/***********************************************************

Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,

The Netherlands.

All Rights Reserved

Permission to use, copy, modify, and distribute this software and its

documentation for any purpose and without fee is hereby granted,

provided that the above copyright notice appear in all copies and that

both that copyright notice and this permission notice appear in

supporting documentation, and that the names of Stichting Mathematisch

Centrum or CWI or Corporation for National Research Initiatives or

CNRI not be used in advertising or publicity pertaining to

distribution of the software without specific, written prior

permission.

While CWI is the initial source for this software, a modified version

is made available by the Corporation for National Research Initiatives

(CNRI) at the Internet address ftp://ftp.python.org.

STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH

REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF

MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH

CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL

DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR

PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER

TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR

PERFORMANCE OF THIS SOFTWARE.

******************************************************************/

/* Execute compiled code */

/* XXX TO DO:

XXX how to pass arguments to call_trace?

XXX totally get rid of access stuff

XXX speed up searching for keywords by using a dictionary

XXX document it!

*/

#include "allobjects.h"

#include "compile.h"

#include "frameobject.h"

#include "eval.h"

#include "opcode.h"

#include "graminit.h"

#include <ctype.h>

/* Turn this on if your compiler chokes on the big switch: */

/* #define CASE_TOO_BIG 1 */

#ifdef DEBUG

/* For debugging the interpreter: */

#define LLTRACE 1 /* Low-level trace feature */

#define CHECKEXC 1 /* Double-check exception checking */

#endif

/* Forward declarations */

static object *eval_code2 PROTO((codeobject *,

object *, object *,

object **, int,

object **, int,

object **, int,

object *));

#ifdef LLTRACE

static int prtrace PROTO((object *, char *));

#endif

static void call_exc_trace PROTO((object **, object**, frameobject *));

static int call_trace

PROTO((object **, object **, frameobject *, char *, object *));

static object *add PROTO((object *, object *));

static object *sub PROTO((object *, object *));

static object *powerop PROTO((object *, object *));

static object *mul PROTO((object *, object *));

static object *divide PROTO((object *, object *));

static object *mod PROTO((object *, object *));

static object *neg PROTO((object *));

static object *pos PROTO((object *));

static object *not PROTO((object *));

static object *invert PROTO((object *));

static object *lshift PROTO((object *, object *));

static object *rshift PROTO((object *, object *));

static object *and PROTO((object *, object *));

static object *xor PROTO((object *, object *));

static object *or PROTO((object *, object *));

static object *call_builtin PROTO((object *, object *, object *));

static object *call_function PROTO((object *, object *, object *));

static object *apply_subscript PROTO((object *, object *));

static object *loop_subscript PROTO((object *, object *));

static int slice_index PROTO((object *, int, int *));

static object *apply_slice PROTO((object *, object *, object *));

static object *build_slice PROTO((object *, object *, object *));

static int assign_subscript PROTO((object *, object *, object *));

static int assign_slice PROTO((object *, object *, object *, object *));

static int cmp_exception PROTO((object *, object *));

static int cmp_member PROTO((object *, object *));

static object *cmp_outcome PROTO((int, object *, object *));

static int import_from PROTO((object *, object *, object *));

static object *build_class PROTO((object *, object *, object *));

#ifdef SUPPORT_OBSOLETE_ACCESS

static int access_statement PROTO((object *, object *, frameobject *));

#endif

static int exec_statement PROTO((object *, object *, object *));

static object *find_from_args PROTO((frameobject *, int));

/* Pointer to current frame, used to link new frames to */

static frameobject *current_frame;

#ifdef WITH_THREAD

#include <errno.h>

#include "thread.h"

static type_lock interpreter_lock = 0;

static long main_thread = 0;

void

init_save_thread()

{

if (interpreter_lock)

return;

interpreter_lock = allocate_lock();

acquire_lock(interpreter_lock, 1);

main_thread = get_thread_ident();

