Prepare for radical source tree reorganization. zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 144 insertions, 0 deletions

diff --git a/REORG.TODO/nptl/register-atfork.c b/REORG.TODO/nptl/register-atfork.c
new file mode 100644
index 0000000000..e6a62b84b5
--- /dev/null
+++ b/REORG.TODO/nptl/register-atfork.c
@@ -0,0 +1,144 @@
+/* Copyright (C) 2002-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fork.h>
+#include <atomic.h>
+
+
+struct fork_handler *__fork_handlers;
+
+/* Lock to protect allocation and deallocation of fork handlers.  */
+int __fork_lock = LLL_LOCK_INITIALIZER;
+
+
+/* Number of pre-allocated handler entries.  */
+#define NHANDLER 48
+
+/* Memory pool for fork handler structures.  */
+static struct fork_handler_pool
+{
+  struct fork_handler_pool *next;
+  struct fork_handler mem[NHANDLER];
+} fork_handler_pool;
+
+
+static struct fork_handler *
+fork_handler_alloc (void)
+{
+  struct fork_handler_pool *runp = &fork_handler_pool;
+  struct fork_handler *result = NULL;
+  unsigned int i;
+
+  do
+    {
+      /* Search for an empty entry.  */
+      for (i = 0; i < NHANDLER; ++i)
+	if (runp->mem[i].refcntr == 0)
+	  goto found;
+    }
+  while ((runp = runp->next) != NULL);
+
+  /* We have to allocate a new entry.  */
+  runp = (struct fork_handler_pool *) calloc (1, sizeof (*runp));
+  if (runp != NULL)
+    {
+      /* Enqueue the new memory pool into the list.  */
+      runp->next = fork_handler_pool.next;
+      fork_handler_pool.next = runp;
+
+      /* We use the last entry on the page.  This means when we start
+	 searching from the front the next time we will find the first
+	 entry unused.  */
+      i = NHANDLER - 1;
+
+    found:
+      result = &runp->mem[i];
+      result->refcntr = 1;
+      result->need_signal = 0;
+    }
+
+  return result;
+}
+
+
+int
+__register_atfork (void (*prepare) (void), void (*parent) (void),
+		   void (*child) (void), void *dso_handle)
+{
+  /* Get the lock to not conflict with other allocations.  */
+  lll_lock (__fork_lock, LLL_PRIVATE);
+
+  struct fork_handler *newp = fork_handler_alloc ();
+
+  if (newp != NULL)
+    {
+      /* Initialize the new record.  */
+      newp->prepare_handler = prepare;
+      newp->parent_handler = parent;
+      newp->child_handler = child;
+      newp->dso_handle = dso_handle;
+
+      __linkin_atfork (newp);
+    }
+
+  /* Release the lock.  */
+  lll_unlock (__fork_lock, LLL_PRIVATE);
+
+  return newp == NULL ? ENOMEM : 0;
+}
+libc_hidden_def (__register_atfork)
+
+
+void
+attribute_hidden
+__linkin_atfork (struct fork_handler *newp)
+{
+  do
+    newp->next = __fork_handlers;
+  while (catomic_compare_and_exchange_bool_acq (&__fork_handlers,
+						newp, newp->next) != 0);
+}
+
+
+libc_freeres_fn (free_mem)
+{
+  /* Get the lock to not conflict with running forks.  */
+  lll_lock (__fork_lock, LLL_PRIVATE);
+
+  /* No more fork handlers.  */
+  __fork_handlers = NULL;
+
+  /* Free eventually allocated memory blocks for the object pool.  */
+  struct fork_handler_pool *runp = fork_handler_pool.next;
+
+  memset (&fork_handler_pool, '\0', sizeof (fork_handler_pool));
+
+  /* Release the lock.  */
+  lll_unlock (__fork_lock, LLL_PRIVATE);
+
+  /* We can free the memory after releasing the lock.  */
+  while (runp != NULL)
+    {
+      struct fork_handler_pool *oldp = runp;
+      runp = runp->next;
+      free (oldp);
+    }
+}