guile/libguile/load.c

/*	Copyright (C) 1995,1996,1998,1999 Free Software Foundation, Inc.
 * 
 * This program 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 2, or (at your option)
 * any later version.
 * 
 * This program 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 this software; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307 USA
 *
 * As a special exception, the Free Software Foundation gives permission
 * for additional uses of the text contained in its release of GUILE.
 *
 * The exception is that, if you link the GUILE library with other files
 * to produce an executable, this does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * Your use of that executable is in no way restricted on account of
 * linking the GUILE library code into it.
 *
 * This exception does not however invalidate any other reasons why
 * the executable file might be covered by the GNU General Public License.
 *
 * This exception applies only to the code released by the
 * Free Software Foundation under the name GUILE.  If you copy
 * code from other Free Software Foundation releases into a copy of
 * GUILE, as the General Public License permits, the exception does
 * not apply to the code that you add in this way.  To avoid misleading
 * anyone as to the status of such modified files, you must delete
 * this exception notice from them.
 *
 * If you write modifications of your own for GUILE, it is your choice
 * whether to permit this exception to apply to your modifications.
 * If you do not wish that, delete this exception notice.  */


#include <stdio.h>
#include "_scm.h"
#include "libpath.h"
#include "fports.h"
#include "read.h"
#include "eval.h"
#include "throw.h"
#include "alist.h"
#include "dynwind.h"

#include "load.h"

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

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

#ifndef R_OK
#define R_OK 4
#endif


/* 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;

static void
swap_port (void *data)
{
  SCM *save_port = data, tmp = scm_cur_loadp;
  scm_cur_loadp = *save_port;
  *save_port = tmp;
}

static SCM
load (void *data)
{
  SCM port = (SCM) data, form;
  while (1)
    {
      form = scm_read (port);
      if (SCM_EOF_OBJECT_P (form))
	break;
      scm_eval_x (form);
    }
  return SCM_UNSPECIFIED;
}

SCM_PROC(s_primitive_load, "primitive-load", 1, 0, 0, scm_primitive_load);
SCM 
scm_primitive_load (filename)
     SCM filename;
{
  SCM hook = *scm_loc_load_hook;
  SCM_ASSERT (SCM_NIMP (filename) && SCM_ROSTRINGP (filename), filename,
	      SCM_ARG1, s_primitive_load);
  SCM_ASSERT (hook == SCM_BOOL_F
	      || (scm_procedure_p (hook) == SCM_BOOL_T),
	      hook, "value of %load-hook is neither a procedure nor #f",
	      s_primitive_load);

  if (hook != SCM_BOOL_F)
    scm_apply (hook, scm_listify (filename, SCM_UNDEFINED), SCM_EOL);

  {
    SCM port, save_port;
    port = scm_open_file (filename,
			  scm_makfromstr ("r", (scm_sizet) sizeof (char), 0));
    save_port = port;
    scm_internal_dynamic_wind (swap_port,
			       load,
			       swap_port,
			       (void *) port,
			       &save_port);
    scm_close_port (port);
  }
  return SCM_UNSPECIFIED;
}


/* Builtin path to scheme library files. */
#ifdef SCM_PKGDATA_DIR
SCM_PROC (s_sys_package_data_dir, "%package-data-dir", 0, 0, 0, scm_sys_package_data_dir);
SCM
scm_sys_package_data_dir ()
{
  return scm_makfrom0str (SCM_PKGDATA_DIR);
}
#endif /* SCM_PKGDATA_DIR */


/* 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;


/* Parse the null-terminated string PATH as if it were a standard path
   environment variable (i.e. a colon-separated list of strings), and
   prepend the elements to TAIL.  */
SCM
scm_internal_parse_path (char *path, SCM tail)
{
  if (path && path[0] != '\0')
    {
      char *scan, *elt_end;

      /* Scan backwards from the end of the string, to help
	 construct the list in the right order.  */
      scan = elt_end = path + strlen (path);
      do {
	/* Scan back to the beginning of the current element.  */
	do scan--;
	while (scan >= path && *scan != ':');
	tail = scm_cons (scm_makfromstr (scan + 1, elt_end - (scan + 1), 0),
			 tail);
	elt_end = scan;
      } while (scan >= path);
    }

  return tail;
}


SCM_PROC (s_parse_path, "parse-path", 1, 1, 0, scm_parse_path);

