/* ltdl.c -- system independent dlopen wrapper
   Copyright (C) 1998-1999 Free Software Foundation, Inc.
   Originally by Thomas Tanner <tanner@ffii.org>
   This file is part of GNU Libtool.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.

As a special exception to the GNU Library General Public License,
if you distribute this file as part of a program that uses GNU libtool
to create libraries and programs, you may include it under the same
distribution terms that you use for the rest of that program.

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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307  USA
*/

#define _LTDL_COMPILE_

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

#if HAVE_STRING_H
#include <string.h>
#endif

#if HAVE_STRINGS_H
#include <strings.h>
#endif

#if HAVE_CTYPE_H
#include <ctype.h>
#endif

#if HAVE_MALLOC_H
#include <malloc.h>
#endif

#if HAVE_MEMORY_H
#include <memory.h>
#endif

#if HAVE_STDLIB_H
#include <stdlib.h>
#endif

#if HAVE_STDIO_H
#include <stdio.h>
#endif

#if HAVE_BOEHM_GC
#include <gc.h>
#endif

#include "ltdl.h"

/* max. filename length */
#ifndef LTDL_FILENAME_MAX
#define LTDL_FILENAME_MAX 1024
#endif

#undef	LTDL_READTEXT_MODE
/* fopen() mode flags for reading a text file */
#ifdef _WIN32
#define LTDL_READTEXT_MODE "rt"
#else
#define LTDL_READTEXT_MODE "r"
#endif

#undef	LTDL_SYMBOL_LENGTH
/* This is the maximum symbol size that won't require malloc/free */
#define LTDL_SYMBOL_LENGTH	128

#undef	LTDL_SYMBOL_OVERHEAD
/* This accounts for the _LTX_ separator */
#define LTDL_SYMBOL_OVERHEAD	5

static const char objdir[] = LTDL_OBJDIR;
#ifdef	LTDL_SHLIB_EXT
static const char shlib_ext[] = LTDL_SHLIB_EXT;
#endif

static const char unknown_error[] = "unknown error";
static const char dlopen_not_supported_error[] = "dlopen support not available";
static const char file_not_found_error[] = "file not found";
static const char no_symbols_error[] = "no symbols defined";
static const char cannot_open_error[] = "can't open the module";
static const char cannot_close_error[] = "can't close the module";
static const char symbol_error[] = "symbol not found";
static const char memory_error[] = "not enough memory";
static const char invalid_handle_error[] = "invalid handle";
static const char buffer_overflow_error[] = "internal buffer overflow";
static const char shutdown_error[] = "library already shutdown";

#ifndef HAVE_PRELOADED_SYMBOLS
/* If libtool won't define it, we'd better do */
const lt_dlsymlist lt_preloaded_symbols[1] = { { 0, 0 } };
#endif

static const char *last_error = 0;

lt_ptr_t (*lt_dlmalloc) LTDL_PARAMS((size_t size)) = (lt_ptr_t(*)LTDL_PARAMS((size_t)))malloc;
void	 (*lt_dlfree)  LTDL_PARAMS((lt_ptr_t ptr)) = (void(*)LTDL_PARAMS((lt_ptr_t)))free;

typedef struct lt_dltype_t {
	struct lt_dltype_t *next;
	const char *sym_prefix;	/* prefix for symbols */
	int (*mod_init) LTDL_PARAMS((void));
	int (*mod_exit) LTDL_PARAMS((void));
	int (*lib_open) LTDL_PARAMS((lt_dlhandle handle, const char *filename));
	int (*lib_close) LTDL_PARAMS((lt_dlhandle handle));
	lt_ptr_t (*find_sym) LTDL_PARAMS((lt_dlhandle handle, const char *symbol));
} lt_dltype_t;

#define LTDL_TYPE_TOP 0

typedef	struct lt_dlhandle_t {
	struct lt_dlhandle_t *next;
	lt_dltype_t *type;	/* dlopening interface */
	char	*filename;	/* file name */
	char	*name;		/* module name */
	int	usage;		/* usage */
	int	depcount;	/* number of dependencies */
	lt_dlhandle *deplibs;	/* dependencies */
	lt_ptr_t handle;	/* system handle */
	lt_ptr_t system;	/* system specific data */
} lt_dlhandle_t;

#undef strdup
#define strdup xstrdup

static inline char *
strdup(str)
	const char *str;
{
	char *tmp;

	if (!str)
		return 0;
	tmp = (char*) lt_dlmalloc(strlen(str)+1);
	if (tmp)
		strcpy(tmp, str);
	return tmp;
}

#if ! HAVE_STRCHR

# if HAVE_INDEX

#  define strchr index

# else

#  define strchr xstrchr

static inline const char*
strchr(str, ch)
	const char *str;
	int ch;
{
	const char *p;

	for (p = str; *p != (char)ch && *p != '\0'; p++)
		/*NOWORK*/;

	return (*p == (char)ch) ? p : 0;
}

# endif

#endif

#if ! HAVE_STRRCHR

# if HAVE_RINDEX

#  define strrchr rindex

# else

#  define strrchr xstrrchr

static inline const char*
strrchr(str, ch)
	const char *str;
	int ch;
{
	const char *p;

	for (p = str; *p != '\0'; p++)
		/*NOWORK*/;

	while (*p != (char)ch && p >= str)
		p--;

	return (*p == (char)ch) ? p : 0;
}

# endif

#endif

#if HAVE_LIBDL

/* dynamic linking with dlopen/dlsym */

#if HAVE_DLFCN_H
# include <dlfcn.h>
#endif

#ifdef RTLD_GLOBAL
# define LTDL_GLOBAL	RTLD_GLOBAL
#else
# ifdef DL_GLOBAL
#  define LTDL_GLOBAL	DL_GLOBAL
# else
#  define LTDL_GLOBAL	0
# endif
#endif

