Ticket #2108: Fixed memory leak in fish_linear_start() function.

[midnight-commander.git] / lib / vfs / mc-vfs / fish.c

/* Virtual File System: FISH implementation for transfering files over
   shell connections.

   Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
   2007 Free Software Foundation, Inc.
   
   Written by: 1998 Pavel Machek
   Spaces fix: 2000 Michal Svec

   Derived from ftpfs.c.
   
   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: FISH implementation for transfering files over
 * shell connections
 * \author Pavel Machek
 * \author Michal Svec
 * \date 1998, 2000
 *
 * Derived from ftpfs.c
 * Read README.fish for protocol specification.
 *
 * Syntax of path is: \verbatim /#sh:user@host[:Cr]/path \endverbatim
 *      where C means you want compressed connection,
 *      and r means you want to use rsh
 *
 * Namespace: fish_vfs_ops exported.
 */

/* Define this if your ssh can take -I option */

#include <config.h>
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <grp.h>
#include <sys/time.h>           /* gettimeofday() */
#include <stdlib.h>
#include <string.h>

#include "lib/global.h"
#include "lib/fs.h"
#include "lib/tty/tty.h"        /* enable/disable interrupt key */
#include "lib/strescape.h"
#include "lib/unixcompat.h"

#include "src/wtools.h" /* message() */
#include "src/main.h"   /* print_vfs_message */
#include "utilvfs.h"
#include "xdirentry.h"
#include "vfs.h"
#include "vfs-impl.h"
#include "gc.h"         /* vfs_stamp_create */
#include "netutil.h"
#include "fish.h"

int fish_directory_timeout = 900;

#define DO_RESOLVE_SYMLINK 1
#define DO_OPEN            2
#define DO_FREE_RESOURCE   4

#define FISH_FLAG_COMPRESSED 1
#define FISH_FLAG_RSH        2

#define OPT_FLUSH        1
#define OPT_IGNORE_ERROR 2

/*
 * Reply codes.
 */
#define PRELIM          1       /* positive preliminary */
#define COMPLETE        2       /* positive completion */
#define CONTINUE        3       /* positive intermediate */
#define TRANSIENT       4       /* transient negative completion */
#define ERROR           5       /* permanent negative completion */

/* command wait_flag: */
#define NONE        0x00
#define WAIT_REPLY  0x01
#define WANT_STRING 0x02
static char reply_str [80];

static struct vfs_class vfs_fish_ops;

static int
 fish_command (struct vfs_class *me, struct vfs_s_super *super,
               int wait_reply, const char *fmt, ...)
    __attribute__ ((format (__printf__, 4, 5)));

static int fish_decode_reply (char *s, int was_garbage)
{
    int code;
    if (!sscanf(s, "%d", &code)) {
        code = 500;
        return 5;
    }
    if (code<100) return was_garbage ? ERROR : (!code ? COMPLETE : PRELIM);
    return code / 100;
}

/* Returns a reply code, check /usr/include/arpa/ftp.h for possible values */
static int fish_get_reply (struct vfs_class *me, int sock, char *string_buf, int string_len)
{
    char answer[1024];
    int was_garbage = 0;
    
    for (;;) {
        if (!vfs_s_get_line(me, sock, answer, sizeof(answer), '\n')) {
            if (string_buf)
                *string_buf = 0;
            return 4;
        }

        if (strncmp(answer, "### ", 4)) {
            was_garbage = 1;
            if (string_buf)
                g_strlcpy(string_buf, answer, string_len);
        } else return fish_decode_reply(answer+4, was_garbage);
    }
}

#define SUP super->u.fish

static int
fish_command (struct vfs_class *me, struct vfs_s_super *super,
              int wait_reply, const char *fmt, ...)
{
    va_list ap;
    char *str;
    int status;
    FILE *logfile = MEDATA->logfile;

    va_start (ap, fmt);

    str = g_strdup_vprintf (fmt, ap);
    va_end (ap);

    if (logfile) {
        fwrite (str, strlen (str), 1, logfile);
        fflush (logfile);
    }

    tty_enable_interrupt_key ();

    status = write (SUP.sockw, str, strlen (str));
    g_free (str);

    tty_disable_interrupt_key ();
    if (status < 0)
        return TRANSIENT;

    if (wait_reply)
        return fish_get_reply (me, SUP.sockr,
                               (wait_reply & WANT_STRING) ? reply_str :
                               NULL, sizeof (reply_str) - 1);
    return COMPLETE;
}

static void
fish_free_archive (struct vfs_class *me, struct vfs_s_super *super)
{
    if ((SUP.sockw != -1) || (SUP.sockr != -1)) {
        print_vfs_message (_("fish: Disconnecting from %s"),
                           super->name ? super->name : "???");
        fish_command (me, super, NONE, "#BYE\nexit\n");
        close (SUP.sockw);
        close (SUP.sockr);
        SUP.sockw = SUP.sockr = -1;
    }
    g_free (SUP.host);
    g_free (SUP.user);
    g_free (SUP.cwdir);
    g_free (SUP.password);
}

static void
fish_pipeopen(struct vfs_s_super *super, const char *path, const char *argv[])
{
    int fileset1[2], fileset2[2];
    int res;

    if ((pipe(fileset1)<0) || (pipe(fileset2)<0)) 
        vfs_die("Cannot pipe(): %m.");
    
    if ((res = fork())) {
        if (res<0) vfs_die("Cannot fork(): %m.");
        /* We are the parent */
        close(fileset1[0]);
        SUP.sockw = fileset1[1];
        close(fileset2[1]);
        SUP.sockr = fileset2[0];
    } else {
        close(0);
        dup(fileset1[0]);
        close(fileset1[0]); close(fileset1[1]);
        close(1); close(2);
        dup(fileset2[1]);
        /* stderr to /dev/null */
        open ("/dev/null", O_WRONLY);
        close(fileset2[0]); close(fileset2[1]);
        execvp(path, const_cast(char **, argv));
        _exit(3);
    }
}

