modules: allow only a single function access point.

Exporting non-function symbols barely works on Windows, so change
the module loading API to use a single function access point which
is then responsible for calling back to install symbols and macros.
* m4/m4module.h, m4/m4module.c (m4_install_builtins)
(m4_install_macros): New APIs for saving builtins and macros into
the module struct.
* m4/m4module.c (install_macro_table, install_builtin_table):
Adjust accordingly.
(m4__module_open): Simplify accordingly.
* m4/m4private.h (BUILTIN_SYMBOL, MACRO_SYMBOL): Remove.
* modules/gnu.c, modules/import.c, modules/m4.c, modules/modtest.c,
modules/mpeval.c, modules/shadow.c, modules/time.c,
modules/traditional.c (m4_builtin_table, m4_macro_table): Make
static, and remove LTX symbol mangling macros.
(M4INIT_HANDLER): Call m4_install_builtins and/or m4_install_macros.
* tests/options.at: Now that init_func is always called, adjust
expected debug output.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>

13 files changed, 147 insertions, 126 deletions

diff --git a/m4/m4module.h b/m4/m4module.h
index a6bd5139..92710a7e 100644
--- a/m4/m4module.h
+++ b/m4/m4module.h
@@ -237,6 +237,9 @@ extern m4_module *  m4_module_load     (m4 *, const char *, m4_obstack *);
 extern void *       m4_module_import   (m4 *, const char *, const char *,
                                         m4_obstack *);
 
+extern void         m4_install_builtins (m4*, m4_module *, const m4_builtin*);
+extern void         m4_install_macros   (m4*, m4_module *, const m4_macro*);
+
 extern const char * m4_get_module_name (const m4_module *);
 extern m4_module *  m4_module_next     (m4_module *);
 
diff --git a/m4/m4private.h b/m4/m4private.h
index 29f2bfe9..35957223 100644
--- a/m4/m4private.h
+++ b/m4/m4private.h
@@ -173,8 +173,6 @@ extern void m4__builtin_print (m4_obstack *, const m4__builtin *, bool,
 
 /* --- MODULE MANAGEMENT --- */
 
-#define BUILTIN_SYMBOL          "m4_builtin_table"
-#define MACRO_SYMBOL            "m4_macro_table"
 #define INIT_SYMBOL             "m4_init_module"
 
 /* Representation of a loaded m4 module.  */
@@ -182,6 +180,7 @@ struct m4_module
 {
   lt_dlhandle handle;           /* All ltdl module information.  */
   m4__builtin *builtins;        /* Sorted array of builtins.  */
+  m4_macro *macros;		/* Unsorted array of macros.  */
   size_t builtins_len;          /* Number of builtins.  */
 };
 
diff --git a/m4/module.c b/m4/module.c
index ebedcffe..a2215f0e 100644
--- a/m4/module.c
+++ b/m4/module.c
@@ -39,10 +39,17 @@
  * libdld or lt_dlpreload from libtool if shared libraries are not
  * available on the host machine.
  *
- * An M4 module will usually define an external symbol called
- * `m4_builtin_table'.  This symbol points to a table of `m4_builtin'.
- * The table is saved as libltdl caller data and each definition therein
- * is added to the symbol table.
+ * An M4 module will usually define an external symbol named after the
+ * basename of the loadable module:
+ *
+ *   void
+ *   mymod_LTX_m4_init_module (m4 *context, m4_module *module,
+ *                             m4_obstack *obs)
+ *
+ * The function is only called the first time the module is included
+ * and generally uses either `m4_install_builtins' or
+ * `m4_install_macros' (or both!) to register whatever builtins and
+ * macros are provided by the module.
  *
  * To load a module, call m4_module_load(), which searches for the
  * module in directories from M4PATH. The search path is initialized
@@ -50,20 +57,10 @@
  * time default where the modules shipped with M4 itself are installed.
  * `m4_module_load' returns NULL on failure, or else an opaque module
  * handle for the newly mapped vm segment containing the module code.
- * If the module is not already loaded, m4_module_load() retrieves its
- * value for the symbol `m4_builtin_table', which is installed using
- * set_module_builtin_table().
- *
- * In addition to builtin functions, you can also define static macro
- * expansions in the `m4_macro_table' symbol.  If you define this symbol
- * in your modules, it should be an array of `m4_macro's, mapping macro
- * names to the expansion text.  Any macros defined in `m4_macro_table'
- * are installed into the M4 symbol table with set_module_macro_table().
- *
- * Each time a module is loaded, the module function prototyped as
- * "M4INIT_HANDLER (<module name>)" is called, if defined.  Any value
- * stored in OBS by this function becomes the expansion of the macro
- * which called it.
+ * If the module is not already loaded, m4_module_load() the builtins
+ * and macros registered by `mymod_LTX_m4_init_module' are installed
+ * into the symbol table using `install_builtin_table' and `install_
+ * macro_table' respectively.
  **/
 
