1 /* Cleanup routines for GDB, the GNU debugger.
3 Copyright (C) 1986-2013 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
21 #include "gdb_assert.h"
23 /* The cleanup list records things that have to be undone
24 if an error happens (descriptors to be closed, memory to be freed, etc.)
25 Each link in the chain records a function to call and an
28 Use make_cleanup to add an element to the cleanup chain.
29 Use do_cleanups to do all cleanup actions back to a given
30 point in the chain. Use discard_cleanups to remove cleanups
31 from the chain back to a given point, not doing them.
33 If the argument is pointer to allocated memory, then you need
34 to additionally set the 'free_arg' member to a function that will
35 free that memory. This function will be called both when the cleanup
36 is executed and when it's discarded. */
41 void (*function
) (void *);
42 void (*free_arg
) (void *);
46 /* Used to mark the end of a cleanup chain.
47 The value is chosen so that it:
48 - is non-NULL so that make_cleanup never returns NULL,
49 - causes a segv if dereferenced
50 [though this won't catch errors that a value of, say,
51 ((struct cleanup *) -1) will]
52 - displays as something useful when printed in gdb.
53 This is const for a bit of extra robustness.
54 It is initialized to coax gcc into putting it into .rodata.
55 All fields are initialized to survive -Wextra. */
56 static const struct cleanup sentinel_cleanup
= { 0, 0, 0, 0 };
58 /* Handy macro to use when referring to sentinel_cleanup. */
59 #define SENTINEL_CLEANUP ((struct cleanup *) &sentinel_cleanup)
61 /* Chain of cleanup actions established with make_cleanup,
62 to be executed if an error happens. */
63 static struct cleanup
*cleanup_chain
= SENTINEL_CLEANUP
;
65 /* Chain of cleanup actions established with make_final_cleanup,
66 to be executed when gdb exits. */
67 static struct cleanup
*final_cleanup_chain
= SENTINEL_CLEANUP
;
69 /* Main worker routine to create a cleanup.
70 PMY_CHAIN is a pointer to either cleanup_chain or final_cleanup_chain.
71 FUNCTION is the function to call to perform the cleanup.
72 ARG is passed to FUNCTION when called.
73 FREE_ARG, if non-NULL, is called after the cleanup is performed.
75 The result is a pointer to the previous chain pointer
76 to be passed later to do_cleanups or discard_cleanups. */
78 static struct cleanup
*
79 make_my_cleanup2 (struct cleanup
**pmy_chain
, make_cleanup_ftype
*function
,
80 void *arg
, void (*free_arg
) (void *))
83 = (struct cleanup
*) xmalloc (sizeof (struct cleanup
));
84 struct cleanup
*old_chain
= *pmy_chain
;
86 new->next
= *pmy_chain
;
87 new->function
= function
;
88 new->free_arg
= free_arg
;
92 gdb_assert (old_chain
!= NULL
);
96 /* Worker routine to create a cleanup without a destructor.
97 PMY_CHAIN is a pointer to either cleanup_chain or final_cleanup_chain.
98 FUNCTION is the function to call to perform the cleanup.
99 ARG is passed to FUNCTION when called.
101 The result is a pointer to the previous chain pointer
102 to be passed later to do_cleanups or discard_cleanups. */
104 static struct cleanup
*
105 make_my_cleanup (struct cleanup
**pmy_chain
, make_cleanup_ftype
*function
,
108 return make_my_cleanup2 (pmy_chain
, function
, arg
, NULL
);
111 /* Add a new cleanup to the cleanup_chain,
112 and return the previous chain pointer
113 to be passed later to do_cleanups or discard_cleanups.
114 Args are FUNCTION to clean up with, and ARG to pass to it. */
117 make_cleanup (make_cleanup_ftype
*function
, void *arg
)
119 return make_my_cleanup (&cleanup_chain
, function
, arg
);
122 /* Same as make_cleanup except also includes TDOR, a destructor to free ARG.
123 DTOR is invoked when the cleanup is performed or when it is discarded. */
126 make_cleanup_dtor (make_cleanup_ftype
*function
, void *arg
,
127 void (*dtor
) (void *))
129 return make_my_cleanup2 (&cleanup_chain
,
130 function
, arg
, dtor
);
133 /* Same as make_cleanup except the cleanup is added to final_cleanup_chain. */
136 make_final_cleanup (make_cleanup_ftype
*function
, void *arg
)
138 return make_my_cleanup (&final_cleanup_chain
, function
, arg
);
141 /* Worker routine to perform cleanups.
