frameobject.c

/* Frame object implementation */

#include"Python.h"

#include"code.h"
#include"frameobject.h"
#include"opcode.h"
#include"structmember.h"

#undef MIN
#undef MAX
#defineMIN(a, b) ((a) < (b) ? (a) : (b))
#defineMAX(a, b) ((a) > (b) ? (a) : (b))

#defineOFF(x) offsetof(PyFrameObject, x)

staticPyMemberDefframe_memberlist[] = {
 {"f_back", T_OBJECT, OFF(f_back), RO},
 {"f_code", T_OBJECT, OFF(f_code), RO},
 {"f_builtins", T_OBJECT, OFF(f_builtins),RO},
 {"f_globals", T_OBJECT, OFF(f_globals), RO},
 {"f_lasti", T_INT, OFF(f_lasti), RO},
 {NULL} /* Sentinel */
};

#defineWARN_GET_SET(NAME) \
static PyObject * frame_get_ ## NAME(PyFrameObject *f) { \
 if (PyErr_WarnPy3k(#NAME " has been removed in 3.x", 2) < 0) \
 return NULL; \
 if (f->NAME) { \
 Py_INCREF(f->NAME); \
 return f->NAME; \
 } \
 Py_RETURN_NONE; \
} \
static int frame_set_ ## NAME(PyFrameObject *f, PyObject *new) { \
 if (PyErr_WarnPy3k(#NAME " has been removed in 3.x", 2) < 0) \
 return -1; \
 if (f->NAME) { \
 Py_CLEAR(f->NAME); \
 } \
 if (new == Py_None) \
 new = NULL; \
 Py_XINCREF(new); \
 f->NAME = new; \
 return 0; \
}


WARN_GET_SET(f_exc_traceback)
WARN_GET_SET(f_exc_type)
WARN_GET_SET(f_exc_value)


staticPyObject*
frame_getlocals(PyFrameObject*f, void*closure)
{
PyFrame_FastToLocals(f);
Py_INCREF(f->f_locals);
returnf->f_locals;
}

int
PyFrame_GetLineNumber(PyFrameObject*f)
{
if (f->f_trace)
returnf->f_lineno;
else
returnPyCode_Addr2Line(f->f_code, f->f_lasti);
}

staticPyObject*
frame_getlineno(PyFrameObject*f, void*closure)
{
returnPyInt_FromLong(PyFrame_GetLineNumber(f));
}

/* Setter for f_lineno - you can set f_lineno from within a trace function in
 * order to jump to a given line of code, subject to some restrictions. Most
 * lines are OK to jump to because they don't make any assumptions about the
 * state of the stack (obvious because you could remove the line and the code
 * would still work without any stack errors), but there are some constructs
 * that limit jumping:
 *
 * o Lines with an 'except' statement on them can't be jumped to, because
 * they expect an exception to be on the top of the stack.
 * o Lines that live in a 'finally' block can't be jumped from or to, since
 * the END_FINALLY expects to clean up the stack after the 'try' block.
 * 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.
 */
staticint
frame_setlineno(PyFrameObject*f, PyObject*p_new_lineno)
{
intnew_lineno=0; /* The new value of f_lineno */
intnew_lasti=0; /* The new value of f_lasti */
intnew_iblock=0; /* The new value of f_iblock */
unsigned char*code=NULL; /* The bytecode for the frame... */
Py_ssize_tcode_len=0; /* ...and its length */
unsigned char*lnotab=NULL; /* Iterating over co_lnotab */
Py_ssize_tlnotab_len=0; /* (ditto) */
intoffset=0; /* (ditto) */
intline=0; /* (ditto) */
intaddr=0; /* (ditto) */
intmin_addr=0; /* Scanning the SETUPs and POPs */
intmax_addr=0; /* (ditto) */
intdelta_iblock=0; /* (ditto) */
intmin_delta_iblock=0; /* (ditto) */
intmin_iblock=0; /* (ditto) */
intf_lasti_setup_addr=0; /* Policing no-jump-into-finally */
intnew_lasti_setup_addr=0; /* (ditto) */
intblockstack[CO_MAXBLOCKS]; /* Walking the 'finally' blocks */
intin_finally[CO_MAXBLOCKS]; /* (ditto) */
intblockstack_top=0; /* (ditto) */
unsigned charsetup_op=0; /* (ditto) */

