diff options
Diffstat (limited to 'Objects/frameobject.c')
| -rw-r--r-- | Objects/frameobject.c | 39 |
1 files changed, 35 insertions, 4 deletions
diff --git a/Objects/frameobject.c b/Objects/frameobject.c index bf1c7c5..1758745 100644 --- a/Objects/frameobject.c +++ b/Objects/frameobject.c @@ -89,6 +89,9 @@ frame_getlineno(PyFrameObject *f, void *closure) * o 'try'/'for'/'while' blocks can't be jumped into because the blockstack * needs to be set up before their code runs, and for 'for' loops the * iterator needs to be on the stack. + * o Jumps cannot be made from within a trace function invoked with a + * 'return' or 'exception' event since the eval loop has been exited at + * that time. */ static int frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno) @@ -122,13 +125,32 @@ frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno) return -1; } + /* Upon the 'call' trace event of a new frame, f->f_lasti is -1 and + * f->f_trace is NULL, check first on the first condition. + * Forbidding jumps from the 'call' event of a new frame is a side effect + * of allowing to set f_lineno only from trace functions. */ + if (f->f_lasti == -1) { + PyErr_Format(PyExc_ValueError, + "can't jump from the 'call' trace event of a new frame"); + return -1; + } + /* You can only do this from within a trace function, not via * _getframe or similar hackery. */ - if (!f->f_trace) - { + if (!f->f_trace) { PyErr_Format(PyExc_ValueError, - "f_lineno can only be set by a" - " line trace function"); + "f_lineno can only be set by a trace function"); + return -1; + } + + /* Forbid jumps upon a 'return' trace event (except after executing a + * YIELD_VALUE opcode, f_stacktop is not NULL in that case) and upon an + * 'exception' trace event. + * Jumps from 'call' trace events have already been forbidden above for new + * frames, so this check does not change anything for 'call' events. */ + if (f->f_stacktop == NULL) { + PyErr_SetString(PyExc_ValueError, + "can only jump from a 'line' trace event"); return -1; } @@ -178,6 +200,15 @@ frame_setlineno(PyFrameObject *f, PyObject* p_new_lineno) min_addr = MIN(new_lasti, f->f_lasti); max_addr = MAX(new_lasti, f->f_lasti); + /* The trace function is called with a 'return' trace event after the + * execution of a yield statement. */ + assert(f->f_lasti != -1); + if (code[f->f_lasti] == YIELD_VALUE) { + PyErr_SetString(PyExc_ValueError, + "can't jump from a yield statement"); + return -1; + } + /* You can't jump onto a line with an 'except' statement on it - * they expect to have an exception on the top of the stack, which * won't be true if you jump to them. They always start with code |