/* We may have to define LTDL_LAZY_OR_NOW in the command line if we
   find out it does not work in some platform. */
#ifndef LTDL_LAZY_OR_NOW
# ifdef RTLD_LAZY
#  define LTDL_LAZY_OR_NOW	RTLD_LAZY
# else
#  ifdef DL_LAZY
#   define LTDL_LAZY_OR_NOW	DL_LAZY
#  else
#   ifdef RTLD_NOW
#    define LTDL_LAZY_OR_NOW	RTLD_NOW
#   else
#    ifdef DL_NOW
#     define LTDL_LAZY_OR_NOW	DL_NOW
#    else
#     define LTDL_LAZY_OR_NOW	0
#    endif
#   endif
#  endif
# endif
#endif

static int
sys_dl_init LTDL_PARAMS((void))
{
	return 0;
}

static int
sys_dl_exit LTDL_PARAMS((void))
{
	return 0;
}

static int
sys_dl_open (handle, filename)
	lt_dlhandle handle;
	const char *filename;
{
	handle->handle = dlopen(filename, LTDL_GLOBAL | LTDL_LAZY_OR_NOW);
	if (!handle->handle) {
#if HAVE_DLERROR
		last_error = dlerror();
#else
		last_error = cannot_open_error;
#endif
		return 1;
	}
	return 0;
}

static int
sys_dl_close (handle)
	lt_dlhandle handle;
{
	if (dlclose(handle->handle) != 0) {
#if HAVE_DLERROR
		last_error = dlerror();
#else
		last_error = cannot_close_error;
#endif
		return 1;
	}
	return 0;
}

static lt_ptr_t
sys_dl_sym (handle, symbol)
	lt_dlhandle handle;
	const char *symbol;
{
	lt_ptr_t address = dlsym(handle->handle, symbol);
	
	if (!address)
#if HAVE_DLERROR
		last_error = dlerror();
#else
		last_error = symbol_error;
#endif
	return address;
}

static
lt_dltype_t
#ifdef NEED_USCORE
sys_dl = { LTDL_TYPE_TOP, "_", sys_dl_init, sys_dl_exit,
	sys_dl_open, sys_dl_close, sys_dl_sym };
#else
sys_dl = { LTDL_TYPE_TOP, 0, sys_dl_init, sys_dl_exit,
	sys_dl_open, sys_dl_close, sys_dl_sym };
#endif

#undef LTDL_TYPE_TOP
#define LTDL_TYPE_TOP &sys_dl

#endif

#if HAVE_SHL_LOAD

/* dynamic linking with shl_load (HP-UX) (comments from gmodule) */

#ifdef HAVE_DL_H
#include <dl.h>
#endif

/* some flags are missing on some systems, so we provide
 * harmless defaults.
 *
 * Mandatory:
 * BIND_IMMEDIATE  - Resolve symbol references when the library is loaded.
 * BIND_DEFERRED   - Delay code symbol resolution until actual reference.
 *
 * Optionally:
 * BIND_FIRST	   - Place the library at the head of the symbol search order.
 * BIND_NONFATAL   - The default BIND_IMMEDIATE behavior is to treat all unsatisfied
 *		     symbols as fatal.	This flag allows binding of unsatisfied code
 *		     symbols to be deferred until use.
 *		     [Perl: For certain libraries, like DCE, deferred binding often
 *		     causes run time problems.	Adding BIND_NONFATAL to BIND_IMMEDIATE
 *		     still allows unresolved references in situations like this.]
 * BIND_NOSTART	   - Do not call the initializer for the shared library when the
 *		     library is loaded, nor on a future call to shl_unload().
 * BIND_VERBOSE	   - Print verbose messages concerning possible unsatisfied symbols.
 *
 * hp9000s700/hp9000s800:
 * BIND_RESTRICTED - Restrict symbols visible by the library to those present at
 *		     library load time.
 * DYNAMIC_PATH	   - Allow the loader to dynamically search for the library specified
 *		     by the path argument.
 */

#ifndef	DYNAMIC_PATH
#define	DYNAMIC_PATH	0
#endif	/* DYNAMIC_PATH */
#ifndef	BIND_RESTRICTED
#define	BIND_RESTRICTED	0
#endif	/* BIND_RESTRICTED */

