1 /* cv.h 2 * 3 * Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, 2000, 4 * 2001, 2002, 2003, 2004, 2005, 2006, 2007, 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 13 struct 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 61 typedef 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 100 Null CV pointer. 101 102 =head1 CV Manipulation Functions 103 104 =for apidoc Am|HV*|CvSTASH|CV* cv 105 Returns the stash of the CV. 106 107 =cut 108 */ 109 110 #define Nullcv Null(CV*) 111 112 #define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash 113 #define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_start 114 #define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_root 115 #define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_xsub 116 #define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_xsubany 117 #define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv 118 #define CvFILE(sv) ((XPVCV*)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 *_cv = (CV *)sv; \ 127 assert(SvTYPE(_cv) == SVt_PVCV || \ 128 SvTYPE(_cv) == SVt_PVFM); \ 129 &((XPVCV*)SvANY(_cv))->xiv_u.xivu_i32; \ 130 })) 131 #else 132 # define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xiv_u.xivu_i32 133 #endif 134 #define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist 135 #define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside 136 #define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags 137 #define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq 138 139 #define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */ 140 #define CVf_LOCKED 0x0002 /* CV locks itself or first arg on entry */ 141 #define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */ 142 143 #define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */ 144 #define CVf_CLONE 0x0020 /* anon CV uses external lexicals */ 145 #define CVf_CLONED 0x0040 /* a clone of one of those */ 146 #define CVf_ANON 0x0080 /* CvGV() can't be trusted */ 147 #define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv, 148 * require, eval). */ 149 #define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV 150 (esp. useful for special XSUBs) */ 151 #define CVf_CONST 0x0400 /* inlinable sub */ 152 #define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */ 153 154 /* This symbol for optimised communication between toke.c and op.c: */ 155 #define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LOCKED|CVf_LVALUE) 156 157 #define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE) 158 #define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE) 159 #define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE) 160 161 #define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED) 162 #define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED) 163 #define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED) 164 165 #define CvANON(cv) (CvFLAGS(cv) & CVf_ANON) 166 #define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON) 167 #define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON) 168 169 #define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE) 170 #define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE) 171 #define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE) 172 173 #define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG) 174 #define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG) 175 #define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG) 176 177 #define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD) 178 #define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD) 179 #define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD) 180 181 #define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED) 182 #define CvLOCKED_on(cv) (CvFLAGS(cv) |= CVf_LOCKED) 183 #define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED) 184 185 #define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE) 186 #define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE) 187 #define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE) 188 189 #define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv)) 190 #define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv)) 191 #define CvEVAL_off(cv) CvUNIQUE_off(cv) 192 193 /* BEGIN|CHECK|INIT|UNITCHECK|END */ 194 #define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv)) 195 #define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv)) 196 #define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv)) 197 198 #define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST) 199 #define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST) 200 #define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST) 201 202 #define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE) 203 #define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE) 204 #define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE) 205 206 #define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB) 207 #define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB) 208 #define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB) 209 210 /* Flags for newXS_flags */ 211 #define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */ 212 213 /* 214 =head1 CV reference counts and CvOUTSIDE 215 216 =for apidoc m|bool|CvWEAKOUTSIDE|CV *cv 217 218 Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing 219 CV (if any). Because pointers to anonymous sub prototypes are 220 stored in C<&> pad slots, it is a possible to get a circular reference, 221 with the parent pointing to the child and vice-versa. To avoid the 222 ensuing memory leak, we do not increment the reference count of the CV 223 pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent 224 has a C<&> pad slot pointing back to us. In this case, we set the 225 C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what 226 circumstances we should decrement the refcount of the parent when freeing 227 the child. 228 229 There is a further complication with non-closure anonymous subs (i.e. those 230 that do not refer to any lexicals outside that sub). In this case, the 231 anonymous prototype is shared rather than being cloned. This has the 232 consequence that the parent may be freed while there are still active 233 children, eg 234 235 BEGIN { $a = sub { eval '$x' } } 236 237 In this case, the BEGIN is freed immediately after execution since there 238 are no active references to it: the anon sub prototype has 239 C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same 240 CV, so it doesn't contribute to BEGIN's refcount either. When $a is 241 executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed, 242 and the freed BEGIN is accessed. 243 244 To avoid this, whenever a CV and its associated pad is freed, any 245 C<&> entries in the pad are explicitly removed from the pad, and if the 246 refcount of the pointed-to anon sub is still positive, then that 247 child's C<CvOUTSIDE> is set to point to its grandparent. This will only 248 occur in the single specific case of a non-closure anon prototype 249 having one or more active references (such as C<$a> above). 250 251 One other thing to consider is that a CV may be merely undefined 252 rather than freed, eg C<undef &foo>. In this case, its refcount may 253 not have reached zero, but we still delete its pad and its C<CvROOT> etc. 254 Since various children may still have their C<CvOUTSIDE> pointing at this 255 undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that 256 the chain of lexical scopes is unbroken. For example, the following 257 should print 123: 258 259 my $x = 123; 260 sub tmp { sub { eval '$x' } } 261 my $a = tmp(); 262 undef &tmp; 263 print $a->(); 264 265 =cut 266 */ 267 268 /* 269 * Local variables: 270 * c-indentation-style: bsd 271 * c-basic-offset: 4 272 * indent-tabs-mode: t 273 * End: 274 * 275 * ex: set ts=8 sts=4 sw=4 noet: 276 */ 277