Add loadable modules using Daniel Colascione's ideas.scratch/dynamic-modules-2

See https://lists.gnu.org/archive/html/emacs-devel/2015-02/msg00960.html

* src/Makefile.in (base_obj): add module.o
  (LIBES): add -lltdl

* src/emacs.c (main): add syms_of_module

* src/lisp.h: add syms_of_module

* src/emacs_module.h: New file; emacs API for modules.

* src/module.c: New file; implement API.

* modules/basic/Makefile: New file; build example module on Linux.

* modules/basic/basic.c: New file; simple example module.

1 files changed, 175 insertions, 0 deletions

diff --git a/src/emacs_module.h b/src/emacs_module.h
new file mode 100644
index 00000000000..2dbb2a2f5ce
--- /dev/null
+++ b/src/emacs_module.h
@@ -0,0 +1,175 @@
+/*
+  emacs_module.h - Module API
+  Copyright (C) 2015 Free Software Foundation, Inc.
+
+  This file is part of GNU Emacs.
+
+  GNU Emacs is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  GNU Emacs 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 General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef EMACS_MODULE_H
+#define EMACS_MODULE_H
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+/* Current environment */
+typedef struct emacs_env_25 emacs_env;
+
+/* The size of emacs_value must match EMACS_INT:
+   32 bit system: 32 bits
+   32 bit system with --with-wide-int: 64 bits
+   64 bit system: 64 bits.
+
+   When compiling modules, define the macro EMACS_VALUE_TYPE by the
+   result of `module-emacs_value-type'. */
+typedef EMACS_VALUE_TYPE emacs_value;
+
+/* Struct passed to a module init function (emacs_module_init) */
+struct emacs_runtime {
+  size_t size;
+  emacs_env* (*get_environment)(struct emacs_runtime *ert);
+};
+
+
+/* Function prototype for the module init function */
+typedef int (*emacs_init_function)(struct emacs_runtime *ert);
+
+/* Function prototype for the module Lisp functions */
+typedef emacs_value (*emacs_subr)(emacs_env *env,
+                                  int nargs,
+                                  emacs_value args[]);
+struct emacs_env_25 {
+  /*
+   * Structure size (for version checking)
+   */
+
+  size_t size;
+
+  /*
+   * Constants
+   */
+  emacs_value Qt_value;
+  emacs_value Qnil_value;
+
+  /*
+   * Memory management
+   */
+
+  emacs_value (*make_global_reference)(emacs_env *env,
+                                       emacs_value any_reference);
+
+  void (*free_global_reference)(emacs_env *env,
+                                emacs_value global_reference);
+
+  /*
+   * Error handling
+   */
+
+  bool (*error_check)(emacs_env *env);
+
+  void (*clear_error)(emacs_env *env);
+
+  bool (*get_error)(emacs_env *env,
+                    emacs_value *error_symbol_out,
+                    emacs_value *error_data_out);
+
+  void (*signal_error)(emacs_env *env,
+                       const char* msg,
+                       emacs_value error_data);
+
+  /*
+   * Function registration
+   */
+
+  emacs_value (*make_function)(emacs_env *env,
+                               int min_arity,
+                               int max_arity,
+                               emacs_subr function);
+
+  emacs_value (*funcall)(emacs_env *env,
+                         emacs_value function,
+                         int nargs,
+                         emacs_value args[]);
+
+  emacs_value (*intern)(emacs_env *env,
+                        const char *symbol_name);
+
+  emacs_value (*intern_soft)(emacs_env *env,
+                             const char *symbol_name);
+
+  void (*bind_function) (emacs_env *env,
+                         const char *name,
+                         emacs_value definition);
+
+  /*
+   * Type conversion
+   */
+
+  emacs_value (*type_of)(emacs_env *env,
+                         emacs_value value);
+
+  int64_t (*fixnum_to_int)(emacs_env *env,
+                           emacs_value value);
+
+  emacs_value (*make_fixnum)(emacs_env *env,
+                             int64_t value);
+
+  double (*float_to_c_double)(emacs_env *env,
+                              emacs_value value);
+
+  emacs_value (*make_float)(emacs_env *env,
+                            double value);
+
+  bool (*copy_string_contents)(emacs_env *env,
+                               emacs_value value,
+                               char *buffer,
+                               size_t* length_inout);
+
+  size_t (*buffer_byte_length)(emacs_env   *env,
+                               emacs_value  start,
+                               emacs_value  end);
+  /* Return the size in bytes of the buffer substring in the current
+     buffer from START to END */
+
+  void (*copy_buffer_substring)(emacs_env   *env,
+                                emacs_value  start,
+                                emacs_value  end,
+                                char        *buffer,
+                                size_t*      length_inout);
+  /* Copy buffer string from current buffer, BEG to END (integers or
+     markers), to BUFFER. On call, LENGTH_INOUT is the size in bytes
+     of BUFFER; on return, it is the size in bytes of the copied
+     string.
+
+     If BUFFER is too small, signals an error. Use buffer_byte_length
+     to ensure BUFFER is not too small. */
+
+  emacs_value (*make_string)(emacs_env *env,
+                             const char *contents);
+
+  /*
+   * miscellaneous
+   */
+
+  void (*message)(emacs_env *env,
+                  emacs_value msg);
+  /* msg must be already formatted */
+
+  emacs_value (*symbol_value)(emacs_env *env,
+                              emacs_value symbol);
+};
+
+#endif /* EMACS_MODULE_H */