#define	LTDL_BIND_FLAGS	(BIND_IMMEDIATE | BIND_NONFATAL | DYNAMIC_PATH)

static int
sys_shl_init LTDL_PARAMS((void))
{
	return 0;
}

static int
sys_shl_exit LTDL_PARAMS((void))
{
	return 0;
}

static int
sys_shl_open (handle, filename)
	lt_dlhandle handle;
	const char *filename;
{
	handle->handle = shl_load(filename, LTDL_BIND_FLAGS, 0L);
	if (!handle->handle) {
		last_error = cannot_open_error;
		return 1;
	}
	return 0;
}

static int
sys_shl_close (handle)
	lt_dlhandle handle;
{
	if (shl_unload((shl_t) (handle->handle)) != 0) {
		last_error = cannot_close_error;
		return 1;
	}
	return 0;
}

static lt_ptr_t
sys_shl_sym (handle, symbol)
	lt_dlhandle handle;
	const char *symbol;
{
	lt_ptr_t address;

	if (handle->handle && shl_findsym((shl_t*) &(handle->handle),
	    symbol, TYPE_UNDEFINED, &address) == 0)
		if (address)
			return address;
	last_error = symbol_error;
	return 0;
}

static
lt_dltype_t
sys_shl = { LTDL_TYPE_TOP, 0, sys_shl_init, sys_shl_exit,
	sys_shl_open, sys_shl_close, sys_shl_sym };

#undef LTDL_TYPE_TOP
#define LTDL_TYPE_TOP &sys_shl

#endif

#if HAVE_DLD

/* dynamic linking with dld */

#if HAVE_DLD_H
#include <dld.h>
#endif

static int
sys_dld_init LTDL_PARAMS((void))
{
	return 0;
}

static int
sys_dld_exit LTDL_PARAMS((void))
{
	return 0;
}

static int
sys_dld_open (handle, filename)
	lt_dlhandle handle;
	const char *filename;
{
	handle->handle = strdup(filename);
	if (!handle->handle) {
		last_error = memory_error;
		return 1;
	}
	if (dld_link(filename) != 0) {
		last_error = cannot_open_error;
		lt_dlfree(handle->handle);
		return 1;
	}
	return 0;
}

static int
sys_dld_close (handle)
	lt_dlhandle handle;
{
	if (dld_unlink_by_file((char*)(handle->handle), 1) != 0) {
		last_error = cannot_close_error;
		return 1;
	}
	lt_dlfree(handle->filename);
	return 0;
}

static lt_ptr_t
sys_dld_sym (handle, symbol)
	lt_dlhandle handle;
	const char *symbol;
{
	lt_ptr_t address = dld_get_func(symbol);
	
	if (!address)
		last_error = symbol_error;
	return address;
}

static
lt_dltype_t
sys_dld = { LTDL_TYPE_TOP, 0, sys_dld_init, sys_dld_exit,
	sys_dld_open, sys_dld_close, sys_dld_sym };

#undef LTDL_TYPE_TOP
#define LTDL_TYPE_TOP &sys_dld

#endif

#ifdef _WIN32

/* dynamic linking for Win32 */

#include <windows.h>

static int
sys_wll_init LTDL_PARAMS((void))
{
	return 0;
}

static int
sys_wll_exit LTDL_PARAMS((void))
{
	return 0;
}

/* Forward declaration; required to implement handle search below. */
static lt_dlhandle handles;

static int
sys_wll_open (handle, filename)
	lt_dlhandle handle;
	const char *filename;
{
	lt_dlhandle cur;
	char *searchname = NULL;
	char *ext = strrchr(filename, '.');

	if (ext) {
		/* FILENAME already has an extension. */
		searchname = strdup(filename);
	} else {
		/* Append a `.' to stop Windows from adding an
		   implicit `.dll' extension. */
		searchname = (char*)lt_dlmalloc(2+ strlen(filename));
		strcpy(searchname, filename);
		strcat(searchname, ".");
	}
    
	handle->handle = LoadLibrary(searchname);
	lt_dlfree(searchname);
	
	/* libltdl expects this function to fail if it is unable
	   to physically load the library.  Sadly, LoadLibrary
	   will search the loaded libraries for a match and return
	   one of them if the path search load fails.

	   We check whether LoadLibrary is returning a handle to
	   an already loaded module, and simulate failure if we
	   find one. */
	cur = handles;
	while (cur) {
		if (!cur->handle) {
			cur = 0;
			break;
		}
		if (cur->handle == handle->handle)
			break;
		cur = cur->next;
	}

	if (cur || !handle->handle) {
		last_error = cannot_open_error;
		return 1;
	}

	return 0;
}

static int
sys_wll_close (handle)
	lt_dlhandle handle;
{
	if (FreeLibrary(handle->handle) == 0) {
		last_error = cannot_close_error;
		return 1;
	}
	return 0;
}

static lt_ptr_t
sys_wll_sym (handle, symbol)
	lt_dlhandle handle;
	const char *symbol;
{
	lt_ptr_t address = GetProcAddress(handle->handle, symbol);
	
	if (!address)
		last_error = symbol_error;
	return address;
}

static
lt_dltype_t
sys_wll = { LTDL_TYPE_TOP, 0, sys_wll_init, sys_wll_exit,
	sys_wll_open, sys_wll_close, sys_wll_sym };

