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never retain a generator's caller's exception state on the generator after a yield/return

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This requires some trickery to properly save the exception state if the
generator creates its own exception state.
This commit is contained in:
Benjamin Peterson 2011-07-03 16:25:11 -05:00
parent 9cf960c94f
commit ac91341333
3 changed files with 51 additions and 4 deletions
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40
Python/ceval.c
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@ -1145,6 +1145,23 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
f->f_exc_traceback = tmp; \
}
#define RESTORE_AND_CLEAR_EXC_STATE() \
{ \
PyObject *type, *value, *tb; \
type = tstate->exc_type; \
value = tstate->exc_value; \
tb = tstate->exc_traceback; \
tstate->exc_type = f->f_exc_type; \
tstate->exc_value = f->f_exc_value; \
tstate->exc_traceback = f->f_exc_traceback; \
f->f_exc_type = NULL; \
f->f_exc_value = NULL; \
f->f_exc_traceback = NULL; \
Py_XDECREF(type); \
Py_XDECREF(value); \
Py_XDECREF(tb); \
}
/* Start of code */
if (f == NULL)
@ -3017,10 +3034,25 @@ fast_block_end:
retval = NULL;
fast_yield:
if (co->co_flags & CO_GENERATOR && (why == WHY_YIELD || why == WHY_RETURN))
/* Put aside the current exception state and restore that of the
calling frame. */
SWAP_EXC_STATE();
if (co->co_flags & CO_GENERATOR && (why == WHY_YIELD || why == WHY_RETURN)) {
/* The purpose of this block is to put aside the generator's exception
state and restore that of the calling frame. If the current
exception state is from the caller, we clear the exception values
on the generator frame, so they are not swapped back in latter. The
origin of the current exception state is determined by checking for
except handler blocks, which we must be in iff a new exception
state came into existence in this frame. (An uncaught exception
would have why == WHY_EXCEPTION, and we wouldn't be here). */
int i;
for (i = 0; i < f->f_iblock; i++)
if (f->f_blockstack[i].b_type == EXCEPT_HANDLER)
break;
if (i == f->f_iblock)
/* We did not create this exception. */
RESTORE_AND_CLEAR_EXC_STATE()
else
SWAP_EXC_STATE()
}
if (tstate->use_tracing) {
if (tstate->c_tracefunc) {