2000-12-01  Gary V. Vaughan  <address@hidden>

	* doc/libtool.texi (Libltdl interface):  Add documentation.
	* libltdl/ltdl.h (lt_dlmakeresident, lt_dlisresident):  Add
	prototypes.
	(LT_DLERROR_CLOSE_RESIDENT_MODULE): New error status.
	* libltdl/ltdl.c (lt_dlmakeresident, lt_dlisresident):  Allow
	making and testing of resident module status, which prevents a
	module from being lt_dlclosed.
	(lt_dlopen):  If lt_dlopen()ing self, make the module resident.
	(lt_dlclose):  Return an error if the module is resident.

Index: doc/libtool.texi
===================================================================
RCS file: /home/cvs/libtool/doc/libtool.texi,v
retrieving revision 1.109
diff -u -p -r1.109 libtool.texi
--- doc/libtool.texi	2000/11/21 08:53:33	1.109
+++ doc/libtool.texi	2000/12/02 01:33:04
@@ -2846,6 +2846,23 @@ directories.  Return 0 on success.
 Return the current user-defined library search path.
 @end deftypefun
 
address@hidden int lt_dlmakeresident (lt_dlhandle @var{handle})
+Mark a module so that it cannot be @samp{lt_dlclose}d.  This can be
+useful if a module implements some core functionality in your project,
+which would cause your code to crash if removed.  Return 0 on success.
+
+If you use @samp{lt_dlopen (NULL)} to get a @var{handle} for the running
+binary, that handle will always be marked as resident, and consequently
+cannot be successfully @samp{lt_dlclose}d.
address@hidden deftypefun
+
address@hidden int lt_dlisresident (lt_dlhandle @var{handle})
+Check whether a particular module has be marked as resident, returning 1
+if it has or 0 otherwise.  If there is an error while executing this
+function, return -1 and set an error message for retrieval with
address@hidden
address@hidden deftypefun
+
 @deftypefun {const lt_dlinfo *}lt_dlgetinfo (lt_dlhandle @var{handle})
 Return a pointer to a struct that contains some information about
 the module @var{handle}.  The contents of the struct must not be modified.
Index: libltdl/ltdl.c
===================================================================
RCS file: /home/cvs/libtool/libltdl/ltdl.c,v
retrieving revision 1.115
diff -u -p -r1.115 ltdl.c
--- libltdl/ltdl.c	2000/11/29 22:59:56	1.115
+++ libltdl/ltdl.c	2000/12/02 01:33:09
@@ -122,8 +122,20 @@ struct lt_dlhandle_struct {
   lt_dlhandle	       *deplibs;	/* dependencies */
   lt_module		module;		/* system module handle */
   lt_ptr		system;		/* system specific data */
+  int			flags;		/* various boolean stats */
 };
 
+/* Various boolean flags can be stored in the flags field of an
+   lt_dlhandle_struct... */
+#define LT_DLGET_FLAG(handle, flag) ((handle)->flags&(flag) == (flag))
+#define LT_DLSET_FLAG(handle, flag) ((handle)->flags |= (flag))
+
+#define LT_DLRESIDENT_FLAG	    (0x01 << 0)
+/* ...add more flags here... */
+
+#define LT_DLIS_RESIDENT(handle)    LT_DLGET_FLAG(handle, LT_DLRESIDENT_FLAG)
+
+
 static	const char	objdir[]		= LTDL_OBJDIR;
 #ifdef	LTDL_SHLIB_EXT
 static	const char	shlib_ext[]		= LTDL_SHLIB_EXT;
@@ -1089,15 +1101,21 @@ lt_dlexit ()
     {
       int	level;
 
+      while (handles && LT_DLIS_RESIDENT (handles))
+	{
+	  handles = handles->next;
+	}
+
       /* close all modules */
       for (level = 1; handles; ++level)
 	{
 	  lt_dlhandle cur = handles;
+
 	  while (cur)
 	    {
 	      lt_dlhandle tmp = cur;
 	      cur = cur->next;
-	      if (tmp->info.ref_count <= level)
+	      if (!LT_DLIS_RESIDENT (cur) && tmp->info.ref_count <= level)
 		{
 		  if (lt_dlclose (tmp))
 		    {
@@ -1630,7 +1648,12 @@ unload_deplibs(handle)
   if (handle->depcount)
     {
       for (i = 0; i < handle->depcount; ++i)
-	errors += lt_dlclose (handle->deplibs[i]);
+	{
+	  if (!LT_DLIS_RESIDENT (handle->deplibs[i]))
+	    {
+	      errors += lt_dlclose (handle->deplibs[i]);
+	    }
+	}
     }
 
   return errors;
@@ -1712,6 +1735,9 @@ lt_dlopen (filename)
       handle->deplibs		= 0;
       newhandle			= handle;
 