#undef LTDL_TYPE_TOP
#define LTDL_TYPE_TOP &sys_wll

#endif

#ifdef __BEOS__

/* dynamic linking for BeOS */

#include <kernel/image.h>

static int
sys_bedl_init LTDL_PARAMS((void))
{
	return 0;
}

static int
sys_bedl_exit LTDL_PARAMS((void))
{
	return 0;
}

static int
sys_bedl_open (handle, filename)
	lt_dlhandle handle;
	const char *filename;
{
	image_id image = 0;
	
	if (filename) {
		image = load_add_on(filename);
	} else {
		image_info info; 
		int32 cookie = 0; 
		if (get_next_image_info(0, &cookie, &info) == B_OK)
			image = load_add_on(info.name);
	}
	if (image <= 0) {
		last_error = cannot_open_error;
		return 1;
	}
	handle->handle = (void*) image;
	return 0;
}

static int
sys_bedl_close (handle)
	lt_dlhandle handle;
{
	if (unload_add_on((image_id)handle->handle) != B_OK) {
		last_error = cannot_close_error;
		return 1;
	}
	return 0;
}

static lt_ptr_t
sys_bedl_sym (handle, symbol)
	lt_dlhandle handle;
	const char *symbol;
{
	lt_ptr_t address = 0;
	image_id image = (image_id)handle->handle;
   
	if (get_image_symbol(image, symbol, B_SYMBOL_TYPE_ANY,
		&address) != B_OK) {
		last_error = symbol_error;
		return 0;
	}
	return address;
}

static
lt_dltype_t
sys_bedl = { LTDL_TYPE_TOP, 0, sys_bedl_init, sys_bedl_exit,
	sys_bedl_open, sys_bedl_close, sys_bedl_sym };

#undef LTDL_TYPE_TOP
#define LTDL_TYPE_TOP &sys_bedl

#endif

/* emulate dynamic linking using preloaded_symbols */

typedef struct lt_dlsymlists_t {
	struct lt_dlsymlists_t *next;
	const lt_dlsymlist *syms;
} lt_dlsymlists_t;

static const lt_dlsymlist *default_preloaded_symbols = 0;
static lt_dlsymlists_t *preloaded_symbols = 0;

static int
presym_init LTDL_PARAMS((void))
{
	preloaded_symbols = 0;
	if (default_preloaded_symbols)
		return lt_dlpreload(default_preloaded_symbols);
	return 0;
}

static int
presym_free_symlists LTDL_PARAMS((void))
{
	lt_dlsymlists_t	*lists = preloaded_symbols;
	
	while (lists) {
		lt_dlsymlists_t	*tmp = lists;
		
		lists = lists->next;
		lt_dlfree(tmp);
	}
	preloaded_symbols = 0;
	return 0;
}

static int
presym_exit LTDL_PARAMS((void))
{
	presym_free_symlists();
	return 0;
}

static int
presym_add_symlist (preloaded)
	const lt_dlsymlist *preloaded;
{
	lt_dlsymlists_t *tmp;
	lt_dlsymlists_t *lists = preloaded_symbols;
	
	while (lists) {
		if (lists->syms == preloaded)
			return 0;
		lists = lists->next;
	}

	tmp = (lt_dlsymlists_t*) lt_dlmalloc(sizeof(lt_dlsymlists_t));
	if (!tmp) {
		last_error = memory_error;
		return 1;
	}
	tmp->syms = preloaded;
	tmp->next = 0;
	if (!preloaded_symbols)
		preloaded_symbols = tmp;
	else {
		/* append to the end */
		lists = preloaded_symbols;
		while (lists->next)
			lists = lists->next;
		lists->next = tmp;
	}
	return 0;
}

static int
presym_open (handle, filename)
	lt_dlhandle handle;
	const char *filename;
{
	lt_dlsymlists_t *lists = preloaded_symbols;

	if (!lists) {
		last_error = no_symbols_error;
		return 1;
	}
	if (!filename)
		filename = "@PROGRAM@";
	while (lists) {
		const lt_dlsymlist *syms = lists->syms;
	
		while (syms->name) {
			if (!syms->address &&
			    strcmp(syms->name, filename) == 0) {
				handle->handle = (lt_ptr_t) syms;
				return 0;
			}
			syms++;
		}
		lists = lists->next;
	}
	last_error = file_not_found_error;
	return 1;
}

static int
presym_close (handle)
	lt_dlhandle handle;
{
	/* Just to silence gcc -Wall */
	handle = 0;
	return 0;
}

static lt_ptr_t
presym_sym (handle, symbol)
	lt_dlhandle handle;
	const char *symbol;
{
	lt_dlsymlist *syms = (lt_dlsymlist*)(handle->handle);

	syms++;
	while (syms->address) {
		if (strcmp(syms->name, symbol) == 0)
			return syms->address;
		syms++;
	}
	last_error = symbol_error;
	return 0;
}

static
lt_dltype_t
presym = { LTDL_TYPE_TOP, 0, presym_init, presym_exit,
	   presym_open, presym_close, presym_sym };

