cop.h

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/*    cop.h
 *
 *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
 *    2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, by Larry Wall and others
 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 * Control ops (cops) are one of the three ops OP_NEXTSTATE, OP_DBSTATE,
 * and OP_SETSTATE that (loosely speaking) are separate statements.
 * They hold information important for lexical state and error reporting.
 * At run time, PL_curcop is set to point to the most recently executed cop,
 * and thus can be used to determine our current state.
 */

/* A jmpenv packages the state required to perform a proper non-local jump.
 * Note that there is a start_env initialized when perl starts, and top_env
 * points to this initially, so top_env should always be non-null.
 *
 * Existence of a non-null top_env->je_prev implies it is valid to call
 * longjmp() at that runlevel (we make sure start_env.je_prev is always
 * null to ensure this).
 *
 * je_mustcatch, when set at any runlevel to TRUE, means eval ops must
 * establish a local jmpenv to handle exception traps.  Care must be taken
 * to restore the previous value of je_mustcatch before exiting the
 * stack frame iff JMPENV_PUSH was not called in that stack frame.
 * GSAR 97-03-27
 */

struct jmpenv {
    struct jmpenv *	je_prev;
    Sigjmp_buf		je_buf;		/* only for use if !je_throw */
    int			je_ret;		/* last exception thrown */
    bool		je_mustcatch;	/* need to call longjmp()? */
};

typedef struct jmpenv JMPENV;

#ifdef OP_IN_REGISTER
#define OP_REG_TO_MEM	PL_opsave = op
#define OP_MEM_TO_REG	op = PL_opsave
#else
#define OP_REG_TO_MEM	NOOP
#define OP_MEM_TO_REG	NOOP
#endif

/*
 * How to build the first jmpenv.
 *
 * top_env needs to be non-zero. It points to an area
 * in which longjmp() stuff is stored, as C callstack
 * info there at least is thread specific this has to
 * be per-thread. Otherwise a 'die' in a thread gives
 * that thread the C stack of last thread to do an eval {}!
 */

#define JMPENV_BOOTSTRAP \
    STMT_START {				\
	Zero(&PL_start_env, 1, JMPENV);		\
	PL_start_env.je_ret = -1;		\
	PL_start_env.je_mustcatch = TRUE;	\
	PL_top_env = &PL_start_env;		\
    } STMT_END

/*
 *   PERL_FLEXIBLE_EXCEPTIONS
 * 
 * All the flexible exceptions code has been removed.
 * See the following threads for details:
 *
 *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2004-07/msg00378.html
 * 
 * Joshua's original patches (which weren't applied) and discussion:
 * 
 *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01396.html
 *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01489.html
 *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01491.html
 *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01608.html
 *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg02144.html
 *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg02998.html
 * 
 * Chip's reworked patch and discussion:
 * 
 *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1999-03/msg00520.html
 * 
 * The flaw in these patches (which went unnoticed at the time) was
 * that they moved some code that could potentially die() out of the
 * region protected by the setjmp()s.  This caused exceptions within
 * END blocks and such to not be handled by the correct setjmp().
 * 
 * The original patches that introduces flexible exceptions were:
 *
 *   http://public.activestate.com/cgi-bin/perlbrowse?patch=3386
 *   http://public.activestate.com/cgi-bin/perlbrowse?patch=5162
 */

#define dJMPENV		JMPENV cur_env

#define JMPENV_PUSH(v) \
    STMT_START {							\
	DEBUG_l(Perl_deb(aTHX_ "Setting up jumplevel %p, was %p\n",	\
			 (void*)&cur_env, (void*)PL_top_env));			\
	cur_env.je_prev = PL_top_env;					\
	OP_REG_TO_MEM;							\
	cur_env.je_ret = PerlProc_setjmp(cur_env.je_buf, SCOPE_SAVES_SIGNAL_MASK);		\
	OP_MEM_TO_REG;							\
	PL_top_env = &cur_env;						\
	cur_env.je_mustcatch = FALSE;					\
	(v) = cur_env.je_ret;						\
    } STMT_END

