1/* cv.h 2 * 3 * Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, 2000, 2001, 4 * 2002, 2003, 2004, 2005, 2006, 2007, 2008 by Larry Wall and others 5 * 6 * You may distribute under the terms of either the GNU General Public 7 * License or the Artistic License, as specified in the README file. 8 * 9 */ 10 11/* This structure must the beginning of XPVFM in sv.h */ 12 13struct xpvcv { 14 union { 15 NV xnv_nv; /* numeric value, if any */ 16 HV * xgv_stash; 17 struct { 18 U32 xlow; 19 U32 xhigh; 20 } xpad_cop_seq; /* used by pad.c for cop_sequence */ 21 struct { 22 U32 xbm_previous; /* how many characters in string before rare? */ 23 U8 xbm_flags; 24 U8 xbm_rare; /* rarest character in string */ 25 } xbm_s; /* fields from PVBM */ 26 } xnv_u; 27 STRLEN xpv_cur; /* length of xp_pv as a C string */ 28 STRLEN xpv_len; /* allocated size */ 29 union { 30 IV xivu_iv; 31 UV xivu_uv; 32 void * xivu_p1; 33 I32 xivu_i32; /* depth, >= 2 indicates recursive call */ 34 HEK * xivu_namehek; 35 } xiv_u; 36 union { 37 MAGIC* xmg_magic; /* linked list of magicalness */ 38 HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */ 39 } xmg_u; 40 HV* xmg_stash; /* class package */ 41 42 HV * xcv_stash; 43 union { 44 OP * xcv_start; 45 ANY xcv_xsubany; 46 } xcv_start_u; 47 union { 48 OP * xcv_root; 49 void (*xcv_xsub) (pTHX_ CV*); 50 } xcv_root_u; 51 GV * xcv_gv; 52 char * xcv_file; 53 PADLIST * xcv_padlist; 54 CV * xcv_outside; 55 U32 xcv_outside_seq; /* the COP sequence (at the point of our 56 * compilation) in the lexically enclosing 57 * sub */ 58 cv_flags_t xcv_flags; 59}; 60 61typedef struct { 62 STRLEN xpv_cur; /* length of xp_pv as a C string */ 63 STRLEN xpv_len; /* allocated size */ 64 union { 65 IV xivu_iv; 66 UV xivu_uv; 67 void * xivu_p1; 68 I32 xivu_i32; /* depth, >= 2 indicates recursive call */ 69 HEK * xivu_namehek; 70 } xiv_u; 71 union { 72 MAGIC* xmg_magic; /* linked list of magicalness */ 73 HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */ 74 } xmg_u; 75 HV* xmg_stash; /* class package */ 76 77 HV * xcv_stash; 78 union { 79 OP * xcv_start; 80 ANY xcv_xsubany; 81 } xcv_start_u; 82 union { 83 OP * xcv_root; 84 void (*xcv_xsub) (pTHX_ CV*); 85 } xcv_root_u; 86 GV * xcv_gv; 87 char * xcv_file; 88 PADLIST * xcv_padlist; 89 CV * xcv_outside; 90 U32 xcv_outside_seq; /* the COP sequence (at the point of our 91 * compilation) in the lexically enclosing 92 * sub */ 93 cv_flags_t xcv_flags; 94} xpvcv_allocated; 95 96/* 97=head1 Handy Values 98 99=for apidoc AmU||Nullcv 100Null CV pointer. 101 102=head1 CV Manipulation Functions 103 104=for apidoc Am|HV*|CvSTASH|CV* cv 105Returns the stash of the CV. 106 107=cut 108*/ 109 110#define Nullcv Null(CV*) 111 112#define CvSTASH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash 113#define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start 114#define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root 115#define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub 116#define CvXSUBANY(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany 117#define CvGV(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv 118#define CvFILE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_file 119#ifdef USE_ITHREADS 120# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop))) 121#else 122# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop)) 123#endif 124#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv))) 125#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN) 126# define CvDEPTH(sv) (*({const CV *const _cvdepth = (const CV *)sv; \ 127 assert(SvTYPE(_cvdepth) == SVt_PVCV); \ 128 &((XPVCV*)SvANY(_cvdepth))->xiv_u.xivu_i32; \ 129 })) 130#else 131# define CvDEPTH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xiv_u.xivu_i32 132#endif 133#define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist 134#define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside 135#define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags 136#define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq 137 138#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */ 139#define CVf_LOCKED 0x0002 /* CV locks itself or first arg on entry */ 140#define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */ 141 142#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */ 143#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */ 144#define CVf_CLONED 0x0040 /* a clone of one of those */ 145#define CVf_ANON 0x0080 /* CvGV() can't be trusted */ 146#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv, 147 * require, eval). */ 148#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV 149 (esp. useful for special XSUBs) */ 150#define CVf_CONST 0x0400 /* inlinable sub */ 151#define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */ 152 153/* This symbol for optimised communication between toke.c and op.c: */ 154#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LOCKED|CVf_LVALUE) 155 156#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE) 157#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE) 