if (p_new_lineno==NULL) {
PyErr_SetString(PyExc_AttributeError, "cannot delete attribute");
return-1;
 }
/* f_lineno must be an integer. */
if (!PyInt_Check(p_new_lineno)) {
PyErr_SetString(PyExc_ValueError,
"lineno must be an integer");
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) {
PyErr_Format(PyExc_ValueError,
"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;
 }

/* Fail if the line comes before the start of the code block. */
new_lineno= (int) PyInt_AsLong(p_new_lineno);
if (new_lineno<f->f_code->co_firstlineno) {
PyErr_Format(PyExc_ValueError,
"line %d comes before the current code block",
new_lineno);
return-1;
 }
elseif (new_lineno==f->f_code->co_firstlineno) {
new_lasti=0;
new_lineno=f->f_code->co_firstlineno;
 }
else {
/* Find the bytecode offset for the start of the given
 * line, or the first code-owning line after it. */
char*tmp;
PyString_AsStringAndSize(f->f_code->co_lnotab,
&tmp, &lnotab_len);
lnotab= (unsigned char*) tmp;
addr=0;
line=f->f_code->co_firstlineno;
new_lasti=-1;
for (offset=0; offset<lnotab_len; offset+=2) {
addr+=lnotab[offset];
line+=lnotab[offset+1];
if (line >= new_lineno) {
new_lasti=addr;
new_lineno=line;
break;
 }
 }
 }

/* If we didn't reach the requested line, return an error. */
if (new_lasti==-1) {
PyErr_Format(PyExc_ValueError,
"line %d comes after the current code block",
new_lineno);
return-1;
 }

/* We're now ready to look at the bytecode. */
PyString_AsStringAndSize(f->f_code->co_code, (char**)&code, &code_len);
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
 * that either pops the exception using POP_TOP (plain 'except:'
 * lines do this) or duplicates the exception on the stack using
 * DUP_TOP (if there's an exception type specified). See compile.c,
 * 'com_try_except' for the full details. There aren't any other
 * cases (AFAIK) where a line's code can start with DUP_TOP or
 * POP_TOP, but if any ever appear, they'll be subject to the same
 * restriction (but with a different error message). */
if (code[new_lasti] ==DUP_TOP||code[new_lasti] ==POP_TOP) {
PyErr_SetString(PyExc_ValueError,
"can't jump to 'except' line as there's no exception");
return-1;
 }

/* You can't jump into or out of a 'finally' block because the 'try'
 * block leaves something on the stack for the END_FINALLY to clean
 * up. So we walk the bytecode, maintaining a simulated blockstack.
 * When we reach the old or new address and it's in a 'finally' block
 * we note the address of the corresponding SETUP_FINALLY. The jump
 * is only legal if neither address is in a 'finally' block or
 * they're both in the same one. 'blockstack' is a stack of the
 * bytecode addresses of the SETUP_X opcodes, and 'in_finally' tracks
 * whether we're in a 'finally' block at each blockstack level. */
f_lasti_setup_addr=-1;
new_lasti_setup_addr=-1;
memset(blockstack, '\0', sizeof(blockstack));
memset(in_finally, '\0', sizeof(in_finally));
blockstack_top=0;
for (addr=0; addr<code_len; addr++) {
unsigned charop=code[addr];
switch (op) {
caseSETUP_LOOP:
caseSETUP_EXCEPT:
caseSETUP_FINALLY:
caseSETUP_WITH:
blockstack[blockstack_top++] =addr;
in_finally[blockstack_top-1] =0;
break;

