Check for go/scm mtime ordering rather than equality.

[bpt/guile.git] / libguile / load.c

/* Copyright (C) 1995,1996,1998,1999,2000,2001, 2004, 2006, 2008, 2009, 2010 Free Software Foundation, Inc.
 * 
 * This 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 3 of
 * the License, or (at your option) any later version.
 *
 * This 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 this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */


\f

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <string.h>
#include <stdio.h>

#include "libguile/_scm.h"
#include "libguile/private-gc.h" /* scm_getenv_int */
#include "libguile/libpath.h"
#include "libguile/fports.h"
#include "libguile/read.h"
#include "libguile/eval.h"
#include "libguile/throw.h"
#include "libguile/alist.h"
#include "libguile/dynwind.h"
#include "libguile/root.h"
#include "libguile/strings.h"
#include "libguile/modules.h"
#include "libguile/chars.h"
#include "libguile/srfi-13.h"

#include "libguile/validate.h"
#include "libguile/load.h"
#include "libguile/fluids.h"

#include "libguile/vm.h" /* for load-compiled/vm */

#include <sys/types.h>
#include <sys/stat.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif /* HAVE_UNISTD_H */

#ifdef HAVE_PWD_H
#include <pwd.h>
#endif /* HAVE_PWD_H */

#ifndef R_OK
#define R_OK 4
#endif

\f
/* Loading a file, given an absolute filename.  */

/* Hook to run when we load a file, perhaps to announce the fact somewhere.
   Applied to the full name of the file.  */
static SCM *scm_loc_load_hook;

/* The current reader (a fluid).  */
static SCM the_reader = SCM_BOOL_F;


SCM_DEFINE (scm_primitive_load, "primitive-load", 1, 0, 0, 
           (SCM filename),
            "Load the file named @var{filename} and evaluate its contents in\n"
            "the top-level environment. The load paths are not searched;\n"
            "@var{filename} must either be a full pathname or be a pathname\n"
            "relative to the current directory.  If the  variable\n"
            "@code{%load-hook} is defined, it should be bound to a procedure\n"
            "that will be called before any code is loaded.  See the\n"
            "documentation for @code{%load-hook} later in this section.")
#define FUNC_NAME s_scm_primitive_load
{
  SCM hook = *scm_loc_load_hook;
  char *encoding;
  SCM_VALIDATE_STRING (1, filename);
  if (scm_is_true (hook) && scm_is_false (scm_procedure_p (hook)))
    SCM_MISC_ERROR ("value of %load-hook is neither a procedure nor #f",
                    SCM_EOL);

  if (!scm_is_false (hook))
    scm_call_1 (hook, filename);

  { /* scope */
    SCM port = scm_open_file (filename, scm_from_locale_string ("r"));
    scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE);
    scm_i_dynwind_current_load_port (port);

    encoding = scm_i_scan_for_encoding (port);
    if (encoding)
      scm_i_set_port_encoding_x (port, encoding);
    else
      /* The file has no encoding declared.  We'll presume Latin-1.  */
      scm_i_set_port_encoding_x (port, NULL);

    while (1)
      {
        SCM reader, form;

        /* Lookup and use the current reader to read the next
           expression. */
        reader = scm_fluid_ref (the_reader);
        if (reader == SCM_BOOL_F)
          form = scm_read (port);
        else
          form = scm_call_1 (reader, port);

        if (SCM_EOF_OBJECT_P (form))
          break;

        scm_primitive_eval_x (form);
      }

    scm_dynwind_end ();
    scm_close_port (port);
  }
  return SCM_UNSPECIFIED;
}
#undef FUNC_NAME

SCM
scm_c_primitive_load (const char *filename)
{
  return scm_primitive_load (scm_from_locale_string (filename));
}