142 PMY_CHAIN is a pointer to either cleanup_chain or final_cleanup_chain.
143 OLD_CHAIN is the result of a "make" cleanup routine.
144 Cleanups are performed until we get back to the old end of the chain. */
147 do_my_cleanups (struct cleanup
**pmy_chain
,
148 struct cleanup
*old_chain
)
152 while ((ptr
= *pmy_chain
) != old_chain
)
154 *pmy_chain
= ptr
->next
; /* Do this first in case of recursion. */
155 (*ptr
->function
) (ptr
->arg
);
157 (*ptr
->free_arg
) (ptr
->arg
);
162 /* Return a value that can be passed to do_cleanups, do_final_cleanups to
163 indicate perform all cleanups. */
168 return SENTINEL_CLEANUP
;
171 /* Discard cleanups and do the actions they describe
172 until we get back to the point OLD_CHAIN in the cleanup_chain. */
175 do_cleanups (struct cleanup
*old_chain
)
177 do_my_cleanups (&cleanup_chain
, old_chain
);
180 /* Discard cleanups and do the actions they describe
181 until we get back to the point OLD_CHAIN in the final_cleanup_chain. */
184 do_final_cleanups (struct cleanup
*old_chain
)
186 do_my_cleanups (&final_cleanup_chain
, old_chain
);
189 /* Main worker routine to discard cleanups.
190 PMY_CHAIN is a pointer to either cleanup_chain or final_cleanup_chain.
191 OLD_CHAIN is the result of a "make" cleanup routine.
192 Cleanups are discarded until we get back to the old end of the chain. */
195 discard_my_cleanups (struct cleanup
**pmy_chain
,
196 struct cleanup
*old_chain
)
200 while ((ptr
= *pmy_chain
) != old_chain
)
202 *pmy_chain
= ptr
->next
;
204 (*ptr
->free_arg
) (ptr
->arg
);
209 /* Discard cleanups, not doing the actions they describe,
210 until we get back to the point OLD_CHAIN in the cleanup chain. */
213 discard_cleanups (struct cleanup
*old_chain
)
215 discard_my_cleanups (&cleanup_chain
, old_chain
);
218 /* Discard final cleanups, not doing the actions they describe,
219 until we get back to the point OLD_CHAIN in the final cleanup chain. */
222 discard_final_cleanups (struct cleanup
*old_chain
)
224 discard_my_cleanups (&final_cleanup_chain
, old_chain
);
227 /* Main worker routine to save cleanups.
228 PMY_CHAIN is a pointer to either cleanup_chain or final_cleanup_chain.
229 The chain is emptied and the result is a pointer to the old chain. */
231 static struct cleanup
*
232 save_my_cleanups (struct cleanup
**pmy_chain
)
234 struct cleanup
*old_chain
= *pmy_chain
;
236 *pmy_chain
= SENTINEL_CLEANUP
;
240 /* Set the cleanup_chain to 0, and return the old cleanup_chain. */
245 return save_my_cleanups (&cleanup_chain
);
248 /* Set the final_cleanup_chain to 0, and return the old
249 final_cleanup_chain. */
252 save_final_cleanups (void)
254 return save_my_cleanups (&final_cleanup_chain
);
257 /* Main worker routine to save cleanups.
258 PMY_CHAIN is a pointer to either cleanup_chain or final_cleanup_chain.
259 The chain is restored from CHAIN. */
262 restore_my_cleanups (struct cleanup
**pmy_chain
, struct cleanup
*chain
)
267 /* Restore the cleanup chain from a previously saved chain. */
270 restore_cleanups (struct cleanup
*chain
)
272 restore_my_cleanups (&cleanup_chain
, chain
);
275 /* Restore the final cleanup chain from a previously saved chain. */
278 restore_final_cleanups (struct cleanup
*chain
)
280 restore_my_cleanups (&final_cleanup_chain
, chain
);
283 /* Provide a known function that does nothing, to use as a base for
284 a possibly long chain of cleanups. This is useful where we
285 use the cleanup chain for handling normal cleanups as well as dealing
286 with cleanups that need to be done as a result of a call to error().
287 In such cases, we may not be certain where the first cleanup is, unless
288 we have a do-nothing one to always use as the base. */
291 null_cleanup (void *arg
)
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