158#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE) 159 160#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED) 161#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED) 162#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED) 163 164#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON) 165#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON) 166#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON) 167 168#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE) 169#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE) 170#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE) 171 172#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG) 173#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG) 174#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG) 175 176#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD) 177#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD) 178#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD) 179 180#define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED) 181#define CvLOCKED_on(cv) (CvFLAGS(cv) |= CVf_LOCKED) 182#define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED) 183 184#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE) 185#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE) 186#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE) 187 188#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv)) 189#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv)) 190#define CvEVAL_off(cv) CvUNIQUE_off(cv) 191 192/* BEGIN|CHECK|INIT|UNITCHECK|END */ 193#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv)) 194#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv)) 195#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv)) 196 197#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST) 198#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST) 199#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST) 200 201#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE) 202#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE) 203#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE) 204 205#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB) 206#define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB) 207#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB) 208 209/* Flags for newXS_flags */ 210#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */ 211 212/* 213=head1 CV reference counts and CvOUTSIDE 214 215=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv 216 217Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing 218CV (if any). Because pointers to anonymous sub prototypes are 219stored in C<&> pad slots, it is a possible to get a circular reference, 220with the parent pointing to the child and vice-versa. To avoid the 221ensuing memory leak, we do not increment the reference count of the CV 222pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent 223has a C<&> pad slot pointing back to us. In this case, we set the 224C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what 225circumstances we should decrement the refcount of the parent when freeing 226the child. 227 228There is a further complication with non-closure anonymous subs (i.e. those 229that do not refer to any lexicals outside that sub). In this case, the 230anonymous prototype is shared rather than being cloned. This has the 231consequence that the parent may be freed while there are still active 232children, eg 233 234 BEGIN { $a = sub { eval '$x' } } 235 236In this case, the BEGIN is freed immediately after execution since there 237are no active references to it: the anon sub prototype has 238C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same 239CV, so it doesn't contribute to BEGIN's refcount either. When $a is 240executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed, 241and the freed BEGIN is accessed. 242 243To avoid this, whenever a CV and its associated pad is freed, any 244C<&> entries in the pad are explicitly removed from the pad, and if the 245refcount of the pointed-to anon sub is still positive, then that 246child's C<CvOUTSIDE> is set to point to its grandparent. This will only 247occur in the single specific case of a non-closure anon prototype 248having one or more active references (such as C<$a> above). 249 250One other thing to consider is that a CV may be merely undefined 251rather than freed, eg C<undef &foo>. In this case, its refcount may 252not have reached zero, but we still delete its pad and its C<CvROOT> etc. 253Since various children may still have their C<CvOUTSIDE> pointing at this 254undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that 255the chain of lexical scopes is unbroken. For example, the following 256should print 123: 257 258 my $x = 123; 259 sub tmp { sub { eval '$x' } } 260 my $a = tmp(); 261 undef &tmp; 262 print $a->(); 263 264=cut 265*/ 266 267/* 268 * Local variables: 269 * c-indentation-style: bsd 270 * c-basic-offset: 4 271 * indent-tabs-mode: t 272 * End: 273 * 274 * ex: set ts=8 sts=4 sw=4 noet: 275 */ 276