/* The returned directory should always contain a trailing slash */
static char *fish_getcwd(struct vfs_class *me, struct vfs_s_super *super)
{
    if (fish_command (me, super, WANT_STRING, "#PWD\npwd; echo '### 200'\n") == COMPLETE)
        return  g_strconcat (reply_str, "/", (char *) NULL);
    ERRNOR (EIO, NULL);
}

static int
fish_open_archive_int (struct vfs_class *me, struct vfs_s_super *super)
{
    {
        char gbuf[10];
        const char *argv[10];   /* All of 10 is used now */
        const char *xsh = (SUP.flags == FISH_FLAG_RSH ? "rsh" : "ssh");
        int i = 0;

        argv[i++] = xsh;
        if (SUP.flags == FISH_FLAG_COMPRESSED)
            argv[i++] = "-C";

        if (SUP.flags > FISH_FLAG_RSH)
        {
            argv[i++] = "-p";
            g_snprintf (gbuf, sizeof (gbuf), "%d", SUP.flags);
            argv[i++] = gbuf;
        }

        /*
         * Add the user name to the ssh command line only if it was explicitly
         * set in vfs URL. rsh/ssh will get current user by default
         * plus we can set convenient overrides in  ~/.ssh/config (explicit -l
         * option breaks it for some)
         */

        if (SUP.user) {
                argv[i++] = "-l";
                argv[i++] = SUP.user;
        }
        else
        {
                /* The rest of the code assumes it to be a valid username */
                SUP.user = vfs_get_local_username();
        }

        argv[i++] = SUP.host;
        argv[i++] = "echo FISH:; /bin/sh";
        argv[i++] = NULL;

        fish_pipeopen (super, xsh, argv);
    }
    {
        char answer[2048];
        print_vfs_message (_("fish: Waiting for initial line..."));
        if (!vfs_s_get_line (me, SUP.sockr, answer, sizeof (answer), ':'))
            ERRNOR (E_PROTO, -1);
        print_vfs_message ("%s", answer);
        if (strstr (answer, "assword")) {

            /* Currently, this does not work. ssh reads passwords from
               /dev/tty, not from stdin :-(. */

            message (D_ERROR, MSG_ERROR,
                     _
                     ("Sorry, we cannot do password authenticated connections for now."));
            ERRNOR (EPERM, -1);
            if (!SUP.password) {
                char *p, *op;
                p = g_strconcat (_(" fish: Password required for "),
                                 SUP.user, " ", (char *) NULL);
                op = vfs_get_password (p);
                g_free (p);
                if (op == NULL)
                    ERRNOR (EPERM, -1);
                SUP.password = op;
            }
            print_vfs_message (_("fish: Sending password..."));
            write (SUP.sockw, SUP.password, strlen (SUP.password));
            write (SUP.sockw, "\n", 1);
        }
    }

    print_vfs_message (_("fish: Sending initial line..."));
    /*
     * Run `start_fish_server'. If it doesn't exist - no problem,
     * we'll talk directly to the shell.
     */
    if (fish_command
        (me, super, WAIT_REPLY,
         "#FISH\necho; start_fish_server 2>&1; echo '### 200'\n") !=
        COMPLETE)
        ERRNOR (E_PROTO, -1);

    print_vfs_message (_("fish: Handshaking version..."));
    if (fish_command
        (me, super, WAIT_REPLY,
         "#VER 0.0.0\necho '### 000'\n") != COMPLETE)
        ERRNOR (E_PROTO, -1);

    /* Set up remote locale to C, otherwise dates cannot be recognized */
    if (fish_command
        (me, super, WAIT_REPLY,
         "LANG=C; LC_ALL=C; LC_TIME=C\n"
         "export LANG; export LC_ALL; export LC_TIME\n" "echo '### 200'\n")
        != COMPLETE)
        ERRNOR (E_PROTO, -1);

    print_vfs_message (_("fish: Setting up current directory..."));
    SUP.cwdir = fish_getcwd (me, super);
    print_vfs_message (_("fish: Connected, home %s."), SUP.cwdir);
#if 0
    super->name =
        g_strconcat ("/#sh:", SUP.user, "@", SUP.host, "/", (char *) NULL);
#endif
    super->name = g_strdup (PATH_SEP_STR);

    super->root =
        vfs_s_new_inode (me, super,
                         vfs_s_default_stat (me, S_IFDIR | 0755));
    return 0;
}

static int
fish_open_archive (struct vfs_class *me, struct vfs_s_super *super,
                   const char *archive_name, char *op)
{
    char *host, *user, *password, *p;
    int flags;