casePOP_BLOCK:
assert(blockstack_top>0);
setup_op=code[blockstack[blockstack_top-1]];
if (setup_op==SETUP_FINALLY||setup_op==SETUP_WITH) {
in_finally[blockstack_top-1] =1;
 }
else {
blockstack_top--;
 }
break;

caseEND_FINALLY:
/* Ignore END_FINALLYs for SETUP_EXCEPTs - they exist
 * in the bytecode but don't correspond to an actual
 * 'finally' block. (If blockstack_top is 0, we must
 * be seeing such an END_FINALLY.) */
if (blockstack_top>0) {
setup_op=code[blockstack[blockstack_top-1]];
if (setup_op==SETUP_FINALLY||setup_op==SETUP_WITH) {
blockstack_top--;
 }
 }
break;
 }

/* For the addresses we're interested in, see whether they're
 * within a 'finally' block and if so, remember the address
 * of the SETUP_FINALLY. */
if (addr==new_lasti||addr==f->f_lasti) {
inti=0;
intsetup_addr=-1;
for (i=blockstack_top-1; i >= 0; i--) {
if (in_finally[i]) {
setup_addr=blockstack[i];
break;
 }
 }

if (setup_addr!=-1) {
if (addr==new_lasti) {
new_lasti_setup_addr=setup_addr;
 }

if (addr==f->f_lasti) {
f_lasti_setup_addr=setup_addr;
 }
 }
 }

if (op >= HAVE_ARGUMENT) {
addr+=2;
 }
 }

/* Verify that the blockstack tracking code didn't get lost. */
assert(blockstack_top==0);

/* After all that, are we jumping into / out of a 'finally' block? */
if (new_lasti_setup_addr!=f_lasti_setup_addr) {
PyErr_SetString(PyExc_ValueError,
"can't jump into or out of a 'finally' block");
return-1;
 }


/* Police block-jumping (you can't jump into the middle of a block)
 * and ensure that the blockstack finishes up in a sensible state (by
 * popping any blocks we're jumping out of). We look at all the
 * blockstack operations between the current position and the new
 * one, and keep track of how many blocks we drop out of on the way.
 * By also keeping track of the lowest blockstack position we see, we
 * can tell whether the jump goes into any blocks without coming out
 * again - in that case we raise an exception below. */
delta_iblock=0;
for (addr=min_addr; addr<max_addr; addr++) {
unsigned charop=code[addr];
switch (op) {
caseSETUP_LOOP:
caseSETUP_EXCEPT:
caseSETUP_FINALLY:
caseSETUP_WITH:
delta_iblock++;
break;

casePOP_BLOCK:
delta_iblock--;
break;
 }

min_delta_iblock=MIN(min_delta_iblock, delta_iblock);

if (op >= HAVE_ARGUMENT) {
addr+=2;
 }
 }

/* Derive the absolute iblock values from the deltas. */
min_iblock=f->f_iblock+min_delta_iblock;
if (new_lasti>f->f_lasti) {
/* Forwards jump. */
new_iblock=f->f_iblock+delta_iblock;
 }
else {
/* Backwards jump. */
new_iblock=f->f_iblock-delta_iblock;
 }

/* Are we jumping into a block? */
if (new_iblock>min_iblock) {
PyErr_SetString(PyExc_ValueError,
"can't jump into the middle of a block");
return-1;
 }

/* Pop any blocks that we're jumping out of. */
while (f->f_iblock>new_iblock) {
PyTryBlock*b=&f->f_blockstack[--f->f_iblock];
while ((f->f_stacktop-f->f_valuestack) >b->b_level) {
PyObject*v= (*--f->f_stacktop);
Py_DECREF(v);
 }
if (b->b_type==SETUP_WITH) {
/* Pop the exit function. */
PyObject*v= (*--f->f_stacktop);
Py_DECREF(v);
 }
 }

