mc/vfs/vfs.c

/* Virtual File System switch code
   Copyright (C) 1995, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
   2007 Free Software Foundation, Inc.
   
   Written by: 1995 Miguel de Icaza
               1995 Jakub Jelinek
	       1998 Pavel Machek
   
   This program 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.
   
   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 Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

/**
 * \file
 * \brief Source: Virtual File System switch code
 * \author Miguel de Icaza
 * \author Jakub Jelinek
 * \author Pavel Machek
 * \date 1995, 1998
 * \warning funtions like extfs_lstat() have right to destroy any
 * strings you pass to them. This is acutally ok as you g_strdup what
 * you are passing to them, anyway; still, beware.
 *
 * Namespace: exports *many* functions with vfs_ prefix; exports
 * parse_ls_lga and friends which do not have that prefix.
 */

#include <config.h>

#include <stdio.h>
#include <stdlib.h>		/* For atol() */
#include <stdarg.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <signal.h>
#include <ctype.h>	/* is_digit() */
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <dirent.h>

#include "../src/global.h"

#include "../src/wtools.h"	/* message() */
#include "../src/main.h"	/* print_vfs_message */
#include "../src/strutil.h"

#include "utilvfs.h"
#include "gc.h"
#include "vfs.h"
#ifdef USE_NETCODE
#   include "tcputil.h"
#endif
#include "ftpfs.h"
#include "mcfs.h"
#include "smbfs.h"
#include "local.h"

/** They keep track of the current directory */
static struct vfs_class *current_vfs;
static char *current_dir;

struct vfs_openfile {
    int handle;
    struct vfs_class *vclass;
    void *fsinfo;
};

struct vfs_dirinfo{
    DIR *info;
    GIConv converter;
};


static GPtrArray *vfs_openfiles;
static long vfs_free_handle_list = -1;
#define VFS_FIRST_HANDLE 100

static struct vfs_class *localfs_class;
static GString *vfs_str_buffer;

static const char *supported_encodings[] = {
    "UTF8", 
    "UTF-8",
    "BIG5", 
    "ASCII",
    "ISO8859",
    "ISO-8859",
    "ISO_8859",
    "KOI8",
    "CP852",
    "CP866",
    "CP125",
    NULL
};

/** Create new VFS handle and put it to the list */
static int
vfs_new_handle (struct vfs_class *vclass, void *fsinfo)
{
    struct vfs_openfile *h;

    h = g_new (struct vfs_openfile, 1);
    h->fsinfo = fsinfo;
    h->vclass = vclass;

    /* Allocate the first free handle */
    h->handle = vfs_free_handle_list;
    if (h->handle == -1) {
        /* No free allocated handles, allocate one */
        h->handle = vfs_openfiles->len;
        g_ptr_array_add (vfs_openfiles, h);
    } else {
        vfs_free_handle_list = (long) g_ptr_array_index (vfs_openfiles, vfs_free_handle_list);
        g_ptr_array_index (vfs_openfiles, h->handle) = h;
    }

    h->handle += VFS_FIRST_HANDLE;
    return h->handle;
}

/** Find VFS class by file handle */
static struct vfs_class *
vfs_op (int handle)
{
    struct vfs_openfile *h;

    if (handle < VFS_FIRST_HANDLE ||
        (guint)(handle - VFS_FIRST_HANDLE) >= vfs_openfiles->len)
        return NULL;

    h = (struct vfs_openfile *) g_ptr_array_index (
                                vfs_openfiles, handle - VFS_FIRST_HANDLE);
    if (!h)
	return NULL;

    g_assert (h->handle == handle);

    return h->vclass;
}

/** Find private file data by file handle */
static void *
vfs_info (int handle)
{
    struct vfs_openfile *h;

    if (handle < VFS_FIRST_HANDLE ||
        (guint)(handle - VFS_FIRST_HANDLE) >= vfs_openfiles->len)
        return NULL;

    h = (struct vfs_openfile *) g_ptr_array_index (
                                vfs_openfiles, handle - VFS_FIRST_HANDLE);
    if (!h)
	return NULL;

    g_assert (h->handle == handle);

    return h->fsinfo;
}

/** Free open file data for given file handle */
static void
vfs_free_handle (int handle)
{
    if (handle < VFS_FIRST_HANDLE ||
        (guint)(handle - VFS_FIRST_HANDLE) >= vfs_openfiles->len)
        return;

    g_ptr_array_index (vfs_openfiles, handle - VFS_FIRST_HANDLE) =
			(void *) vfs_free_handle_list;
    vfs_free_handle_list = handle - VFS_FIRST_HANDLE;
}

static struct vfs_class *vfs_list;

int
vfs_register_class (struct vfs_class *vfs)
{
    if (vfs->init)		/* vfs has own initialization function */
	if (!(*vfs->init)(vfs))	/* but it failed */
	    return 0;

    vfs->next = vfs_list;
    vfs_list = vfs;

    return 1;
}

/** Return VFS class for the given prefix */
static struct vfs_class *
vfs_prefix_to_class (char *prefix)
{
    struct vfs_class *vfs;

