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 match the beginning of XPVFM in sv.h */ 12 13 struct xpvcv { 14 _XPV_HEAD; 15 _XPVCV_COMMON; 16 I32 xcv_depth; /* >= 2 indicates recursive call */ 17 }; 18 19 /* 20 =head1 Handy Values 21 22 =for apidoc AmU||Nullcv 23 Null CV pointer. 24 25 (deprecated - use C<(CV *)NULL> instead) 26 27 =head1 CV Manipulation Functions 28 29 This section documents functions to manipulate CVs which are code-values, 30 or subroutines. For more information, see L<perlguts>. 31 32 =for apidoc Am|HV*|CvSTASH|CV* cv 33 Returns the stash of the CV. A stash is the symbol table hash, containing 34 the package-scoped variables in the package where the subroutine was defined. 35 For more information, see L<perlguts>. 36 37 This also has a special use with XS AUTOLOAD subs. 38 See L<perlguts/Autoloading with XSUBs>. 39 40 =cut 41 */ 42 43 #ifndef PERL_CORE 44 # define Nullcv Null(CV*) 45 #endif 46 47 #define CvSTASH(sv) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash) 48 #define CvSTASH_set(cv,st) Perl_cvstash_set(aTHX_ cv, st) 49 #define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start 50 #define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root 51 #define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub 52 #define CvXSUBANY(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany 53 #define CvGV(sv) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv) 54 #define CvGV_set(cv,gv) Perl_cvgv_set(aTHX_ cv, gv) 55 #define CvFILE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_file 56 #ifdef USE_ITHREADS 57 # define CvFILE_set_from_cop(sv, cop) \ 58 (CvFILE(sv) = savepv(CopFILE(cop)), CvDYNFILE_on(sv)) 59 #else 60 # define CvFILE_set_from_cop(sv, cop) \ 61 (CvFILE(sv) = CopFILE(cop), CvDYNFILE_off(sv)) 62 #endif 63 #define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv))) 64 #if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN) 65 # define CvDEPTH(sv) (*({const CV *const _cvdepth = (const CV *)sv; \ 66 assert(SvTYPE(_cvdepth) == SVt_PVCV); \ 67 &((XPVCV*)SvANY(_cvdepth))->xcv_depth; \ 68 })) 69 #else 70 # define CvDEPTH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_depth 71 #endif 72 #define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist 73 #define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside 74 #define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags 75 #define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq 76 77 /* These two are sometimes called on non-CVs */ 78 #define CvPROTO(sv) \ 79 ( \ 80 SvPOK(sv) \ 81 ? SvTYPE(sv) == SVt_PVCV && CvAUTOLOAD(sv) \ 82 ? SvEND(sv)+1 : SvPVX_const(sv) \ 83 : NULL \ 84 ) 85 #define CvPROTOLEN(sv) \ 86 ( \ 87 SvPOK(sv) \ 88 ? SvTYPE(sv) == SVt_PVCV && CvAUTOLOAD(sv) \ 89 ? SvLEN(sv)-SvCUR(sv)-2 \ 90 : SvCUR(sv) \ 91 : 0 \ 92 ) 93 94 #define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */ 95 #define CVf_LVALUE 0x0002 /* CV return value can be used as lvalue */ 96 #define CVf_CONST 0x0004 /* inlinable sub */ 97 #define CVf_ISXSUB 0x0008 /* CV is an XSUB, not pure perl. */ 98 99 #define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */ 100 #define CVf_CLONE 0x0020 /* anon CV uses external lexicals */ 101 #define CVf_CLONED 0x0040 /* a clone of one of those */ 102 #define CVf_ANON 0x0080 /* CV is not pointed to by a GV */ 103 #define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv, 104 * require, eval). */ 105 #define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV 106 (esp. useful for special XSUBs) */ 107 #define CVf_CVGV_RC 0x0400 /* CvGV is reference counted */ 108 #define CVf_DYNFILE 0x1000 /* The filename isn't static */ 109 #define CVf_AUTOLOAD 0x2000 /* SvPVX contains AUTOLOADed sub name */ 110 111 /* This symbol for optimised communication between toke.c and op.c: */ 112 #define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LVALUE) 113 114 #define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE) 115 #define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE) 116 #define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE) 117 118 #define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED) 119 #define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED) 120 #define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED) 121 122 #define CvANON(cv) (CvFLAGS(cv) & CVf_ANON) 123 #define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON) 124 #define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON) 125 126 #define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE) 127 #define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE) 128 #define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE) 129 130 #define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG) 131 #define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG) 132 #define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG) 