/* Finally set the new f_lineno and f_lasti and return OK. */
f->f_lineno=new_lineno;
f->f_lasti=new_lasti;
return0;
}

staticPyObject*
frame_gettrace(PyFrameObject*f, void*closure)
{
PyObject*trace=f->f_trace;

if (trace==NULL)
trace=Py_None;

Py_INCREF(trace);

returntrace;
}

staticint
frame_settrace(PyFrameObject*f, PyObject*v, void*closure)
{
/* We rely on f_lineno being accurate when f_trace is set. */
f->f_lineno=PyFrame_GetLineNumber(f);

if (v==Py_None)
v=NULL;
Py_XINCREF(v);
Py_XSETREF(f->f_trace, v);

return0;
}

staticPyObject*
frame_getrestricted(PyFrameObject*f, void*closure)
{
returnPyBool_FromLong(PyFrame_IsRestricted(f));
}

staticPyGetSetDefframe_getsetlist[] = {
 {"f_locals", (getter)frame_getlocals, NULL, NULL},
 {"f_lineno", (getter)frame_getlineno,
 (setter)frame_setlineno, NULL},
 {"f_trace", (getter)frame_gettrace, (setter)frame_settrace, NULL},
 {"f_restricted",(getter)frame_getrestricted,NULL, NULL},
 {"f_exc_traceback", (getter)frame_get_f_exc_traceback,
 (setter)frame_set_f_exc_traceback, NULL},
 {"f_exc_type", (getter)frame_get_f_exc_type,
 (setter)frame_set_f_exc_type, NULL},
 {"f_exc_value", (getter)frame_get_f_exc_value,
 (setter)frame_set_f_exc_value, NULL},
 {0}
};

/* Stack frames are allocated and deallocated at a considerable rate.
 In an attempt to improve the speed of function calls, we:

 1. Hold a single "zombie" frame on each code object. This retains
 the allocated and initialised frame object from an invocation of
 the code object. The zombie is reanimated the next time we need a
 frame object for that code object. Doing this saves the malloc/
 realloc required when using a free_list frame that isn't the
 correct size. It also saves some field initialisation.

 In zombie mode, no field of PyFrameObject holds a reference, but
 the following fields are still valid:

 * ob_type, ob_size, f_code, f_valuestack;

 * f_locals, f_trace,
 f_exc_type, f_exc_value, f_exc_traceback are NULL;

 * f_localsplus does not require re-allocation and
 the local variables in f_localsplus are NULL.

 2. We also maintain a separate free list of stack frames (just like
 integers are allocated in a special way -- see intobject.c). When
 a stack frame is on the free list, only the following members have
 a meaning:
 ob_type == &Frametype
 f_back next item on free list, or NULL
 f_stacksize size of value stack
 ob_size size of localsplus
 Note that the value and block stacks are preserved -- this can save
 another malloc() call or two (and two free() calls as well!).
 Also note that, unlike for integers, each frame object is a
 malloc'ed object in its own right -- it is only the actual calls to
 malloc() that we are trying to save here, not the administration.
 After all, while a typical program may make millions of calls, a
 call depth of more than 20 or 30 is probably already exceptional
 unless the program contains run-away recursion. I hope.

 Later, PyFrame_MAXFREELIST was added to bound the # of frames saved on
 free_list. Else programs creating lots of cyclic trash involving
 frames could provoke free_list into growing without bound.
*/

staticPyFrameObject*free_list=NULL;
staticintnumfree=0; /* number of frames currently in free_list */
/* max value for numfree */
#definePyFrame_MAXFREELIST 200

staticvoid
frame_dealloc(PyFrameObject*f)
{
PyObject**p, **valuestack;
PyCodeObject*co;