    /* Avoid last class (localfs) that would accept any prefix */
    for (vfs = vfs_list; vfs->next; vfs = vfs->next) {
	if (vfs->which) {
	    if ((*vfs->which) (vfs, prefix) == -1)
		continue;
	    return vfs;
	}
	if (vfs->prefix
	    && !strncmp (prefix, vfs->prefix, strlen (vfs->prefix)))
	    return vfs;
    }
    return NULL;
}

/** Strip known vfs suffixes from a filename (possible improvement: strip
 *  suffix from last path component).
 *  \return a malloced string which has to be freed.
 */
char *
vfs_strip_suffix_from_filename (const char *filename)
{
    struct vfs_class *vfs;
    char *semi;
    char *p;

    if (!filename)
	vfs_die ("vfs_strip_suffix_from_path got NULL: impossible");

    p = g_strdup (filename);
    if (!(semi = strrchr (p, '#')))
	return p;

    /* Avoid last class (localfs) that would accept any prefix */
    for (vfs = vfs_list; vfs->next; vfs = vfs->next) {
	if (vfs->which) {
	    if ((*vfs->which) (vfs, semi + 1) == -1)
		continue;
	    *semi = '\0';	/* Found valid suffix */
	    return p;
	}
	if (vfs->prefix
	    && !strncmp (semi + 1, vfs->prefix, strlen (vfs->prefix))) {
	    *semi = '\0';	/* Found valid suffix */
	    return p;
	}
    }
    return p;
}

static int
path_magic (const char *path)
{
    struct stat buf;

    if (!stat(path, &buf))
        return 0;

    return 1;
}

/**
 * Splits path '/p1#op/inpath' into inpath,op; returns which vfs it is.
 * What is left in path is p1. You still want to g_free(path), you DON'T
 * want to free neither *inpath nor *op
 */
struct vfs_class *
vfs_split (char *path, char **inpath, char **op)
{
    char *semi;
    char *slash;
    struct vfs_class *ret;

    if (!path)
	vfs_die("Cannot split NULL");
    
    semi = strrchr (path, '#');
    if (!semi || !path_magic(path))
	return NULL;

    slash = strchr (semi, PATH_SEP);
    *semi = 0;

    if (op)
	*op = NULL;

    if (inpath)
	*inpath = NULL;

    if (slash)
	*slash = 0;

    if ((ret = vfs_prefix_to_class (semi+1))){
	if (op) 
	    *op = semi + 1;
	if (inpath)
	    *inpath = slash ? slash + 1 : NULL;
	return ret;
    }


    if (slash)
	*slash = PATH_SEP;
    ret = vfs_split (path, inpath, op);
    *semi = '#';
    return ret;
}

static struct vfs_class *
_vfs_get_class (char *path)
{
    char *semi;
    char *slash;
    struct vfs_class *ret;

    g_return_val_if_fail(path, NULL);

    semi = strrchr (path, '#');
    if (!semi || !path_magic (path))
	return NULL;
    
    slash = strchr (semi, PATH_SEP);
    *semi = 0;
    if (slash)
	*slash = 0;
    
    ret = vfs_prefix_to_class (semi+1);

    if (slash)
	*slash = PATH_SEP;
    if (!ret)
	ret = _vfs_get_class (path);

    *semi = '#';
    return ret;
}

struct vfs_class *
vfs_get_class (const char *pathname)
{
    struct vfs_class *vfs;
    char *path = g_strdup (pathname);

    vfs = _vfs_get_class (path);
    g_free (path);

    if (!vfs)
	vfs = localfs_class;

    return vfs;
}

const char *
vfs_get_encoding (const char *path)
{
    static char result[16];
    char *work;
    char *semi;
    char *slash;
    
    work = g_strdup (path);
    semi = g_strrstr (work, "#enc:");
    
    if (semi != NULL) {
        semi+= 5 * sizeof (char);
        slash = strchr (semi, PATH_SEP);
        if (slash != NULL)
            slash[0] = '\0';
            
        g_strlcpy (result, semi, sizeof(result));
        g_free (work);
        return result;
    }  else {
        g_free (work);
        return NULL;
    }
}

