| 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 | */ |