    (void) archive_name;

    p = vfs_split_url (strchr (op, ':') + 1, &host, &user, &flags,
                       &password, 0, URL_NOSLASH | URL_USE_ANONYMOUS);

    g_free (p);

    SUP.host = host;
    SUP.user = user;
    SUP.flags = flags;
    if (!strncmp (op, "rsh:", 4))
        SUP.flags = FISH_FLAG_RSH;
    SUP.cwdir = NULL;
    if (password)
        SUP.password = password;
    return fish_open_archive_int (me, super);
}

static int
fish_archive_same (struct vfs_class *me, struct vfs_s_super *super,
                   const char *archive_name, char *op, void *cookie)
{
    char *host, *user;
    int flags;
    int result;

    (void) me;
    (void) archive_name;
    (void) cookie;

    op = vfs_split_url (strchr (op, ':') + 1, &host, &user, &flags, 0, 0,
                        URL_NOSLASH | URL_USE_ANONYMOUS);

    g_free (op);

    if (user == NULL)
        user = vfs_get_local_username();

    result = ((strcmp (host, SUP.host) == 0)
              && (strcmp (user, SUP.user) == 0)
              && (flags == SUP.flags));

    g_free (host);
    g_free (user);

    return result;
}

static int
fish_dir_load(struct vfs_class *me, struct vfs_s_inode *dir, char *remote_path)
{
    struct vfs_s_super *super = dir->super;
    char buffer[8192];
    struct vfs_s_entry *ent = NULL;
    FILE *logfile;
    char *quoted_path;
    int reply_code;
    gchar *shell_commands;

#if 0
    /*
     * Simple FISH debug interface :]
     */
    if (!(MEDATA->logfile))
    {
        MEDATA->logfile = fopen("/tmp/mc-FISH.sh", "w");
    }
#endif /* 0 */

    logfile = MEDATA->logfile;

    print_vfs_message(_("fish: Reading directory %s..."), remote_path);

    gettimeofday(&dir->timestamp, NULL);
    dir->timestamp.tv_sec += fish_directory_timeout;
    quoted_path = strutils_shell_escape (remote_path);
    shell_commands = g_strconcat(
                "#LIST /%s\n"
                "if `perl -v > /dev/null 2>&1` ; then\n"
                  "perl -e '\n"
                   "use strict;\n"
                   "use POSIX;\n"
                   "use Fcntl;\n"
                   "use POSIX \":fcntl_h\"; #S_ISLNK was here until 5.6\n"
                   "import Fcntl \":mode\" unless defined &S_ISLNK; #and is now here\n"
                   "my $dirname = $ARGV[0];\n"
                   "if (opendir ( DIR, $dirname )) {\n"
                   "while( (my $filename = readdir(DIR))){\n"
                   "my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,$blksize,$blocks) = lstat(\"$dirname/$filename\");\n"
                   "my $mloctime= strftime(\"%%m-%%d-%%Y %%H:%%M\", localtime $mtime);\n"
        ,
                   "my $strutils_shell_escape_regex= s/([;<>\\*\\|`&\\$!#\\(\\)\\[\\]\\{\\}:'\\''\"\\ \\\\])/\\\\$1/g;\n"
                   "my $e_filename = $filename;\n"
                   "$e_filename =~ $strutils_shell_escape_regex;\n"
                   "if (S_ISLNK($mode) ) {\n"
                   "my $linkname = readlink (\"$dirname/$filename\");\n"
                   "$linkname =~ $strutils_shell_escape_regex;\n"
                   "\n"
                          "printf(\"R%%o %%o $uid.$gid\\n"
                                    "S$size\\n"
                                    "d$mloctime\\n"
                                    ":\\\"$e_filename\\\" -> \\\"$linkname\\\"\\n"
                                    "\\n\", S_IMODE($mode), S_IFMT($mode));\n"
                   "} else {\n"
                          "printf(\"R%%o %%o $uid.$gid\\n"
                                    "S$size\\n"
                                    "d$mloctime\\n"
                                    ":\\\"$e_filename\\\"\\n"
                                    "\\n\", S_IMODE($mode), S_IFMT($mode));\n"
                   "}}\n"
        ,
                   "printf(\"### 200\\n\");\n"
                   "closedir(DIR);\n"
                   "} else {\n"
                    "printf(\"### 500\\n\");\n"
                   "}\n"
                   "exit 0\n"
                   "' /%s ||\n" /* ARGV[0] - path to browse */
                   "    echo '### 500'\n" /* do not hang if perl is to eval it */
                "elif `ls -1 /%s >/dev/null 2>&1` ; then\n"
                  "if `ls -Q /%s >/dev/null 2>&1`; then\n"
                          "LSOPT=\"-Qlan\";\n"
                          "ADD=0;\n"
                  "else\n"
                          "LSOPT=\"-lan\";\n"
                          "ADD=1;\n"
                  "fi\n"
                  "ls $LSOPT /%s 2>/dev/null | grep '^[^cbt]' | (\n"
                          "while read p l u g s m d y n n2 n3; do\n"
                                  "if test \"$m\" = \"0\" ; then \n"
                                          "s=$d; m=$y; d=$n y=$n2; n=$n3\n"
                                  "else\n"
                                          "n=$n\" \"$n2\" \"$n3\n"
                                  "fi\n"
                                  "if [ $ADD  = 0 ]; then\n"
                                          "echo \"P$p $u.$g\nS$s\nd$m $d $y\n:$n\n\"\n"
                                  "elif `sed --version >/dev/null 2>&1` ; then\n"
                                          "file=`echo $n | sed -e 's#^\\(.*\\) -> \\(.*\\)#\\1\" -> \"\\2#'`\n"
        ,
                                          "echo \"P$p $u $g\nS$s\nd$m $d $y\n:\"$file\"\n\"\n"
                                  "else\n"
                                          "echo \"P$p $u $g\nS$s\nd$m $d $y\n:\"$n\"\n\"\n"
                                  "fi\n"
                          "done )\n"
                  "ls $LSOPT /%s 2>/dev/null | grep '^[cb]' | (\n"
                          "while read p l u g a i m d y n n2 n3; do\n"
                                  "if test \"$a\" = \"0\" ; then \n"
                                          "a=$m; i=$d; m=$y; d=$n y=$n2; n=$n3\n"
                                  "else\n"
                                          "n=$n\" \"$n2\" \"$n3\n"
                                  "fi\n"
                                  "if [ $ADD = 0 ]; then\n"
                                          "echo \"P$p $u.$g\nE$a$i\nd$m $d $y\n:$n\n\"\n"
                                  "elif `sed --version >/dev/null 2>&1` ; then\n"
                                          "file=`echo $n | sed -e 's#^\\(.*\\) -> \\(.*\\)#\\1\" -> \"\\2#'`\n"
                                          "echo \"P$p $u $g\nS$s\nd$m $d $y\n:\"$file\"\n\"\n"
                                  "else\n"
                                          "echo \"P$p $u $g\nS$s\nd$m $d $y\n:\"$n\"\n\"\n"
                                  "fi\n"
                          "done)\n"
                  "echo '### 200'\n"
        "else\n"
                  "echo '### 500'\n"
        "fi\n"
        , (char *) NULL
    );