/* return if encoding can by used in vfs (is ascci full compactible) */
/* contains only a few encoding now */
static int 
vfs_supported_enconding (const char *encoding) {
    int t;
    int result = 0;
    
    for (t = 0; supported_encodings[t] != NULL; t++) {
        result+= (g_ascii_strncasecmp (encoding, supported_encodings[t], 
                  strlen (supported_encodings[t])) == 0); 
    }
    
    return result;
}

/* now used only by vfs_translate_path, but could be used in other vfs 
 * plugin to automatic detect encoding
 * path - path to translate
 * size - how many bytes from path translate
 * defcnv - convertor, that is used as default, when path does not contain any
 *          #enc: subtring
 * buffer - used to store result of translation
 */ 
static estr_t
_vfs_translate_path (const char *path, int size,
                     GIConv defcnv, GString *buffer)
{
    const char *semi;
    const char *ps;
    const char *slash;
    estr_t state = ESTR_SUCCESS;
    static char encoding[16];
    GIConv coder;
    int ms;

    if (size == 0) return 0;
    size = ( size > 0) ? size : (signed int)strlen (path);

    /* try found #end: */
    semi = g_strrstr_len (path, size, "#enc:");
    if (semi != NULL) {
        /* first must be translated part before #enc: */
        ms = semi - path;

        /* remove '/' before #enc */
        ps = str_cget_prev_char (semi);
        if (ps[0] == PATH_SEP) ms = ps - path;

        state = _vfs_translate_path (path, ms, defcnv, buffer);

        if (state != ESTR_SUCCESS)
	    return state;
        /* now can be translated part after #enc: */

        semi+= 5;
        slash = strchr (semi, PATH_SEP);
        /* ignore slashes after size; */
        if (slash - path >= size) slash = NULL;

        ms = (slash != NULL) ? slash - semi : (int) strlen (semi);
        ms = min ((unsigned int) ms, sizeof (encoding) - 1);
        /* limit encoding size (ms) to path size (size) */
        if (semi + ms > path + size) ms = path + size - semi;
        memcpy (encoding, semi, ms);
        encoding[ms] = '\0';

        switch (vfs_supported_enconding (encoding)) {
            case 1:
                coder = str_crt_conv_to (encoding);
                if (coder != INVALID_CONV)  {
                    if (slash != NULL) {
                        state = str_vfs_convert_to (coder, slash, 
                                path + size - slash, buffer);
                    } else if (buffer->str[0] == '\0') {
                        /* exmaple "/#enc:utf-8" */
                        g_string_append_c(buffer, PATH_SEP);
                    }
                    str_close_conv (coder);
                    return state;
                } else {
                    errno = EINVAL;
                    return ESTR_FAILURE;
                }
                break;
            default:
                errno = EINVAL;
                return ESTR_FAILURE;
        }
    } else {
        /* path can be translated whole at once */
        state = str_vfs_convert_to (defcnv, path, size, buffer);
        return state;
    }

    return ESTR_SUCCESS;
}

char *
vfs_translate_path (const char *path) 
{
    estr_t state;

    g_string_set_size(vfs_str_buffer,0);
    state = _vfs_translate_path (path, -1, str_cnv_from_term, vfs_str_buffer);
    /*
     strict version
     return (state == 0) ? vfs_str_buffer->data : NULL;
    */
    return (state != ESTR_FAILURE) ? vfs_str_buffer->str : NULL;
}

char *
vfs_translate_path_n (const char *path) 
{
    char *result;

    result = vfs_translate_path (path);
    return (result != NULL) ? g_strdup (result) : NULL;
}

char *
vfs_canon_and_translate (const char *path) 
{
    char *canon;
    char *result;
    if (path == NULL)
        canon = g_strdup ("");
    else
        canon = vfs_canon (path);
    result = vfs_translate_path_n (canon);
    g_free (canon);
    return result;
}

static int
ferrno (struct vfs_class *vfs)
{
    return vfs->ferrno ? (*vfs->ferrno)(vfs) : E_UNKNOWN; 
    /* Hope that error message is obscure enough ;-) */
}

int
mc_open (const char *filename, int flags, ...)
{
    int  mode;
    void *info;
    va_list ap;

    char *file = vfs_canon_and_translate (filename);
    if (file != NULL) {
    struct vfs_class *vfs = vfs_get_class (file);