 #define MODULE_SELF_NAME        "!myself!"
@@ -73,8 +70,9 @@ static const char*  module_dlerror (void);
 static void         install_builtin_table (m4*, m4_module *);
 static void         install_macro_table   (m4*, m4_module *);
 
-static int          m4__module_interface        (lt_dlhandle handle,
-                                                 const char *id_string);
+static int          compare_builtin_CB    (const void *a, const void *b);
+static int          m4__module_interface  (lt_dlhandle handle,
+                                           const char *id_string);
 
 static lt_dlinterface_id iface_id = NULL;
 
@@ -117,6 +115,36 @@ m4_module_import (m4 *context, const char *module_name,
   return symbol_address;
 }
 
+void
+m4_install_builtins (m4 *context, m4_module *module, const m4_builtin *bp)
+{
+  assert (context);
+  assert (module);
+  assert (bp);
+
+  const m4_builtin *tmp;
+  m4__builtin *builtin;
+  for (tmp = bp; tmp->name; tmp++)
+    module->builtins_len++;
+  module->builtins = (m4__builtin *) xnmalloc (module->builtins_len,
+                                               sizeof *module->builtins);
+  for (builtin = module->builtins; bp->name != NULL; bp++, builtin++)
+    {
+      /* Sanity check that builtins meet the required interface. */
+      assert (bp->min_args <= bp->max_args);
+      assert (bp->min_args > 0 ||
+              (bp->flags & (M4_BUILTIN_BLIND|M4_BUILTIN_SIDE_EFFECT)) == 0);
+      assert (bp->max_args ||
+              (bp->flags & M4_BUILTIN_FLATTEN_ARGS) == 0);
+      assert ((bp->flags & ~M4_BUILTIN_FLAGS_MASK) == 0);
+      memcpy (&builtin->builtin, bp, sizeof *bp);
+      builtin->builtin.name = xstrdup (bp->name);
+      builtin->module = module;
+    }
+  qsort (module->builtins, module->builtins_len,
+         sizeof *module->builtins, compare_builtin_CB);
+}
+
 static void
 install_builtin_table (m4 *context, m4_module *module)
 {
@@ -144,6 +172,16 @@ install_builtin_table (m4 *context, m4_module *module)
                       m4_get_module_name (module));
 }
 
+void
+m4_install_macros (m4 *context, m4_module *module, const m4_macro *mp)
+{
+  assert (context);
+  assert (module);
+  assert (mp);
+
+  module->macros = (m4_macro *) mp;
+}
+
 static void
 install_macro_table (m4 *context, m4_module *module)
 {
@@ -152,7 +190,7 @@ install_macro_table (m4 *context, m4_module *module)
   assert (context);
   assert (module);
 
-  mp = (const m4_macro *) lt_dlsym (module->handle, MACRO_SYMBOL);
+  mp = module->macros;
 
   if (mp)
     {
@@ -174,7 +212,7 @@ install_macro_table (m4 *context, m4_module *module)
 
       m4_debug_message (context, M4_DEBUG_TRACE_MODULE,
                         _("module %s: macros loaded"),
-                        m4_get_module_name (module));
+		        m4_get_module_name (module));
     }
 }
 
@@ -209,9 +247,7 @@ m4__module_interface (lt_dlhandle handle, const char *id_string)
     return 0;
 
   /* A valid m4 module must provide at least one of these symbols.  */
-  return !(lt_dlsym (handle, INIT_SYMBOL)
-           || lt_dlsym (handle, BUILTIN_SYMBOL)
-           || lt_dlsym (handle, MACRO_SYMBOL));
+  return !(lt_dlsym (handle, INIT_SYMBOL));
 }
 