    fish_command (me, super, NONE, shell_commands,
            quoted_path, quoted_path, quoted_path, quoted_path, quoted_path, quoted_path);

    g_free(shell_commands);
    g_free (quoted_path);
    ent = vfs_s_generate_entry(me, NULL, dir, 0);
    while (1) {
        int res = vfs_s_get_line_interruptible (me, buffer, sizeof (buffer), SUP.sockr); 
        if ((!res) || (res == EINTR)) {
            vfs_s_free_entry(me, ent);
            me->verrno = ECONNRESET;
            goto error;
        }
        if (logfile) {
            fputs (buffer, logfile);
            fputs ("\n", logfile);
            fflush (logfile);
        }
        if (!strncmp(buffer, "### ", 4))
            break;
        if ((!buffer[0])) {
            if (ent->name) {
                vfs_s_insert_entry(me, dir, ent);
                ent = vfs_s_generate_entry(me, NULL, dir, 0);
            }
            continue;
        }
        
#define ST ent->ino->st

        switch(buffer[0]) {
        case ':': {
            char *temp;
            char *data_start = buffer+1;
            char *filename = data_start;
            char *linkname = data_start;
            char *filename_bound = filename + strlen(filename);
            char *linkname_bound = filename_bound;
            if (!strcmp(data_start, "\".\"") || !strcmp(data_start, "\"..\""))
                        break;  /* We'll do "." and ".." ourselves */

                if (S_ISLNK(ST.st_mode)) {
                        /* we expect: "escaped-name" -> "escaped-name"
                        //     -> cannot occur in filenames,
                        //     because it will be escaped to -\> */

                        if (*filename == '"')
                                ++filename;

                        linkname = strstr(filename, "\" -> \"");
                        if (!linkname)
                        {
                                /* broken client, or smth goes wrong */
                                linkname = filename_bound;
                                if (filename_bound > filename
                                    && *(filename_bound - 1) == '"')
                                        --filename_bound; /* skip trailing " */
                        }
                        else
                        {
                                filename_bound = linkname;
                                linkname += 6; /* strlen ("\" -> \"") */
                                if (*(linkname_bound - 1) == '"')
                                        --linkname_bound; /* skip trailing " */
                        }

                        ent->name = str_dup_range(filename, filename_bound);
                        temp = ent->name;
                        ent->name = strutils_shell_unescape(ent->name);
                        g_free(temp);