    /* Get the mode flag */
    if (flags & O_CREAT) {
    	va_start (ap, flags);
    	mode = va_arg (ap, int);
    	va_end (ap);
    } else
        mode = 0;
    
    if (!vfs->open) {
	g_free (file);
	errno = -EOPNOTSUPP;
	return -1;
    }

    info = (*vfs->open) (vfs, file, flags, mode);	/* open must be supported */
    g_free (file);
    if (!info){
	errno = ferrno (vfs);
	return -1;
    }

    return vfs_new_handle (vfs, info);
    } else return -1;
}


#define MC_NAMEOP(name, inarg, callarg) \
int mc_##name inarg \
{ \
    struct vfs_class *vfs; \
    int result; \
    char *mpath = vfs_canon_and_translate (path); \
    if (mpath != NULL) { \
    vfs = vfs_get_class (mpath); \
    if (vfs == NULL){ \
	g_free (mpath); \
	return -1; \
    } \
    result = vfs->name ? (*vfs->name)callarg : -1; \
    g_free (mpath); \
    if (result == -1) \
	errno = vfs->name ? ferrno (vfs) : E_NOTSUPP; \
    return result; \
    } else return -1; \
}

MC_NAMEOP (chmod, (const char *path, mode_t mode), (vfs, mpath, mode))
MC_NAMEOP (chown, (const char *path, uid_t owner, gid_t group), (vfs, mpath, owner, group))
MC_NAMEOP (utime, (const char *path, struct utimbuf *times), (vfs, mpath, times))
MC_NAMEOP (readlink, (const char *path, char *buf, int bufsiz), (vfs, mpath, buf, bufsiz))
MC_NAMEOP (unlink, (const char *path), (vfs, mpath))
MC_NAMEOP (mkdir, (const char *path, mode_t mode), (vfs, mpath, mode))
MC_NAMEOP (rmdir, (const char *path), (vfs, mpath))
MC_NAMEOP (mknod, (const char *path, mode_t mode, dev_t dev), (vfs, mpath, mode, dev))

int 
mc_symlink (const char *name1, const char *path)
{ 
    struct vfs_class *vfs; 
    int result; 
    char *mpath;
    char *lpath;
    char *tmp;
    
    mpath = vfs_canon_and_translate (path); 
    if (mpath != NULL) {
        tmp = g_strdup (name1);
        lpath = vfs_translate_path_n (tmp);
        g_free (tmp);
    
        if (lpath != NULL) {
            vfs = vfs_get_class (mpath); 
            result = vfs->symlink ? (*vfs->symlink) (vfs, lpath, mpath) : -1;
            g_free (lpath);
    
            if (result == -1) 
                errno = vfs->symlink ? ferrno (vfs) : E_NOTSUPP; 
            return result; 
        } 
        g_free (mpath); 
    }
    return -1;
}

#define MC_HANDLEOP(name, inarg, callarg) \
ssize_t mc_##name inarg \
{ \
    struct vfs_class *vfs; \
    int result; \
    if (handle == -1) \
	return -1; \
    vfs = vfs_op (handle); \
    if (vfs == NULL) \
	 return -1; \
    result = vfs->name ? (*vfs->name)callarg : -1; \
    if (result == -1) \
	errno = vfs->name ? ferrno (vfs) : E_NOTSUPP; \
    return result; \
}

MC_HANDLEOP(read,  (int handle, void *buffer,    int count), (vfs_info (handle), buffer, count))
MC_HANDLEOP(write, (int handle, const void *buf, int nbyte), (vfs_info (handle), buf,    nbyte))


#define MC_RENAMEOP(name) \
int mc_##name (const char *fname1, const char *fname2) \
{ \
    struct vfs_class *vfs; \
    int result; \
    char *name2, *name1; \
    name1 = vfs_canon_and_translate (fname1); \
    if (name1 != NULL) { \
        name2 = vfs_canon_and_translate (fname2); \
        if (name2 != NULL) { \
    vfs = vfs_get_class (name1); \
    if (vfs != vfs_get_class (name2)){ \
    	errno = EXDEV; \
    	g_free (name1); \
    	g_free (name2); \
	return -1; \
    } \
    result = vfs->name ? (*vfs->name)(vfs, name1, name2) : -1; \
    g_free (name1); \
    g_free (name2); \
    if (result == -1) \
        errno = vfs->name ? ferrno (vfs) : E_NOTSUPP; \
    return result; \
    } else { \
        g_free (name1); \
        return -1; \
    } \
    } else return -1; \
}