}

#endif

/* Functions save_thread and restore_thread are always defined so

dynamically loaded modules needn't be compiled separately for use

with and without threads: */

object *

save_thread()

{

#ifdef WITH_THREAD

if (interpreter_lock) {

object *res;

res = (object *)current_frame;

current_frame = NULL;

release_lock(interpreter_lock);

return res;

}

#endif

return NULL;

}

void

restore_thread(x)

object *x;

{

#ifdef WITH_THREAD

if (interpreter_lock) {

int err;

err = errno;

acquire_lock(interpreter_lock, 1);

errno = err;

current_frame = (frameobject *)x;

}

#endif

}

/* Mechanism whereby asynchronously executing callbacks (e.g. UNIX

signal handlers or Mac I/O completion routines) can schedule calls

to a function to be called synchronously.

The synchronous function is called with one void* argument.

It should return 0 for success or -1 for failure -- failure should

be accompanied by an exception.

If registry succeeds, the registry function returns 0; if it fails

(e.g. due to too many pending calls) it returns -1 (without setting

an exception condition).

Note that because registry may occur from within signal handlers,

or other asynchronous events, calling malloc() is unsafe!

#ifdef WITH_THREAD

Any thread can schedule pending calls, but only the main thread

will execute them.

#endif

XXX WARNING! ASYNCHRONOUSLY EXECUTING CODE!

There are two possible race conditions:

(1) nested asynchronous registry calls;

(2) registry calls made while pending calls are being processed.

While (1) is very unlikely, (2) is a real possibility.

The current code is safe against (2), but not against (1).

The safety against (2) is derived from the fact that only one

thread (the main thread) ever takes things out of the queue.

*/

static int ticker = 0; /* main loop counter to do periodic things */

#define NPENDINGCALLS 32

static struct {

int (*func) PROTO((ANY *));

ANY *arg;

} pendingcalls[NPENDINGCALLS];

static volatile int pendingfirst = 0;

static volatile int pendinglast = 0;

int

Py_AddPendingCall(func, arg)

int (*func) PROTO((ANY *));

ANY *arg;

{

static int busy = 0;

int i, j;

/* XXX Begin critical section */

/* XXX If you want this to be safe against nested

XXX asynchronous calls, you'll have to work harder! */

if (busy)

return -1;

busy = 1;

i = pendinglast;

j = (i + 1) % NPENDINGCALLS;

if (j == pendingfirst)

return -1; /* Queue full */

pendingcalls[i].func = func;

pendingcalls[i].arg = arg;

pendinglast = j;

ticker = 0; /* Signal main loop */

busy = 0;

/* XXX End critical section */

return 0;

}

int

Py_MakePendingCalls()

{

static int busy = 0;

#ifdef WITH_THREAD

if (get_thread_ident() != main_thread) {

ticker = 0; /* We're not done yet */

return 0;

}

#endif

if (busy) {

ticker = 0; /* We're not done yet */

return 0;

}

busy = 1;

for (;;) {

int i;

int (*func) PROTO((ANY *));

ANY *arg;

i = pendingfirst;

if (i == pendinglast)

break; /* Queue empty */

func = pendingcalls[i].func;

arg = pendingcalls[i].arg;

pendingfirst = (i + 1) % NPENDINGCALLS;

if (func(arg) < 0) {

busy = 0;

ticker = 0; /* We're not done yet */

return -1;

}

}

busy = 0;

return 0;

}

/* Status code for main loop (reason for stack unwind) */

enum why_code {

WHY_NOT, /* No error */

WHY_EXCEPTION, /* Exception occurred */

WHY_RERAISE, /* Exception re-raised by 'finally' */

WHY_RETURN, /* 'return' statement */

WHY_BREAK /* 'break' statement */

};

/* Backward compatible interface */

object *

eval_code(co, globals, locals)

codeobject *co;

object *globals;

object *locals;

{

return eval_code2(co,

globals, locals,

(object **)NULL, 0,

(object **)NULL, 0,

(object **)NULL, 0,

(object *)NULL);