                        ent->ino->linkname = str_dup_range(linkname, linkname_bound);
                        temp = ent->ino->linkname;
                        ent->ino->linkname = strutils_shell_unescape(ent->ino->linkname);
                        g_free(temp);
                } else {
                        /* we expect: "escaped-name" */
                        if (filename_bound - filename > 2)
                        {
                                /*
                                 there is at least 2 "
                                 and we skip them
                                */
                                if (*filename == '"')
                                        ++filename;
                                if (*(filename_bound - 1) == '"')
                                        --filename_bound;
                        }
                        ent->name = str_dup_range(filename, filename_bound);
                        temp = ent->name;
                        ent->name = strutils_shell_unescape(ent->name);
                        g_free(temp);
                }
                break;
        }
        case 'S':
#ifdef HAVE_ATOLL
            ST.st_size = (off_t) atoll (buffer+1);
#else
            ST.st_size = (off_t) atof (buffer+1);
#endif
            break;
        case 'P': {
            size_t skipped;
            vfs_parse_filemode (buffer + 1, &skipped, &ST.st_mode);
            break;
        }
        case 'R': {
            /*
               raw filemode:
               we expect: Roctal-filemode octal-filetype uid.gid
            */
            size_t skipped;
            vfs_parse_raw_filemode (buffer + 1, &skipped, &ST.st_mode);
            break;
        }
        case 'd': {
                      vfs_split_text(buffer+1);
                      if (!vfs_parse_filedate(0, &ST.st_ctime))
                          break;
                      ST.st_atime = ST.st_mtime = ST.st_ctime;
                  }
                  break;
        case 'D': {
                      struct tm tim;
                      if (sscanf(buffer+1, "%d %d %d %d %d %d", &tim.tm_year, &tim.tm_mon, 
                                 &tim.tm_mday, &tim.tm_hour, &tim.tm_min, &tim.tm_sec) != 6)
                          break;
                      ST.st_atime = ST.st_mtime = ST.st_ctime = mktime(&tim);
                  }
                  break;
        case 'E': {
                      int maj, min;
                      if (sscanf(buffer+1, "%d,%d", &maj, &min) != 2)
                          break;
#ifdef HAVE_STRUCT_STAT_ST_RDEV
                      ST.st_rdev = makedev (maj, min);
#endif
                  }
        }
    }
    
    vfs_s_free_entry (me, ent);
    reply_code = fish_decode_reply(buffer + 4, 0);
    if (reply_code == COMPLETE) {
        g_free (SUP.cwdir);
        SUP.cwdir = g_strdup (remote_path);
        print_vfs_message (_("%s: done."), me->name);
        return 0;
    } else if (reply_code == ERROR) {
        me->verrno = EACCES;
    } else {
        me->verrno = E_REMOTE;
    }

error:
    print_vfs_message (_("%s: failure"), me->name);
    return -1;
}

static int
fish_file_store(struct vfs_class *me, struct vfs_s_fh *fh, char *name, char *localname)
{
    struct vfs_s_super *super = FH_SUPER;
    int n, total;
    char buffer[8192];
    struct stat s;
    int was_error = 0;
    int h;
    char *quoted_name;

    h = open (localname, O_RDONLY);

    if (h == -1)
        ERRNOR (EIO, -1);
    if (fstat(h, &s)<0) {
        close (h);
        ERRNOR (EIO, -1);
    }

    /* First, try this as stor:
     *
     *     ( head -c number ) | ( cat > file; cat >/dev/null )
     *
     *  If `head' is not present on the remote system, `dd' will be used.
     * Unfortunately, we cannot trust most non-GNU `head' implementations
     * even if `-c' options is supported. Therefore, we separate GNU head
     * (and other modern heads?) using `-q' and `-' . This causes another
     * implementations to fail (because of "incorrect options").
     *
     *  Fallback is:
     *
     *     rest=<number>
     *     while [ $rest -gt 0 ]
     *     do
     *        cnt=`expr \( $rest + 255 \) / 256`
     *        n=`dd bs=256 count=$cnt | tee -a <target_file> | wc -c`
     *        rest=`expr $rest - $n`
     *     done
     *
     *  `dd' was not designed for full filling of input buffers,
     *  and does not report exact number of bytes (not blocks).
     *  Therefore a more complex shell script is needed.
     *
     *   On some systems non-GNU head writes "Usage:" error report to stdout
     *  instead of stderr. It makes impossible the use of "head || dd"
     *  algorithm for file appending case, therefore just "dd" is used for it.
     */

    quoted_name = strutils_shell_escape(name);
    print_vfs_message(_("fish: store %s: sending command..."), quoted_name );

    /* FIXME: File size is limited to ULONG_MAX */
    if (!fh->u.fish.append)
        n = fish_command (me, super, WAIT_REPLY,
                 "#STOR %lu /%s\n"
                 "echo '### 001'\n"
                 "file=/%s\n"
                 "res=`exec 3>&1\n"
                 "(\n"
                   "head -c %lu -q - || echo DD >&3\n"
                 ") 2>/dev/null | (\n"
                   "cat > $file\n"
                   "cat > /dev/null\n"
                 ")`; [ \"$res\" = DD ] && {\n"
                        "> \"$file\"\n"
                        "rest=%lu\n"
                        "while [ $rest -gt 0 ]\n"
                        "do\n"
                        "    cnt=`expr \\( $rest + 255 \\) / 256`\n"
                        "    n=`dd bs=256 count=$cnt | tee -a \"$file\" | wc -c`\n"
                        "    rest=`expr $rest - $n`\n"
                        "done\n"
                 "}; echo '### 200'\n",
                 (unsigned long) s.st_size, quoted_name,
                 quoted_name, (unsigned long) s.st_size,
                 (unsigned long) s.st_size);
    else
        n = fish_command (me, super, WAIT_REPLY,
                 "#STOR %lu /%s\n"
                 "echo '### 001'\n"
                 "{\n"
                        "file=/%s\n"
                        "rest=%lu\n"
                        "while [ $rest -gt 0 ]\n"
                        "do\n"
                        "    cnt=`expr \\( $rest + 255 \\) / 256`\n"
                        "    n=`dd bs=256 count=$cnt | tee -a $file | wc -c`\n"
                        "    rest=`expr $rest - $n`\n"
                        "done\n"
                 "}; echo '### 200'\n",
                 (unsigned long) s.st_size, quoted_name,
                 quoted_name, (unsigned long) s.st_size);