MC_RENAMEOP (link)
MC_RENAMEOP (rename)


int
mc_ctl (int handle, int ctlop, void *arg)
{
    struct vfs_class *vfs = vfs_op (handle);

    return vfs->ctl ? (*vfs->ctl)(vfs_info (handle), ctlop, arg) : 0;
}

int
mc_setctl (const char *path, int ctlop, void *arg)
{
    struct vfs_class *vfs;
    int result;
    char *mpath;

    if (!path)
	vfs_die("You don't want to pass NULL to mc_setctl.");
    
    mpath = vfs_canon_and_translate (path);
    if (mpath != NULL) {
    vfs = vfs_get_class (mpath);
    result = vfs->setctl ? (*vfs->setctl)(vfs, mpath, ctlop, arg) : 0;
    g_free (mpath);
    return result;
    } else return -1;
}

int
mc_close (int handle)
{
    struct vfs_class *vfs;
    int result;

    if (handle == -1 || !vfs_info (handle))
	return -1;
    
    vfs = vfs_op (handle);
    if (handle < 3)
	return close (handle);

    if (!vfs->close)
        vfs_die ("VFS must support close.\n");
    result = (*vfs->close)(vfs_info (handle));
    vfs_free_handle (handle);
    if (result == -1)
	errno = ferrno (vfs);
    
    return result;
}

DIR *
mc_opendir (const char *dirname)
{
    int  handle, *handlep;
    void *info;
    struct vfs_class *vfs;
    char *canon;
    char *dname;
    struct vfs_dirinfo *dirinfo;
    const char *encoding;

    canon = vfs_canon (dirname);
    dname = vfs_translate_path_n (canon);

    if (dname != NULL) {
        vfs = vfs_get_class (dname);
    info = vfs->opendir ? (*vfs->opendir)(vfs, dname) : NULL;
    g_free (dname);
    
    if (!info){
        errno = vfs->opendir ? ferrno (vfs) : E_NOTSUPP;
            g_free (canon);
	return NULL;
    }
    
        dirinfo = g_new (struct vfs_dirinfo, 1);
        dirinfo->info = info;
    
        encoding = vfs_get_encoding (canon);
        g_free (canon);
        dirinfo->converter = (encoding != NULL) ? str_crt_conv_from (encoding) :
                str_cnv_from_term;
        if (dirinfo->converter == INVALID_CONV) dirinfo->converter =str_cnv_from_term;
    
        handle = vfs_new_handle (vfs, dirinfo);

    handlep = g_new (int, 1);
    *handlep = handle;
    return (DIR *) handlep;
    } else {
        g_free (canon);
        return NULL;
    }
}

static struct dirent * mc_readdir_result = NULL;

struct dirent *
mc_readdir (DIR *dirp)
{
    int handle;
    struct vfs_class *vfs;
    struct dirent *entry = NULL;
    struct vfs_dirinfo *dirinfo;
    estr_t state;

    if (!mc_readdir_result)
    {
        /* We can't just allocate struct dirent as (see man dirent.h)
         * struct dirent has VERY nonnaive semantics of allocating
         * d_name in it. Moreover, linux's glibc-2.9 allocates dirents _less_,
         * than 'sizeof (struct dirent)' making full bitwise (sizeof dirent) copy
         * heap corrupter. So, allocate longliving dirent with at least
         * (NAME_MAX + 1) for d_name in it.
         * Strictly saying resulting dirent is unusable as we don't adjust internal
         * structures, holding dirent size. But we don't use it in libc infrastructure.
         * TODO: to make simpler homemade dirent-alike structure.
         */
        mc_readdir_result = (struct dirent *)malloc(sizeof(struct dirent) + NAME_MAX + 1);
    }

    if (!dirp) {
	errno = EFAULT;
	return NULL;
    }
    handle = *(int *) dirp;
    vfs = vfs_op (handle);
    dirinfo = vfs_info (handle);
    if (vfs->readdir) {
        entry = (*vfs->readdir) (dirinfo->info);
        if (entry == NULL) return NULL;
        g_string_set_size(vfs_str_buffer,0);
        state = str_vfs_convert_from (dirinfo->converter,
                                          entry->d_name, vfs_str_buffer);
        mc_readdir_result->d_ino = entry->d_ino;
        g_strlcpy (mc_readdir_result->d_name, vfs_str_buffer->str, NAME_MAX + 1);
    }
    if (entry == NULL) errno = vfs->readdir ? ferrno (vfs) : E_NOTSUPP;
    return (entry != NULL) ? mc_readdir_result : NULL;
}