}

/* Interpreter main loop */

#ifndef MAX_RECURSION_DEPTH

#define MAX_RECURSION_DEPTH 10000

#endif

static int recursion_depth = 0;

static object *

eval_code2(co, globals, locals,

args, argcount, kws, kwcount, defs, defcount, owner)

codeobject *co;

object *globals;

object *locals;

object **args;

int argcount;

object **kws; /* length: 2*kwcount */

int kwcount;

object **defs;

int defcount;

object *owner;

{

register unsigned char *next_instr;

register int opcode; /* Current opcode */

register int oparg; /* Current opcode argument, if any */

register object **stack_pointer;

register enum why_code why; /* Reason for block stack unwind */

register int err; /* Error status -- nonzero if error */

register object *x; /* Result object -- NULL if error */

register object *v; /* Temporary objects popped off stack */

register object *w;

register object *u;

register object *t;

register frameobject *f; /* Current frame */

register object **fastlocals;

object *retval; /* Return value */

#ifdef SUPPORT_OBSOLETE_ACCESS

int defmode = 0; /* Default access mode for new variables */

#endif

#ifdef LLTRACE

int lltrace;

#endif

#if defined(DEBUG) || defined(LLTRACE)

/* Make it easier to find out where we are with a debugger */

char *filename = getstringvalue(co->co_filename);

#endif

/* Code access macros */

#define GETCONST(i) Getconst(f, i)

#define GETNAME(i) Getname(f, i)

#define GETNAMEV(i) Getnamev(f, i)

#define FIRST_INSTR() (GETUSTRINGVALUE(f->f_code->co_code))

#define INSTR_OFFSET() (next_instr - FIRST_INSTR())

#define NEXTOP() (*next_instr++)

#define NEXTARG() (next_instr += 2, (next_instr[-1]<<8) + next_instr[-2])

#define JUMPTO(x) (next_instr = FIRST_INSTR() + (x))

#define JUMPBY(x) (next_instr += (x))

/* Stack manipulation macros */

#define STACK_LEVEL() (stack_pointer - f->f_valuestack)

#define EMPTY() (STACK_LEVEL() == 0)

#define TOP() (stack_pointer[-1])

#define BASIC_PUSH(v) (*stack_pointer++ = (v))

#define BASIC_POP() (*--stack_pointer)

#define CHECK_STACK(n) (STACK_LEVEL() + (n) < f->f_nvalues || \

(stack_pointer = extend_stack(f, STACK_LEVEL(), n)))

#ifdef LLTRACE

#define PUSH(v) (BASIC_PUSH(v), lltrace && prtrace(TOP(), "push"))

#define POP() (lltrace && prtrace(TOP(), "pop"), BASIC_POP())

#else

#define PUSH(v) BASIC_PUSH(v)

#define POP() BASIC_POP()

#endif

/* Local variable macros */

#define GETLOCAL(i) (fastlocals[i])

#define SETLOCAL(i, value) do { XDECREF(GETLOCAL(i)); \

GETLOCAL(i) = value; } while (0)

#ifdef USE_STACKCHECK

if (recursion_depth%10 == 0 && PyOS_CheckStack()) {

err_setstr(MemoryError, "Stack overflow");

return NULL;

}

#endif

if (globals == NULL) {

err_setstr(SystemError, "eval_code2: NULL globals");

return NULL;

}

#ifdef LLTRACE

lltrace = dictlookup(globals, "__lltrace__") != NULL;

#endif

f = newframeobject(

current_frame, /*back*/

co, /*code*/

globals, /*globals*/

locals, /*locals*/

owner, /*owner*/

50, /*nvalues*/

20); /*nblocks*/

if (f == NULL)

return NULL;

current_frame = f;

if (co->co_nlocals > 0)

fastlocals = ((listobject *)f->f_fastlocals)->ob_item;

if (co->co_argcount > 0 ||

co->co_flags & (CO_VARARGS | CO_VARKEYWORDS)) {

int i;

int n = argcount;

object *kwdict = NULL;

if (co->co_flags & CO_VARKEYWORDS) {

kwdict = newmappingobject();

if (kwdict == NULL)

goto fail;