\f
/* Builtin path to scheme library files. */
#ifdef SCM_PKGDATA_DIR
SCM_DEFINE (scm_sys_package_data_dir, "%package-data-dir", 0, 0, 0, 
            (),
            "Return the name of the directory where Scheme packages, modules and\n"
            "libraries are kept.  On most Unix systems, this will be\n"
            "@samp{/usr/local/share/guile}.")
#define FUNC_NAME s_scm_sys_package_data_dir
{
  return scm_from_locale_string (SCM_PKGDATA_DIR);
}
#undef FUNC_NAME
#endif /* SCM_PKGDATA_DIR */

#ifdef SCM_LIBRARY_DIR
SCM_DEFINE (scm_sys_library_dir, "%library-dir", 0,0,0,
            (),
            "Return the directory where the Guile Scheme library files are installed.\n"
            "E.g., may return \"/usr/share/guile/1.3.5\".")
#define FUNC_NAME s_scm_sys_library_dir
{
  return scm_from_locale_string (SCM_LIBRARY_DIR);
}
#undef FUNC_NAME
#endif /* SCM_LIBRARY_DIR */

#ifdef SCM_SITE_DIR
SCM_DEFINE (scm_sys_site_dir, "%site-dir", 0,0,0,
            (),
            "Return the directory where the Guile site files are installed.\n"
            "E.g., may return \"/usr/share/guile/site\".")
#define FUNC_NAME s_scm_sys_site_dir
{
  return scm_from_locale_string (SCM_SITE_DIR);
}
#undef FUNC_NAME
#endif /* SCM_SITE_DIR */



\f
/* Initializing the load path, and searching it.  */

/* List of names of directories we search for files to load.  */
static SCM *scm_loc_load_path;

/* List of extensions we try adding to the filenames.  */
static SCM *scm_loc_load_extensions;

/* Like %load-path and %load-extensions, but for compiled files. */
static SCM *scm_loc_load_compiled_path;
static SCM *scm_loc_load_compiled_extensions;

/* Whether we should try to auto-compile. */
static SCM *scm_loc_load_should_autocompile;

/* The fallback path for autocompilation */
static SCM *scm_loc_compile_fallback_path;

SCM_DEFINE (scm_parse_path, "parse-path", 1, 1, 0, 
            (SCM path, SCM tail),
            "Parse @var{path}, which is expected to be a colon-separated\n"
            "string, into a list and return the resulting list with\n"
            "@var{tail} appended. If @var{path} is @code{#f}, @var{tail}\n"
            "is returned.")
#define FUNC_NAME s_scm_parse_path
{
#ifdef __MINGW32__
  SCM sep = SCM_MAKE_CHAR (';');
#else
  SCM sep = SCM_MAKE_CHAR (':');
#endif
  
  if (SCM_UNBNDP (tail))
    tail = SCM_EOL;
  return (scm_is_false (path)
          ? tail
          : scm_append_x (scm_list_2 (scm_string_split (path, sep), tail)));
}
#undef FUNC_NAME


/* Initialize the global variable %load-path, given the value of the
   SCM_SITE_DIR and SCM_LIBRARY_DIR preprocessor symbols and the
   GUILE_LOAD_PATH environment variable.  */
void
scm_init_load_path ()
{
  char *env;
  SCM path = SCM_EOL;
  SCM cpath = SCM_EOL;

#ifdef SCM_LIBRARY_DIR
  env = getenv ("GUILE_SYSTEM_PATH");
  if (env && strcmp (env, "") == 0)
    /* special-case interpret system-path=="" as meaning no system path instead
       of '("") */
    ; 
  else if (env)
    path = scm_parse_path (scm_from_locale_string (env), path);
  else
    path = scm_list_3 (scm_from_locale_string (SCM_LIBRARY_DIR),
                       scm_from_locale_string (SCM_SITE_DIR),
                       scm_from_locale_string (SCM_PKGDATA_DIR));

  env = getenv ("GUILE_SYSTEM_COMPILED_PATH");
  if (env && strcmp (env, "") == 0)
    /* like above */
    ; 
  else if (env)
    cpath = scm_parse_path (scm_from_locale_string (env), cpath);
  else
    cpath = scm_cons (scm_from_locale_string (SCM_CCACHE_DIR), cpath);

