1 /* go-defer.c -- manage the defer stack. 2 3 Copyright 2009 The Go Authors. All rights reserved. 4 Use of this source code is governed by a BSD-style 5 license that can be found in the LICENSE file. */ 6 7 #include <stddef.h> 8 9 #include "runtime.h" 10 #include "go-alloc.h" 11 #include "go-panic.h" 12 #include "go-defer.h" 13 14 /* This function is called each time we need to defer a call. */ 15 16 void __go_defer(_Bool * frame,void (* pfn)(void *),void * arg)17__go_defer (_Bool *frame, void (*pfn) (void *), void *arg) 18 { 19 G *g; 20 struct __go_defer_stack *n; 21 22 g = runtime_g (); 23 n = runtime_newdefer (); 24 n->__next = g->defer; 25 n->__frame = frame; 26 n->__panic = g->panic; 27 n->__pfn = pfn; 28 n->__arg = arg; 29 n->__retaddr = NULL; 30 n->__makefunc_can_recover = 0; 31 n->__special = 0; 32 g->defer = n; 33 } 34 35 /* This function is called when we want to undefer the stack. */ 36 37 void __go_undefer(_Bool * frame)38__go_undefer (_Bool *frame) 39 { 40 G *g; 41 42 g = runtime_g (); 43 while (g->defer != NULL && g->defer->__frame == frame) 44 { 45 struct __go_defer_stack *d; 46 void (*pfn) (void *); 47 48 d = g->defer; 49 pfn = d->__pfn; 50 d->__pfn = NULL; 51 52 if (pfn != NULL) 53 (*pfn) (d->__arg); 54 55 g->defer = d->__next; 56 57 /* This may be called by a cgo callback routine to defer the 58 call to syscall.CgocallBackDone, in which case we will not 59 have a memory context. Don't try to free anything in that 60 case--the GC will release it later. */ 61 if (runtime_m () != NULL) 62 runtime_freedefer (d); 63 64 /* Since we are executing a defer function here, we know we are 65 returning from the calling function. If the calling 66 function, or one of its callees, paniced, then the defer 67 functions would be executed by __go_panic. */ 68 *frame = 1; 69 } 70 } 71 72 /* This function is called to record the address to which the deferred 73 function returns. This may in turn be checked by __go_can_recover. 74 The frontend relies on this function returning false. */ 75 76 _Bool __go_set_defer_retaddr(void * retaddr)77__go_set_defer_retaddr (void *retaddr) 78 { 79 G *g; 80 81 g = runtime_g (); 82 if (g->defer != NULL) 83 g->defer->__retaddr = __builtin_extract_return_addr (retaddr); 84 return 0; 85 } 86