#undef LTDL_TYPE_TOP
#define LTDL_TYPE_TOP &presym

static char *user_search_path = 0;
static lt_dlhandle handles = 0;
static int initialized = 0;

static lt_dltype_t *types = LTDL_TYPE_TOP;
#undef LTDL_TYPE_TOP

int
lt_dlinit LTDL_PARAMS((void))
{
	/* initialize libltdl */
	lt_dltype_t **type = &types;
	int typecount = 0;

	if (initialized) {	/* Initialize only at first call. */
		initialized++;
		return 0;
	}
	handles = 0;
	user_search_path = 0; /* empty search path */

	while (*type) {
		if ((*type)->mod_init())
			*type = (*type)->next; /* Remove it from the list */
		else {
			type = &(*type)->next; /* Keep it */
			typecount++;
		}
	}
	if (typecount == 0) {
		last_error = dlopen_not_supported_error;
		return 1;
	}
	last_error = 0;
	initialized = 1;
	return 0;
}

int
lt_dlpreload (preloaded)
	const lt_dlsymlist *preloaded;
{
	if (preloaded)
		return presym_add_symlist(preloaded);
	presym_free_symlists();
	if (default_preloaded_symbols)
		return lt_dlpreload(default_preloaded_symbols);
	return 0;
}

int
lt_dlpreload_default (preloaded)
	const lt_dlsymlist *preloaded;
{
	default_preloaded_symbols = preloaded;
	return 0;
}

int
lt_dlexit LTDL_PARAMS((void))
{
	/* shut down libltdl */
	lt_dltype_t *type = types;
	int	errors;
	
	if (!initialized) {
		last_error = shutdown_error;
		return 1;
	}
	if (initialized != 1) { /* shut down only at last call. */
		initialized--;
		return 0;
	}
	/* close all modules */
	errors = 0;
	while (handles) {
		/* FIXME: what if a module depends on another one? */
		if (lt_dlclose(handles))
			errors++;
	}
	initialized = 0;
	while (type) {
		if (type->mod_exit())
			errors++;
		type = type->next;
	}
	return errors;
}

static int
tryall_dlopen (handle, filename)
	lt_dlhandle *handle;
	const char *filename;
{
	lt_dlhandle cur;
	lt_dltype_t *type = types;
	const char *saved_error = last_error;
	
	/* check whether the module was already opened */
	cur = handles;
	while (cur) {
		if (!cur->filename && !filename)
			break;
		if (cur->filename && filename && 
		    strcmp(cur->filename, filename) == 0)
			break;
		cur = cur->next;
	}
	if (cur) {
		cur->usage++;
		*handle = cur;
		return 0;
	}
	
	cur = *handle;
	if (filename) {
		cur->filename = strdup(filename);
		if (!cur->filename) {
			last_error = memory_error;
			return 1;
		}
	} else
		cur->filename = 0;
	while (type) {
		if (type->lib_open(cur, filename) == 0)
			break;
		type = type->next;
	}
	if (!type) {
		if (cur->filename)
			lt_dlfree(cur->filename);
		return 1;
	}
	cur->type = type;
	last_error = saved_error;
	return 0;
}

static int
find_module (handle, dir, libdir, dlname, old_name, installed)
	lt_dlhandle *handle;
	const char *dir;
	const char *libdir;
	const char *dlname;
	const char *old_name;
	int installed;
{
	int	error;
	char	*filename;
	/* try to open the old library first; if it was dlpreopened, 
	   we want the preopened version of it, even if a dlopenable
	   module is available */
	if (old_name && tryall_dlopen(handle, old_name) == 0)
		return 0;
	/* try to open the dynamic library */
	if (dlname) {
		/* try to open the installed module */
		if (installed && libdir) {
			filename = (char*)
				lt_dlmalloc(strlen(libdir)+1+strlen(dlname)+1);
			if (!filename) {
				last_error = memory_error;
				return 1;
			}
			strcpy(filename, libdir);
			strcat(filename, "/");
			strcat(filename, dlname);
			error = tryall_dlopen(handle, filename) == 0;
			lt_dlfree(filename);
			if (error)
				return 0;
		}
		/* try to open the not-installed module */
		if (!installed) {
			filename = (char*)
				lt_dlmalloc((dir ? strlen(dir) : 0)
				       + strlen(objdir)	+ strlen(dlname) + 1);
			if (!filename) {
				last_error = memory_error;
				return 1;
			}
			if (dir)
				strcpy(filename, dir);
			else
				*filename = 0;
			strcat(filename, objdir);
			strcat(filename, dlname);

			error = tryall_dlopen(handle, filename) == 0;
			lt_dlfree(filename);
			if (error)
				return 0;
		}
		/* hmm, maybe it was moved to another directory */
		{
			filename = (char*)
				lt_dlmalloc((dir ? strlen(dir) : 0)
				       + strlen(dlname) + 1);
			if (dir)
				strcpy(filename, dir);
			else
				*filename = 0;
			strcat(filename, dlname);
			error = tryall_dlopen(handle, filename) == 0;
			lt_dlfree(filename);
			if (error)
				return 0;
		}
	}
	last_error = file_not_found_error;
	return 1;
}

static lt_ptr_t
find_file (basename, search_path, pdir, handle)
	const char *basename;
	const char *search_path;
	char **pdir;
	lt_dlhandle *handle;
{
	/* when handle != NULL search a library, otherwise a file */
	/* return NULL on failure, otherwise the file/handle */

	char	*filename = 0;
	int     filenamesize = 0;
	const char *next = search_path;
	int	lenbase = strlen(basename);
	
	if (!next || !*next) {
		last_error = file_not_found_error;
		return 0;
	}
	while (next) {
		int lendir;
		const char *cur = next;