#endif /* SCM_LIBRARY_DIR */

  {
    char cachedir[1024];
    char *e;
#ifdef HAVE_GETPWENT
    struct passwd *pwd;
#endif

#define FALLBACK_DIR \
    "guile/ccache/" SCM_EFFECTIVE_VERSION "-" SCM_OBJCODE_MACHINE_VERSION_STRING

    if ((e = getenv ("XDG_CACHE_HOME")))
      snprintf (cachedir, sizeof(cachedir), "%s/" FALLBACK_DIR, e);
    else if ((e = getenv ("HOME")))
      snprintf (cachedir, sizeof(cachedir), "%s/.cache/" FALLBACK_DIR, e);
#ifdef HAVE_GETPWENT
    else if ((pwd = getpwuid (getuid ())) && pwd->pw_dir)
      snprintf (cachedir, sizeof(cachedir), "%s/.cache/" FALLBACK_DIR,
                pwd->pw_dir);
#endif /* HAVE_GETPWENT */
    else
      cachedir[0] = 0;

    if (cachedir[0])
      *scm_loc_compile_fallback_path = scm_from_locale_string (cachedir);
  }

  env = getenv ("GUILE_LOAD_PATH");
  if (env)
    path = scm_parse_path (scm_from_locale_string (env), path);

  env = getenv ("GUILE_LOAD_COMPILED_PATH");
  if (env)
    cpath = scm_parse_path (scm_from_locale_string (env), cpath);

  *scm_loc_load_path = path;
  *scm_loc_load_compiled_path = cpath;
}

SCM scm_listofnullstr;

/* Utility functions for assembling C strings in a buffer.
 */

struct stringbuf {
  char *buf, *ptr;
  size_t buf_len;
};

static void
stringbuf_free (void *data)
{
  struct stringbuf *buf = (struct stringbuf *)data;
  free (buf->buf);
}

static void
stringbuf_grow (struct stringbuf *buf)
{
  size_t ptroff = buf->ptr - buf->buf;
  buf->buf_len *= 2; 
  buf->buf = scm_realloc (buf->buf, buf->buf_len);
  buf->ptr = buf->buf + ptroff;
}

static void
stringbuf_cat_locale_string (struct stringbuf *buf, SCM str)
{
  size_t max_len = buf->buf_len - (buf->ptr - buf->buf) - 1;
  size_t len = scm_to_locale_stringbuf (str, buf->ptr, max_len);
  if (len > max_len)
    {
      /* buffer is too small, double its size and try again. 
       */
      stringbuf_grow (buf);
      stringbuf_cat_locale_string (buf, str);
    }
  else
    {
      /* string fits, terminate it and check for embedded '\0'.
       */
      buf->ptr[len] = '\0';
      if (strlen (buf->ptr) != len)
        scm_misc_error (NULL,
                        "string contains #\\nul character: ~S",
                        scm_list_1 (str));
      buf->ptr += len;
    }
}

static void
stringbuf_cat (struct stringbuf *buf, char *str)
{
  size_t max_len = buf->buf_len - (buf->ptr - buf->buf) - 1;
  size_t len = strlen (str);
  if (len > max_len)
    {
      /* buffer is too small, double its size and try again. 
       */
      stringbuf_grow (buf);
      stringbuf_cat (buf, str);
    }
  else
    {
      /* string fits, copy it into buffer.
       */
      strcpy (buf->ptr, str);
      buf->ptr += len;
    }
}

  
static int
scm_c_string_has_an_ext (char *str, size_t len, SCM extensions)
{
  for (; !scm_is_null (extensions); extensions = SCM_CDR (extensions))
    {
      char *ext;
      size_t extlen;
      int match;
      ext = scm_to_locale_string (SCM_CAR (extensions));
      extlen = strlen (ext);
      match = (len > extlen && str[len - extlen - 1] == '.'
               && strncmp (str + (len - extlen), ext, extlen) == 0);
      free (ext);
      if (match)
        return 1;
    }
  return 0;
}

