/* GMODULE - GLIB wrapper code for dynamic module loading

 * Copyright (C) 1998, 2000 Tim Janik

 *

 * 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, see <http://www.gnu.org/licenses/>.

 */

/* 

 * MT safe

 */

/* because we are compatible with archive format only since AIX 4.3 */

#define __AR_BIG__

#include "config.h"

#include <ar.h>

#include <stdlib.h>

#include <dlfcn.h>

/* --- functions --- */

static gchar*

fetch_dlerror (gboolean replace_null)

{

  gchar *msg = dlerror ();

  /* make sure we always return an error message != NULL, if

   * expected to do so. */

  if (!msg && replace_null)

    return "unknown dl-error";

  return msg;

}

static gchar* _g_module_get_member(const gchar* file_name)

{

  gchar* member = NULL;

  struct fl_hdr file_header;

  struct ar_hdr ar_header;

  long first_member;

  long name_len;

  int fd;

  fd = open(file_name, O_RDONLY);

  if (fd == -1)

    return NULL;

  if (read(fd, (void*)&file_header, FL_HSZ) != FL_HSZ)

    goto exit;

  if (strncmp(file_header.fl_magic, AIAMAGBIG, SAIAMAG) != 0)

    goto exit;

  /* read first archive file member header */

  first_member = atol(file_header.fl_fstmoff);

  if (lseek(fd, first_member, SEEK_SET) != first_member)

    goto exit;

  if (read(fd, (void*)&ar_header, AR_HSZ - 2) != AR_HSZ - 2)

    goto exit;

  /* read member name */

  name_len = atol(ar_header.ar_namlen);

  member = g_malloc(name_len+1);

  if (!member)

    goto exit;

  if (read(fd, (void*)member, name_len) != name_len)

    {

      g_free(member);

      member = NULL;

      goto exit;

    }

  member[name_len] = 0;

exit:

  close(fd);

  return member;

}

static gpointer

_g_module_open (const gchar *file_name,

		gboolean     bind_lazy,

		gboolean     bind_local)

{

  gpointer handle;

  gchar* member;

  gchar* full_name;

  /* extract name of first member of archive */

  member = _g_module_get_member (file_name);

  if (member != NULL)

    {

      full_name = g_strconcat (file_name, "(", member, ")", NULL);

      g_free (member);

    }

  else

    full_name = g_strdup (file_name);

  handle = dlopen (full_name, 

		   (bind_local ? RTLD_LOCAL : RTLD_GLOBAL) | RTLD_MEMBER | (bind_lazy ? RTLD_LAZY : RTLD_NOW));

  g_free (full_name);

  if (!handle)

    g_module_set_error (fetch_dlerror (TRUE));

  return handle;

}

static gpointer

_g_module_self (void)

{

  gpointer handle;

  handle = dlopen (NULL, RTLD_GLOBAL | RTLD_LAZY);

  if (!handle)

    g_module_set_error (fetch_dlerror (TRUE));

  return handle;

}

static void

_g_module_close (gpointer handle,

		 gboolean is_unref)

{

  /* are there any systems out there that have dlopen()/dlclose()

   * without a reference count implementation?

   */

  is_unref |= 1;

  if (is_unref)

    {

      if (dlclose (handle) != 0)

	g_module_set_error (fetch_dlerror (TRUE));

    }

}

static gpointer

_g_module_symbol (gpointer     handle,

		  const gchar *symbol_name)

{

  gpointer p;

  p = dlsym (handle, symbol_name);

  if (!p)

    g_module_set_error (fetch_dlerror (FALSE));

  return p;

}

static gchar*

_g_module_build_path (const gchar *directory,

		      const gchar *module_name)

{

  if (directory && *directory) {

    if (strncmp (module_name, "lib", 3) == 0)

      return g_strconcat (directory, "/", module_name, NULL);

    else

      return g_strconcat (directory, "/lib", module_name, "." G_MODULE_SUFFIX, NULL);

  } else if (strncmp (module_name, "lib", 3) == 0)

    return g_strdup (module_name);

  else

    return g_strconcat ("lib", module_name, "." G_MODULE_SUFFIX, NULL);

}