}

if (argcount > co->co_argcount) {

if (!(co->co_flags & CO_VARARGS)) {

err_setstr(TypeError, "too many arguments");

goto fail;

}

n = co->co_argcount;

}

for (i = 0; i < n; i++) {

x = args[i];

INCREF(x);

SETLOCAL(i, x);

}

if (co->co_flags & CO_VARARGS) {

u = newtupleobject(argcount - n);

for (i = n; i < argcount; i++) {

x = args[i];

INCREF(x);

SETTUPLEITEM(u, i-n, x);

}

SETLOCAL(co->co_argcount, u);

}

for (i = 0; i < kwcount; i++) {

object *keyword = kws[2*i];

object *value = kws[2*i + 1];

int j;

/* XXX slow -- speed up using dictionary? */

for (j = 0; j < co->co_argcount; j++) {

object *nm = GETTUPLEITEM(co->co_varnames, j);

if (cmpobject(keyword, nm) == 0)

break;

}

if (j >= co->co_argcount) {

if (kwdict == NULL) {

err_setval(TypeError, keyword);

goto fail;

}

mappinginsert(kwdict, keyword, value);

}

else {

if (GETLOCAL(j) != NULL) {

err_setstr(TypeError,

"keyword parameter redefined");

goto fail;

}

INCREF(value);

SETLOCAL(j, value);

}

}

if (argcount < co->co_argcount) {

int m = co->co_argcount - defcount;

for (i = argcount; i < m; i++) {

if (GETLOCAL(i) == NULL) {

err_setstr(TypeError,

"not enough arguments");

goto fail;

}

}

if (n > m)

i = n - m;

else

i = 0;

for (; i < defcount; i++) {

if (GETLOCAL(m+i) == NULL) {

object *def = defs[i];

INCREF(def);

SETLOCAL(m+i, def);

}

}

}

if (kwdict != NULL) {

i = co->co_argcount;

if (co->co_flags & CO_VARARGS)

i++;

SETLOCAL(i, kwdict);

}

if (0) {

fail:

XDECREF(kwdict);

goto fail2;

}

}

else {

if (argcount > 0 || kwcount > 0) {

err_setstr(TypeError, "no arguments expected");

fail2:

current_frame = f->f_back;

DECREF(f);

return NULL;

}

}

if (sys_trace != NULL) {

/* sys_trace, if defined, is a function that will

be called on *every* entry to a code block.

Its return value, if not None, is a function that

will be called at the start of each executed line

of code. (Actually, the function must return

itself in order to continue tracing.)

The trace functions are called with three arguments:

a pointer to the current frame, a string indicating

why the function is called, and an argument which

depends on the situation. The global trace function

(sys.trace) is also called whenever an exception

is detected. */

if (call_trace(&sys_trace, &f->f_trace, f, "call",

None/*XXX how to compute arguments now?*/)) {

/* Trace function raised an error */

current_frame = f->f_back;

DECREF(f);

return NULL;

}

}

if (sys_profile != NULL) {

/* Similar for sys_profile, except it needn't return

itself and isn't called for "line" events */

if (call_trace(&sys_profile, (object**)0, f, "call",

None/*XXX*/)) {

current_frame = f->f_back;

DECREF(f);

return NULL;

}

}

if (++recursion_depth > MAX_RECURSION_DEPTH) {

--recursion_depth;

err_setstr(RuntimeError, "Maximum recursion depth exceeded");

current_frame = f->f_back;

DECREF(f);

return NULL;

}

next_instr = GETUSTRINGVALUE(f->f_code->co_code);

stack_pointer = f->f_valuestack;

why = WHY_NOT;

err = 0;

x = None; /* Not a reference, just anything non-NULL */

for (;;) {

/* Do periodic things.

Doing this every time through the loop would add

too much overhead (a function call per instruction).

So we do it only every Nth instruction.

