[binutils-gdb] Rewrite final cleanups

[binutils-gdb] Rewrite final cleanups

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=1eae7be116ddabb13b34d2c2e8e0dc13fbae2a0d

commit 1eae7be116ddabb13b34d2c2e8e0dc13fbae2a0d
Author: Tom Tromey <tromey@adacore.com>
Date:   Fri Feb 23 13:10:28 2024 -0700

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

Diff:
---
 gdb/compile/compile.c    |  30 +++++-------
 gdb/debuginfod-support.c |  14 ++----
 gdb/python/python.c      |   4 +-
 gdbsupport/cleanups.cc   | 122 +++++------------------------------------------
 gdbsupport/cleanups.h    |  17 ++-----
 5 files changed, 33 insertions(+), 154 deletions(-)

diff --git a/gdb/compile/compile.c b/gdb/compile/compile.c
index 8cb2e8ac7f1..27cff2553ee 100644
--- a/gdb/compile/compile.c
+++ b/gdb/compile/compile.c
@@ -427,23 +427,6 @@ compile_print_command (const char *arg, int from_tty)
     }
 }
 
-/* A cleanup function to remove a directory and all its contents.  */
-
-static void
-do_rmdir (void *arg)
-{
-  const char *dir = (const char *) arg;
-  char *zap;
-  int wstat;
-
-  gdb_assert (startswith (dir, TMP_PREFIX));
-  zap = concat ("rm -rf ", dir, (char *) NULL);
-  wstat = system (zap);
-  if (wstat == -1 || !WIFEXITED (wstat) || WEXITSTATUS (wstat) != 0)
-    warning (_("Could not remove temporary directory %s"), dir);
-  XDELETEVEC (zap);
-}
-
 /* Return the name of the temporary directory to use for .o files, and
    arrange for the directory to be removed at shutdown.  */
 
@@ -465,7 +448,18 @@ get_compile_file_tempdir (void)
     perror_with_name (_("Could not make temporary directory"));
 
   tempdir_name = xstrdup (tempdir_name);
-  make_final_cleanup (do_rmdir, tempdir_name);
+  add_final_cleanup ([] ()
+    {
+      char *zap;
+      int wstat;
+
+      gdb_assert (startswith (tempdir_name, TMP_PREFIX));
+      zap = concat ("rm -rf ", tempdir_name, (char *) NULL);
+      wstat = system (zap);
+      if (wstat == -1 || !WIFEXITED (wstat) || WEXITSTATUS (wstat) != 0)
+	warning (_("Could not remove temporary directory %s"), tempdir_name);
+      XDELETEVEC (zap);
+    });
   return tempdir_name;
 }
 
diff --git a/gdb/debuginfod-support.c b/gdb/debuginfod-support.c
index 7d8ada39e96..9bb3748c8c3 100644
--- a/gdb/debuginfod-support.c
+++ b/gdb/debuginfod-support.c
@@ -188,15 +188,6 @@ progressfn (debuginfod_client *c, long cur, long total)
   return 0;
 }
 
-/* Cleanup ARG, which is a debuginfod_client pointer.  */
-
-static void
-cleanup_debuginfod_client (void *arg)
-{
-  debuginfod_client *client = static_cast<debuginfod_client *> (arg);
-  debuginfod_end (client);
-}
-
 /* Return a pointer to the single global debuginfod_client, initialising it
    first if needed.  */
 
@@ -221,7 +212,10 @@ get_debuginfod_client ()
 	     handlers, which is too late.
 
 	     So instead, we make use of GDB's final cleanup mechanism.  */
-	  make_final_cleanup (cleanup_debuginfod_client, global_client);
+	  add_final_cleanup ([] ()
+	    {
+	      debuginfod_end (global_client);
+	    });
 	  debuginfod_set_progressfn (global_client, progressfn);
 	}
     }
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 8aa674c28d3..8f8ee7c0680 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -2057,7 +2057,7 @@ static struct cmd_list_element *user_show_python_list;
    interpreter.  This lets Python's 'atexit' work.  */
 
 static void
-finalize_python (void *ignore)
+finalize_python ()
 {
   struct active_ext_lang_state *previous_active;
 
@@ -2297,7 +2297,7 @@ init_done:
   /* Release the GIL while gdb runs.  */
   PyEval_SaveThread ();
 
-  make_final_cleanup (finalize_python, NULL);
+  add_final_cleanup (finalize_python);
 
   /* Only set this when initialization has succeeded.  */
   gdb_python_initialized = 1;
diff --git a/gdbsupport/cleanups.cc b/gdbsupport/cleanups.cc
index 619db023063..cc14523b2d1 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 3e64f7d1684..985cf81ff7d 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 */