 
@@ -379,46 +415,10 @@ m4__module_open (m4 *context, const char *name, m4_obstack *obs)
         {
           void *old;
           const char *err;
-          const m4_builtin *bp;
 
           module = (m4_module *) xzalloc (sizeof *module);
           module->handle = handle;
 
-          /* TODO - change module interface to return function pointer
-             that supplies both table and length of table, rather than
-             returning data pointer that must have a sentinel
-             entry?  */
-          bp = (m4_builtin *) lt_dlsym (module->handle, BUILTIN_SYMBOL);
-          if (bp)
-            {
-              const m4_builtin *tmp;
-              m4__builtin *builtin;
-              for (tmp = bp; tmp->name; tmp++)
-                module->builtins_len++;
-              module->builtins =
-                (m4__builtin *) xnmalloc (module->builtins_len,
-                                          sizeof *module->builtins);
-              for (builtin = module->builtins; bp->name != NULL;
-                   bp++, builtin++)
-                {
-                  /* Sanity check that builtins meet the required
-                     interface.  */
-                  assert (bp->min_args <= bp->max_args);
-                  assert (bp->min_args > 0
-                          || (bp->flags & (M4_BUILTIN_BLIND
-                                           | M4_BUILTIN_SIDE_EFFECT)) == 0);
-                  assert (bp->max_args
-                          || (bp->flags & M4_BUILTIN_FLATTEN_ARGS) == 0);
-                  assert ((bp->flags & ~M4_BUILTIN_FLAGS_MASK) == 0);
-
-                  memcpy (&builtin->builtin, bp, sizeof *bp);
-                  builtin->builtin.name = xstrdup (bp->name);
-                  builtin->module = module;
-                }
-            }
-          qsort (module->builtins, module->builtins_len,
-                 sizeof *module->builtins, compare_builtin_CB);
-
           /* clear out any stale errors, since we have to use
              lt_dlerror to distinguish between success and
              failure.  */
@@ -429,23 +429,22 @@ m4__module_open (m4 *context, const char *name, m4_obstack *obs)
           if (err)
             m4_error (context, EXIT_FAILURE, 0, NULL,
                       _("unable to load module `%s': %s"), name, err);
-        }
 
-      /* Find and run any initializing function in the opened module,
-         each time the module is opened.  */
-      init_func = (m4_module_init_func *) lt_dlsym (handle, INIT_SYMBOL);
-      if (init_func)
-        {
-          init_func (context, module, obs);
+          /* Find and run any initializing function in the opened module,
+             the first time the module is opened.  */
+          init_func = (m4_module_init_func *) lt_dlsym (handle, INIT_SYMBOL);
+          if (init_func)
+            {
+              init_func (context, module, obs);
 
-          m4_debug_message (context, M4_DEBUG_TRACE_MODULE,
-                            _("module %s: init hook called"), name);
-        }
-      else if (!lt_dlsym (handle, BUILTIN_SYMBOL)
-               && !lt_dlsym (handle, MACRO_SYMBOL))
-        {
-          m4_error (context, EXIT_FAILURE, 0, NULL,
-                    _("module `%s' has no entry points"), name);
+              m4_debug_message (context, M4_DEBUG_TRACE_MODULE,
+                                _("module %s: init hook called"), name);
+            }
+          else
+            {
+              m4_error (context, EXIT_FAILURE, 0, NULL,
+                        _("module `%s' has no entry point"), name);
+            }
         }
 
       m4_debug_message (context, M4_DEBUG_TRACE_MODULE,
diff --git a/modules/gnu.c b/modules/gnu.c
index ae3024f7..5c9b0eed 100644
--- a/modules/gnu.c
+++ b/modules/gnu.c
@@ -32,11 +32,6 @@
 #include "spawn-pipe.h"
 #include "wait-process.h"
 
-/* Rename exported symbols for dlpreload()ing.  */
-#define m4_builtin_table        gnu_LTX_m4_builtin_table
-#define m4_macro_table          gnu_LTX_m4_macro_table
-
-
 /* Maintain each of the builtins implemented in this modules along
    with their details in a single table for easy maintenance.
 
