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 }; 17 18 /* 19 =head1 Handy Values 20 21 =for apidoc AmU||Nullcv 22 Null CV pointer. 23 24 (deprecated - use C<(CV *)NULL> instead) 25 26 =head1 CV Manipulation Functions 27 28 This section documents functions to manipulate CVs which are code-values, 29 or subroutines. For more information, see L<perlguts>. 30 31 =for apidoc Am|HV*|CvSTASH|CV* cv 32 Returns the stash of the CV. A stash is the symbol table hash, containing 33 the package-scoped variables in the package where the subroutine was defined. 34 For more information, see L<perlguts>. 35 36 This also has a special use with XS AUTOLOAD subs. 37 See L<perlguts/Autoloading with XSUBs>. 38 39 =cut 40 */ 41 42 #ifndef PERL_CORE 43 # define Nullcv Null(CV*) 44 #endif 45 46 #define CvSTASH(sv) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash) 47 #define CvSTASH_set(cv,st) Perl_cvstash_set(aTHX_ cv, st) 48 #define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start 49 #define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root 50 #define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub 51 #define CvXSUBANY(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany 52 #define CvGV(sv) S_CvGV((const CV *)(sv)) 53 #define CvGV_set(cv,gv) Perl_cvgv_set(aTHX_ cv, gv) 54 #define CvFILE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_file 55 #ifdef USE_ITHREADS 56 # define CvFILE_set_from_cop(sv, cop) \ 57 (CvFILE(sv) = savepv(CopFILE(cop)), CvDYNFILE_on(sv)) 58 #else 59 # define CvFILE_set_from_cop(sv, cop) \ 60 (CvFILE(sv) = CopFILE(cop), CvDYNFILE_off(sv)) 61 #endif 62 #define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv))) 63 #define CvDEPTH(sv) (*S_CvDEPTHp((const CV *)sv)) 64 #define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist 65 #define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside 66 #define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags 67 #define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq 68 69 /* These two are sometimes called on non-CVs */ 70 #define CvPROTO(sv) \ 71 ( \ 72 SvPOK(sv) \ 73 ? SvTYPE(sv) == SVt_PVCV && CvAUTOLOAD(sv) \ 74 ? SvEND(sv)+1 : SvPVX_const(sv) \ 75 : NULL \ 76 ) 77 #define CvPROTOLEN(sv) \ 78 ( \ 79 SvPOK(sv) \ 80 ? SvTYPE(sv) == SVt_PVCV && CvAUTOLOAD(sv) \ 81 ? SvLEN(sv)-SvCUR(sv)-2 \ 82 : SvCUR(sv) \ 83 : 0 \ 84 ) 85 86 #define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */ 87 #define CVf_LVALUE 0x0002 /* CV return value can be used as lvalue */ 88 #define CVf_CONST 0x0004 /* inlinable sub */ 89 #define CVf_ISXSUB 0x0008 /* CV is an XSUB, not pure perl. */ 90 91 #define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */ 92 #define CVf_CLONE 0x0020 /* anon CV uses external lexicals */ 93 #define CVf_CLONED 0x0040 /* a clone of one of those */ 94 #define CVf_ANON 0x0080 /* CV is not pointed to by a GV */ 95 #define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv, 96 * require, eval). */ 97 #define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV 98 (esp. useful for special XSUBs) */ 99 #define CVf_CVGV_RC 0x0400 /* CvGV is reference counted */ 100 #ifdef PERL_CORE 101 # define CVf_SLABBED 0x0800 /* Holds refcount on op slab */ 102 #endif 103 #define CVf_DYNFILE 0x1000 /* The filename isn't static */ 104 #define CVf_AUTOLOAD 0x2000 /* SvPVX contains AUTOLOADed sub name */ 105 #define CVf_HASEVAL 0x4000 /* contains string eval */ 106 #define CVf_NAMED 0x8000 /* Has a name HEK */ 107 108 /* This symbol for optimised communication between toke.c and op.c: */ 109 #define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LVALUE) 110 111 #define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE) 112 #define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE) 113 #define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE) 114 115 #define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED) 116 #define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED) 117 #define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED) 118 119 #define CvANON(cv) (CvFLAGS(cv) & CVf_ANON) 120 #define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON) 121 #define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON) 122 123 /* CvEVAL or CvSPECIAL */ 124 #define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE) 125 #define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE) 126 #define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE) 127 128 #define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG) 129 #define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG) 130 #define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG) 131 132 #define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD) 133 #define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD) 134 #define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD) 135 136 #define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE) 137 #define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE) 138 #define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE) 139 140 /* eval or PL_main_cv */ 141 #define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv)) 142 #define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv)) 143 #define CvEVAL_off(cv) CvUNIQUE_off(cv) 144 145 /* BEGIN|CHECK|INIT|UNITCHECK|END */ 146 #define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv)) 