Commit | Line | Data |
---|---|---|
920dae64 AT |
1 | /* cv.h |
2 | * | |
3 | * Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, | |
4 | * 2000, 2001, 2002, 2003, 2004, 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 XPVCV in B/C.pm and the beginning of XPVFM | |
12 | * in sv.h */ | |
13 | ||
14 | struct xpvcv { | |
15 | char * xpv_pv; /* pointer to malloced string (for prototype) */ | |
16 | STRLEN xpv_cur; /* length of xp_pv as a C string */ | |
17 | STRLEN xpv_len; /* allocated size */ | |
18 | IV xof_off; /* integer value */ | |
19 | NV xnv_nv; /* numeric value, if any */ | |
20 | MAGIC* xmg_magic; /* magic for scalar array */ | |
21 | HV* xmg_stash; /* class package */ | |
22 | ||
23 | HV * xcv_stash; | |
24 | OP * xcv_start; | |
25 | OP * xcv_root; | |
26 | void (*xcv_xsub) (pTHX_ CV*); | |
27 | ANY xcv_xsubany; | |
28 | GV * xcv_gv; | |
29 | char * xcv_file; | |
30 | long xcv_depth; /* >= 2 indicates recursive call */ | |
31 | PADLIST * xcv_padlist; | |
32 | CV * xcv_outside; | |
33 | #ifdef USE_5005THREADS | |
34 | perl_mutex *xcv_mutexp; | |
35 | struct perl_thread *xcv_owner; /* current owner thread */ | |
36 | #endif /* USE_5005THREADS */ | |
37 | cv_flags_t xcv_flags; | |
38 | U32 xcv_outside_seq; /* the COP sequence (at the point of our | |
39 | * compilation) in the lexically enclosing | |
40 | * sub */ | |
41 | }; | |
42 | ||
43 | /* | |
44 | =head1 Handy Values | |
45 | ||
46 | =for apidoc AmU||Nullcv | |
47 | Null CV pointer. | |
48 | ||
49 | =head1 CV Manipulation Functions | |
50 | ||
51 | =for apidoc Am|HV*|CvSTASH|CV* cv | |
52 | Returns the stash of the CV. | |
53 | ||
54 | =cut | |
55 | */ | |
56 | ||
57 | #define Nullcv Null(CV*) | |
58 | ||
59 | #define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash | |
60 | #define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start | |
61 | #define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root | |
62 | #define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_xsub | |
63 | #define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_xsubany | |
64 | #define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv | |
65 | #define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file | |
66 | #ifdef USE_ITHREADS | |
67 | # define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop))) | |
68 | #else | |
69 | # define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop)) | |
70 | #endif | |
71 | #define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv))) | |
72 | #define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xcv_depth | |
73 | #define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist | |
74 | #define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside | |
75 | #ifdef USE_5005THREADS | |
76 | #define CvMUTEXP(sv) ((XPVCV*)SvANY(sv))->xcv_mutexp | |
77 | #define CvOWNER(sv) ((XPVCV*)SvANY(sv))->xcv_owner | |
78 | #endif /* USE_5005THREADS */ | |
79 | #define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags | |
80 | #define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq | |
81 | ||
82 | #define CVf_CLONE 0x0001 /* anon CV uses external lexicals */ | |
83 | #define CVf_CLONED 0x0002 /* a clone of one of those */ | |
84 | #define CVf_ANON 0x0004 /* CvGV() can't be trusted */ | |
85 | #define CVf_OLDSTYLE 0x0008 | |
86 | #define CVf_UNIQUE 0x0010 /* sub is only called once (eg PL_main_cv, | |
87 | * require, eval). Not to be confused | |
88 | * with the GVf_UNIQUE flag associated | |
89 | * with the :unique attribute */ | |
90 | #define CVf_NODEBUG 0x0020 /* no DB::sub indirection for this CV | |
91 | (esp. useful for special XSUBs) */ | |
92 | #define CVf_METHOD 0x0040 /* CV is explicitly marked as a method */ | |
93 | #define CVf_LOCKED 0x0080 /* CV locks itself or first arg on entry */ | |
94 | #define CVf_LVALUE 0x0100 /* CV return value can be used as lvalue */ | |
95 | #define CVf_CONST 0x0200 /* inlinable sub */ | |
96 | #define CVf_WEAKOUTSIDE 0x0400 /* CvOUTSIDE isn't ref counted */ | |
97 | ||
98 | /* This symbol for optimised communication between toke.c and op.c: */ | |
99 | #define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LOCKED|CVf_LVALUE) | |
100 | ||
101 | #define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE) | |
102 | #define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE) | |
103 | #define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE) | |
104 | ||
105 | #define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED) | |
106 | #define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED) | |
107 | #define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED) | |
108 | ||
109 | #define CvANON(cv) (CvFLAGS(cv) & CVf_ANON) | |
110 | #define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON) | |
111 | #define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON) | |
112 | ||
113 | #ifdef PERL_XSUB_OLDSTYLE | |
114 | #define CvOLDSTYLE(cv) (CvFLAGS(cv) & CVf_OLDSTYLE) | |
115 | #define CvOLDSTYLE_on(cv) (CvFLAGS(cv) |= CVf_OLDSTYLE) | |