SCM
scm_parse_path (SCM path, SCM tail)
{
  SCM_ASSERT (SCM_FALSEP (path) || (SCM_NIMP (path) && SCM_ROSTRINGP (path)),
	      path,
	      SCM_ARG1,
	      s_parse_path);
  if (SCM_UNBNDP (tail))
    tail = SCM_EOL;
  return (SCM_FALSEP (path)
	  ? tail
	  : scm_internal_parse_path (SCM_ROCHARS (path), tail));
}


/* 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 ()
{
  SCM path = SCM_EOL;

#ifdef SCM_LIBRARY_DIR
  path = scm_listify (scm_makfrom0str (SCM_SITE_DIR),
		      scm_makfrom0str (SCM_LIBRARY_DIR),
		      scm_makfrom0str (SCM_PKGDATA_DIR),
		      SCM_UNDEFINED);
#endif /* SCM_LIBRARY_DIR */

  path = scm_internal_parse_path (getenv ("GUILE_LOAD_PATH"), path);

  *scm_loc_load_path = path;
}

SCM scm_listofnullstr;

/* 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_PROC(s_search_path, "search-path", 2, 1, 0, scm_search_path);
SCM 
scm_search_path (path, filename, extensions)
     SCM path;
     SCM filename;
     SCM extensions;
{
  char *filename_chars;
  int filename_len;
  size_t max_path_len;		/* maximum length of any PATH element */
  size_t max_ext_len;		/* maximum length of any EXTENSIONS element */

  SCM_ASSERT (scm_ilength (path) >= 0, path, SCM_ARG1, s_search_path);
  SCM_ASSERT (SCM_NIMP (filename) && SCM_ROSTRINGP (filename), filename,
	      SCM_ARG2, s_search_path);
  if (SCM_UNBNDP (extensions))
    extensions = SCM_EOL;
  else
    SCM_ASSERT (scm_ilength (extensions) >= 0, extensions,
		SCM_ARG3, s_search_path);

  filename_chars = SCM_ROCHARS (filename);
  filename_len = SCM_ROLENGTH (filename);

  /* If FILENAME is absolute, return it unchanged.  */
  if (filename_len >= 1 && filename_chars[0] == '/')
    return filename;

  /* Find the length of the longest element of path.  */
  {
    SCM walk;

    max_path_len = 0;
    for (walk = path; SCM_NIMP (walk); walk = SCM_CDR (walk))
      {
	SCM elt = SCM_CAR (walk);
	SCM_ASSERT (SCM_NIMP (elt) && SCM_ROSTRINGP (elt), elt,
		    "path is not a list of strings",
		    s_search_path);
	if (SCM_ROLENGTH (elt) > max_path_len)
	  max_path_len = SCM_ROLENGTH (elt);
      }
  }

  /* 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 == '.')
	  {
	    /* This filename already has an extension, so cancel the
               list of extensions.  */
	    extensions = SCM_EOL;
	    break;
	  }
	else if (*endp == '/')
	  /* This filename has no extension, so keep the current list
             of extensions.  */
	  break;
      }
  }

  /* Find the length of the longest element of the load extensions
     list.  */
  {
    SCM walk;

    max_ext_len = 0;
    for (walk = extensions; SCM_NIMP (walk); walk = SCM_CDR (walk))
      {
	SCM elt = SCM_CAR (walk);
	SCM_ASSERT (SCM_NIMP (elt) && SCM_ROSTRINGP (elt), elt,
		    "extension list is not a list of strings",
		    s_search_path);
	if (SCM_ROLENGTH (elt) > max_ext_len)
	  max_ext_len = SCM_ROLENGTH (elt);
      }
  }

  SCM_DEFER_INTS;

  {
    SCM result = SCM_BOOL_F;
    int buf_size = max_path_len + 1 + filename_len + max_ext_len + 1;
    char *buf = scm_must_malloc (buf_size, s_search_path);

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

    /* Try every path element.  At this point, we know the path is a
       proper list of strings.  */
    for (; SCM_NIMP (path); path = SCM_CDR (path))
      {
	int len;
	SCM dir = SCM_CAR (path);
	SCM exts;

	/* Concatenate the path name and the filename. */
	len = SCM_ROLENGTH (dir);
	memcpy (buf, SCM_ROCHARS (dir), len);
	if (len >= 1 && buf[len - 1] != '/')
	  buf[len++] = '/';
	memcpy (buf + len, filename_chars, filename_len);
	len += filename_len;