		next = strchr(cur, ':');
		if (!next)
			next = cur + strlen(cur);
		lendir = next - cur;
		if (*next == ':')
			++next;
		else
			next = 0;
		if (lendir == 0)
			continue;
		if (lendir + 1 + lenbase >= filenamesize) {
			if (filename)
				lt_dlfree(filename);
			filenamesize = lendir + 1 + lenbase + 1;
			filename = (char*) lt_dlmalloc(filenamesize);
			if (!filename) {
				last_error = memory_error;
				return 0;
			}
		}
		strncpy(filename, cur, lendir);
		if (filename[lendir-1] != '/')
			filename[lendir++] = '/';
		strcpy(filename+lendir, basename);
		if (handle) {
			if (tryall_dlopen(handle, filename) == 0) {
				lt_dlfree(filename);
				return (lt_ptr_t) handle;
			}
		} else {
			FILE *file = fopen(filename, LTDL_READTEXT_MODE);
			if (file) {
				if (*pdir)
					lt_dlfree(*pdir);
				filename[lendir] = '\0';
				*pdir = strdup(filename);
				if (!*pdir) {
					/* We could have even avoided the
					   strdup, but there would be some
					   memory overhead. */
					*pdir = filename;
				} else
					lt_dlfree(filename);
				return (lt_ptr_t) file;
			}
		}
	}
	if (filename)
		lt_dlfree(filename);
	last_error = file_not_found_error;
	return 0;
}

static int
load_deplibs(handle, deplibs)
	lt_dlhandle handle;
	const char *deplibs;
{
	/* FIXME: load deplibs */
	handle->depcount = 0;
	handle->deplibs = 0;
	/* Just to silence gcc -Wall */
	deplibs = 0;
	return 0;
}

static int
unload_deplibs(handle)
	lt_dlhandle handle;
{
	/* FIXME: unload deplibs */
	/* Just to silence gcc -Wall */
	handle = 0;
	return 0;
}

static inline int
trim (dest, str)
	char **dest;
	const char *str;
{
	/* remove the leading and trailing "'" from str 
	   and store the result in dest */
	char *tmp;
	const char *end = strrchr(str, '\'');
	int len = strlen(str);

	if (*dest)
		lt_dlfree(*dest);
	if (len > 3 && str[0] == '\'') {
		tmp = (char*) lt_dlmalloc(end - str);
		if (!tmp) {
			last_error = memory_error;
			return 1;
		}
		strncpy(tmp, &str[1], (end - str) - 1);
		tmp[len-3] = '\0';
		*dest = tmp;
	} else
		*dest = 0;
	return 0;
}

static inline int
free_vars(dir, name, dlname, oldname, libdir, deplibs)
	char *dir;
	char *name;
	char *dlname;
	char *oldname;
	char *libdir;
	char *deplibs;
{
	if (dir)
		lt_dlfree(dir);
	if (name)
		lt_dlfree(name);
	if (dlname)
		lt_dlfree(dlname);
	if (oldname)
		lt_dlfree(oldname);
	if (libdir)
		lt_dlfree(libdir);
	if (deplibs)
		lt_dlfree(deplibs);
	return 0;
}

lt_dlhandle
lt_dlopen (filename)
	const char *filename;
{
	lt_dlhandle handle, newhandle;
	const char *basename, *ext;
	const char *saved_error = last_error;
	char	*dir = 0, *name = 0;
	
	if (!filename) {
		handle = (lt_dlhandle) lt_dlmalloc(sizeof(lt_dlhandle_t));
		if (!handle) {
			last_error = memory_error;
			return 0;
		}
		handle->usage = 0;
		handle->depcount = 0;
		handle->deplibs = 0;
		newhandle = handle;
		if (tryall_dlopen(&newhandle, 0) != 0) {
			lt_dlfree(handle);
			return 0;
		}
		goto register_handle;
	}
	basename = strrchr(filename, '/');
	if (basename) {
		basename++;
		dir = (char*) lt_dlmalloc(basename - filename + 1);
		if (!dir) {
			last_error = memory_error;
			return 0;
		}
		strncpy(dir, filename, basename - filename);
		dir[basename - filename] = '\0';
	} else
		basename = filename;
	/* check whether we open a libtool module (.la extension) */
	ext = strrchr(basename, '.');
	if (ext && strcmp(ext, ".la") == 0) {
		/* this seems to be a libtool module */
		FILE	*file;
		int	i;
		char	*dlname = 0, *old_name = 0;
		char	*libdir = 0, *deplibs = 0;
		char	*line;
		int	error = 0;
		/* if we can't find the installed flag, it is probably an
		   installed libtool archive, produced with an old version
		   of libtool */
		int     installed = 1; 