/* Search PATH for a directory containing a file named FILENAME.
   The file must be readable, and not a directory.
   If we find one, return its full filename; otherwise, return #f.
   If FILENAME is absolute, return it unchanged.
   If given, EXTENSIONS is a list of strings; for each directory 
   in PATH, we search for FILENAME concatenated with each EXTENSION.  */
SCM_DEFINE (scm_search_path, "search-path", 2, 0, 1,
            (SCM path, SCM filename, SCM rest),
            "Search @var{path} for a directory containing a file named\n"
            "@var{filename}. The file must be readable, and not a directory.\n"
            "If we find one, return its full filename; otherwise, return\n"
            "@code{#f}.  If @var{filename} is absolute, return it unchanged.\n"
            "If given, @var{extensions} is a list of strings; for each\n"
            "directory in @var{path}, we search for @var{filename}\n"
            "concatenated with each @var{extension}.")
#define FUNC_NAME s_scm_search_path
{
  struct stringbuf buf;
  char *filename_chars;
  size_t filename_len;
  SCM extensions, require_exts;
  SCM result = SCM_BOOL_F;

  if (SCM_UNBNDP (rest) || scm_is_null (rest))
    {
      /* Called either by Scheme code that didn't provide the optional
         arguments, or C code that used the Guile 1.8 signature (2 required,
         1 optional arg) and passed '() or nothing as the EXTENSIONS
         argument.  */
      extensions = SCM_EOL;
      require_exts = SCM_UNDEFINED;
    }
  else
    {
      if (scm_is_null (SCM_CAR (rest)) || scm_is_pair (SCM_CAR (rest)))
        {
          /* Called by Scheme code written for 1.9.  */
          extensions = SCM_CAR (rest);
          if (scm_is_null (SCM_CDR (rest)))
            require_exts = SCM_UNDEFINED;
          else
            {
              require_exts = SCM_CADR (rest);
              if (SCM_UNLIKELY (!scm_is_null (SCM_CDDR (rest))))
                scm_wrong_num_args (scm_from_locale_string (FUNC_NAME));
            }
        }
      else
        {
          /* Called by C code that uses the 1.8 signature, i.e., which
             expects the 3rd argument to be EXTENSIONS.  */
          extensions = rest;
          require_exts = SCM_UNDEFINED;
        }
    }

  if (SCM_UNBNDP (extensions))
    extensions = SCM_EOL;

  SCM_VALIDATE_LIST (3, extensions);

  if (SCM_UNBNDP (require_exts))
    require_exts = SCM_BOOL_F;

  scm_dynwind_begin (0);

  filename_chars = scm_to_locale_string (filename);
  filename_len = strlen (filename_chars);
  scm_dynwind_free (filename_chars);

  /* If FILENAME is absolute, return it unchanged.  */
#ifdef __MINGW32__
  if (((filename_len >= 1) && 
       (filename_chars[0] == '/' || filename_chars[0] == '\\')) ||
      ((filename_len >= 3) && filename_chars[1] == ':' &&
       ((filename_chars[0] >= 'a' && filename_chars[0] <= 'z') ||
        (filename_chars[0] >= 'A' && filename_chars[0] <= 'Z')) &&
       (filename_chars[2] == '/' || filename_chars[2] == '\\')))
#else
  if (filename_len >= 1 && filename_chars[0] == '/')
#endif
    {
      SCM res = filename;
      if (scm_is_true (require_exts) &&
          !scm_c_string_has_an_ext (filename_chars, filename_len,
                                    extensions))
        res = SCM_BOOL_F;

      scm_dynwind_end ();
      return res;
    }

  /* If FILENAME has an extension, don't try to add EXTENSIONS to it.  */
  {
    char *endp;