The ticker is reset to zero if there are pending

calls (see Py_AddPendingCalls() and

Py_MakePendingCalls() above). */

if (--ticker < 0) {

ticker = sys_checkinterval;

if (pendingfirst != pendinglast) {

if (Py_MakePendingCalls() < 0) {

why = WHY_EXCEPTION;

goto on_error;

}

}

if (sigcheck()) {

why = WHY_EXCEPTION;

goto on_error;

}

#ifdef WITH_THREAD

if (interpreter_lock) {

/* Give another thread a chance */

current_frame = NULL;

release_lock(interpreter_lock);

/* Other threads may run now */

acquire_lock(interpreter_lock, 1);

current_frame = f;

}

#endif

}

/* Extract opcode and argument */

#if defined(DEBUG) || defined(LLTRACE)

f->f_lasti = INSTR_OFFSET();

#endif

opcode = NEXTOP();

if (HAS_ARG(opcode))

oparg = NEXTARG();

#ifdef LLTRACE

/* Instruction tracing */

if (lltrace) {

if (HAS_ARG(opcode)) {

printf("%d: %d, %d\n",

(int) (INSTR_OFFSET() - 3),

opcode, oparg);

}

else {

printf("%d: %d\n",

(int) (INSTR_OFFSET() - 1), opcode);

}

}

#endif

if (!CHECK_STACK(3)) {

x = NULL;

break;

}

/* Main switch on opcode */

switch (opcode) {

/* BEWARE!

It is essential that any operation that fails sets either

x to NULL, err to nonzero, or why to anything but WHY_NOT,

and that no operation that succeeds does this! */

/* case STOP_CODE: this is an error! */

case POP_TOP:

v = POP();

DECREF(v);

break;

case ROT_TWO:

v = POP();

w = POP();

PUSH(v);

PUSH(w);

break;

case ROT_THREE:

v = POP();

w = POP();

x = POP();

PUSH(v);

PUSH(x);

PUSH(w);

break;

case DUP_TOP:

v = TOP();

INCREF(v);

PUSH(v);

break;

case UNARY_POSITIVE:

v = POP();

x = pos(v);

DECREF(v);

PUSH(x);

break;

case UNARY_NEGATIVE:

v = POP();

x = neg(v);

DECREF(v);

PUSH(x);

break;

case UNARY_NOT:

v = POP();

x = not(v);

DECREF(v);

PUSH(x);

break;

case UNARY_CONVERT:

v = POP();

x = reprobject(v);

DECREF(v);

PUSH(x);

break;

case UNARY_INVERT:

v = POP();

x = invert(v);

DECREF(v);

PUSH(x);

break;

case BINARY_POWER:

w = POP();

v = POP();

x = powerop(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_MULTIPLY:

w = POP();

v = POP();

x = mul(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_DIVIDE:

w = POP();

v = POP();

x = divide(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_MODULO:

w = POP();

v = POP();

x = mod(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_ADD:

w = POP();

v = POP();

x = add(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_SUBTRACT:

w = POP();

v = POP();

x = sub(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_SUBSCR:

w = POP();

v = POP();

x = apply_subscript(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_LSHIFT:

w = POP();

v = POP();

x = lshift(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_RSHIFT:

w = POP();

v = POP();

x = rshift(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_AND:

w = POP();

v = POP();

x = and(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_XOR:

w = POP();

v = POP();

x = xor(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case BINARY_OR:

w = POP();

v = POP();

x = or(v, w);

DECREF(v);

DECREF(w);

PUSH(x);

break;

case SLICE+0:

case SLICE+1:

case SLICE+2:

case SLICE+3:

if ((opcode-SLICE) & 2)

w = POP();

else

w = NULL;

if ((opcode-SLICE) & 1)

v = POP();

else

v = NULL;

u = POP();

x = apply_slice(u, v, w);

DECREF(u);

XDECREF(v);

XDECREF(w);