int
mc_closedir (DIR *dirp)
{
    int handle = *(int *) dirp;
    struct vfs_class *vfs = vfs_op (handle);
    int result;
    struct vfs_dirinfo *dirinfo;

    dirinfo = vfs_info (handle);
    if (dirinfo->converter != str_cnv_from_term) str_close_conv (dirinfo->converter);

    result = vfs->closedir ? (*vfs->closedir)(dirinfo->info) : -1;
    vfs_free_handle (handle);
    g_free (dirinfo);
    g_free (dirp);
    return result; 
}

int mc_stat (const char *filename, struct stat *buf) {
    struct vfs_class *vfs;
    int result;
    char *path;
    
    path = vfs_canon_and_translate (filename);
    
    if (path != NULL) {
        vfs = vfs_get_class (path);
    
    result = vfs->stat ? (*vfs->stat) (vfs, path, buf) : -1;
    
    g_free (path);
    
    if (result == -1)
	errno = vfs->name ? ferrno (vfs) : E_NOTSUPP;
    return result;
    } else return -1;
}

int mc_lstat (const char *filename, struct stat *buf) {
    struct vfs_class *vfs;
    int result;
    char *path;
    
    path = vfs_canon_and_translate (filename);
    
    if (path != NULL) {
        vfs = vfs_get_class (path);
    result = vfs->lstat ? (*vfs->lstat) (vfs, path, buf) : -1;
    g_free (path);
    if (result == -1)
	errno = vfs->name ? ferrno (vfs) : E_NOTSUPP;
    return result;
    } else return -1;
}

int mc_fstat (int handle, struct stat *buf) {
    struct vfs_class *vfs;
    int result;

    if (handle == -1)
	return -1;
    vfs = vfs_op (handle);
    result = vfs->fstat ? (*vfs->fstat) (vfs_info (handle), buf) : -1;
    if (result == -1)
	errno = vfs->name ? ferrno (vfs) : E_NOTSUPP;
    return result;
}

/**
 * Return current directory.  If it's local, reread the current directory
 * from the OS.  You must g_strdup() whatever this function returns.
 */
static const char *
_vfs_get_cwd (void)
{
    char *sys_cwd;
    char *trans;
    const char *encoding;
    char *tmp;
    estr_t state;
    struct stat my_stat, my_stat2;

    trans = vfs_translate_path_n (current_dir); /* add check if NULL */
    
    if (!_vfs_get_class (trans)) {
        encoding = vfs_get_encoding (current_dir);
        if (encoding == NULL) {
            tmp = g_get_current_dir ();
            if (tmp != NULL) { /* One of the directories in the path is not readable */
		g_string_set_size(vfs_str_buffer,0);
                state = str_vfs_convert_from (str_cnv_from_term, tmp, vfs_str_buffer);
                g_free (tmp);
                sys_cwd = (state == ESTR_SUCCESS) ? g_strdup (vfs_str_buffer->str) : NULL;
                if (!sys_cwd)
		    return current_dir;

	/* Otherwise check if it is O.K. to use the current_dir */
                if (!cd_symlinks || mc_stat (sys_cwd, &my_stat) 
	    || mc_stat (current_dir, &my_stat2)
	    || my_stat.st_ino != my_stat2.st_ino
	    || my_stat.st_dev != my_stat2.st_dev) {
	    g_free (current_dir);
                    current_dir = sys_cwd;
                    return sys_cwd;
                     }/* Otherwise we return current_dir below */
            }
    }
    }
    g_free (trans);
    return current_dir;
}

static void
vfs_setup_wd (void)
{
    current_dir = g_strdup (PATH_SEP_STR);
    _vfs_get_cwd ();

    if (strlen (current_dir) > MC_MAXPATHLEN - 2)
	vfs_die ("Current dir too long.\n");

    current_vfs = vfs_get_class (current_dir);
}

/**
 * Return current directory. If it's local, reread the current directory
 * from the OS. Put directory to the provided buffer.
 */
char *
mc_get_current_wd (char *buffer, int size)
{
    const char *cwd = _vfs_get_cwd ();

    g_strlcpy (buffer, cwd, size);
    return buffer;
}

/**
 * Return current directory without any OS calls.
 */
char *
vfs_get_current_dir (void)
{
    return current_dir;
}

off_t mc_lseek (int fd, off_t offset, int whence)
{
    struct vfs_class *vfs;
    int result;

    if (fd == -1)
	return -1;

    vfs = vfs_op (fd);
    result = vfs->lseek ? (*vfs->lseek)(vfs_info (fd), offset, whence) : -1;
    if (result == -1)
        errno = vfs->lseek ? ferrno (vfs) : E_NOTSUPP;
    return result;
}

