
	erts_smp_mtx_unlock(&smq_mtx);
#else
	erts_queue_message(tracer, 0, bp, mess, NIL);
#endif
    }
}


/* Sends trace message:
 *    {trace_ts, ParentPid, spawn, ChildPid, {Mod, Func, Args}, Timestamp}
 * or {trace, ParentPid, spawn, ChildPid, {Mod, Func, Args}}
 *
 * 'pid' is the ChildPid, 'mod' and 'func' must be atomic,
 * and 'args' may be a deep term.
 */
void
trace_proc_spawn(Process *p, Eterm pid, 
		 Eterm mod, Eterm func, Eterm args)
{
    Eterm mfa;
    Eterm mess;
    Eterm* hp;

    if (is_internal_port(p->tracer_proc)) {
	Eterm local_heap[4+6+5];
	hp = local_heap;
	mfa = TUPLE3(hp, mod, func, args);
	hp += 4;
	mess = TUPLE5(hp, am_trace, p->id, am_spawn, pid, mfa);
	hp += 6;
	erts_smp_mtx_lock(&smq_mtx);
	if (p->trace_flags & F_TIMESTAMP) {
	    hp = patch_ts(mess, hp);
	}
	send_to_port(p, mess, &p->tracer_proc, &p->trace_flags);
	erts_smp_mtx_unlock(&smq_mtx);
    } else {
	Eterm tmp;
	ErlHeapFragment *bp;
	ErlOffHeap *off_heap;
#ifndef ERTS_SMP
	Process *tracer;
#endif
	size_t sz_args, sz_pid;
	Uint need;

	ASSERT(is_internal_pid(p->tracer_proc)
	       && internal_pid_index(p->tracer_proc) < erts_max_processes);

#ifndef ERTS_SMP
	tracer = process_tab[internal_pid_index(p->tracer_proc)];
	if (INVALID_PID(tracer, p->tracer_proc)
	    || (tracer->trace_flags & F_TRACER) == 0) {
	    p->trace_flags &= ~TRACEE_FLAGS;
	    p->tracer_proc = NIL;
	    return;
	}
#endif

	sz_args = size_object(args);
	sz_pid = size_object(pid);
	need = sz_args + 4 + 6 + TS_SIZE(p);
#ifdef ERTS_SMP
	bp = new_message_buffer(need);
	hp = bp->mem;
	off_heap = &bp->off_heap;
#else
	hp = erts_alloc_message_heap(need, &bp, &off_heap, tracer, 0);
#endif

	tmp = copy_struct(args, sz_args, &hp, off_heap);
	mfa = TUPLE3(hp, mod, func, tmp);
	hp += 4;
	tmp = copy_struct(pid, sz_pid, &hp, off_heap);
	mess = TUPLE5(hp, am_trace, p->id, am_spawn, tmp, mfa);
	hp += 6;

	erts_smp_mtx_lock(&smq_mtx);

	if (p->trace_flags & F_TIMESTAMP) {
	    hp = patch_ts(mess, hp);
	}

#ifdef ERTS_SMP
	enqueue_sys_msg_unlocked(SYS_MSG_TYPE_TRACE,
				 p->id, p->tracer_proc, mess, bp);
	erts_smp_mtx_unlock(&smq_mtx);
#else
	erts_queue_message(tracer, 0, bp, mess, NIL);
#endif
    }
}

void save_calls(Process *p, Export *e)
{
   if (p->ct) {
     Export **ct = &p->ct->ct[0];
     int len = p->ct->len;

     ct[p->ct->cur] = e;
     if (++p->ct->cur >= len) {
       p->ct->cur = 0;
     }
     if (p->ct->n < len) {
       p->ct->n++;
     }
   }
}

/* 
 * Entry point called by the trace wrap functions in erl_bif_wrap.c
 *
 * The trace wrap functions are themselves called through the export
 * entries instead of the original BIF functions.
 */
Eterm
erts_bif_trace(int bif_index, Process* p, 
	       Eterm arg1, Eterm arg2, Eterm arg3, Uint *I)
{
    Eterm result;
    int meta = !!(erts_bif_trace_flags[bif_index] & BIF_TRACE_AS_META);

    ERTS_CHK_HAVE_ONLY_MAIN_PROC_LOCK(p->id);

    if (!ARE_TRACE_FLAGS_ON(p, F_TRACE_CALLS) && (! meta)) {
	/* Warning! This is an Optimization. 
	 *
	 * If neither meta trace is active nor process trace flags then 
	 * no tracing will occur. Doing the whole else branch will 
	 * also do nothing, only slower.
	 */
	Eterm (*func)(Process*, Eterm, Eterm, Eterm, Uint*) = bif_table[bif_index].f;
	result = func(p, arg1, arg2, arg3, I);
    } else {
	Eterm (*func)(Process*, Eterm, Eterm, Eterm, Uint*);
	Export* ep = bif_export[bif_index];
	Uint32 flags = 0, flags_meta = 0;
	int global = !!(erts_bif_trace_flags[bif_index] & BIF_TRACE_AS_GLOBAL);
	int local  = !!(erts_bif_trace_flags[bif_index] & BIF_TRACE_AS_LOCAL);
	Eterm meta_tracer_pid = NIL;
	int applying = (I == &(ep->code[3])); /* Yup, the apply code for a bif
					       * is actually in the 
					       * export entry */
	Eterm *cp = p->cp;
	