    if (n != PRELIM) {
        close (h);
        ERRNOR(E_REMOTE, -1);
    }
    total = 0;
    
    while (1) {
        int t;
        while ((n = read(h, buffer, sizeof(buffer))) < 0) {
            if ((errno == EINTR) && tty_got_interrupt ())
                continue;
            print_vfs_message(_("fish: Local read failed, sending zeros") );
            close(h);
            h = open( "/dev/zero", O_RDONLY );
        }
        if (n == 0)
            break;
        if ((t = write (SUP.sockw, buffer, n)) != n) {
            if (t == -1) {
                me->verrno = errno;
            } else { 
                me->verrno = EIO;
            }
            goto error_return;
        }
        tty_disable_interrupt_key ();
        total += n;
        print_vfs_message(_("fish: storing %s %d (%lu)"), 
                          was_error ? _("zeros") : _("file"), total,
                          (unsigned long) s.st_size);
    }
    close(h);
    g_free(quoted_name);
    if ((fish_get_reply (me, SUP.sockr, NULL, 0) != COMPLETE) || was_error)
        ERRNOR (E_REMOTE, -1);
    return 0;
error_return:
    close(h);
    fish_get_reply(me, SUP.sockr, NULL, 0);
    g_free(quoted_name);
    return -1;
}

static int
fish_linear_start (struct vfs_class *me, struct vfs_s_fh *fh, off_t offset)
{
    char *name;
    char *quoted_name;
    if (offset)
        ERRNOR (E_NOTSUPP, 0);
    name = vfs_s_fullpath (me, fh->ino);
    if (name == NULL)
        return 0;
    quoted_name = strutils_shell_escape (name);
    g_free (name);
    fh->u.fish.append = 0;

    /*
     * Check whether the remote file is readable by using `dd' to copy 
     * a single byte from the remote file to /dev/null. If `dd' completes
     * with exit status of 0 use `cat' to send the file contents to the
     * standard output (i.e. over the network).
     */
    offset = fish_command (me, FH_SUPER, WANT_STRING,
                "#RETR /%s\n"
                "if dd if=/%s of=/dev/null bs=1 count=1 2>/dev/null ;\n"
                "then\n"
                "ls -ln /%s 2>/dev/null | (\n"
                  "read p l u g s r\n"
                  "echo $s\n"
                ")\n"
                "echo '### 100'\n"
                "cat /%s\n"
                "echo '### 200'\n"
                "else\n"
                "echo '### 500'\n"
                "fi\n",
                quoted_name, quoted_name, quoted_name, quoted_name );
    g_free (quoted_name);
    if (offset != PRELIM) ERRNOR (E_REMOTE, 0);
    fh->linear = LS_LINEAR_OPEN;
    fh->u.fish.got = 0;
    errno = 0;
#if SIZEOF_OFF_T == SIZEOF_LONG
    fh->u.fish.total = strtol (reply_str, NULL, 10);
#else
    fh->u.fish.total = strtoll (reply_str, NULL, 10);
#endif
    if (errno != 0)
        ERRNOR (E_REMOTE, 0);
    return 1;
}

static void
fish_linear_abort (struct vfs_class *me, struct vfs_s_fh *fh)
{
    struct vfs_s_super *super = FH_SUPER;
    char buffer[8192];
    int n;

    print_vfs_message( _("Aborting transfer...") );
    do {
        n = MIN(8192, fh->u.fish.total - fh->u.fish.got);
        if (n) {
            if ((n = read(SUP.sockr, buffer, n)) < 0)
                return;
            fh->u.fish.got += n;
        }
    } while (n);

    if (fish_get_reply (me, SUP.sockr, NULL, 0) != COMPLETE)
        print_vfs_message( _("Error reported after abort.") );
    else
        print_vfs_message( _("Aborted transfer would be successful.") );
}

static int
fish_linear_read (struct vfs_class *me, struct vfs_s_fh *fh, void *buf, int len)
{
    struct vfs_s_super *super = FH_SUPER;
    int n = 0;
    len = MIN( fh->u.fish.total - fh->u.fish.got, len );
    tty_disable_interrupt_key ();
    while (len && ((n = read (SUP.sockr, buf, len))<0)) {
        if ((errno == EINTR) && !tty_got_interrupt ())
            continue;
        break;
    }
    tty_enable_interrupt_key();

    if (n>0) fh->u.fish.got += n;
    if (n<0) fish_linear_abort(me, fh);
    if ((!n) && ((fish_get_reply (me, SUP.sockr, NULL, 0) != COMPLETE)))
        ERRNOR (E_REMOTE, -1);
    ERRNOR (errno, n);
}

static void
fish_linear_close (struct vfs_class *me, struct vfs_s_fh *fh)
{
    if (fh->u.fish.total != fh->u.fish.got)
        fish_linear_abort(me, fh);
}

static int
fish_ctl (void *fh, int ctlop, void *arg)
{
    (void) arg;
    (void) fh;
    (void) ctlop;
    return 0;
#if 0
    switch (ctlop) {
        case VFS_CTL_IS_NOTREADY:
            {
                int v;

