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[perl #96126] Allocate CvFILE more simply
[perl5.git] / cv.h
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a0d0e21e 1/* cv.h
79072805 2 *
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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
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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 *
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9 */
10
7c60e434 11/* This structure must the beginning of XPVFM in sv.h */
44a8e56a 12
79072805 13struct xpvcv {
20f4945e 14 _XPV_HEAD;
20f4945e 15 _XPVCV_COMMON;
c4648999 16 I32 xcv_depth; /* >= 2 indicates recursive call */
79072805 17};
748a9306 18
954c1994 19/*
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20=head1 Handy Values
21
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22=for apidoc AmU||Nullcv
23Null CV pointer.
24
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25(deprecated - use C<(CV *)NULL> instead)
26
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27=head1 CV Manipulation Functions
28
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29This section documents functions to manipulate CVs which are code-values,
30or subroutines. For more information, see L<perlguts>.
31
954c1994 32=for apidoc Am|HV*|CvSTASH|CV* cv
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33Returns the stash of the CV. A stash is the symbol table hash, containing
34the package-scoped variables in the package where the subroutine was defined.
35For more information, see L<perlguts>.
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36
37=cut
38*/
39
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40#ifndef PERL_CORE
41# define Nullcv Null(CV*)
42#endif
a5f75d66 43
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44#define CvSTASH(sv) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash)
45#define CvSTASH_set(cv,st) Perl_cvstash_set(aTHX_ cv, st)
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46#define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start
47#define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root
48#define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub
49#define CvXSUBANY(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany
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50#define CvGV(sv) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv)
51#define CvGV_set(cv,gv) Perl_cvgv_set(aTHX_ cv, gv)
8f629a87 52#define CvFILE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_file
a636914a 53#ifdef USE_ITHREADS
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54# define CvFILE_set_from_cop(sv, cop) \
55 (CvFILE(sv) = savepv(CopFILE(cop)), CvDYNFILE_on(sv))
a636914a 56#else
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57# define CvFILE_set_from_cop(sv, cop) \
58 (CvFILE(sv) = CopFILE(cop), CvDYNFILE_off(sv))
a636914a 59#endif
9ec2a764 60#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
bb172083 61#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
8f629a87 62# define CvDEPTH(sv) (*({const CV *const _cvdepth = (const CV *)sv; \
5129b2ca 63 assert(SvTYPE(_cvdepth) == SVt_PVCV); \
c4648999 64 &((XPVCV*)SvANY(_cvdepth))->xcv_depth; \
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65 }))
66#else
c4648999 67# define CvDEPTH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_depth
bb172083 68#endif
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69#define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist
70#define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside
71#define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags
72#define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq
a5f75d66 73
5b4563c8 74#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
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75#define CVf_LVALUE 0x0002 /* CV return value can be used as lvalue */
76#define CVf_CONST 0x0004 /* inlinable sub */
77#define CVf_ISXSUB 0x0008 /* CV is an XSUB, not pure perl. */
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78
79#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
80#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
81#define CVf_CLONED 0x0040 /* a clone of one of those */
cfc1e951 82#define CVf_ANON 0x0080 /* CV is not pointed to by a GV */
5b4563c8 83#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d 84 * require, eval). */
5b4563c8 85#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01 86 (esp. useful for special XSUBs) */
cfc1e951 87#define CVf_CVGV_RC 0x0400 /* CvGV is reference counted */
bad4ae38 88#define CVf_DYNFILE 0x1000 /* The filename isn't static */
7dafbf52 89
d3cea301 90/* This symbol for optimised communication between toke.c and op.c: */
e95ab0c0 91#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LVALUE)
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92
93#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
94#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE)
95#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
96
97#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
98#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED)
99#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
100
101#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
102#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON)
103#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805 104
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105#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
106#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE)
107#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
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108
109#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
110#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG)
111#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
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112
113#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
114#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD)
115#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
116
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117#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
118#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE)
119#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
120
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121#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
122#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
123#define CvEVAL_off(cv) CvUNIQUE_off(cv)
124
3c10abe3 125/* BEGIN|CHECK|INIT|UNITCHECK|END */
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126#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
127#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
128#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
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129
130#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
131#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST)
132#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029 133
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134#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
135#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
136#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
137
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138#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
139#define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB)
140#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
141
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142#define CvCVGV_RC(cv) (CvFLAGS(cv) & CVf_CVGV_RC)
143#define CvCVGV_RC_on(cv) (CvFLAGS(cv) |= CVf_CVGV_RC)
144#define CvCVGV_RC_off(cv) (CvFLAGS(cv) &= ~CVf_CVGV_RC)
145
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146#define CvDYNFILE(cv) (CvFLAGS(cv) & CVf_DYNFILE)
147#define CvDYNFILE_on(cv) (CvFLAGS(cv) |= CVf_DYNFILE)
148#define CvDYNFILE_off(cv) (CvFLAGS(cv) &= ~CVf_DYNFILE)
149
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150/* Flags for newXS_flags */
151#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */
152
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153/*
154=head1 CV reference counts and CvOUTSIDE
155
156=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv
157
158Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
159CV (if any). Because pointers to anonymous sub prototypes are
160stored in C<&> pad slots, it is a possible to get a circular reference,
161with the parent pointing to the child and vice-versa. To avoid the
162ensuing memory leak, we do not increment the reference count of the CV
163pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
164has a C<&> pad slot pointing back to us. In this case, we set the
165C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
166circumstances we should decrement the refcount of the parent when freeing
167the child.
168
eeb8d49e 169There is a further complication with non-closure anonymous subs (i.e. those
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170that do not refer to any lexicals outside that sub). In this case, the
171anonymous prototype is shared rather than being cloned. This has the
172consequence that the parent may be freed while there are still active
173children, eg
174
175 BEGIN { $a = sub { eval '$x' } }
176
177In this case, the BEGIN is freed immediately after execution since there
178are no active references to it: the anon sub prototype has
179C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
180CV, so it doesn't contribute to BEGIN's refcount either. When $a is
181executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
182and the freed BEGIN is accessed.
183
184To avoid this, whenever a CV and its associated pad is freed, any
185C<&> entries in the pad are explicitly removed from the pad, and if the
186refcount of the pointed-to anon sub is still positive, then that
187child's C<CvOUTSIDE> is set to point to its grandparent. This will only
188occur in the single specific case of a non-closure anon prototype
189having one or more active references (such as C<$a> above).
190
191One other thing to consider is that a CV may be merely undefined
192rather than freed, eg C<undef &foo>. In this case, its refcount may
193not have reached zero, but we still delete its pad and its C<CvROOT> etc.
194Since various children may still have their C<CvOUTSIDE> pointing at this
195undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
196the chain of lexical scopes is unbroken. For example, the following
197should print 123:
198
199 my $x = 123;
200 sub tmp { sub { eval '$x' } }
201 my $a = tmp();
202 undef &tmp;
203 print $a->();
204
205=cut
206*/
102d3b8a 207
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208typedef OP *(*Perl_call_checker)(pTHX_ OP *, GV *, SV *);
209
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210/*
211 * Local variables:
212 * c-indentation-style: bsd
213 * c-basic-offset: 4
214 * indent-tabs-mode: t
215 * End:
216 *
217 * ex: set ts=8 sts=4 sw=4 noet:
218 */