Rewrite final cleanups

This patch rewrites final cleanups to use std::function and otherwise
be more C++-ish.

2 files changed, 15 insertions, 124 deletions

diff --git a/gdbsupport/cleanups.cc b/gdbsupport/cleanups.cc
index 619db02..cc14523 100644
--- a/gdbsupport/cleanups.cc
+++ b/gdbsupport/cleanups.cc
@@ -19,126 +19,26 @@
 
 #include "common-defs.h"
 #include "cleanups.h"
+#include <vector>
 
-/* 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.
+/* All the cleanup functions.  */
 
-   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.
+static std::vector<std::function<void ()>> all_cleanups;
 
-   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.  */
+/* See cleanups.h.  */
 
-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)
+void
+add_final_cleanup (std::function<void ()> &&func)
 {
-  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);
-    }
+  all_cleanups.emplace_back (std::move (func));
 }
 
-/* Discard final cleanups and do the actions they describe.  */
+/* See cleanups.h.  */
 
 void
 do_final_cleanups ()
 {
-  do_my_cleanups (&final_cleanup_chain, SENTINEL_CLEANUP);
+  for (auto &func : all_cleanups)
+    func ();
+  all_cleanups.clear ();
 }
diff --git a/gdbsupport/cleanups.h b/gdbsupport/cleanups.h
index 3e64f7d..985cf81 100644
--- a/gdbsupport/cleanups.h
+++ b/gdbsupport/cleanups.h
@@ -19,21 +19,12 @@
 #ifndef COMMON_CLEANUPS_H
 #define COMMON_CLEANUPS_H
 
-/* Outside of cleanups.c, this is an opaque type.  */
-struct cleanup;
+#include <functional>
 
-/* NOTE: cagney/2000-03-04: This typedef is strictly for the
-   make_cleanup function declarations below.  Do not use this typedef
-   as a cast when passing functions into the make_cleanup() code.
-   Instead either use a bounce function or add a wrapper function.
-   Calling a f(char*) function with f(void*) is non-portable.  */
-typedef void (make_cleanup_ftype) (void *);
-
-/* Function type for the dtor in make_cleanup_dtor.  */
-typedef void (make_cleanup_dtor_ftype) (void *);
-
-extern struct cleanup *make_final_cleanup (make_cleanup_ftype *, void *);
+/* Register a function that will be called on exit.  */
+extern void add_final_cleanup (std::function<void ()> &&func);
 
+/* Run all the registered functions.  */
 extern void do_final_cleanups ();
 
 #endif /* COMMON_CLEANUPS_H */