    for (endp = filename_chars + filename_len - 1;
         endp >= filename_chars;
         endp--)
      {
        if (*endp == '.')
          {
            if (scm_is_true (require_exts) &&
                !scm_c_string_has_an_ext (filename_chars, filename_len,
                                          extensions))
              {
                /* This filename has an extension, but not one of the right
                   ones... */
                scm_dynwind_end ();
                return SCM_BOOL_F;
              }
            /* This filename already has an extension, so cancel the
               list of extensions.  */
            extensions = SCM_EOL;
            break;
          }
#ifdef __MINGW32__
        else if (*endp == '/' || *endp == '\\')
#else
        else if (*endp == '/')
#endif
          /* This filename has no extension, so keep the current list
             of extensions.  */
          break;
      }
  }

  /* This simplifies the loop below a bit.
   */
  if (scm_is_null (extensions))
    extensions = scm_listofnullstr;

  buf.buf_len = 512;
  buf.buf = scm_malloc (buf.buf_len);
  scm_dynwind_unwind_handler (stringbuf_free, &buf, SCM_F_WIND_EXPLICITLY);

  /* Try every path element.
   */
  for (; scm_is_pair (path); path = SCM_CDR (path))
    {
      SCM dir = SCM_CAR (path);
      SCM exts;
      size_t sans_ext_len;

      buf.ptr = buf.buf;
      stringbuf_cat_locale_string (&buf, dir);
        
      /* Concatenate the path name and the filename. */
      
#ifdef __MINGW32__
      if ((buf.ptr > buf.buf) && (buf.ptr[-1] != '/') && (buf.ptr[-1] != '\\'))
#else
      if ((buf.ptr > buf.buf) && (buf.ptr[-1] != '/'))
#endif
        stringbuf_cat (&buf, "/");

      stringbuf_cat (&buf, filename_chars);
      sans_ext_len = buf.ptr - buf.buf;

      /* Try every extension. */
      for (exts = extensions; scm_is_pair (exts); exts = SCM_CDR (exts))
        {
          SCM ext = SCM_CAR (exts);
          struct stat mode;
          
          buf.ptr = buf.buf + sans_ext_len;
          stringbuf_cat_locale_string (&buf, ext);
          
          /* If the file exists at all, we should return it.  If the
             file is inaccessible, then that's an error.  */

          if (stat (buf.buf, &mode) == 0
              && ! (mode.st_mode & S_IFDIR))
            {
              result = scm_from_locale_string (buf.buf);
              goto end;
            }
        }
      
      if (!SCM_NULL_OR_NIL_P (exts))
        scm_wrong_type_arg_msg (NULL, 0, extensions, "proper list");
    }

  if (!SCM_NULL_OR_NIL_P (path))
    scm_wrong_type_arg_msg (NULL, 0, path, "proper list");

 end:
  scm_dynwind_end ();
  return result;
}
#undef FUNC_NAME


/* Search %load-path for a directory containing a file named FILENAME.
   The file must be readable, and not a directory.
   If we find one, return its full filename; otherwise, return #f.
   If FILENAME is absolute, return it unchanged.  */
SCM_DEFINE (scm_sys_search_load_path, "%search-load-path", 1, 0, 0, 
            (SCM filename),
            "Search @var{%load-path} for the file named @var{filename},\n"
            "which must be readable by the current user.  If @var{filename}\n"
            "is found in the list of paths to search or is an absolute\n"
            "pathname, return its full pathname.  Otherwise, return\n"
            "@code{#f}.  Filenames may have any of the optional extensions\n"
            "in the @code{%load-extensions} list; @code{%search-load-path}\n"
            "will try each extension automatically.")
#define FUNC_NAME s_scm_sys_search_load_path
{
  SCM path = *scm_loc_load_path;
  SCM exts = *scm_loc_load_extensions;
  SCM_VALIDATE_STRING (1, filename);

  if (scm_ilength (path) < 0)
    SCM_MISC_ERROR ("%load-path is not a proper list", SCM_EOL);
  if (scm_ilength (exts) < 0)
    SCM_MISC_ERROR ("%load-extension list is not a proper list", SCM_EOL);
  return scm_search_path (path, filename, exts);
}
#undef FUNC_NAME