PyObject_GC_UnTrack(f);
Py_TRASHCAN_SAFE_BEGIN(f)
/* Kill all local variables */
valuestack=f->f_valuestack;
for (p=f->f_localsplus; p<valuestack; p++)
Py_CLEAR(*p);

/* Free stack */
if (f->f_stacktop!=NULL) {
for (p=valuestack; p<f->f_stacktop; p++)
Py_XDECREF(*p);
 }

Py_XDECREF(f->f_back);
Py_DECREF(f->f_builtins);
Py_DECREF(f->f_globals);
Py_CLEAR(f->f_locals);
Py_CLEAR(f->f_trace);
Py_CLEAR(f->f_exc_type);
Py_CLEAR(f->f_exc_value);
Py_CLEAR(f->f_exc_traceback);

co=f->f_code;
if (co->co_zombieframe==NULL)
co->co_zombieframe=f;
elseif (numfree<PyFrame_MAXFREELIST) {
++numfree;
f->f_back=free_list;
free_list=f;
 }
else
PyObject_GC_Del(f);

Py_DECREF(co);
Py_TRASHCAN_SAFE_END(f)
}

staticint
frame_traverse(PyFrameObject*f, visitprocvisit, void*arg)
{
PyObject**fastlocals, **p;
inti, slots;

Py_VISIT(f->f_back);
Py_VISIT(f->f_code);
Py_VISIT(f->f_builtins);
Py_VISIT(f->f_globals);
Py_VISIT(f->f_locals);
Py_VISIT(f->f_trace);
Py_VISIT(f->f_exc_type);
Py_VISIT(f->f_exc_value);
Py_VISIT(f->f_exc_traceback);

/* locals */
slots=f->f_code->co_nlocals+PyTuple_GET_SIZE(f->f_code->co_cellvars) +PyTuple_GET_SIZE(f->f_code->co_freevars);
fastlocals=f->f_localsplus;
for (i=slots; --i >= 0; ++fastlocals)
Py_VISIT(*fastlocals);

/* stack */
if (f->f_stacktop!=NULL) {
for (p=f->f_valuestack; p<f->f_stacktop; p++)
Py_VISIT(*p);
 }
return0;
}

staticvoid
frame_clear(PyFrameObject*f)
{
PyObject**fastlocals, **p, **oldtop;
inti, slots;

/* Before anything else, make sure that this frame is clearly marked
 * as being defunct! Else, e.g., a generator reachable from this
 * frame may also point to this frame, believe itself to still be
 * active, and try cleaning up this frame again.
 */
oldtop=f->f_stacktop;
f->f_stacktop=NULL;

Py_CLEAR(f->f_exc_type);
Py_CLEAR(f->f_exc_value);
Py_CLEAR(f->f_exc_traceback);
Py_CLEAR(f->f_trace);

/* locals */
slots=f->f_code->co_nlocals+PyTuple_GET_SIZE(f->f_code->co_cellvars) +PyTuple_GET_SIZE(f->f_code->co_freevars);
fastlocals=f->f_localsplus;
for (i=slots; --i >= 0; ++fastlocals)
Py_CLEAR(*fastlocals);

/* stack */
if (oldtop!=NULL) {
for (p=f->f_valuestack; p<oldtop; p++)
Py_CLEAR(*p);
 }
}

staticPyObject*
frame_sizeof(PyFrameObject*f)
{
Py_ssize_tres, extras, ncells, nfrees;

ncells=PyTuple_GET_SIZE(f->f_code->co_cellvars);
nfrees=PyTuple_GET_SIZE(f->f_code->co_freevars);
extras=f->f_code->co_stacksize+f->f_code->co_nlocals+
ncells+nfrees;
/* subtract one as it is already included in PyFrameObject */
res=sizeof(PyFrameObject) + (extras-1) *sizeof(PyObject*);

returnPyInt_FromSsize_t(res);
}

PyDoc_STRVAR(sizeof__doc__,
"F.__sizeof__() -> size of F in memory, in bytes");

staticPyMethodDefframe_methods[] = {
 {"__sizeof__", (PyCFunction)frame_sizeof, METH_NOARGS,
sizeof__doc__},
 {NULL, NULL} /* sentinel */
};