	/* Try every extension.  At this point, we know the extension
	   list is a proper, nonempty list of strings.  */
	for (exts = extensions; SCM_NIMP (exts); exts = SCM_CDR (exts))
	  {
	    SCM ext = SCM_CAR (exts);
	    int ext_len = SCM_ROLENGTH (ext);
	    struct stat mode;

	    /* Concatenate the extension. */
	    memcpy (buf + len, SCM_ROCHARS (ext), ext_len);
	    buf[len + ext_len] = '\0';
	    
	    /* If the file exists at all, we should return it.  If the
	       file is inaccessible, then that's an error.  */
	    if (stat (buf, &mode) == 0
		&& ! (mode.st_mode & S_IFDIR))
	      {
		result = scm_makfromstr (buf, len + ext_len, 0);
		goto end;
	      }
	  }
      }

  end:
    scm_must_free (buf);
    scm_done_malloc (- buf_size);
    SCM_ALLOW_INTS;
    return result;
  }
}


/* 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_PROC(s_sys_search_load_path, "%search-load-path", 1, 0, 0, scm_sys_search_load_path);
SCM 
scm_sys_search_load_path (filename)
     SCM filename;
{
  SCM path = *scm_loc_load_path;
  SCM exts = *scm_loc_load_extensions;
  SCM_ASSERT (SCM_NIMP (filename) && SCM_ROSTRINGP (filename), filename,
	      SCM_ARG1, s_sys_search_load_path);
  SCM_ASSERT (scm_ilength (path) >= 0, path, "load path is not a proper list",
	      s_sys_search_load_path);
  SCM_ASSERT (scm_ilength (exts) >= 0, exts,
	      "load extension list is not a proper list",
	      s_sys_search_load_path);
  return scm_search_path (path,
			  filename,
			  exts);
}


SCM_PROC(s_primitive_load_path, "primitive-load-path", 1, 0, 0, scm_primitive_load_path);
SCM 
scm_primitive_load_path (filename)
     SCM filename;
{
  SCM full_filename;

  SCM_ASSERT (SCM_NIMP (filename) && SCM_ROSTRINGP (filename), filename,
	      SCM_ARG1, s_primitive_load_path);

  full_filename = scm_sys_search_load_path (filename);

  if (SCM_FALSEP (full_filename))
    {
      int absolute = (SCM_ROLENGTH (filename) >= 1
		      && SCM_ROCHARS (filename)[0] == '/');
      scm_misc_error (s_primitive_load_path,
		      (absolute
		       ? "Unable to load file %S"
		       : "Unable to find file %S in load path"),
		      scm_listify (filename, SCM_UNDEFINED));
    }

  return scm_primitive_load (full_filename);
}

/* The following function seems trivial - and indeed it is.  Its
 * existence is motivated by its ability to evaluate expressions
 * without copying them first (as is done in "eval").
 */

SCM_SYMBOL (scm_end_of_file_key, "end-of-file");

SCM_PROC (s_read_and_eval_x, "read-and-eval!", 0, 1, 0, scm_read_and_eval_x);

SCM
scm_read_and_eval_x (port)
     SCM port;
{
  SCM form = scm_read (port);
  if (SCM_EOF_OBJECT_P (form))
    scm_ithrow (scm_end_of_file_key, SCM_EOL, 1);
  return scm_eval_x (form);
}


/* Information about the build environment.  */

/* 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_CDRLOC (scm_sysintern ("%guile-build-info", SCM_EOL));
  unsigned int i;

  for (i = 0; i < (sizeof (info) / sizeof (info[0])); i++)
    *loc = scm_acons (SCM_CAR (scm_intern0 (info[i].name)),
		      scm_makfrom0str (info[i].value),
		      *loc);
}



void
scm_init_load ()
{
  scm_listofnullstr = scm_permanent_object (SCM_LIST1 (scm_nullstr));
  scm_loc_load_path = SCM_CDRLOC (scm_sysintern ("%load-path", SCM_EOL));
  scm_loc_load_extensions
    = SCM_CDRLOC (scm_sysintern ("%load-extensions",
				 scm_listify (scm_makfrom0str (".scm"),
					      scm_makfrom0str (""),
					      SCM_UNDEFINED)));
  scm_loc_load_hook = SCM_CDRLOC (scm_sysintern ("%load-hook", SCM_BOOL_F));

  init_build_info ();

#include "load.x"
}