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- /* Cleanup routines for GDB, the GNU debugger.
- Copyright (C) 1986-2022 Free Software Foundation, Inc.
- This file is part of GDB.
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
- #include "common-defs.h"
- #include "cleanups.h"
- /* The cleanup list records things that have to be undone
- if an error happens (descriptors to be closed, memory to be freed, etc.)
- Each link in the chain records a function to call and an
- argument to give it.
- Use make_cleanup to add an element to the cleanup chain.
- Use do_cleanups to do all cleanup actions back to a given
- point in the chain. Use discard_cleanups to remove cleanups
- from the chain back to a given point, not doing them.
- If the argument is pointer to allocated memory, then you need
- to additionally set the 'free_arg' member to a function that will
- free that memory. This function will be called both when the cleanup
- is executed and when it's discarded. */
- struct cleanup
- {
- struct cleanup *next;
- void (*function) (void *);
- void (*free_arg) (void *);
- void *arg;
- };
- /* Used to mark the end of a cleanup chain.
- The value is chosen so that it:
- - is non-NULL so that make_cleanup never returns NULL,
- - causes a segv if dereferenced
- [though this won't catch errors that a value of, say,
- ((struct cleanup *) -1) will]
- - displays as something useful when printed in gdb.
- This is const for a bit of extra robustness.
- It is initialized to coax gcc into putting it into .rodata.
- All fields are initialized to survive -Wextra. */
- static const struct cleanup sentinel_cleanup = { 0, 0, 0, 0 };
- /* Handy macro to use when referring to sentinel_cleanup. */
- #define SENTINEL_CLEANUP ((struct cleanup *) &sentinel_cleanup)
- /* Chain of cleanup actions established with make_final_cleanup,
- to be executed when gdb exits. */
- static struct cleanup *final_cleanup_chain = SENTINEL_CLEANUP;
- /* Main worker routine to create a cleanup.
- PMY_CHAIN is a pointer to either cleanup_chain or final_cleanup_chain.
- FUNCTION is the function to call to perform the cleanup.
- ARG is passed to FUNCTION when called.
- FREE_ARG, if non-NULL, is called after the cleanup is performed.
- The result is a pointer to the previous chain pointer
- to be passed later to do_cleanups or discard_cleanups. */
- static struct cleanup *
- make_my_cleanup2 (struct cleanup **pmy_chain, make_cleanup_ftype *function,
- void *arg, void (*free_arg) (void *))
- {
- struct cleanup *newobj = XNEW (struct cleanup);
- struct cleanup *old_chain = *pmy_chain;
- newobj->next = *pmy_chain;
- newobj->function = function;
- newobj->free_arg = free_arg;
- newobj->arg = arg;
- *pmy_chain = newobj;
- gdb_assert (old_chain != NULL);
- return old_chain;
- }
- /* Worker routine to create a cleanup without a destructor.
- PMY_CHAIN is a pointer to either cleanup_chain or final_cleanup_chain.
- FUNCTION is the function to call to perform the cleanup.
- ARG is passed to FUNCTION when called.
- The result is a pointer to the previous chain pointer
- to be passed later to do_cleanups or discard_cleanups. */
- static struct cleanup *
- make_my_cleanup (struct cleanup **pmy_chain, make_cleanup_ftype *function,
- void *arg)
- {
- return make_my_cleanup2 (pmy_chain, function, arg, NULL);
- }
- /* Add a new cleanup to the final cleanup_chain,
- and return the previous chain pointer
- to be passed later to do_cleanups or discard_cleanups.
- Args are FUNCTION to clean up with, and ARG to pass to it. */
- struct cleanup *
- make_final_cleanup (make_cleanup_ftype *function, void *arg)
- {
- return make_my_cleanup (&final_cleanup_chain, function, arg);
- }
- /* Worker routine to perform cleanups.
- PMY_CHAIN is a pointer to either cleanup_chain or final_cleanup_chain.
- OLD_CHAIN is the result of a "make" cleanup routine.
- Cleanups are performed until we get back to the old end of the chain. */
- static void
- do_my_cleanups (struct cleanup **pmy_chain,
- struct cleanup *old_chain)
- {
- struct cleanup *ptr;
- while ((ptr = *pmy_chain) != old_chain)
- {
- *pmy_chain = ptr->next; /* Do this first in case of recursion. */
- (*ptr->function) (ptr->arg);
- if (ptr->free_arg)
- (*ptr->free_arg) (ptr->arg);
- xfree (ptr);
- }
- }
- /* Discard final cleanups and do the actions they describe. */
- void
- do_final_cleanups ()
- {
- do_my_cleanups (&final_cleanup_chain, SENTINEL_CLEANUP);
- }
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