116 | #define CvOLDSTYLE_off(cv) (CvFLAGS(cv) &= ~CVf_OLDSTYLE) | |
117 | #endif | |
118 | ||
119 | #define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE) | |
120 | #define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE) | |
121 | #define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE) | |
122 | ||
123 | #define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG) | |
124 | #define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG) | |
125 | #define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG) | |
126 | ||
127 | #define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD) | |
128 | #define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD) | |
129 | #define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD) | |
130 | ||
131 | #define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED) | |
132 | #define CvLOCKED_on(cv) (CvFLAGS(cv) |= CVf_LOCKED) | |
133 | #define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED) | |
134 | ||
135 | #define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE) | |
136 | #define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE) | |
137 | #define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE) | |
138 | ||
139 | #define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv)) | |
140 | #define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv)) | |
141 | #define CvEVAL_off(cv) CvUNIQUE_off(cv) | |
142 | ||
143 | /* BEGIN|CHECK|INIT|END */ | |
144 | #define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv)) | |
145 | #define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv)) | |
146 | #define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv)) | |
147 | ||
148 | #define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST) | |
149 | #define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST) | |
150 | #define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST) | |
151 | ||
152 | #define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE) | |
153 | #define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE) | |
154 | #define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE) | |
155 | ||
156 | ||
157 | /* | |
158 | =head1 CV reference counts and CvOUTSIDE | |
159 | ||
160 | =for apidoc m|bool|CvWEAKOUTSIDE|CV *cv | |
161 | ||
162 | Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing | |
163 | CV (if any). Because pointers to anonymous sub prototypes are | |
164 | stored in C<&> pad slots, it is a possible to get a circular reference, | |
165 | with the parent pointing to the child and vice-versa. To avoid the | |
166 | ensuing memory leak, we do not increment the reference count of the CV | |
167 | pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent | |
168 | has a C<&> pad slot pointing back to us. In this case, we set the | |
169 | C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what | |
170 | circumstances we should decrement the refcount of the parent when freeing | |
171 | the child. | |
172 | ||
173 | There is a further complication with non-closure anonymous subs (i.e. those | |
174 | that do not refer to any lexicals outside that sub). In this case, the | |
175 | anonymous prototype is shared rather than being cloned. This has the | |
176 | consequence that the parent may be freed while there are still active | |
177 | children, eg | |
178 | ||
179 | BEGIN { $a = sub { eval '$x' } } | |
180 | ||
181 | In this case, the BEGIN is freed immediately after execution since there | |
182 | are no active references to it: the anon sub prototype has | |
183 | C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same | |
184 | CV, so it doesn't contribute to BEGIN's refcount either. When $a is | |
185 | executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed, | |
186 | and the freed BEGIN is accessed. | |
187 | ||
188 | To avoid this, whenever a CV and its associated pad is freed, any | |
189 | C<&> entries in the pad are explicitly removed from the pad, and if the | |
190 | refcount of the pointed-to anon sub is still positive, then that | |
191 | child's C<CvOUTSIDE> is set to point to its grandparent. This will only | |
192 | occur in the single specific case of a non-closure anon prototype | |
193 | having one or more active references (such as C<$a> above). | |
194 | ||
195 | One other thing to consider is that a CV may be merely undefined | |
196 | rather than freed, eg C<undef &foo>. In this case, its refcount may | |
197 | not have reached zero, but we still delete its pad and its C<CvROOT> etc. | |
198 | Since various children may still have their C<CvOUTSIDE> pointing at this | |
199 | undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that | |
200 | the chain of lexical scopes is unbroken. For example, the following | |
201 | should print 123: | |
202 | ||
203 | my $x = 123; | |
204 | sub tmp { sub { eval '$x' } } | |
205 | my $a = tmp(); | |
206 | undef &tmp; | |
207 | print $a->(); | |
208 | ||
209 | =cut | |
210 | */ |