static int
compiled_is_fresh (SCM full_filename, SCM compiled_filename)
{
  char *source, *compiled;
  struct stat stat_source, stat_compiled;
  int res;

  source = scm_to_locale_string (full_filename);
  compiled = scm_to_locale_string (compiled_filename);

  if (stat (source, &stat_source) == 0
      && stat (compiled, &stat_compiled) == 0
      && stat_source.st_mtime <= stat_compiled.st_mtime)
    {
      res = 1;
    }
  else
    {
      scm_puts (";;; note: source file ", scm_current_error_port ());
      scm_puts (source, scm_current_error_port ());
      scm_puts ("\n;;;       newer than compiled ", scm_current_error_port ());
      scm_puts (compiled, scm_current_error_port ());
      scm_puts ("\n", scm_current_error_port ());
      res = 0;
    }

  free (source);
  free (compiled);
  return res;
}

SCM_KEYWORD (kw_env, "env");

static SCM
do_try_autocompile (void *data)
{
  SCM source = PTR2SCM (data);
  SCM comp_mod, compile_file;

  scm_puts (";;; compiling ", scm_current_error_port ());
  scm_display (source, scm_current_error_port ());
  scm_newline (scm_current_error_port ());

  comp_mod = scm_c_resolve_module ("system base compile");
  compile_file = scm_module_variable
    (comp_mod, scm_from_locale_symbol ("compile-file"));

  if (scm_is_true (compile_file))
    {
      /* Auto-compile in the context of the current module.  */
      SCM res = scm_call_3 (scm_variable_ref (compile_file), source,
                            kw_env, scm_current_module ());
      scm_puts (";;; compiled ", scm_current_error_port ());
      scm_display (res, scm_current_error_port ());
      scm_newline (scm_current_error_port ());
      return res;
    }
  else
    {
      scm_puts (";;; it seems ", scm_current_error_port ());
      scm_display (source, scm_current_error_port ());
      scm_puts ("\n;;; is part of the compiler; skipping autocompilation\n",
                scm_current_error_port ());
      return SCM_BOOL_F;
    }
}

static SCM
autocompile_catch_handler (void *data, SCM tag, SCM throw_args)
{
  SCM source = PTR2SCM (data);
  scm_puts (";;; WARNING: compilation of ", scm_current_error_port ());
  scm_display (source, scm_current_error_port ());
  scm_puts (" failed:\n", scm_current_error_port ());
  scm_puts (";;; key ", scm_current_error_port ());
  scm_write (tag, scm_current_error_port ());
  scm_puts (", throw args ", scm_current_error_port ());
  scm_write (throw_args, scm_current_error_port ());
  scm_newline (scm_current_error_port ());
  return SCM_BOOL_F;
}

SCM_DEFINE (scm_sys_warn_autocompilation_enabled, "%warn-autocompilation-enabled", 0, 0, 0,
            (void), "")
#define FUNC_NAME s_scm_sys_warn_autocompilation_enabled
{
  static int message_shown = 0;

  if (!message_shown)
    {
      scm_puts (";;; note: autocompilation is enabled, set GUILE_AUTO_COMPILE=0\n"
                ";;;       or pass the --no-autocompile argument to disable.\n",
                scm_current_error_port ());
      message_shown = 1;
    }

  return SCM_UNSPECIFIED;
}
#undef FUNC_NAME

static SCM
scm_try_autocompile (SCM source)
{
  if (scm_is_false (*scm_loc_load_should_autocompile))
    return SCM_BOOL_F;

  scm_sys_warn_autocompilation_enabled ();
  return scm_c_catch (SCM_BOOL_T,
                      do_try_autocompile,
                      SCM2PTR (source),
                      autocompile_catch_handler,
                      SCM2PTR (source),
                      NULL, NULL);
}