#define JMPENV_POP \
    STMT_START {							\
	DEBUG_l(Perl_deb(aTHX_ "popping jumplevel was %p, now %p\n",	\
			 (void*)PL_top_env, (void*)cur_env.je_prev));			\
	PL_top_env = cur_env.je_prev;					\
    } STMT_END

#define JMPENV_JUMP(v) \
    STMT_START {						\
	OP_REG_TO_MEM;						\
	if (PL_top_env->je_prev)				\
	    PerlProc_longjmp(PL_top_env->je_buf, (v));		\
	if ((v) == 2)						\
	    PerlProc_exit(STATUS_EXIT);		                \
	PerlIO_printf(PerlIO_stderr(), "panic: top_env\n");	\
	PerlProc_exit(1);					\
    } STMT_END

#define CATCH_GET		(PL_top_env->je_mustcatch)
#define CATCH_SET(v)		(PL_top_env->je_mustcatch = (v))



struct cop {
    BASEOP
    /* On LP64 putting this here takes advantage of the fact that BASEOP isn't
       an exact multiple of 8 bytes to save structure padding.  */
    line_t      cop_line;       /* line # of this command */
    char *	cop_label;	/* label for this construct */
#ifdef USE_ITHREADS
    char *	cop_stashpv;	/* package line was compiled in */
    char *	cop_file;	/* file name the following line # is from */
#else
    HV *	cop_stash;	/* package line was compiled in */
    GV *	cop_filegv;	/* file the following line # is from */
#endif
    U32		cop_hints;	/* hints bits from pragmata */
    U32		cop_seq;	/* parse sequence number */
    /* Beware. mg.c and warnings.pl assume the type of this is STRLEN *:  */
    STRLEN *	cop_warnings;	/* lexical warnings bitmask */
    /* compile time state of %^H.  See the comment in op.c for how this is
       used to recreate a hash to return from caller.  */
    struct refcounted_he * cop_hints_hash;
};

#ifdef USE_ITHREADS
#  define CopFILE(c)		((c)->cop_file)
#  define CopFILEGV(c)		(CopFILE(c) \
				 ? gv_fetchfile(CopFILE(c)) : NULL)
				 
#  ifdef NETWARE
#    define CopFILE_set(c,pv)	((c)->cop_file = savepv(pv))
#    define CopFILE_setn(c,pv,l)  ((c)->cop_file = savepv((pv),(l)))
#  else
#    define CopFILE_set(c,pv)	((c)->cop_file = savesharedpv(pv))
#    define CopFILE_setn(c,pv,l)  ((c)->cop_file = savesharedpvn((pv),(l)))
#  endif

#  define CopFILESV(c)		(CopFILE(c) \
				 ? GvSV(gv_fetchfile(CopFILE(c))) : NULL)
#  define CopFILEAV(c)		(CopFILE(c) \
				 ? GvAV(gv_fetchfile(CopFILE(c))) : NULL)
#  ifdef DEBUGGING
#    define CopFILEAVx(c)	(assert(CopFILE(c)), \
				   GvAV(gv_fetchfile(CopFILE(c))))
#  else
#    define CopFILEAVx(c)	(GvAV(gv_fetchfile(CopFILE(c))))
#  endif
#  define CopSTASHPV(c)		((c)->cop_stashpv)

#  ifdef NETWARE
#    define CopSTASHPV_set(c,pv)	((c)->cop_stashpv = ((pv) ? savepv(pv) : NULL))
#  else
#    define CopSTASHPV_set(c,pv)	((c)->cop_stashpv = savesharedpv(pv))
#  endif