@@ -70,7 +65,7 @@
 
 
 /* Generate a table for mapping m4 symbol names to handler functions. */
-const m4_builtin m4_builtin_table[] =
+static const m4_builtin m4_builtin_table[] =
 {
 #define BUILTIN(handler, macros, blind, side, min, max)                 \
   M4BUILTIN_ENTRY (handler, #handler, macros, blind, side, min, max)
@@ -83,7 +78,7 @@ const m4_builtin m4_builtin_table[] =
 
 
 /* A table for mapping m4 symbol names to simple expansion text. */
-const m4_macro m4_macro_table[] =
+static const m4_macro m4_macro_table[] =
 {
   /* name               text    min     max */
 #if UNIX
@@ -102,6 +97,13 @@ const m4_macro m4_macro_table[] =
 };
 
 
+M4INIT_HANDLER (gnu)
+{
+  m4_install_builtins (context, module, m4_builtin_table);
+  m4_install_macros   (context, module, m4_macro_table);
+}
+
+
 
 /* Regular expressions.  Reuse re_registers among multiple
    re_pattern_buffer allocations to reduce malloc usage.  */
diff --git a/modules/import.c b/modules/import.c
index ebce6e45..679a50d5 100644
--- a/modules/import.c
+++ b/modules/import.c
@@ -41,7 +41,7 @@
   builtin_functions
 #undef BUILTIN
 
-const m4_builtin m4_builtin_table[] =
+static const m4_builtin m4_builtin_table[] =
 {
 #define BUILTIN(handler, macros, blind, side, min, max)                 \
   M4BUILTIN_ENTRY (handler, #handler, macros, blind, side, min, max)
@@ -53,6 +53,12 @@ const m4_builtin m4_builtin_table[] =
 };
 
 
+M4INIT_HANDLER (import)
+{
+  m4_install_builtins (context, module, m4_builtin_table);
+}
+
+
 
 typedef bool export_test_func (const char *);
 typedef bool no_such_func (const char *);
diff --git a/modules/m4.c b/modules/m4.c
index f9449fe0..ecae4c3a 100644
--- a/modules/m4.c
+++ b/modules/m4.c
@@ -39,8 +39,6 @@
 #include <modules/m4.h>
 
 /* Rename exported symbols for dlpreload()ing.  */
-#define m4_builtin_table        m4_LTX_m4_builtin_table
-
 #define m4_set_sysval           m4_LTX_m4_set_sysval
 #define m4_sysval_flush         m4_LTX_m4_sysval_flush
 #define m4_dump_symbols         m4_LTX_m4_dump_symbols
@@ -127,6 +125,12 @@ const m4_builtin m4_builtin_table[] =
 };
 
 
+M4INIT_HANDLER (m4)
+{
+  m4_install_builtins (context, module, m4_builtin_table);
+}
+
+
 
 /* The rest of this file is code for builtins and expansion of user
    defined macros.  All the functions for builtins have a prototype as:
diff --git a/modules/modtest.c b/modules/modtest.c
index 385049b4..75450f7e 100644
--- a/modules/modtest.c
+++ b/modules/modtest.c
@@ -29,9 +29,6 @@
 #endif
 
 /* Rename exported symbols for dlpreload()ing.  */
-#define m4_builtin_table        modtest_LTX_m4_builtin_table
-#define m4_macro_table          modtest_LTX_m4_macro_table
-
 #define export_test             modtest_LTX_export_test
 
 extern bool export_test (const char *foo);
@@ -44,7 +41,7 @@ extern bool export_test (const char *foo);
   builtin_functions
 #undef BUILTIN
 
-const m4_builtin m4_builtin_table[] =
+static const m4_builtin m4_builtin_table[] =
 {
 #define BUILTIN(handler, macros, blind, side, min, max)                 \
   M4BUILTIN_ENTRY (handler, #handler, macros, blind, side, min, max)
@@ -55,7 +52,7 @@ const m4_builtin m4_builtin_table[] =
   { NULL, NULL, 0, 0, 0 },
 };
 
-const m4_macro m4_macro_table[] =
+static const m4_macro m4_macro_table[] =
 {
   /* name               text            min     max */
   { "__test__",         "`modtest'",    0,      0 },
@@ -73,6 +70,9 @@ M4INIT_HANDLER (modtest)
 {
   const char *s = "Test module loaded.\n";
 
