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, 242 insertions, 0 deletions

diff --git a/REORG.TODO/iconv/gconv_dl.c b/REORG.TODO/iconv/gconv_dl.c
new file mode 100644
index 0000000000..241836204d
--- /dev/null
+++ b/REORG.TODO/iconv/gconv_dl.c
@@ -0,0 +1,242 @@
+/* Handle loading/unloading of shared object for transformation.
+   Copyright (C) 1997-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   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 <assert.h>
+#include <dlfcn.h>
+#include <inttypes.h>
+#include <search.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libc-lock.h>
+#include <sys/param.h>
+
+#include <gconv_int.h>
+#include <sysdep.h>
+
+
+#ifdef DEBUG
+/* For debugging purposes.  */
+static void print_all (void);
+#endif
+
+
+/* This is a tuning parameter.  If a transformation module is not used
+   anymore it gets not immediately unloaded.  Instead we wait a certain
+   number of load attempts for further modules.  If none of the
+   subsequent load attempts name the same object it finally gets unloaded.
+   Otherwise it is still available which hopefully is the frequent case.
+   The following number is the number of unloading attempts we wait
+   before unloading.  */
+#define TRIES_BEFORE_UNLOAD	2
+
+/* Array of loaded objects.  This is shared by all threads so we have
+   to use semaphores to access it.  */
+static void *loaded;
+
+/* Comparison function for searching `loaded_object' tree.  */
+static int
+known_compare (const void *p1, const void *p2)
+{
+  const struct __gconv_loaded_object *s1 =
+    (const struct __gconv_loaded_object *) p1;
+  const struct __gconv_loaded_object *s2 =
+    (const struct __gconv_loaded_object *) p2;
+
+  return strcmp (s1->name, s2->name);
+}
+
+/* Open the gconv database if necessary.  A non-negative return value
+   means success.  */
+struct __gconv_loaded_object *
+internal_function
+__gconv_find_shlib (const char *name)
+{
+  struct __gconv_loaded_object *found;
+  void *keyp;
+
+  /* Search the tree of shared objects previously requested.  Data in
+     the tree are `loaded_object' structures, whose first member is a
+     `const char *', the lookup key.  The search returns a pointer to
+     the tree node structure; the first member of the is a pointer to
+     our structure (i.e. what will be a `loaded_object'); since the
+     first member of that is the lookup key string, &FCT_NAME is close
+     enough to a pointer to our structure to use as a lookup key that
+     will be passed to `known_compare' (above).  */
+
+  keyp = __tfind (&name, &loaded, known_compare);
+  if (keyp == NULL)
+    {
+      /* This name was not known before.  */
+      size_t namelen = strlen (name) + 1;
+
+      found = malloc (sizeof (struct __gconv_loaded_object) + namelen);
+      if (found != NULL)
+	{
+	  /* Point the tree node at this new structure.  */
+	  found->name = (char *) memcpy (found + 1, name, namelen);
+	  found->counter = -TRIES_BEFORE_UNLOAD - 1;
+	  found->handle = NULL;
+
+	  if (__builtin_expect (__tsearch (found, &loaded, known_compare)
+				== NULL, 0))
+	    {
+	      /* Something went wrong while inserting the entry.  */
+	      free (found);
+	      found = NULL;
+	    }
+	}
+    }
+  else
+    found = *(struct __gconv_loaded_object **) keyp;
+
+  /* Try to load the shared object if the usage count is 0.  This
+     implies that if the shared object is not loadable, the handle is
+     NULL and the usage count > 0.  */
+  if (found != NULL)
+    {
+      if (found->counter < -TRIES_BEFORE_UNLOAD)
+	{
+	  assert (found->handle == NULL);
+	  found->handle = __libc_dlopen (found->name);
+	  if (found->handle != NULL)
+	    {
+	      found->fct = __libc_dlsym (found->handle, "gconv");
+	      if (found->fct == NULL)
+		{
+		  /* Argh, no conversion function.  There is something
+                     wrong here.  */
+		  __gconv_release_shlib (found);
+		  found = NULL;
+		}
+	      else
+		{
+		  found->init_fct = __libc_dlsym (found->handle, "gconv_init");
+		  found->end_fct = __libc_dlsym (found->handle, "gconv_end");
+
+#ifdef PTR_MANGLE
+		  PTR_MANGLE (found->fct);
+		  if (found->init_fct != NULL)
+		    PTR_MANGLE (found->init_fct);
+		  if (found->end_fct !=  NULL)
+		    PTR_MANGLE (found->end_fct);
+#endif
+
+		  /* We have succeeded in loading the shared object.  */
+		  found->counter = 1;
+		}
+	    }
+	  else
+	    /* Error while loading the shared object.  */
+	    found = NULL;
+	}
+      else if (found->handle != NULL)
+	found->counter = MAX (found->counter + 1, 1);
+    }
+
+  return found;
+}
+
+
+/* This is very ugly but the tsearch functions provide no way to pass
+   information to the walker function.  So we use a global variable.
+   It is MT safe since we use a lock.  */
+static struct __gconv_loaded_object *release_handle;
+
+static void
+do_release_shlib (void *nodep, VISIT value, int level)
+{
+  struct __gconv_loaded_object *obj = *(struct __gconv_loaded_object **) nodep;
+
+  if (value != preorder && value != leaf)
+    return;
+
+  if (obj == release_handle)
+    {
+      /* This is the object we want to unload.  Now decrement the
+	 reference counter.  */
+      assert (obj->counter > 0);
+      --obj->counter;
+    }
+  else if (obj->counter <= 0 && obj->counter >= -TRIES_BEFORE_UNLOAD
+	   && --obj->counter < -TRIES_BEFORE_UNLOAD && obj->handle != NULL)
+    {
+      /* Unload the shared object.  */
+      __libc_dlclose (obj->handle);
+      obj->handle = NULL;
+    }
+}
+
+
+/* Notify system that a shared object is not longer needed.  */
+void
+internal_function
+__gconv_release_shlib (struct __gconv_loaded_object *handle)
+{
+  /* Urgh, this is ugly but we have no other possibility.  */
+  release_handle = handle;
+
+  /* Process all entries.  Please note that we also visit entries
+     with release counts <= 0.  This way we can finally unload them
+     if necessary.  */
+  __twalk (loaded, (__action_fn_t) do_release_shlib);
+}
+
+
+/* We run this if we debug the memory allocation.  */
+static void __libc_freeres_fn_section
+do_release_all (void *nodep)
+{
+  struct __gconv_loaded_object *obj = (struct __gconv_loaded_object *) nodep;
+
+  /* Unload the shared object.  */
+  if (obj->handle != NULL)
+    __libc_dlclose (obj->handle);
+
+  free (obj);
+}
+
+libc_freeres_fn (free_mem)
+{
+  __tdestroy (loaded, do_release_all);
+  loaded = NULL;
+}
+
+
+#ifdef DEBUG
+
+#include <stdio.h>
+
+static void
+do_print (const void *nodep, VISIT value, int level)
+{
+  struct __gconv_loaded_object *obj = *(struct __gconv_loaded_object **) nodep;
+
+  printf ("%10s: \"%s\", %d\n",
+	  value == leaf ? "leaf" :
+	  value == preorder ? "preorder" :
+	  value == postorder ? "postorder" : "endorder",
+	  obj->name, obj->counter);
+}
+
+static void __attribute__ ((used))
+print_all (void)
+{
+  __twalk (loaded, do_print);
+}
+#endif