		/* extract the module name from the file name */
		name = (char*) lt_dlmalloc(ext - basename + 1);
		if (!name) {
			last_error = memory_error;
			if (dir)
				lt_dlfree(dir);
			return 0;
		}
		/* canonicalize the module name */
		for (i = 0; i < ext - basename; i++)
			if (isalnum((int)(basename[i])))
				name[i] = basename[i];
			else
				name[i] = '_';
		name[ext - basename] = '\0';
		/* now try to open the .la file */
		file = fopen(filename, LTDL_READTEXT_MODE);
		if (!file)
			last_error = file_not_found_error;
		if (!file && !dir) {
			/* try other directories */
			file = (FILE*) find_file(basename, 
						 user_search_path,
						 &dir, 0);
			if (!file)
				file = (FILE*) find_file(basename,
						 getenv("LTDL_LIBRARY_PATH"),
						 &dir, 0);
#ifdef LTDL_SHLIBPATH_VAR
			if (!file)
				file = (FILE*) find_file(basename,
						 getenv(LTDL_SHLIBPATH_VAR),
						 &dir, 0);
#endif
		}
		if (!file) {
			if (name)
				lt_dlfree(name);
			if (dir)
				lt_dlfree(dir);
			return 0;
		}
		line = (char*) lt_dlmalloc(LTDL_FILENAME_MAX);
		if (!line) {
			fclose(file);
			last_error = memory_error;
			return 0;
		}
		/* read the .la file */
		while (!feof(file)) {
			if (!fgets(line, LTDL_FILENAME_MAX, file))
				break;
			if (line[0] == '\n' || line[0] == '#')
				continue;
#			undef  STR_DLNAME
#			define STR_DLNAME	"dlname="
			if (strncmp(line, STR_DLNAME,
				sizeof(STR_DLNAME) - 1) == 0)
				error = trim(&dlname,
					&line[sizeof(STR_DLNAME) - 1]);
			else
#			undef  STR_OLD_LIBRARY
#			define STR_OLD_LIBRARY	"old_library="
			if (strncmp(line, STR_OLD_LIBRARY,
				sizeof(STR_OLD_LIBRARY) - 1) == 0)
				error = trim(&old_name,
					&line[sizeof(STR_OLD_LIBRARY) - 1]);
			else
#			undef  STR_LIBDIR
#			define STR_LIBDIR	"libdir="
			if (strncmp(line, STR_LIBDIR,
				sizeof(STR_LIBDIR) - 1) == 0)
				error = trim(&libdir,
					&line[sizeof(STR_LIBDIR) - 1]);
			else
#			undef  STR_DL_DEPLIBS
#			define STR_DL_DEPLIBS	"dl_dependency_libs="
			if (strncmp(line, STR_DL_DEPLIBS,
				sizeof(STR_DL_DEPLIBS) - 1) == 0)
				error = trim(&deplibs,
					&line[sizeof(STR_DL_DEPLIBS) - 1]);
			else
			if (strcmp(line, "installed=yes\n") == 0)
				installed = 1;
			else
			if (strcmp(line, "installed=no\n") == 0)
				installed = 0;
			if (error)
				break;
		}
		fclose(file);
		lt_dlfree(line);
		/* allocate the handle */
		handle = (lt_dlhandle) lt_dlmalloc(sizeof(lt_dlhandle_t));
		if (!handle || error) {
			if (handle)
				lt_dlfree(handle);
			if (!error)
				last_error = memory_error;
			free_vars(name, dir, dlname, old_name, libdir, deplibs);
			return 0;
		}
		handle->usage = 0;
		if (load_deplibs(handle, deplibs) == 0) {
			newhandle = handle;
			/* find_module may replace newhandle */
			if (find_module(&newhandle, dir, libdir, 
					dlname, old_name, installed)) {
				unload_deplibs(handle);
				error = 1;
			}
		} else
			error = 1;
		if (error) {
			lt_dlfree(handle);
			free_vars(name, dir, dlname, old_name, libdir, deplibs);
			return 0;
		}
		if (handle != newhandle) {
			unload_deplibs(handle);
		}
	} else {
		/* not a libtool module */
		handle = (lt_dlhandle) lt_dlmalloc(sizeof(lt_dlhandle_t));
		if (!handle) {
			last_error = memory_error;
			if (dir)
				lt_dlfree(dir);
			return 0;
		}
		handle->usage = 0;
		/* non-libtool modules don't have dependencies */
		handle->depcount = 0;
		handle->deplibs = 0;
		newhandle = handle;
		if (tryall_dlopen(&newhandle, filename)
		    && (dir
			|| (!find_file(basename, user_search_path,
					  0, &newhandle)
			    && !find_file(basename,
					  getenv("LTDL_LIBRARY_PATH"),
					  0, &newhandle)
#ifdef LTDL_SHLIBPATH_VAR
			    && !find_file(basename,
					  getenv(LTDL_SHLIBPATH_VAR),
					  0, &newhandle)
#endif
				))) {
			lt_dlfree(handle);
			if (dir)
				lt_dlfree(dir);
			return 0;
		}
	}
register_handle:
	if (newhandle != handle) {
		lt_dlfree(handle);
		handle = newhandle;
	}
	if (!handle->usage) {
		handle->usage = 1;
		handle->name = name;
		handle->next = handles;
		handles = handle;
	} else if (name)
		lt_dlfree(name);
	if (dir)
		lt_dlfree(dir);
	last_error = saved_error;
	return handle;
}

lt_dlhandle
lt_dlopenext (filename)
	const char *filename;
{
	lt_dlhandle handle;
	char	*tmp;
	int	len;
	const char *saved_error = last_error;
	