+  m4_install_builtins (context, module, m4_builtin_table);
+  m4_install_macros   (context, module, m4_macro_table);
+
   /* Don't depend on OBS so that the traces are the same when used
      directly, or via a frozen file.  */
   fputs (s, stderr);
diff --git a/modules/mpeval.c b/modules/mpeval.c
index 7928a281..49afd765 100644
--- a/modules/mpeval.c
+++ b/modules/mpeval.c
@@ -32,11 +32,6 @@
 #  include <gmp.h>
 #endif
 
-/* Rename exported symbols for dlpreload()ing.  */
-#define m4_builtin_table        mpeval_LTX_m4_builtin_table
-#define m4_macro_table          mpeval_LTX_m4_macro_table
-
-
 /* Maintain each of the builtins implemented in this modules along
    with their details in a single table for easy maintenance.
 
@@ -106,7 +101,7 @@
 
 
 /* Generate a table for mapping m4 symbol names to handler functions. */
-const m4_builtin m4_builtin_table[] =
+static const m4_builtin m4_builtin_table[] =
 {
 #define BUILTIN(handler, macros, blind, side, min, max)                 \
   M4BUILTIN_ENTRY (handler, #handler, macros, blind, side, min, max)
@@ -119,7 +114,7 @@ const m4_builtin m4_builtin_table[] =
 
 
 /* A table for mapping m4 symbol names to simple expansion text. */
-const m4_macro m4_macro_table[] =
+static const m4_macro m4_macro_table[] =
 {
   /* name               text    min     max */
   { "__mpeval__",       "",     0,      0 },
@@ -127,6 +122,13 @@ const m4_macro m4_macro_table[] =
 };
 
 
+M4INIT_HANDLER (mpeval)
+{
+  m4_install_builtins (context, module, m4_builtin_table);
+  m4_install_macros   (context, module, m4_macro_table);
+}
+
+
 /* GMP defines mpq_t as a 1-element array of struct.  Therefore, `mpq_t'
    is not compatible with `const mpq_t'.  */
 typedef mpq_t number;
diff --git a/modules/shadow.c b/modules/shadow.c
index 529425c4..53829937 100644
--- a/modules/shadow.c
+++ b/modules/shadow.c
@@ -28,10 +28,6 @@
 #  include "m4private.h"
 #endif
 
-/* Rename exported symbols for dlpreload()ing.  */
-#define m4_builtin_table        shadow_LTX_m4_builtin_table
-#define m4_macro_table          shadow_LTX_m4_macro_table
-
 /*         function     macros  blind   side    minargs maxargs */
 #define builtin_functions                       \
   BUILTIN (shadow,      false,  false,  false,  0,      -1 )    \
@@ -42,7 +38,7 @@
   builtin_functions
 #undef BUILTIN
 
-const m4_builtin m4_builtin_table[] =
+static const m4_builtin m4_builtin_table[] =
 {
 #define BUILTIN(handler, macros, blind, side, min, max)                 \
   M4BUILTIN_ENTRY (handler, #handler, macros, blind, side, min, max)
@@ -53,7 +49,7 @@ const m4_builtin m4_builtin_table[] =
   { NULL, NULL, 0, 0, 0 },
 };
 
-const m4_macro m4_macro_table[] =
+static const m4_macro m4_macro_table[] =
 {
   /* name               text            min     max */
   { "__test__",         "`shadow'",     0,      0 },
@@ -64,16 +60,13 @@ const m4_macro m4_macro_table[] =
 
 M4INIT_HANDLER (shadow)
 {
-  static bool loaded = false;
-
   const char *s = "Shadow module loaded.";
 
-  /* Only display the message on first load.  */
-  if (obs && !loaded)
-    {
-      loaded = true;
+  if (obs)
       obstack_grow (obs, s, strlen (s));
-    }
+
+  m4_install_builtins (context, module, m4_builtin_table);
+  m4_install_macros   (context, module, m4_macro_table);
 }
 
 
diff --git a/modules/stdlib.c b/modules/stdlib.c
index d8f839cf..b01326df 100644
--- a/modules/stdlib.c
+++ b/modules/stdlib.c
@@ -36,12 +36,9 @@
 #  include "m4private.h"
 #endif
 