                if (!FH->linear)
                    vfs_die ("You may not do this");
                if (FH->linear == LS_LINEAR_CLOSED || FH->linear == LS_LINEAR_PREOPEN)
                    return 0;

                v = vfs_s_select_on_two (FH_SUPER->u.fish.sockr, 0);
                if (((v < 0) && (errno == EINTR)) || v == 0)
                    return 1;
                return 0;
            }
        default:
            return 0;
    }
#endif
}

static int
fish_send_command(struct vfs_class *me, struct vfs_s_super *super, const char *cmd, int flags)
{
    int r;

    r = fish_command (me, super, WAIT_REPLY, "%s", cmd);
    vfs_stamp_create (&vfs_fish_ops, super);
    if (r != COMPLETE) ERRNOR (E_REMOTE, -1);
    if (flags & OPT_FLUSH)
        vfs_s_invalidate(me, super);
    return 0;
}

#define PREFIX \
    char buf[BUF_LARGE]; \
    const char *crpath; \
    char *rpath, *mpath = g_strdup (path); \
    struct vfs_s_super *super; \
    if (!(crpath = vfs_s_get_path_mangle (me, mpath, &super, 0))) { \
        g_free (mpath); \
        return -1; \
    } \
    rpath = strutils_shell_escape(crpath); \
    g_free (mpath);

#define POSTFIX(flags) \
    g_free (rpath); \
    return fish_send_command(me, super, buf, flags);

static int
fish_chmod (struct vfs_class *me, const char *path, int mode)
{
    PREFIX
    g_snprintf(buf, sizeof(buf), "#CHMOD %4.4o /%s\n"
                                 "if chmod %4.4o /%s 2>/dev/null; then\n"
                                    "echo '### 000'\n"
                                 "else\n"
                                    "echo '### 500'\n"
                                 "fi\n",
            mode & 07777, rpath,
            mode & 07777, rpath);
    POSTFIX(OPT_FLUSH);
}

#define FISH_OP(name, string) \
static int fish_##name (struct vfs_class *me, const char *path1, const char *path2) \
{ \
    char buf[BUF_LARGE]; \
    const char *crpath1, *crpath2; \
    char *rpath1, *rpath2, *mpath1, *mpath2; \
    struct vfs_s_super *super1, *super2; \
    if (!(crpath1 = vfs_s_get_path_mangle (me, mpath1 = g_strdup(path1), &super1, 0))) { \
        g_free (mpath1); \
        return -1; \
    } \
    if (!(crpath2 = vfs_s_get_path_mangle (me, mpath2 = g_strdup(path2), &super2, 0))) { \
        g_free (mpath1); \
        g_free (mpath2); \
        return -1; \
    } \
    rpath1 = strutils_shell_escape (crpath1); \
    g_free (mpath1); \
    rpath2 = strutils_shell_escape (crpath2); \
    g_free (mpath2); \
    g_snprintf(buf, sizeof(buf), string "\n", rpath1, rpath2, rpath1, rpath2); \
    g_free (rpath1); \
    g_free (rpath2); \
    return fish_send_command(me, super2, buf, OPT_FLUSH); \
}

FISH_OP(rename, "#RENAME /%s /%s\n"
                "if mv /%s /%s 2>/dev/null; then\n"
                    "echo '### 000'\n"
                "else\n"
                    "echo '### 500'\n"
                "fi\n")
FISH_OP(link,   "#LINK /%s /%s\n"
                "if ln /%s /%s 2>/dev/null; then\n"
                    "echo '### 000'\n"
                "else\n"
                    "echo '### 500'\n"
                "fi\n")

static int fish_symlink (struct vfs_class *me, const char *setto, const char *path)
{
    char *qsetto;
    PREFIX
    qsetto = strutils_shell_escape (setto);
    g_snprintf(buf, sizeof(buf),
            "#SYMLINK %s /%s\n"
            "if ln -s %s /%s 2>/dev/null; then\n"
                "echo '### 000'\n"
            "else\n"
                "echo '### 500'\n"
            "fi\n",
            qsetto, rpath, qsetto, rpath);
    g_free (qsetto);
    POSTFIX(OPT_FLUSH);
}

static int
fish_chown (struct vfs_class *me, const char *path, int owner, int group)
{
    char *sowner, *sgroup;
    struct passwd *pw;
    struct group *gr;

    if ((pw = getpwuid (owner)) == NULL)
        return 0;

    if ((gr = getgrgid (group)) == NULL)
        return 0;

    sowner = pw->pw_name;
    sgroup = gr->gr_name;
    {
        PREFIX
        g_snprintf (buf, sizeof(buf),
            "#CHOWN %s:%s /%s\n"
            "if chown %s:%s /%s 2>/dev/null; then\n"
                "echo '### 000'\n"
            "else\n"
                "echo '### 500'\n"
            "fi\n",
            sowner, sgroup, rpath,
            sowner, sgroup, rpath);
        fish_send_command (me, super, buf, OPT_FLUSH);
        /* FIXME: what should we report if chgrp succeeds but chown fails? */
        /* fish_send_command(me, super, buf, OPT_FLUSH); */
        POSTFIX (OPT_FLUSH)
    }
}

static int fish_unlink (struct vfs_class *me, const char *path)
{
    PREFIX
    g_snprintf(buf, sizeof(buf),
            "#DELE /%s\n"
            "if rm -f /%s 2>/dev/null; then\n"
                "echo '### 000'\n"
            "else\n"
                "echo '### 500'\n"
            "fi\n",
            rpath, rpath);
    POSTFIX(OPT_FLUSH);
}

static int fish_exists (struct vfs_class *me, const char *path)
{
    PREFIX

    g_snprintf(buf, sizeof(buf),
            "#ISEXISTS /%s\n"
            "ls -l /%s >/dev/null 2>/dev/null\n"
            "echo '### '$?\n",
            rpath, rpath);

    g_free (rpath);

    if ( fish_send_command(me, super, buf, OPT_FLUSH) == 0 )
        return 1;

    return 0;
}


static int fish_mkdir (struct vfs_class *me, const char *path, mode_t mode)
{
    int ret_code;