SCM_DEFINE (scm_primitive_load_path, "primitive-load-path", 0, 0, 1,
            (SCM args),
            "Search @var{%load-path} for the file named @var{filename} and\n"
            "load it into the top-level environment.  If @var{filename} is a\n"
            "relative pathname and is not found in the list of search paths,\n"
            "an error is signalled, unless the optional argument\n"
            "@var{exception_on_not_found} is @code{#f}, in which case\n"
            "@code{#f} is returned instead.")
#define FUNC_NAME s_scm_primitive_load_path
{
  SCM filename, exception_on_not_found;
  SCM full_filename, compiled_filename;
  int compiled_is_fallback = 0;

  if (scm_is_string (args))
    {
      /* C code written for 1.8 and earlier expects this function to take a
         single argument (the file name).  */
      filename = args;
      exception_on_not_found = SCM_UNDEFINED;
    }
  else
    {
      /* Starting from 1.9, this function takes 1 required and 1 optional
         argument.  */
      long len;

      SCM_VALIDATE_LIST_COPYLEN (SCM_ARG1, args, len);
      if (len < 1 || len > 2)
        scm_error_num_args_subr (FUNC_NAME);

      filename = SCM_CAR (args);
      SCM_VALIDATE_STRING (SCM_ARG1, filename);

      exception_on_not_found = len > 1 ? SCM_CADR (args) : SCM_UNDEFINED;
    }

  if (SCM_UNBNDP (exception_on_not_found))
    exception_on_not_found = SCM_BOOL_T;

  full_filename = scm_sys_search_load_path (filename);
  if (scm_is_string (full_filename))
    full_filename = scm_canonicalize_path (full_filename);

  compiled_filename =
    scm_search_path (*scm_loc_load_compiled_path,
                     filename,
                     scm_list_2 (*scm_loc_load_compiled_extensions,
                                 SCM_BOOL_T));

  if (scm_is_false (compiled_filename)
      && scm_is_true (full_filename)
      && scm_is_true (*scm_loc_compile_fallback_path)
      && scm_is_pair (*scm_loc_load_compiled_extensions)
      && scm_is_string (scm_car (*scm_loc_load_compiled_extensions)))
    {
      SCM fallback = scm_string_append
        (scm_list_3 (*scm_loc_compile_fallback_path,
                     full_filename,
                     scm_car (*scm_loc_load_compiled_extensions)));
      if (scm_is_true (scm_stat (fallback, SCM_BOOL_F)))
        {
          compiled_filename = fallback;
          compiled_is_fallback = 1;
        }
    }
  
  if (scm_is_false (full_filename) && scm_is_false (compiled_filename))
    {
      if (scm_is_true (exception_on_not_found))
        SCM_MISC_ERROR ("Unable to find file ~S in load path",
                        scm_list_1 (filename));
      else
        return SCM_BOOL_F;
    }

  if (scm_is_false (full_filename)
      || (scm_is_true (compiled_filename)
          && compiled_is_fresh (full_filename, compiled_filename)))
    return scm_load_compiled_with_vm (compiled_filename);

  /* Perhaps there was the installed .go that was stale, but our fallback is
     fresh. Let's try that. Duplicating code, but perhaps that's OK. */

  if (!compiled_is_fallback
      && scm_is_true (*scm_loc_compile_fallback_path)
      && scm_is_pair (*scm_loc_load_compiled_extensions)
      && scm_is_string (scm_car (*scm_loc_load_compiled_extensions)))
    {
      SCM fallback = scm_string_append
        (scm_list_3 (*scm_loc_compile_fallback_path,
                     full_filename,
                     scm_car (*scm_loc_load_compiled_extensions)));
      if (scm_is_true (scm_stat (fallback, SCM_BOOL_F))
          && compiled_is_fresh (full_filename, fallback))
        {
          scm_puts (";;; found fresh local cache at ", scm_current_error_port ());
          scm_display (fallback, scm_current_error_port ());
          scm_newline (scm_current_error_port ());
          return scm_load_compiled_with_vm (fallback);
        }
    }