133 134 #define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD) 135 #define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD) 136 #define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD) 137 138 #define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE) 139 #define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE) 140 #define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE) 141 142 #define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv)) 143 #define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv)) 144 #define CvEVAL_off(cv) CvUNIQUE_off(cv) 145 146 /* BEGIN|CHECK|INIT|UNITCHECK|END */ 147 #define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv)) 148 #define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv)) 149 #define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv)) 150 151 #define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST) 152 #define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST) 153 #define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST) 154 155 #define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE) 156 #define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE) 157 #define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE) 158 159 #define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB) 160 #define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB) 161 #define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB) 162 163 #define CvCVGV_RC(cv) (CvFLAGS(cv) & CVf_CVGV_RC) 164 #define CvCVGV_RC_on(cv) (CvFLAGS(cv) |= CVf_CVGV_RC) 165 #define CvCVGV_RC_off(cv) (CvFLAGS(cv) &= ~CVf_CVGV_RC) 166 167 #define CvDYNFILE(cv) (CvFLAGS(cv) & CVf_DYNFILE) 168 #define CvDYNFILE_on(cv) (CvFLAGS(cv) |= CVf_DYNFILE) 169 #define CvDYNFILE_off(cv) (CvFLAGS(cv) &= ~CVf_DYNFILE) 170 171 #define CvAUTOLOAD(cv) (CvFLAGS(cv) & CVf_AUTOLOAD) 172 #define CvAUTOLOAD_on(cv) (CvFLAGS(cv) |= CVf_AUTOLOAD) 173 #define CvAUTOLOAD_off(cv) (CvFLAGS(cv) &= ~CVf_AUTOLOAD) 174 175 /* Flags for newXS_flags */ 176 #define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */ 177 178 /* 179 =head1 CV reference counts and CvOUTSIDE 180 181 =for apidoc m|bool|CvWEAKOUTSIDE|CV *cv 182 183 Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing 184 CV (if any). Because pointers to anonymous sub prototypes are 185 stored in C<&> pad slots, it is a possible to get a circular reference, 186 with the parent pointing to the child and vice-versa. To avoid the 187 ensuing memory leak, we do not increment the reference count of the CV 188 pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent 189 has a C<&> pad slot pointing back to us. In this case, we set the 190 C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what 191 circumstances we should decrement the refcount of the parent when freeing 192 the child. 193 194 There is a further complication with non-closure anonymous subs (i.e. those 195 that do not refer to any lexicals outside that sub). In this case, the 196 anonymous prototype is shared rather than being cloned. This has the 197 consequence that the parent may be freed while there are still active 198 children, eg 199 200 BEGIN { $a = sub { eval '$x' } } 201 202 In this case, the BEGIN is freed immediately after execution since there 203 are no active references to it: the anon sub prototype has 204 C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same 205 CV, so it doesn't contribute to BEGIN's refcount either. When $a is 206 executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed, 207 and the freed BEGIN is accessed. 208 209 To avoid this, whenever a CV and its associated pad is freed, any 210 C<&> entries in the pad are explicitly removed from the pad, and if the 211 refcount of the pointed-to anon sub is still positive, then that 212 child's C<CvOUTSIDE> is set to point to its grandparent. This will only 213 occur in the single specific case of a non-closure anon prototype 214 having one or more active references (such as C<$a> above). 215 216 One other thing to consider is that a CV may be merely undefined 217 rather than freed, eg C<undef &foo>. In this case, its refcount may 218 not have reached zero, but we still delete its pad and its C<CvROOT> etc. 219 Since various children may still have their C<CvOUTSIDE> pointing at this 220 undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that 221 the chain of lexical scopes is unbroken. For example, the following 222 should print 123: 223 224 my $x = 123; 225 sub tmp { sub { eval '$x' } } 226 my $a = tmp(); 227 undef &tmp; 228 print $a->(); 229 230 =cut 231 */ 232 233 typedef OP *(*Perl_call_checker)(pTHX_ OP *, GV *, SV *); 234 235 /* 236 * Local variables: 237 * c-indentation-style: bsd 238 * c-basic-offset: 4 239 * indent-tabs-mode: t 240 * End: 241 * 242 * ex: set ts=8 sts=4 sw=4 noet: 243 */ 244