    PREFIX

    (void) mode;

    g_snprintf(buf, sizeof(buf),
            "#MKD /%s\n"
            "if mkdir /%s 2>/dev/null; then\n"
                "echo '### 000'\n"
            "else\n"
                "echo '### 500'\n"
            "fi\n",
            rpath, rpath);

    g_free (rpath);
    ret_code = fish_send_command(me, super, buf, OPT_FLUSH);

    if ( ret_code != 0 )
        return ret_code;

    if ( ! fish_exists (me, path) ){
        ERRNOR (EACCES, -1);
    }
    return 0;
}

static int fish_rmdir (struct vfs_class *me, const char *path)
{
    PREFIX
    g_snprintf(buf, sizeof(buf),
            "#RMD /%s\n"
            "if rmdir /%s 2>/dev/null; then\n"
                "echo '### 000'\n"
            "else\n"
                "echo '### 500'\n"
            "fi\n",
            rpath, rpath);
    POSTFIX(OPT_FLUSH);
}

static int
fish_fh_open (struct vfs_class *me, struct vfs_s_fh *fh, int flags,
              int mode)
{
    (void) mode;

    fh->u.fish.append = 0;
    /* File will be written only, so no need to retrieve it */
    if (((flags & O_WRONLY) == O_WRONLY) && !(flags & (O_RDONLY | O_RDWR))) {
        fh->u.fish.append = flags & O_APPEND;
        if (!fh->ino->localname) {
            int tmp_handle =
                vfs_mkstemps (&fh->ino->localname, me->name,
                              fh->ino->ent->name);
            if (tmp_handle == -1)
                return -1;
            close (tmp_handle);
        }
        return 0;
    }
    if (!fh->ino->localname)
        if (vfs_s_retrieve_file (me, fh->ino) == -1)
            return -1;
    if (!fh->ino->localname)
        vfs_die ("retrieve_file failed to fill in localname");
    return 0;
}

static void
fish_fill_names (struct vfs_class *me, fill_names_f func)
{
    struct vfs_s_super *super = MEDATA->supers;
    char *name;

    char gbuf[10];

    while (super)
    {
        const char *flags = "";
        switch (SUP.flags)
        {
            case FISH_FLAG_RSH:
                flags = ":r";
                break;
            case FISH_FLAG_COMPRESSED:
                flags = ":C";
                break;
            default:
                if (SUP.flags > FISH_FLAG_RSH)
                {
                    break;
                    g_snprintf (gbuf, sizeof (gbuf), ":%d", SUP.flags);
                    flags = gbuf;
                }
                break;
        }

        name = g_strconcat ("/#sh:", SUP.user, "@", SUP.host, flags,
                            "/", SUP.cwdir, (char *) NULL);
        (*func)(name);
        g_free (name);
        super = super->next;
    }
}

static void *
fish_open (struct vfs_class *me, const char *file, int flags, int mode)
{
    /*
      sorry, i've places hack here
      cause fish don't able to open files with O_EXCL flag
    */
    flags &= ~O_EXCL;
    return vfs_s_open (me, file, flags, mode);
}


void
init_fish (void)
{
    static struct vfs_s_subclass fish_subclass;

    tcp_init();

    fish_subclass.flags = VFS_S_REMOTE;
    fish_subclass.archive_same = fish_archive_same;
    fish_subclass.open_archive = fish_open_archive;
    fish_subclass.free_archive = fish_free_archive;
    fish_subclass.fh_open = fish_fh_open;
    fish_subclass.dir_load = fish_dir_load;
    fish_subclass.file_store = fish_file_store;
    fish_subclass.linear_start = fish_linear_start;
    fish_subclass.linear_read = fish_linear_read;
    fish_subclass.linear_close = fish_linear_close;

    vfs_s_init_class (&vfs_fish_ops, &fish_subclass);
    vfs_fish_ops.name = "fish";
    vfs_fish_ops.prefix = "sh:";
    vfs_fish_ops.fill_names = fish_fill_names;
    vfs_fish_ops.chmod = fish_chmod;
    vfs_fish_ops.chown = fish_chown;
    vfs_fish_ops.open = fish_open;
    vfs_fish_ops.symlink = fish_symlink;
    vfs_fish_ops.link = fish_link;
    vfs_fish_ops.unlink = fish_unlink;
    vfs_fish_ops.rename = fish_rename;
    vfs_fish_ops.mkdir = fish_mkdir;
    vfs_fish_ops.rmdir = fish_rmdir;
    vfs_fish_ops.ctl = fish_ctl;
    vfs_register_class (&vfs_fish_ops);
}