PyTypeObjectPyFrame_Type= {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"frame",
sizeof(PyFrameObject),
sizeof(PyObject*),
 (destructor)frame_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
PyObject_GenericSetAttr, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
0, /* tp_doc */
 (traverseproc)frame_traverse, /* tp_traverse */
 (inquiry)frame_clear, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
frame_methods, /* tp_methods */
frame_memberlist, /* tp_members */
frame_getsetlist, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
};

staticPyObject*builtin_object;

int_PyFrame_Init()
{
builtin_object=PyString_InternFromString("__builtins__");
if (builtin_object==NULL)
return0;
return1;
}

PyFrameObject*
PyFrame_New(PyThreadState*tstate, PyCodeObject*code, PyObject*globals,
PyObject*locals)
{
PyFrameObject*back=tstate->frame;
PyFrameObject*f;
PyObject*builtins;
Py_ssize_ti;

#ifdefPy_DEBUG
if (code==NULL||globals==NULL|| !PyDict_Check(globals) ||
 (locals!=NULL&& !PyMapping_Check(locals))) {
PyErr_BadInternalCall();
returnNULL;
 }
#endif
if (back==NULL||back->f_globals!=globals) {
builtins=PyDict_GetItem(globals, builtin_object);
if (builtins) {
if (PyModule_Check(builtins)) {
builtins=PyModule_GetDict(builtins);
assert(!builtins||PyDict_Check(builtins));
 }
elseif (!PyDict_Check(builtins))
builtins=NULL;
 }
if (builtins==NULL) {
/* No builtins! Make up a minimal one
 Give them 'None', at least. */
builtins=PyDict_New();
if (builtins==NULL||
PyDict_SetItemString(
builtins, "None", Py_None) <0)
returnNULL;
 }
else
Py_INCREF(builtins);

 }
else {
/* If we share the globals, we share the builtins.
 Save a lookup and a call. */
builtins=back->f_builtins;
assert(builtins!=NULL&&PyDict_Check(builtins));
Py_INCREF(builtins);
 }
if (code->co_zombieframe!=NULL) {
f=code->co_zombieframe;
code->co_zombieframe=NULL;
_Py_NewReference((PyObject*)f);
assert(f->f_code==code);
 }
else {
Py_ssize_textras, ncells, nfrees;
ncells=PyTuple_GET_SIZE(code->co_cellvars);
nfrees=PyTuple_GET_SIZE(code->co_freevars);
extras=code->co_stacksize+code->co_nlocals+ncells+
nfrees;
if (free_list==NULL) {
f=PyObject_GC_NewVar(PyFrameObject, &PyFrame_Type,
extras);
if (f==NULL) {
Py_DECREF(builtins);
returnNULL;
 }
 }
else {
assert(numfree>0);
--numfree;
f=free_list;
free_list=free_list->f_back;
if (Py_SIZE(f) <extras) {
f=PyObject_GC_Resize(PyFrameObject, f, extras);
if (f==NULL) {
Py_DECREF(builtins);
returnNULL;
 }
 }
_Py_NewReference((PyObject*)f);
 }