#  define CopSTASH(c)		(CopSTASHPV(c) \
				 ? gv_stashpv(CopSTASHPV(c),GV_ADD) : NULL)
#  define CopSTASH_set(c,hv)	CopSTASHPV_set(c, (hv) ? HvNAME_get(hv) : NULL)
#  define CopSTASH_eq(c,hv)	((hv) && stashpv_hvname_match(c,hv))
#  define CopLABEL(c)		((c)->cop_label)
#  define CopLABEL_set(c,pv)	(CopLABEL(c) = (pv))
#  ifdef NETWARE
#    define CopSTASH_free(c) SAVECOPSTASH_FREE(c)
#    define CopFILE_free(c) SAVECOPFILE_FREE(c)
#    define CopLABEL_free(c) SAVECOPLABEL_FREE(c)
#    define CopLABEL_alloc(pv)	((pv)?savepv(pv):NULL)
#  else
#    define CopSTASH_free(c)	PerlMemShared_free(CopSTASHPV(c))
#    define CopFILE_free(c)	(PerlMemShared_free(CopFILE(c)),(CopFILE(c) = NULL))
#    define CopLABEL_free(c)	(PerlMemShared_free(CopLABEL(c)),(CopLABEL(c) = NULL))
#    define CopLABEL_alloc(pv)	((pv)?savesharedpv(pv):NULL)
#  endif
#else
#  define CopFILEGV(c)		((c)->cop_filegv)
#  define CopFILEGV_set(c,gv)	((c)->cop_filegv = (GV*)SvREFCNT_inc(gv))
#  define CopFILE_set(c,pv)	CopFILEGV_set((c), gv_fetchfile(pv))
#  define CopFILE_setn(c,pv,l)	CopFILEGV_set((c), gv_fetchfile_flags((pv),(l),0))
#  define CopFILESV(c)		(CopFILEGV(c) ? GvSV(CopFILEGV(c)) : NULL)
#  define CopFILEAV(c)		(CopFILEGV(c) ? GvAV(CopFILEGV(c)) : NULL)
#  ifdef DEBUGGING
#    define CopFILEAVx(c)	(assert(CopFILEGV(c)), GvAV(CopFILEGV(c)))
#  else
#    define CopFILEAVx(c)	(GvAV(CopFILEGV(c)))
# endif
#  define CopFILE(c)		(CopFILEGV(c) && GvSV(CopFILEGV(c)) \
				    ? SvPVX(GvSV(CopFILEGV(c))) : NULL)
#  define CopSTASH(c)		((c)->cop_stash)
#  define CopLABEL(c)		((c)->cop_label)
#  define CopSTASH_set(c,hv)	((c)->cop_stash = (hv))
#  define CopSTASHPV(c)		(CopSTASH(c) ? HvNAME_get(CopSTASH(c)) : NULL)
   /* cop_stash is not refcounted */
#  define CopSTASHPV_set(c,pv)	CopSTASH_set((c), gv_stashpv(pv,GV_ADD))
#  define CopSTASH_eq(c,hv)	(CopSTASH(c) == (hv))
#  define CopLABEL_alloc(pv)	((pv)?savepv(pv):NULL)
#  define CopLABEL_set(c,pv)	(CopLABEL(c) = (pv))
#  define CopSTASH_free(c)	
#  define CopFILE_free(c)	(SvREFCNT_dec(CopFILEGV(c)),(CopFILEGV(c) = NULL))
#  define CopLABEL_free(c)	(Safefree(CopLABEL(c)),(CopLABEL(c) = NULL))

#endif /* USE_ITHREADS */

#define CopSTASH_ne(c,hv)	(!CopSTASH_eq(c,hv))
#define CopLINE(c)		((c)->cop_line)
#define CopLINE_inc(c)		(++CopLINE(c))
#define CopLINE_dec(c)		(--CopLINE(c))
#define CopLINE_set(c,l)	(CopLINE(c) = (l))

/* OutCopFILE() is CopFILE for output (caller, die, warn, etc.) */
#ifdef MACOS_TRADITIONAL
#  define OutCopFILE(c) MacPerl_MPWFileName(CopFILE(c))
#else
#  define OutCopFILE(c) CopFILE(c)
#endif