	if (!filename)
		return lt_dlopen(filename);
	len = strlen(filename);
	if (!len) {
		last_error = file_not_found_error;
		return 0;
	}
	/* try the normal file name */
	handle = lt_dlopen(filename);
	if (handle)
		return handle;
	/* try "filename.la" */
	tmp = (char*) lt_dlmalloc(len+4);
	if (!tmp) {
		last_error = memory_error;
		return 0;
	}
	strcpy(tmp, filename);
	strcat(tmp, ".la");
	handle = lt_dlopen(tmp);
	if (handle) {
		last_error = saved_error;
		lt_dlfree(tmp);
		return handle;
	}
#ifdef LTDL_SHLIB_EXT
	/* try "filename.EXT" */
	if (strlen(shlib_ext) > 3) {
		lt_dlfree(tmp);
		tmp = (char*) lt_dlmalloc(len + strlen(shlib_ext) + 1);
		if (!tmp) {
			last_error = memory_error;
			return 0;
		}
		strcpy(tmp, filename);
	} else
		tmp[len] = '\0';
	strcat(tmp, shlib_ext);
	handle = lt_dlopen(tmp);
	if (handle) {
		last_error = saved_error;
		lt_dlfree(tmp);
		return handle;
	}
#endif	
	last_error = file_not_found_error;
	lt_dlfree(tmp);
	return 0;
}

int
lt_dlclose (handle)
	lt_dlhandle handle;
{
	lt_dlhandle cur, last;
	
	/* check whether the handle is valid */
	last = cur = handles;
	while (cur && handle != cur) {
		last = cur;
		cur = cur->next;
	}
	if (!cur) {
		last_error = invalid_handle_error;
		return 1;
	}
	handle->usage--;
	if (!handle->usage) {
		int	error;
	
		if (handle != handles)
			last->next = handle->next;
		else
			handles = handle->next;
		error = handle->type->lib_close(handle);
		error += unload_deplibs(handle);
		if (handle->filename)
			lt_dlfree(handle->filename);
		if (handle->name)
			lt_dlfree(handle->name);
		lt_dlfree(handle);
		return error;
	}
	return 0;
}

lt_ptr_t
lt_dlsym (handle, symbol)
	lt_dlhandle handle;
	const char *symbol;
{
	int	lensym;
	char	lsym[LTDL_SYMBOL_LENGTH];
	char	*sym;
	lt_ptr_t address;

	if (!handle) {
		last_error = invalid_handle_error;
		return 0;
	}
	if (!symbol) {
		last_error = symbol_error;
		return 0;
	}
	lensym = strlen(symbol);
	if (handle->type->sym_prefix)
		lensym += strlen(handle->type->sym_prefix);
	if (handle->name)
		lensym += strlen(handle->name);
	if (lensym + LTDL_SYMBOL_OVERHEAD < LTDL_SYMBOL_LENGTH)
		sym = lsym;
	else
		sym = (char*) lt_dlmalloc(lensym + LTDL_SYMBOL_OVERHEAD + 1);
	if (!sym) {
		last_error = buffer_overflow_error;
		return 0;
	}
	if (handle->name) {
		const char *saved_error = last_error;
		
		/* this is a libtool module */
		if (handle->type->sym_prefix) {
			strcpy(sym, handle->type->sym_prefix);
			strcat(sym, handle->name);
		} else
			strcpy(sym, handle->name);
		strcat(sym, "_LTX_");
		strcat(sym, symbol);
		/* try "modulename_LTX_symbol" */
		address = handle->type->find_sym(handle, sym);
		if (address) {
			if (sym != lsym)
				lt_dlfree(sym);
			return address;
		}
		last_error = saved_error;
	}
	/* otherwise try "symbol" */
	if (handle->type->sym_prefix) {
		strcpy(sym, handle->type->sym_prefix);
		strcat(sym, symbol);
	} else
		strcpy(sym, symbol);
	address = handle->type->find_sym(handle, sym);
	if (sym != lsym)
		lt_dlfree(sym);
	return address;
}

const char *
lt_dlerror LTDL_PARAMS((void))
{
	const char *error = last_error;
	
	last_error = 0;
	return error;
}

int
lt_dladdsearchdir (search_dir)
	const char *search_dir;
{
	if (!search_dir || !strlen(search_dir))
		return 0;
	if (!user_search_path) {
		user_search_path = strdup(search_dir);
		if (!user_search_path) {
			last_error = memory_error;
			return 1;
		}
	} else {
		char	*new_search_path = (char*)
			lt_dlmalloc(strlen(user_search_path) + 
				strlen(search_dir) + 2); /* ':' + '\0' == 2 */
		if (!new_search_path) {
			last_error = memory_error;
			return 1;
		}
		strcpy(new_search_path, user_search_path);
		strcat(new_search_path, ":");
		strcat(new_search_path, search_dir);
		lt_dlfree(user_search_path);
		user_search_path = new_search_path;
	}
	return 0;
}

int
lt_dlsetsearchpath (search_path)
	const char *search_path;
{
	if (user_search_path)
		lt_dlfree(user_search_path);
	user_search_path = 0; /* reset the search path */
	if (!search_path || !strlen(search_path))
		return 0;
	user_search_path = strdup(search_path);
	if (!user_search_path)
		return 1;
	return 0;
}

const char *
lt_dlgetsearchpath LTDL_PARAMS((void))
{
	return user_search_path;
}