f->f_code=code;
extras=code->co_nlocals+ncells+nfrees;
f->f_valuestack=f->f_localsplus+extras;
for (i=0; i<extras; i++)
f->f_localsplus[i] =NULL;
f->f_locals=NULL;
f->f_trace=NULL;
f->f_exc_type=f->f_exc_value=f->f_exc_traceback=NULL;
 }
f->f_stacktop=f->f_valuestack;
f->f_builtins=builtins;
Py_XINCREF(back);
f->f_back=back;
Py_INCREF(code);
Py_INCREF(globals);
f->f_globals=globals;
/* Most functions have CO_NEWLOCALS and CO_OPTIMIZED set. */
if ((code->co_flags& (CO_NEWLOCALS | CO_OPTIMIZED)) ==
 (CO_NEWLOCALS | CO_OPTIMIZED))
 ; /* f_locals = NULL; will be set by PyFrame_FastToLocals() */
elseif (code->co_flags&CO_NEWLOCALS) {
locals=PyDict_New();
if (locals==NULL) {
Py_DECREF(f);
returnNULL;
 }
f->f_locals=locals;
 }
else {
if (locals==NULL)
locals=globals;
Py_INCREF(locals);
f->f_locals=locals;
 }
f->f_tstate=tstate;

f->f_lasti=-1;
f->f_lineno=code->co_firstlineno;
f->f_iblock=0;

_PyObject_GC_TRACK(f);
returnf;
}

/* Block management */

void
PyFrame_BlockSetup(PyFrameObject*f, inttype, inthandler, intlevel)
{
PyTryBlock*b;
if (f->f_iblock >= CO_MAXBLOCKS)
Py_FatalError("XXX block stack overflow");
b=&f->f_blockstack[f->f_iblock++];
b->b_type=type;
b->b_level=level;
b->b_handler=handler;
}

PyTryBlock*
PyFrame_BlockPop(PyFrameObject*f)
{
PyTryBlock*b;
if (f->f_iblock <= 0)
Py_FatalError("XXX block stack underflow");
b=&f->f_blockstack[--f->f_iblock];
returnb;
}

/* Convert between "fast" version of locals and dictionary version.

 map and values are input arguments. map is a tuple of strings.
 values is an array of PyObject*. At index i, map[i] is the name of
 the variable with value values[i]. The function copies the first
 nmap variable from map/values into dict. If values[i] is NULL,
 the variable is deleted from dict.

 If deref is true, then the values being copied are cell variables
 and the value is extracted from the cell variable before being put
 in dict.

 Exceptions raised while modifying the dict are silently ignored,
 because there is no good way to report them.
 */

staticvoid
map_to_dict(PyObject*map, Py_ssize_tnmap, PyObject*dict, PyObject**values,
intderef)
{
Py_ssize_tj;
assert(PyTuple_Check(map));
assert(PyDict_Check(dict));
assert(PyTuple_Size(map) >= nmap);
for (j=nmap; --j >= 0; ) {
PyObject*key=PyTuple_GET_ITEM(map, j);
PyObject*value=values[j];
assert(PyString_Check(key));
if (deref) {
assert(PyCell_Check(value));
value=PyCell_GET(value);
 }
if (value==NULL) {
if (PyObject_DelItem(dict, key) !=0)
PyErr_Clear();
 }
else {
if (PyObject_SetItem(dict, key, value) !=0)
PyErr_Clear();
 }
 }
}

/* Copy values from the "locals" dict into the fast locals.

 dict is an input argument containing string keys representing
 variables names and arbitrary PyObject* as values.

 map and values are input arguments. map is a tuple of strings.
 values is an array of PyObject*. At index i, map[i] is the name of
 the variable with value values[i]. The function copies the first
 nmap variable from map/values into dict. If values[i] is NULL,
 the variable is deleted from dict.

 If deref is true, then the values being copied are cell variables
 and the value is extracted from the cell variable before being put
 in dict. If clear is true, then variables in map but not in dict
 are set to NULL in map; if clear is false, variables missing in
 dict are ignored.