/* If $[ is non-zero, it's stored in cop_hints under the key "$[", and
   HINT_ARYBASE is set to indicate this.
   Setting it is ineficient due to the need to create 2 mortal SVs, but as
   using $[ is highly discouraged, no sane Perl code will be using it.  */
#define CopARYBASE_get(c)	\
	((CopHINTS_get(c) & HINT_ARYBASE)				\
	 ? SvIV(Perl_refcounted_he_fetch(aTHX_ (c)->cop_hints_hash, 0,	\
					 "$[", 2, 0, 0))		\
	 : 0)
#define CopARYBASE_set(c, b) STMT_START { \
	if (b || ((c)->cop_hints & HINT_ARYBASE)) {			\
	    (c)->cop_hints |= HINT_ARYBASE;				\
	    if ((c) == &PL_compiling)					\
		PL_hints |= HINT_LOCALIZE_HH | HINT_ARYBASE;		\
	    (c)->cop_hints_hash						\
	       = Perl_refcounted_he_new(aTHX_ (c)->cop_hints_hash,	\
					sv_2mortal(newSVpvs("$[")),	\
					sv_2mortal(newSViv(b)));	\
	}								\
    } STMT_END

/* FIXME NATIVE_HINTS if this is changed from op_private (see perl.h)  */
#define CopHINTS_get(c)		((c)->cop_hints + 0)
#define CopHINTS_set(c, h)	STMT_START {				\
				    (c)->cop_hints = (h);		\
				} STMT_END

/*
 * Here we have some enormously heavy (or at least ponderous) wizardry.
 */

/* subroutine context */
struct block_sub {
    CV *	cv;
    GV *	gv;
    GV *	dfoutgv;
    AV *	savearray;
    AV *	argarray;
    I32		olddepth;
    U8		hasargs;
    U8		lval;		/* XXX merge lval and hasargs? */
    PAD		*oldcomppad;
    OP *	retop;	/* op to execute on exit from sub */
};

/* base for the next two macros. Don't use directly.
 * Note that the refcnt of the cv is incremented twice;  The CX one is
 * decremented by LEAVESUB, the other by LEAVE. */

#define PUSHSUB_BASE(cx)						\
	cx->blk_sub.cv = cv;						\
	cx->blk_sub.olddepth = CvDEPTH(cv);				\
	cx->blk_sub.hasargs = hasargs;					\
	cx->blk_sub.retop = NULL;					\
	if (!CvDEPTH(cv)) {						\
	    SvREFCNT_inc_simple_void_NN(cv);				\
	    SvREFCNT_inc_simple_void_NN(cv);				\
	    SAVEFREESV(cv);						\
	}


#define PUSHSUB(cx)							\
	PUSHSUB_BASE(cx)						\
	cx->blk_sub.lval = PL_op->op_private &                          \
	                      (OPpLVAL_INTRO|OPpENTERSUB_INARGS);

/* variant for use by OP_DBSTATE, where op_private holds hint bits */
#define PUSHSUB_DB(cx)							\
	PUSHSUB_BASE(cx)						\
	cx->blk_sub.lval = 0;


#define PUSHFORMAT(cx)							\
	cx->blk_sub.cv = cv;						\
	cx->blk_sub.gv = gv;						\
	cx->blk_sub.retop = NULL;					\
	cx->blk_sub.hasargs = 0;					\
	cx->blk_sub.dfoutgv = PL_defoutgv;				\
	SvREFCNT_inc_void(cx->blk_sub.dfoutgv)

#define POP_SAVEARRAY()						\
    STMT_START {							\
	SvREFCNT_dec(GvAV(PL_defgv));					\
	GvAV(PL_defgv) = cx->blk_sub.savearray;				\
    } STMT_END

/* junk in @_ spells trouble when cloning CVs and in pp_caller(), so don't
 * leave any (a fast av_clear(ary), basically) */
#define CLEAR_ARGARRAY(ary) \
    STMT_START {							\
	AvMAX(ary) += AvARRAY(ary) - AvALLOC(ary);			\
	AvARRAY(ary) = AvALLOC(ary);					\
	AvFILLp(ary) = -1;						\
    } STMT_END

