path: root/gr-run-waveform/xyzzy-load.c

/* Copyright (C) 1995,1996,1998,1999,2000,2001, 2004, 2006 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 2.1 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
 */



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

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

/* libpath.h is generated whenever the Makefile is rebuilt */
#include "libpath.h"

#include <libguile/__scm.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/lang.h>
#include <libguile/chars.h>
#include <libguile/tags.h>
#include <libguile/snarf.h>
#include <libguile/srfi-13.h>
#include <libguile/validate.h>
#include <libguile/load.h>
#include <libguile/fluids.h>

// these headers where not in the original version of this file.
#include <libguile/boolean.h>
#include <libguile/pairs.h>
#include <libguile/gc.h>
#include <libguile/variable.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

#include "xyzzy.h"

// This is the magic number used when loading files
static const char *MAGIC = "-XyZzY-";

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;
    }
}

/* 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_xyzzy_search_path, "xyyzy-search-path", 2, 1, 0,
           (SCM path, SCM filename, SCM extensions),
	    "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_xyzzy_search_path
{
  struct stringbuf buf;
  char *filename_chars;
  size_t filename_len;
  SCM result = SCM_BOOL_F;

  fprintf(stderr, "TRACE %s: %d: %s\n", __FUNCTION__, __LINE__, scm_to_locale_string(filename)); 

  if (SCM_UNBNDP (extensions))
    extensions = SCM_EOL;

  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_dynwind_end ();
      return filename;
    }

  /* 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;
	  }
#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.  */

          
          /* Look in the fake filesystem for this file. If we find it, we prepend a
             magic number to the front so we can identify these special files later
             on when trying to read from them. */
          if (xyzzy_file_exists(filename_chars)) {
            filename = scm_from_locale_string (filename_chars);
          } else {
            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

void
scm_xyzzy_init (void)
{
    scm_c_define_gsubr ("xyzzy-search-path", 2, 1, 0, (SCM (*)()) scm_xyzzy_search_path);
}