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.  */

/* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
   gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */



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

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

  { /* scope */
    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;
}
#undef FUNC_NAME


/* 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_makfrom0str (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_makfrom0str(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_makfrom0str(SCM_SITE_DIR);
}
#undef FUNC_NAME
#endif /* SCM_SITE_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_DEFINE (scm_parse_path, "parse-path", 1, 1, 0, 
            (SCM path, SCM tail),
	    "")
#define FUNC_NAME s_scm_parse_path
{
  SCM_ASSERT (SCM_FALSEP (path) || (SCM_ROSTRINGP (path)),
	      path,
	      SCM_ARG1, FUNC_NAME);
  if (SCM_UNBNDP (tail))
    tail = SCM_EOL;
  return (SCM_FALSEP (path)
	  ? tail
	  : scm_internal_parse_path (SCM_ROCHARS (path), 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 ()
{
  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_DEFINE (scm_search_path, "search-path", 2, 1, 0,
           (SCM path, SCM filename, SCM extensions),
	    "")
#define FUNC_NAME s_scm_search_path
{
  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_VALIDATE_LIST (1,path);
  SCM_VALIDATE_ROSTRING (2,filename);
  if (SCM_UNBNDP (extensions))
    extensions = SCM_EOL;
  else
    SCM_VALIDATE_LIST (3,extensions);

  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_NNULLP (walk); walk = SCM_CDR (walk))
      {
	SCM elt = SCM_CAR (walk);
	SCM_ASSERT (SCM_ROSTRINGP (elt), elt,
		    "path is not a list of strings",
		    FUNC_NAME);
	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.  */
  { /* scope */
    SCM walk;

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

  SCM_DEFER_INTS;

  { /* scope */
    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);

    /* 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_NNULLP (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_NNULLP (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;
  }
}
#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 @var{file}, which must be readable by the\n"
	    "current user.  If @var{file} is found in the list of paths to search or\n"
	    "is an absolute pathname, return its full pathname.  Otherwise, return\n"
	    "@code{#f}.  Filenames may have any of the optional extensions in the\n"
	    "@code{%load-extensions} list; @code{%search-load-path} will try each\n"
	    "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_ROSTRING (1,filename);

  SCM_ASSERT (scm_ilength (path) >= 0, path, "load path is not a proper list",
	      FUNC_NAME);
  SCM_ASSERT (scm_ilength (exts) >= 0, exts,
	      "load extension list is not a proper list",
	      FUNC_NAME);
  return scm_search_path (path, filename, exts);
}
#undef FUNC_NAME


SCM_DEFINE (scm_primitive_load_path, "primitive-load-path", 1, 0, 0, 
           (SCM filename),
	    "Search @var{%load-path} for @var{file} and load it into the top-level\n"
	    "environment.  If @var{file} is a relative pathname and is not found in\n"
	    "the list of search paths, an error is signalled.")
#define FUNC_NAME s_scm_primitive_load_path
{
  SCM full_filename;

  SCM_VALIDATE_ROSTRING (1,filename);

  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 ((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);
}
#undef FUNC_NAME

/* 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_DEFINE (scm_read_and_eval_x, "read-and-eval!", 0, 1, 0, 
            (SCM port),
	    "Read a form from @var{port} (standard input by default), and evaluate it\n"
	    "(memoizing it in the process) in the top-level environment.  If no data\n"
	    "is left to be read from @var{port}, an @code{end-of-file} error is\n"
	    "signalled.")
#define FUNC_NAME s_scm_read_and_eval_x
{
  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);
}
#undef FUNC_NAME


/* 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"
}