PUSH(x);

break;

case STORE_SLICE+0:

case STORE_SLICE+1:

case STORE_SLICE+2:

case STORE_SLICE+3:

if ((opcode-STORE_SLICE) & 2)

w = POP();

else

w = NULL;

if ((opcode-STORE_SLICE) & 1)

v = POP();

else

v = NULL;

u = POP();

t = POP();

err = assign_slice(u, v, w, t); /* u[v:w] = t */

DECREF(t);

DECREF(u);

XDECREF(v);

XDECREF(w);

break;

case DELETE_SLICE+0:

case DELETE_SLICE+1:

case DELETE_SLICE+2:

case DELETE_SLICE+3:

if ((opcode-DELETE_SLICE) & 2)

w = POP();

else

w = NULL;

if ((opcode-DELETE_SLICE) & 1)

v = POP();

else

v = NULL;

u = POP();

err = assign_slice(u, v, w, (object *)NULL);

/* del u[v:w] */

DECREF(u);

XDECREF(v);

XDECREF(w);

break;

case STORE_SUBSCR:

w = POP();

v = POP();

u = POP();

/* v[w] = u */

err = assign_subscript(v, w, u);

DECREF(u);

DECREF(v);

DECREF(w);

break;

case DELETE_SUBSCR:

w = POP();

v = POP();

/* del v[w] */

err = assign_subscript(v, w, (object *)NULL);

DECREF(v);

DECREF(w);

break;

case PRINT_EXPR:

v = POP();

/* Print value except if procedure result */

/* Before printing, also assign to '_' */

if (v != None &&

(err = dictinsert(f->f_builtins, "_", v)) == 0 &&

!suppress_print) {

flushline();

x = sysget("stdout");

err = writeobject(v, x, 0);

softspace(x, 1);

flushline();

}

DECREF(v);

break;

case PRINT_ITEM:

v = POP();

w = sysget("stdout");

if (softspace(w, 1))

writestring(" ", w);

err = writeobject(v, w, PRINT_RAW);

if (err == 0 && is_stringobject(v)) {

/* XXX move into writeobject() ? */

char *s = getstringvalue(v);

int len = getstringsize(v);

if (len > 0 &&

isspace(Py_CHARMASK(s[len-1])) &&

s[len-1] != ' ')

softspace(w, 0);

}

DECREF(v);

break;

case PRINT_NEWLINE:

x = sysget("stdout");

if (x == NULL)

err_setstr(RuntimeError, "lost sys.stdout");

else {

writestring("\n", x);

softspace(x, 0);

}

break;

case BREAK_LOOP:

why = WHY_BREAK;

break;

case RAISE_VARARGS:

u = v = w = NULL;

switch (oparg) {

case 3:

u = POP(); /* traceback */

if (u == None) {

DECREF(u);

u = NULL;

}

else if (!PyTraceBack_Check(u)) {

err_setstr(TypeError,

"raise 3rd arg must be traceback or None");

goto raise_error;

}

/* Fallthrough */

case 2:

v = POP(); /* value */

/* Fallthrough */

case 1:

w = POP(); /* exc */

break;

default:

err_setstr(SystemError,

"bad RAISE_VARARGS oparg");

goto raise_error;

}

if (v == NULL) {

v = None;

INCREF(v);

}

/* A tuple is equivalent to its first element here */

while (is_tupleobject(w) && gettuplesize(w) > 0) {

t = w;

w = GETTUPLEITEM(w, 0);

INCREF(w);

DECREF(t);

}

if (is_stringobject(w)) {

;

} else if (is_classobject(w)) {

if (!is_instanceobject(v)

|| !issubclass((object*)((instanceobject*)v)->in_class,

w)) {

err_setstr(TypeError,

"a class exception must have a value that is an instance of the class");

goto raise_error;

}

} else if (is_instanceobject(w)) {

if (v != None) {

err_setstr(TypeError,

"an instance exception may not have a separate value");

goto raise_error;

}

else {

DECREF(v);

v = w;

w = (object*) ((instanceobject*)w)->in_class;

INCREF(w);