 Exceptions raised while modifying the dict are silently ignored,
 because there is no good way to report them.
*/

staticvoid
dict_to_map(PyObject*map, Py_ssize_tnmap, PyObject*dict, PyObject**values,
intderef, intclear)
{
Py_ssize_tj;
assert(PyTuple_Check(map));
assert(PyDict_Check(dict));
assert(PyTuple_Size(map) >= nmap);
for (j=nmap; --j >= 0; ) {
PyObject*key=PyTuple_GET_ITEM(map, j);
PyObject*value=PyObject_GetItem(dict, key);
assert(PyString_Check(key));
/* We only care about NULLs if clear is true. */
if (value==NULL) {
PyErr_Clear();
if (!clear)
continue;
 }
if (deref) {
assert(PyCell_Check(values[j]));
if (PyCell_GET(values[j]) !=value) {
if (PyCell_Set(values[j], value) <0)
PyErr_Clear();
 }
 } elseif (values[j] !=value) {
Py_XINCREF(value);
Py_XSETREF(values[j], value);
 }
Py_XDECREF(value);
 }
}

void
PyFrame_FastToLocals(PyFrameObject*f)
{
/* Merge fast locals into f->f_locals */
PyObject*locals, *map;
PyObject**fast;
PyObject*error_type, *error_value, *error_traceback;
PyCodeObject*co;
Py_ssize_tj;
intncells, nfreevars;
if (f==NULL)
return;
locals=f->f_locals;
if (locals==NULL) {
locals=f->f_locals=PyDict_New();
if (locals==NULL) {
PyErr_Clear(); /* Can't report it :-( */
return;
 }
 }
co=f->f_code;
map=co->co_varnames;
if (!PyTuple_Check(map))
return;
PyErr_Fetch(&error_type, &error_value, &error_traceback);
fast=f->f_localsplus;
j=PyTuple_GET_SIZE(map);
if (j>co->co_nlocals)
j=co->co_nlocals;
if (co->co_nlocals)
map_to_dict(map, j, locals, fast, 0);
ncells=PyTuple_GET_SIZE(co->co_cellvars);
nfreevars=PyTuple_GET_SIZE(co->co_freevars);
if (ncells||nfreevars) {
map_to_dict(co->co_cellvars, ncells,
locals, fast+co->co_nlocals, 1);
/* If the namespace is unoptimized, then one of the
 following cases applies:
 1. It does not contain free variables, because it
 uses import * or is a top-level namespace.
 2. It is a class namespace.
 We don't want to accidentally copy free variables
 into the locals dict used by the class.
 */
if (co->co_flags&CO_OPTIMIZED) {
map_to_dict(co->co_freevars, nfreevars,
locals, fast+co->co_nlocals+ncells, 1);
 }
 }
PyErr_Restore(error_type, error_value, error_traceback);
}

void
PyFrame_LocalsToFast(PyFrameObject*f, intclear)
{
/* Merge f->f_locals into fast locals */
PyObject*locals, *map;
PyObject**fast;
PyObject*error_type, *error_value, *error_traceback;
PyCodeObject*co;
Py_ssize_tj;
intncells, nfreevars;
if (f==NULL)
return;
locals=f->f_locals;
co=f->f_code;
map=co->co_varnames;
if (locals==NULL)
return;
if (!PyTuple_Check(map))
return;
PyErr_Fetch(&error_type, &error_value, &error_traceback);
fast=f->f_localsplus;
j=PyTuple_GET_SIZE(map);
if (j>co->co_nlocals)
j=co->co_nlocals;
if (co->co_nlocals)
dict_to_map(co->co_varnames, j, locals, fast, 0, clear);
ncells=PyTuple_GET_SIZE(co->co_cellvars);
nfreevars=PyTuple_GET_SIZE(co->co_freevars);
if (ncells||nfreevars) {
dict_to_map(co->co_cellvars, ncells,
locals, fast+co->co_nlocals, 1, clear);
/* Same test as in PyFrame_FastToLocals() above. */
if (co->co_flags&CO_OPTIMIZED) {
dict_to_map(co->co_freevars, nfreevars,
locals, fast+co->co_nlocals+ncells, 1,
clear);
 }
 }
PyErr_Restore(error_type, error_value, error_traceback);
}

/* Clear out the free list */
int