-/* Rename exported symbols for dlpreload()ing.  */
-#define m4_builtin_table        stdlib_LTX_m4_builtin_table
-
 /*         function     macros  blind   side    minargs maxargs */
 #define builtin_functions                                       \
-  BUILTIN (getcwd,      false,  false,  false,  0,      0  )    \
+    BUILTIN (getcwd,    false,  false,  false,  0,      0  )    \
     BUILTIN (getenv,    false,  true,   false,  1,      1  )    \
     BUILTIN (getlogin,  false,  false,  false,  0,      0  )    \
     BUILTIN (getpid,    false,  false,  false,  0,      0  )    \
@@ -61,7 +58,7 @@
   builtin_functions
 #undef BUILTIN
 
-const m4_builtin m4_builtin_table[] =
+static const m4_builtin m4_builtin_table[] =
 {
 #define BUILTIN(handler, macros, blind, side, min, max)                 \
   M4BUILTIN_ENTRY (handler, #handler, macros, blind, side, min, max)
@@ -71,6 +68,13 @@ const m4_builtin m4_builtin_table[] =
 
   { NULL, NULL, 0, 0, 0 },
 };
+
+
+M4INIT_HANDLER (stdlib)
+{
+  m4_install_builtins (context, module, m4_builtin_table);
+}
+
 
 /**
  * getcwd()
diff --git a/modules/time.c b/modules/time.c
index 573d14df..39db75fe 100644
--- a/modules/time.c
+++ b/modules/time.c
@@ -34,9 +34,6 @@
 #  include "m4private.h"
 #endif
 
-/* Rename exported symbols for dlpreload()ing.  */
-#define m4_builtin_table        time_LTX_m4_builtin_table
-
 /*         function     macros  blind   side    minargs maxargs */
 #define builtin_functions                                       \
   BUILTIN (currenttime, false,  false,  false,  0,      0  )    \
@@ -61,7 +58,7 @@
 # endif
 #undef BUILTIN
 
-const m4_builtin m4_builtin_table[] =
+static const m4_builtin m4_builtin_table[] =
 {
 #define BUILTIN(handler, macros, blind, side, min, max)                 \
   M4BUILTIN_ENTRY (handler, #handler, macros, blind, side, min, max)
@@ -77,6 +74,14 @@ const m4_builtin m4_builtin_table[] =
 
   { NULL, NULL, 0, 0, 0 },
 };
+
+
+M4INIT_HANDLER (time)
+{
+  m4_install_builtins (context, module, m4_builtin_table);
+}
+
+
 
 /**
  * currenttime()
diff --git a/modules/traditional.c b/modules/traditional.c
index cb9a32bd..88a4966b 100644
--- a/modules/traditional.c
+++ b/modules/traditional.c
@@ -28,11 +28,8 @@
 #  include "m4private.h"
 #endif
 
-/* Rename exported symbols for dlpreload()ing.  */
-#define m4_macro_table          traditional_LTX_m4_macro_table
-
 /* A table for mapping m4 symbol names to simple expansion text. */
-const m4_macro m4_macro_table[] =
+static const m4_macro m4_macro_table[] =
 {
   /* name               text    min     max */
 #if UNIX
@@ -47,3 +44,8 @@ const m4_macro m4_macro_table[] =
   { "__traditional__",  "",     0,      0 },
   { NULL,               NULL,   0,      0 },
 };
+
+M4INIT_HANDLER (traditional)
+{
+  m4_install_macros (context, module, m4_macro_table);
+}
diff --git a/tests/options.at b/tests/options.at
index 5848fa80..8503f8fc 100644
--- a/tests/options.at
+++ b/tests/options.at
@@ -423,9 +423,11 @@ dnl Test all flags.
 AT_CHECK_M4([-dV in], [0], [[3
 0
 ]], [[m4debug: module m4: opening file
+m4debug: module m4: init hook called
 m4debug: module m4: opened
 m4debug: module m4: builtins loaded
 m4debug: module gnu: opening file
+m4debug: module gnu: init hook called
 m4debug: module gnu: opened
 m4debug: module gnu: builtins loaded
 m4debug: module gnu: macros loaded