+      /* lt_dlclose()ing yourself is very bad!  Disallow it.  */
+      LT_DLSET_FLAG (handle, LT_DLRESIDENT_FLAG);
+
       if (tryall_dlopen (&newhandle, 0) != 0)
 	{
 	  lt_dlfree(handle);
@@ -2012,7 +2038,7 @@ lt_dlopen (filename)
       handle = newhandle;
     }
 
-  if (!handle->info.ref_count)
+  if (handle->info.ref_count == 0)
     {
       handle->info.ref_count	= 1;
       handle->info.name		= name;
@@ -2131,7 +2157,11 @@ lt_dlclose (handle)
 
   handle->info.ref_count--;
 
-  if (!handle->info.ref_count)
+  /* Note that even with resident modules, we must track the ref_count
+     correctly incase the user decides to reset the residency flag
+     later (even though the API makes no provision for that at the
+     moment).  */
+  if (handle->info.ref_count <= 0 && !LT_DLIS_RESIDENT (handle))
     {
       int	error;
       lt_user_data data = handle->loader->dlloader_data;
@@ -2163,6 +2193,12 @@ lt_dlclose (handle)
       return error;
     }
 
+  if (LT_DLIS_RESIDENT (handle))
+    {
+      last_error = LT_DLSTRERROR (CLOSE_RESIDENT_MODULE);
+      return 1;
+    }
+      
   return 0;
 }
 
@@ -2343,6 +2379,34 @@ const char *
 lt_dlgetsearchpath ()
 {
   return user_search_path;
+}
+
+int
+lt_dlmakeresident (handle)
+     lt_dlhandle handle;
+{
+  if (!handle)
+    {
+      last_error = LT_DLSTRERROR (INVALID_HANDLE);
+      return -1;
+    }
+
+  LT_DLSET_FLAG (handle, LT_DLRESIDENT_FLAG);
+
+  return 0;
+}
+
+int
+lt_dlisresident	(handle)
+     lt_dlhandle handle;
+{
+  if (!handle)
+    {
+      last_error = LT_DLSTRERROR (INVALID_HANDLE);
+      return -1;
+    }
+
+  return LT_DLIS_RESIDENT (handle);
 }
 
 const lt_dlinfo *
Index: libltdl/ltdl.h
===================================================================
RCS file: /home/cvs/libtool/libltdl/ltdl.h,v
retrieving revision 1.48
diff -u -p -r1.48 ltdl.h
--- libltdl/ltdl.h	2000/11/29 22:59:56	1.48
+++ libltdl/ltdl.h	2000/12/02 01:33:11
@@ -159,6 +159,10 @@ extern	lt_ptr	    lt_dlsym		LT_PARAMS((l
 extern	const char *lt_dlerror		LT_PARAMS((void));
 extern	int	    lt_dlclose		LT_PARAMS((lt_dlhandle handle));
 
+/* Module residency management. */
+extern	int	    lt_dlmakeresident	LT_PARAMS((lt_dlhandle handle));
+extern	int	    lt_dlisresident	LT_PARAMS((lt_dlhandle handle));
+
 /* Pointers to memory management functions to be used by libltdl. */
 LT_SCOPE  lt_ptr   (*lt_dlmalloc)	LT_PARAMS((size_t size));
 LT_SCOPE  void	   (*lt_dlfree)		LT_PARAMS((lt_ptr ptr));
@@ -269,7 +273,8 @@ extern	int		lt_dlloader_remove  LT_PARAM
     LT_ERROR(INVALID_HANDLE,	    "invalid module handle")		\
     LT_ERROR(BUFFER_OVERFLOW,	    "internal buffer overflow")		\
     LT_ERROR(INVALID_ERRORCODE,     "invalid errorcode")		\
-    LT_ERROR(SHUTDOWN,		    "library already shutdown")
+    LT_ERROR(SHUTDOWN,		    "library already shutdown")		\
+    LT_ERROR(CLOSE_RESIDENT_MODULE, "can't close resident module")
 
 /* Enumerate the symbolic error names. */
 enum {