147 #define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv)) 148 #define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv)) 149 150 #define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST) 151 #define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST) 152 #define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST) 153 154 #define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE) 155 #define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE) 156 #define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE) 157 158 #define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB) 159 #define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB) 160 #define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB) 161 162 #define CvCVGV_RC(cv) (CvFLAGS(cv) & CVf_CVGV_RC) 163 #define CvCVGV_RC_on(cv) (CvFLAGS(cv) |= CVf_CVGV_RC) 164 #define CvCVGV_RC_off(cv) (CvFLAGS(cv) &= ~CVf_CVGV_RC) 165 166 #ifdef PERL_CORE 167 # define CvSLABBED(cv) (CvFLAGS(cv) & CVf_SLABBED) 168 # define CvSLABBED_on(cv) (CvFLAGS(cv) |= CVf_SLABBED) 169 # define CvSLABBED_off(cv) (CvFLAGS(cv) &= ~CVf_SLABBED) 170 #endif 171 172 #define CvDYNFILE(cv) (CvFLAGS(cv) & CVf_DYNFILE) 173 #define CvDYNFILE_on(cv) (CvFLAGS(cv) |= CVf_DYNFILE) 174 #define CvDYNFILE_off(cv) (CvFLAGS(cv) &= ~CVf_DYNFILE) 175 176 #define CvAUTOLOAD(cv) (CvFLAGS(cv) & CVf_AUTOLOAD) 177 #define CvAUTOLOAD_on(cv) (CvFLAGS(cv) |= CVf_AUTOLOAD) 178 #define CvAUTOLOAD_off(cv) (CvFLAGS(cv) &= ~CVf_AUTOLOAD) 179 180 #define CvHASEVAL(cv) (CvFLAGS(cv) & CVf_HASEVAL) 181 #define CvHASEVAL_on(cv) (CvFLAGS(cv) |= CVf_HASEVAL) 182 #define CvHASEVAL_off(cv) (CvFLAGS(cv) &= ~CVf_HASEVAL) 183 184 #define CvNAMED(cv) (CvFLAGS(cv) & CVf_NAMED) 185 #define CvNAMED_on(cv) (CvFLAGS(cv) |= CVf_NAMED) 186 #define CvNAMED_off(cv) (CvFLAGS(cv) &= ~CVf_NAMED) 187 188 /* Flags for newXS_flags */ 189 #define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */ 190 191 PERL_STATIC_INLINE GV * 192 S_CvGV(const CV *sv) 193 { 194 return CvNAMED(sv) 195 ? 0 196 : ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv_u.xcv_gv; 197 } 198 PERL_STATIC_INLINE HEK * 199 CvNAME_HEK(CV *sv) 200 { 201 return CvNAMED(sv) 202 ? ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv_u.xcv_hek 203 : 0; 204 } 205 /* This lowers the refernce count of the previous value, but does *not* 206 increment the reference count of the new value. */ 207 #define CvNAME_HEK_set(cv, hek) ( \ 208 CvNAME_HEK((CV *)(cv)) \ 209 ? unshare_hek(SvANY((CV *)(cv))->xcv_gv_u.xcv_hek) \ 210 : (void)0, \ 211 ((XPVCV*)MUTABLE_PTR(SvANY(cv)))->xcv_gv_u.xcv_hek = (hek), \ 212 CvNAMED_on(cv) \ 213 ) 214 215 /* 216 =head1 CV reference counts and CvOUTSIDE 217 218 =for apidoc m|bool|CvWEAKOUTSIDE|CV *cv 219 220 Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing 221 CV (if any). Because pointers to anonymous sub prototypes are 222 stored in C<&> pad slots, it is a possible to get a circular reference, 223 with the parent pointing to the child and vice-versa. To avoid the 224 ensuing memory leak, we do not increment the reference count of the CV 225 pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent 226 has a C<&> pad slot pointing back to us. In this case, we set the 227 C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what 228 circumstances we should decrement the refcount of the parent when freeing 229 the child. 230 231 There is a further complication with non-closure anonymous subs (i.e. those 232 that do not refer to any lexicals outside that sub). In this case, the 233 anonymous prototype is shared rather than being cloned. This has the 234 consequence that the parent may be freed while there are still active 235 children, eg 236 237 BEGIN { $a = sub { eval '$x' } } 238 239 In this case, the BEGIN is freed immediately after execution since there 240 are no active references to it: the anon sub prototype has 241 C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same 242 CV, so it doesn't contribute to BEGIN's refcount either. When $a is 243 executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed, 244 and the freed BEGIN is accessed. 245 246 To avoid this, whenever a CV and its associated pad is freed, any 247 C<&> entries in the pad are explicitly removed from the pad, and if the 248 refcount of the pointed-to anon sub is still positive, then that 249 child's C<CvOUTSIDE> is set to point to its grandparent. This will only 250 occur in the single specific case of a non-closure anon prototype 251 having one or more active references (such as C<$a> above). 252 253 One other thing to consider is that a CV may be merely undefined 254 rather than freed, eg C<undef &foo>. In this case, its refcount may 255 not have reached zero, but we still delete its pad and its C<CvROOT> etc. 256 Since various children may still have their C<CvOUTSIDE> pointing at this 257 undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that 258 the chain of lexical scopes is unbroken. For example, the following 259 should print 123: 260 261 my $x = 123; 262 sub tmp { sub { eval '$x' } } 263 my $a = tmp(); 264 undef &tmp; 265 print $a->(); 266 267 =cut 268 */ 269 270 typedef OP *(*Perl_call_checker)(pTHX_ OP *, GV *, SV *); 271 272 /* 273 * Local variables: 274 * c-indentation-style: bsd 275 * c-basic-offset: 4 276 * indent-tabs-mode: nil 277 * End: 278 * 279 * ex: set ts=8 sts=4 sw=4 et: 280 */ 281