/**
 * remove //, /./ and /../
 */

#define ISSLASH(a) (!a || (a == '/'))

char *
vfs_canon (const char *path)
{
    if (!path)
	vfs_die("Cannot canonicalize NULL");

    /* Relative to current directory */
    if (*path != PATH_SEP){ 
    	char *local, *result;

	local = concat_dir_and_file (current_dir, path);

	result = vfs_canon (local);
	g_free (local);
	return result;
    }

    /*
     * So we have path of following form:
     * /p1/p2#op/.././././p3#op/p4. Good luck.
     */
    {
	char *result = g_strdup (path);
	canonicalize_pathname (result);
        return result;
    }
}

/**
 * VFS chdir.
 * Return 0 on success, -1 on failure.
 */
int
mc_chdir (const char *path)
{
    char *new_dir;
    char *trans_dir;
    struct vfs_class *old_vfs, *new_vfs;
    vfsid old_vfsid;
    int result;

    new_dir = vfs_canon (path);
    trans_dir = vfs_translate_path_n (new_dir);
    if (trans_dir != NULL) {
        new_vfs = vfs_get_class (trans_dir);
    if (!new_vfs->chdir) {
    	g_free (new_dir);
            g_free (trans_dir);
	return -1;
    }

        result = (*new_vfs->chdir) (new_vfs, trans_dir);

    if (result == -1) {
	errno = ferrno (new_vfs);
	g_free (new_dir);
            g_free (trans_dir);
	return -1;
    }

    old_vfsid = vfs_getid (current_vfs, current_dir);
    old_vfs = current_vfs;

    /* Actually change directory */
    g_free (current_dir);
    current_dir = new_dir;
    current_vfs = new_vfs;

    /* This function uses the new current_dir implicitly */
    vfs_stamp_create (old_vfs, old_vfsid);

    /* Sometimes we assume no trailing slash on cwd */
    if (*current_dir) {
	char *p;
	p = strchr (current_dir, 0) - 1;
	if (*p == PATH_SEP && p > current_dir)
	    *p = 0;
    }

        g_free (trans_dir);
    return 0;
    } else {
        g_free (new_dir);
        return -1;
    }
}

/* Return 1 is the current VFS class is local */
int
vfs_current_is_local (void)
{
    return (current_vfs->flags & VFSF_LOCAL) != 0;
}

/* Return flags of the VFS class of the given filename */
int
vfs_file_class_flags (const char *filename)
{
    struct vfs_class *vfs;
    char *fname;

    fname = vfs_canon_and_translate (filename);
    if (fname != NULL) {
    vfs = vfs_get_class (fname);
    g_free (fname);
    return vfs->flags;
    } else return -1;
}

static char *
mc_def_getlocalcopy (const char *filename)
{
    char *tmp;
    int fdin, fdout, i;
    char buffer[8192];
    struct stat mystat;

    fdin = mc_open (filename, O_RDONLY | O_LINEAR);
    if (fdin == -1)
	return NULL;

    fdout = vfs_mkstemps (&tmp, "vfs", filename);

    if (fdout == -1)
	goto fail;
    while ((i = mc_read (fdin, buffer, sizeof (buffer))) > 0) {
	if (write (fdout, buffer, i) != i)
	    goto fail;
    }
    if (i == -1)
	goto fail;
    i = mc_close (fdin);
    fdin = -1;
    if (i == -1)
	goto fail;
    if (close (fdout) == -1) {
	fdout = -1;
	goto fail;
    }

    if (mc_stat (filename, &mystat) != -1) {
	chmod (tmp, mystat.st_mode);
    }
    return tmp;

  fail:
    if (fdout != -1)
	close (fdout);
    if (fdin != -1)
	mc_close (fdin);
    g_free (tmp);
    return NULL;
}

char *
mc_getlocalcopy (const char *pathname)
{
    char *result;
    char *path;
            
    path = vfs_canon_and_translate (pathname);
    if (path != NULL) {
    struct vfs_class *vfs = vfs_get_class (path);    

    result = vfs->getlocalcopy ? (*vfs->getlocalcopy)(vfs, path) :
                                 mc_def_getlocalcopy (path);
    g_free (path);
    if (!result)
	errno = ferrno (vfs);
    return result;
    } else return NULL;
}