#ifndef _OSE_
	Eterm args[3] = {arg1, arg2, arg3};
#else
	Eterm args[3];
	args[0] = arg1;
	args[1] = arg2;
	args[2] = arg3;
#endif
	
	/* 
	 * Make continuation pointer OK, it is not during direct BIF calls,
	 * but it is correct during apply of bif.
	 */
	if (!applying) { 
	    p->cp = I;
	}
	if (global || local) {
	    flags = erts_call_trace(p, ep->code, ep->match_prog_set, args, 
				       local, &p->tracer_proc);
	}
	if (meta) {
	    flags_meta = erts_bif_mtrace(p, ep->code+3, args, local, 
					 &meta_tracer_pid);
	}
	/* Restore original continuation pointer (if changed). */
	p->cp = cp;
	
	func = bif_table[bif_index].f;

	result = func(p, arg1, arg2, arg3, I);
	
	if (applying && (flags & MATCH_SET_RETURN_TO_TRACE)) {
	    Uint i_return_trace = beam_return_trace[0];
	    Uint i_return_to_trace = beam_return_to_trace[0];
	    Eterm *cpp;
	    /* Maybe advance cp to skip trace stack frames */
	    for (cpp = p->stop;  ;  cp = cp_val(*cpp++)) {
		ASSERT(is_CP((Eterm) cp));
		if (*cp_val((Eterm) cp) == i_return_trace) {
		    /* Skip stack frame variables */
		    while (is_not_CP(*cpp)) cpp++;
		    cpp += 2; /* Skip return_trace parameters */
		} else if (*cp_val((Eterm) cp) == i_return_to_trace) {
		    /* A return_to trace message is going to be generated
		     * by normal means, so we do not have to.
		     */
		    cp = NULL;
		    break;
		} else break;
	    }
	}
	
	/* Try to get these in the order 
	 * they usually appear in normal code... */
	if (is_non_value(result)) {
	    Uint reason = p->freason;
	    if (reason != TRAP && reason != RESCHEDULE) {
		Eterm class;
		Eterm value = p->fvalue;
		Eterm nocatch[3];
		/* Expand error value like in handle_error() */
		if (reason & EXF_ARGLIST) {
		    Eterm *tp;
		    ASSERT(is_tuple(value));
		    tp = tuple_val(value);
		    value = tp[1];
		}
		if ((reason & EXF_THROWN) && (p->catches <= 0)) {
		    value = TUPLE2(nocatch, am_nocatch, value);
		    reason = EXC_ERROR;
		}
		/* Note: expand_error_value() could theoretically 
		 * allocate on the heap, but not for any error
		 * returned by a BIF, and it would do no harm,
		 * just be annoying.
		 */
		value = expand_error_value(p, reason, value);
		class = exception_tag[GET_EXC_CLASS(reason)];
		
		if (flags_meta & MATCH_SET_EXCEPTION_TRACE) {
		    erts_trace_exception(p, ep->code, class, value,
					 &meta_tracer_pid);
		}
		if (flags & MATCH_SET_EXCEPTION_TRACE) {
		    erts_trace_exception(p, ep->code, class, value,
					 &p->tracer_proc);
		}
		if ((flags & MATCH_SET_RETURN_TO_TRACE) && p->catches > 0) {
		    /* can only happen if(local)*/
		    Eterm *ptr = p->stop;
		    ASSERT(is_CP(*ptr));
		    ASSERT(ptr <= STACK_START(p));
		    /* Search the nearest stack frame for a catch */
		    while (++ptr < STACK_START(p)) {
			if (is_CP(*ptr)) break;
			if (is_catch(*ptr)) {
			    if (applying) {
				/* Apply of BIF, cp is in calling function */
				if (cp) erts_trace_return_to(p, cp);
			    } else {
				/* Direct bif call, I points into 
				 * calling function */
				erts_trace_return_to(p, I);
			    }
			}
		    }
		}
		if ((flags_meta|flags) & MATCH_SET_EXCEPTION_TRACE) {
		    erts_smp_proc_lock(p, ERTS_PROC_LOCKS_ALL_MINOR);
		    p->trace_flags |= F_EXCEPTION_TRACE;
		    erts_smp_proc_unlock(p, ERTS_PROC_LOCKS_ALL_MINOR);
		}
	    }
	} else {
	    if (flags_meta & MATCH_SET_RX_TRACE) {
		erts_trace_return(p, ep->code, result, &meta_tracer_pid);
	    }
	    /* MATCH_SET_RETURN_TO_TRACE cannot occur if(meta) */
	    if (flags & MATCH_SET_RX_TRACE) {
		erts_trace_return(p, ep->code, result, &p->tracer_proc);
	    }
	    if (flags & MATCH_SET_RETURN_TO_TRACE) { 
		/* can only happen if(local)*/
		if (applying) {
		    /* Apply of BIF, cp is in calling function */
		    if (cp) erts_trace_return_to(p, cp);
		} else {
		    /* Direct bif call, I points into calling function */
		    erts_trace_return_to(p, I);
		}
	    }
	}