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 */

#include "allobjects.h"

#include "import.h"
#include "sysmodule.h"
#include "bltinmodule.h"
#include "compile.h"
#include "frameobject.h"
#include "eval.h"
#include "ceval.h"
#include "opcode.h"
#include "traceback.h"
#include "graminit.h"
#include "pythonrun.h"

#include <ctype.h>

extern int suppress_print; /* Declared in pythonrun.c, set in pythonmain.c */

/* Turn this on if your compiler chokes on the big switch: */
/* #define CASE_TOO_BIG 1 */

/* Turn this on if you want to debug the interpreter: */
/* (This can be on even if NDEBUG is defined) */
/* #define DEBUG 1 */

#if defined(DEBUG) || !defined(NDEBUG)
/* For debugging the interpreter: */
#define LLTRACE  1	/* Low-level trace feature */
#define CHECKEXC 1	/* Double-check exception checking */
#endif


/* Forward declarations */

#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 *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 *));
static object *call_function PROTO((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 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 *));
static int access_statement PROTO((object *, object *, frameobject *));
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.
*/

#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;
	busy = 0;
	/* XXX End critical section */
	return 0;
}

int
Py_MakePendingCalls()
{
	static int busy = 0;
#ifdef WITH_THREAD
	if (get_thread_ident() != main_thread)
		return 0;
#endif
	if (busy)
		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;
			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 */
};


/* Interpreter main loop */

object *
eval_code(co, globals, locals, owner, arg)
	codeobject *co;
	object *globals;
	object *locals;
	object *owner;
	object *arg;
{
	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 listobject *fastlocals = NULL;
	object *retval;		/* Return value iff why == WHY_RETURN */
	int needmerge = 0;	/* Set if need to merge locals back at end */
	int defmode = 0;	/* Default access mode for new variables */
#ifdef LLTRACE
	int lltrace;
#endif
#if defined( DEBUG ) || defined( LLTRACE )
	/* Make it easier to find out where we are with dbx */
	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

	if (globals == NULL || locals == NULL) {
		err_setstr(SystemError, "eval_code: NULL globals or locals");
		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 (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", arg)) {
			/* 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", arg)) {
			current_frame = f->f_back;
			DECREF(f);
			return NULL;
		}
	}

	next_instr = GETUSTRINGVALUE(f->f_code->co_code);
	stack_pointer = f->f_valuestack;
	
	if (arg != NULL) {
		INCREF(arg);
		PUSH(arg);
	}
	
	why = WHY_NOT;
	err = 0;
	x = None;	/* Not a reference, just anything non-NULL */
	
	for (;;) {
		static int ticker;
		
		/* 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. */
		
		if (pendingfirst != pendinglast) {
			if (Py_MakePendingCalls() < 0) {
				why = WHY_EXCEPTION;
				goto on_error;
			}
		}
		
		if (--ticker < 0) {
			ticker = sys_checkinterval;
			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 */

#ifdef DEBUG
		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_CALL:
			v = POP();
			f->f_lasti = INSTR_OFFSET() - 1; /* For tracing */
			x = call_object(v, (object *)NULL);
			DECREF(v);
			PUSH(x);
			break;
			
		case UNARY_INVERT:
			v = POP();
			x = invert(v);
			DECREF(v);
			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_CALL:
			w = POP();
			v = POP();
			f->f_lasti = INSTR_OFFSET() - 1; /* For tracing */
			x = call_object(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_EXCEPTION:
			v = POP();
			w = POP();
			/* A tuple is equivalent to its first element here */
			while (is_tupleobject(w) && gettuplesize(w) > 0) {
				u = w;
				w = GETTUPLEITEM(u, 0);
				INCREF(w);
				DECREF(u);
			}
			if (is_stringobject(w)) {
				err_setval(w, v);
			} 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");
				else
					err_setval(w,v);
			} else if (is_instanceobject(w)) {
				if (v != None)
					err_setstr(TypeError,
						   "an instance exception may not have a separate value");
				else {
					DECREF(v);
					v = w;
					w = (object*) ((instanceobject*)w)->in_class;
					INCREF(w);
					err_setval(w, v);
				}
			} else
				err_setstr(TypeError,
					"exceptions must be strings, classes, or instances");
			DECREF(v);
			DECREF(w);
			why = WHY_EXCEPTION;
			break;
		
		case LOAD_LOCALS:
			v = f->f_locals;
			INCREF(v);
			PUSH(v);
			break;
		
		case RETURN_VALUE:
			retval = POP();
			why = WHY_RETURN;
			break;

		case LOAD_GLOBALS:
			v = f->f_locals;
			INCREF(v);
			PUSH(v);
			break;

		case EXEC_STMT:
			w = POP();
			v = POP();
			u = POP();
			err = exec_statement(u, v, w);
			DECREF(u);
			DECREF(v);
			DECREF(w);
			break;
		
		case BUILD_FUNCTION:
			v = POP();
			x = newfuncobject(v, f->f_globals);
			DECREF(v);
			PUSH(x);
			break;

		case SET_FUNC_ARGS:
			v = POP(); /* The function */
			w = POP(); /* The argument list */
			err = setfuncargstuff(v, oparg, w);
			PUSH(v);
			DECREF(w);
			break;
		
	s = getstringvalue(prog);
	if (strlen(s) != getstringsize(prog)) {
		err_setstr(ValueError, "embedded '\\0' in exec string");
		return -1;
	}
	if ((v = run_string(s, file_input, globals, locals)) == NULL)
		return -1;
	DECREF(v);
	return 0;
}