static int
mc_def_ungetlocalcopy (struct vfs_class *vfs, const char *filename,
		       const char *local, int has_changed)
{
    int fdin = -1, fdout = -1, i;
    if (has_changed) {
	char buffer[8192];

	if (!vfs->write)
	    goto failed;

	fdin = open (local, O_RDONLY);
	if (fdin == -1)
	    goto failed;
	fdout = mc_open (filename, O_WRONLY | O_TRUNC);
	if (fdout == -1)
	    goto failed;
	while ((i = read (fdin, buffer, sizeof (buffer))) > 0) {
	    if (mc_write (fdout, buffer, i) != i)
		goto failed;
	}
	if (i == -1)
	    goto failed;

	if (close (fdin) == -1) {
	    fdin = -1;
	    goto failed;
	}
	fdin = -1;
	if (mc_close (fdout) == -1) {
	    fdout = -1;
	    goto failed;
	}
    }
    unlink (local);
    return 0;

  failed:
    message (D_ERROR, _("Changes to file lost"), "%s", filename);
    if (fdout != -1)
	mc_close (fdout);
    if (fdin != -1)
	close (fdin);
    unlink (local);
    return -1;
}

int
mc_ungetlocalcopy (const char *pathname, const char *local, int has_changed)
{
    int return_value = 0;
    char *path;
    
    path = vfs_canon_and_translate (pathname);
    if (path != NULL) {
    struct vfs_class *vfs = vfs_get_class (path);

    return_value = vfs->ungetlocalcopy ? 
            (*vfs->ungetlocalcopy)(vfs, path, local, has_changed) :
            mc_def_ungetlocalcopy (vfs, path, local, has_changed);
    g_free (path);
    return return_value;
    } else return -1;
}


void
vfs_init (void)
{
    /* create the VFS handle array */
    vfs_openfiles = g_ptr_array_new ();

    vfs_str_buffer = g_string_new("");
    /* localfs needs to be the first one */
    init_localfs();
    /* fallback value for vfs_get_class() */
    localfs_class = vfs_list;

    init_extfs ();
    init_sfs ();
    init_tarfs ();
    init_cpiofs ();

#ifdef USE_EXT2FSLIB
    init_undelfs ();
#endif /* USE_EXT2FSLIB */

#ifdef USE_NETCODE
    tcp_init();
    init_ftpfs ();
    init_fish ();
#ifdef WITH_SMBFS
    init_smbfs ();
#endif /* WITH_SMBFS */
#ifdef ENABLE_VFS_MCFS
    init_mcfs ();
#endif /* ENABLE_VFS_MCFS */
#endif /* USE_NETCODE */

    vfs_setup_wd ();
}

void
vfs_shut (void)
{
    struct vfs_class *vfs;

    vfs_gc_done ();

    g_free (current_dir);

    for (vfs = vfs_list; vfs; vfs = vfs->next)
	if (vfs->done)
	    (*vfs->done) (vfs);

    g_ptr_array_free (vfs_openfiles, TRUE);
    
    g_string_free (vfs_str_buffer, TRUE);
}

/*
 * These ones grab information from the VFS
 *  and handles them to an upper layer
 */
void
vfs_fill_names (fill_names_f func)
{
    struct vfs_class *vfs;

    for (vfs=vfs_list; vfs; vfs=vfs->next)
        if (vfs->fill_names)
	    (*vfs->fill_names) (vfs, func);
}

/*
 * Returns vfs path corresponding to given url. If passed string is
 * not recognized as url, g_strdup(url) is returned.
 */

static const struct {
    const char *name;
    size_t name_len;
    const char *substitute;
} url_table[] = { {"ftp://", 6, "/#ftp:"},
                  {"mc://", 5, "/#mc:"},
                  {"smb://", 6, "/#smb:"},
                  {"sh://", 5, "/#sh:"},
		  {"ssh://", 6, "/#sh:"},
                  {"a:", 2, "/#a"}
};

char *
vfs_translate_url (const char *url)
{
    size_t i;

    for (i = 0; i < sizeof (url_table)/sizeof (url_table[0]); i++)
       if (strncmp (url, url_table[i].name, url_table[i].name_len) == 0)
           return g_strconcat (url_table[i].substitute, url + url_table[i].name_len, (char*) NULL);

    return g_strdup (url);
}

int vfs_file_is_local (const char *filename)
{
    return vfs_file_class_flags (filename) & VFSF_LOCAL;
}