  /* Otherwise, we bottom out here. */
  {
    SCM freshly_compiled = scm_try_autocompile (full_filename);

    if (scm_is_true (freshly_compiled))
      return scm_load_compiled_with_vm (freshly_compiled);
    else
      return scm_primitive_load (full_filename);
  }
}
#undef FUNC_NAME

SCM
scm_c_primitive_load_path (const char *filename)
{
  return scm_primitive_load_path (scm_from_locale_string (filename));
}

void
scm_init_eval_in_scheme (void)
{
  SCM eval_scm, eval_go;
  eval_scm = scm_search_path (*scm_loc_load_path,
                              scm_from_locale_string ("ice-9/eval.scm"),
                              SCM_EOL);
  eval_go = scm_search_path (*scm_loc_load_compiled_path,
                             scm_from_locale_string ("ice-9/eval.go"),
                             SCM_EOL);
  
  if (scm_is_true (eval_scm) && scm_is_true (eval_go)
      && compiled_is_fresh (eval_scm, eval_go))
    scm_load_compiled_with_vm (eval_go);
  else
    /* if we have no eval.go, we shouldn't load any compiled code at all */
    *scm_loc_load_compiled_path = SCM_EOL;
}

\f
/* Information about the build environment.  */

SCM_VARIABLE_INIT (sys_host_type, "%host-type",
                   scm_from_locale_string (HOST_TYPE));


/* Initialize the scheme variable %guile-build-info, based on data
   provided by the Makefile, via libpath.h.  */
static void
init_build_info ()
{
  static struct { char *name; char *value; } info[] = SCM_BUILD_INFO;
  SCM *loc = SCM_VARIABLE_LOC (scm_c_define ("%guile-build-info", SCM_EOL));
  unsigned long i;

  for (i = 0; i < (sizeof (info) / sizeof (info[0])); i++)
    {
      SCM key = scm_from_locale_symbol (info[i].name);
      SCM val = scm_from_locale_string (info[i].value);
      *loc = scm_acons (key, val, *loc);
    }
}

\f
void
scm_init_load ()
{
  scm_listofnullstr = scm_list_1 (scm_nullstr);
  scm_loc_load_path = SCM_VARIABLE_LOC (scm_c_define ("%load-path", SCM_EOL));
  scm_loc_load_extensions
    = SCM_VARIABLE_LOC (scm_c_define ("%load-extensions",
                                      scm_list_2 (scm_from_locale_string (".scm"),
                                                  scm_nullstr)));
  scm_loc_load_compiled_path
    = SCM_VARIABLE_LOC (scm_c_define ("%load-compiled-path", SCM_EOL));
  scm_loc_load_compiled_extensions
    = SCM_VARIABLE_LOC (scm_c_define ("%load-compiled-extensions",
                                      scm_list_1 (scm_from_locale_string (".go"))));
  scm_loc_load_hook = SCM_VARIABLE_LOC (scm_c_define ("%load-hook", SCM_BOOL_F));

  scm_loc_compile_fallback_path
    = SCM_VARIABLE_LOC (scm_c_define ("%compile-fallback-path", SCM_BOOL_F));
  scm_loc_load_should_autocompile
    = SCM_VARIABLE_LOC (scm_c_define ("%load-should-autocompile", SCM_BOOL_F));

  the_reader = scm_make_fluid ();
  scm_fluid_set_x (the_reader, SCM_BOOL_F);
  scm_c_define("current-reader", the_reader);

  scm_c_define ("load-compiled",
                scm_c_make_gsubr ("load-compiled/vm", 1, 0, 0,
                                  scm_load_compiled_with_vm));

  init_build_info ();

#include "libguile/load.x"
}

void
scm_init_load_should_autocompile ()
{
  *scm_loc_load_should_autocompile =
    scm_from_bool (scm_getenv_int ("GUILE_AUTO_COMPILE", 1));
}
  
  

/*
  Local Variables:
  c-file-style: "gnu"
  End:
*/