#define POPSUB(cx,sv)							\
    STMT_START {							\
	if (cx->blk_sub.hasargs) {					\
	    POP_SAVEARRAY();						\
	    /* abandon @_ if it got reified */				\
	    if (AvREAL(cx->blk_sub.argarray)) {				\
		const SSize_t fill = AvFILLp(cx->blk_sub.argarray);	\
		SvREFCNT_dec(cx->blk_sub.argarray);			\
		cx->blk_sub.argarray = newAV();				\
		av_extend(cx->blk_sub.argarray, fill);			\
		AvREIFY_only(cx->blk_sub.argarray);			\
		CX_CURPAD_SV(cx->blk_sub, 0) = (SV*)cx->blk_sub.argarray;	\
	    }								\
	    else {							\
		CLEAR_ARGARRAY(cx->blk_sub.argarray);			\
	    }								\
	}								\
	sv = (SV*)cx->blk_sub.cv;					\
	if (sv && (CvDEPTH((CV*)sv) = cx->blk_sub.olddepth))		\
	    sv = NULL;						\
    } STMT_END

#define LEAVESUB(sv)							\
    STMT_START {							\
	if (sv)								\
	    SvREFCNT_dec(sv);						\
    } STMT_END

#define POPFORMAT(cx)							\
	setdefout(cx->blk_sub.dfoutgv);					\
	SvREFCNT_dec(cx->blk_sub.dfoutgv);

/* eval context */
struct block_eval {
    U8		old_in_eval;
    U16		old_op_type;
    SV *	old_namesv;
    OP *	old_eval_root;
    SV *	cur_text;
    CV *	cv;
    OP *	retop;	/* op to execute on exit from eval */
    JMPENV *	cur_top_env; /* value of PL_top_env when eval CX created */
};

#define PUSHEVAL(cx,n,fgv)						\
    STMT_START {							\
	cx->blk_eval.old_in_eval = PL_in_eval;				\
	cx->blk_eval.old_op_type = PL_op->op_type;			\
	cx->blk_eval.old_namesv = (n ? newSVpv(n,0) : NULL);		\
	cx->blk_eval.old_eval_root = PL_eval_root;			\
	cx->blk_eval.cur_text = PL_parser ? PL_parser->linestr : NULL;	\
	cx->blk_eval.cv = NULL; /* set by doeval(), as applicable */	\
	cx->blk_eval.retop = NULL;					\
	cx->blk_eval.cur_top_env = PL_top_env; 				\
    } STMT_END

#define POPEVAL(cx)							\
    STMT_START {							\
	PL_in_eval = cx->blk_eval.old_in_eval;				\
	optype = cx->blk_eval.old_op_type;				\
	PL_eval_root = cx->blk_eval.old_eval_root;			\
	if (cx->blk_eval.old_namesv)					\
	    sv_2mortal(cx->blk_eval.old_namesv);			\
    } STMT_END

/* loop context */
struct block_loop {
    char *	label;
    I32		resetsp;
    LOOP *	my_op;	/* My op, that contains redo, next and last ops.  */
    /* (except for non_ithreads we need to modify next_op in pp_ctl.c, hence
	why next_op is conditionally defined below.)  */
#ifdef USE_ITHREADS
    void *	iterdata;
    PAD		*oldcomppad;
#else
    OP *	next_op;
    SV **	itervar;
#endif
    SV *	itersave;
    /* (from inspection of source code) for a .. range of strings this is the
       current string.  */
    SV *	iterlval;
    /* (from inspection of source code) for a foreach loop this is the array
       being iterated over. For a .. range of numbers it's the current value.
       A check is often made on the SvTYPE of iterary to determine whether
       we are iterating over an array or a range. (numbers or strings)  */
    AV *	iterary;
    IV		iterix;
    /* (from inspection of source code) for a .. range of numbers this is the
       maximum value.  */
    IV		itermax;
};
/* It might be possible to squeeze this structure further. As best I can tell
   itermax and iterlval are never used at the same time, so it might be possible
   to make them into a union. However, I'm not confident that there are enough
   flag bits/NULLable pointers in this structure alone to encode which is
   active. There is, however, U8 of space free in struct block, which could be
   used. Right now it may not be worth squeezing this structure further, as it's
   the largest part of struct block, and currently struct block is 64 bytes on
   an ILP32 system, which will give good cache alignment.
*/

#ifdef USE_ITHREADS
#  define CxITERVAR(c)							\
	((c)->blk_loop.iterdata						\