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;;; tramp.el --- Transparent Remote Access, Multiple Protocol

;; Copyright (C) 1998-2011 Free Software Foundation, Inc.

;; Author: Kai Großjohann <kai.grossjohann@gmx.net>
;;         Michael Albinus <michael.albinus@gmx.de>
;; Keywords: comm, processes
;; Package: tramp

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs 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 General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; This package provides remote file editing, similar to ange-ftp.
;; The difference is that ange-ftp uses FTP to transfer files between
;; the local and the remote host, whereas tramp.el uses a combination
;; of rsh and rcp or other work-alike programs, such as ssh/scp.
;;
;; For more detailed instructions, please see the info file.
;;
;; Notes:
;; -----
;;
;; This package only works for Emacs 22.1 and higher, and for XEmacs 21.4
;; and higher.  For XEmacs 21, you need the package `fsf-compat' for
;; the `with-timeout' macro.
;;
;; Also see the todo list at the bottom of this file.
;;
;; The current version of Tramp can be retrieved from the following URL:
;;            http://ftp.gnu.org/gnu/tramp/
;;
;; There's a mailing list for this, as well.  Its name is:
;;            tramp-devel@gnu.org
;; You can use the Web to subscribe, under the following URL:
;;            http://lists.gnu.org/mailman/listinfo/tramp-devel
;;
;; For the adventurous, the current development sources are available
;; via CVS.  You can find instructions about this at the following URL:
;;            http://savannah.gnu.org/projects/tramp/
;; Click on "CVS" in the navigation bar near the top.
;;
;; Don't forget to put on your asbestos longjohns, first!

;;; Code:

(require 'tramp-compat)

;;; User Customizable Internal Variables:

(defgroup tramp nil
  "Edit remote files with a combination of rsh and rcp or similar programs."
  :group 'files
  :group 'comm
  :version "22.1")

;; Maybe we need once a real Tramp mode, with key bindings etc.
;;;###autoload
(defcustom tramp-mode t
  "*Whether Tramp is enabled.
If it is set to nil, all remote file names are used literally."
  :group 'tramp
  :type 'boolean)

(defcustom tramp-verbose 3
  "*Verbosity level for Tramp messages.
Any level x includes messages for all levels 1 .. x-1.  The levels are

 0  silent (no tramp messages at all)
 1  errors
 2  warnings
 3  connection to remote hosts (default level)
 4  activities
 5  internal
 6  sent and received strings
 7  file caching
 8  connection properties
 9  test commands
10  traces (huge)."
  :group 'tramp
  :type 'integer)

;; Emacs case.
(eval-and-compile
  (when (boundp 'backup-directory-alist)
    (defcustom tramp-backup-directory-alist nil
      "Alist of filename patterns and backup directory names.
Each element looks like (REGEXP . DIRECTORY), with the same meaning like
in `backup-directory-alist'.  If a Tramp file is backed up, and DIRECTORY
is a local file name, the backup directory is prepended with Tramp file
name prefix \(method, user, host\) of file.

\(setq tramp-backup-directory-alist backup-directory-alist\)

gives the same backup policy for Tramp files on their hosts like the
policy for local files."
      :group 'tramp
      :type '(repeat (cons (regexp :tag "Regexp matching filename")
                           (directory :tag "Backup directory name"))))))

;; XEmacs case.  We cannot check for `bkup-backup-directory-info', because
;; the package "backup-dir" might not be loaded yet.
(eval-and-compile
  (when (featurep 'xemacs)
    (defcustom tramp-bkup-backup-directory-info nil
      "*Alist of (FILE-REGEXP BACKUP-DIR OPTIONS ...))
It has the same meaning like `bkup-backup-directory-info' from package
`backup-dir'.  If a Tramp file is backed up, and BACKUP-DIR is a local
file name, the backup directory is prepended with Tramp file name prefix
\(method, user, host\) of file.

\(setq tramp-bkup-backup-directory-info bkup-backup-directory-info\)

gives the same backup policy for Tramp files on their hosts like the
policy for local files."
      :type '(repeat
              (list (regexp :tag "File regexp")
                    (string :tag "Backup Dir")
                    (set :inline t
                         (const ok-create)
                         (const full-path)
                         (const prepend-name)
                         (const search-upward))))
      :group 'tramp)))

(defcustom tramp-auto-save-directory nil
  "*Put auto-save files in this directory, if set.
The idea is to use a local directory so that auto-saving is faster."
  :group 'tramp
  :type '(choice (const nil) string))

(defcustom tramp-encoding-shell
  (if (memq system-type '(windows-nt))
      (getenv "COMSPEC")
    "/bin/sh")
  "*Use this program for encoding and decoding commands on the local host.
This shell is used to execute the encoding and decoding command on the
local host, so if you want to use `~' in those commands, you should
choose a shell here which groks tilde expansion.  `/bin/sh' normally
does not understand tilde expansion.

For encoding and decoding, commands like the following are executed:

    /bin/sh -c COMMAND < INPUT > OUTPUT

This variable can be used to change the \"/bin/sh\" part.  See the
variable `tramp-encoding-command-switch' for the \"-c\" part.

If the shell must be forced to be interactive, see
`tramp-encoding-command-interactive'.

Note that this variable is not used for remote commands.  There are
mechanisms in tramp.el which automatically determine the right shell to
use for the remote host."
  :group 'tramp
  :type '(file :must-match t))

(defcustom tramp-encoding-command-switch
  (if (string-match "cmd\\.exe" tramp-encoding-shell)
      "/c"
    "-c")
  "*Use this switch together with `tramp-encoding-shell' for local commands.
See the variable `tramp-encoding-shell' for more information."
  :group 'tramp
  :type 'string)

(defcustom tramp-encoding-command-interactive
  (unless (string-match "cmd\\.exe" tramp-encoding-shell) "-i")
  "*Use this switch together with `tramp-encoding-shell' for interactive shells.
See the variable `tramp-encoding-shell' for more information."
  :group 'tramp
  :type '(choice (const nil) string))

;;;###tramp-autoload
(defvar tramp-methods nil
  "*Alist of methods for remote files.
This is a list of entries of the form (NAME PARAM1 PARAM2 ...).
Each NAME stands for a remote access method.  Each PARAM is a
pair of the form (KEY VALUE).  The following KEYs are defined:
  * `tramp-remote-shell'
    This specifies the shell to use on the remote host.  This
    MUST be a Bourne-like shell.  It is normally not necessary to
    set this to any value other than \"/bin/sh\": Tramp wants to
    use a shell which groks tilde expansion, but it can search
    for it.  Also note that \"/bin/sh\" exists on all Unixen,
    this might not be true for the value that you decide to use.
    You Have Been Warned.
  * `tramp-remote-shell-args'
    For implementation of `shell-command', this specifies the
    arguments to let `tramp-remote-shell' run a single command.
  * `tramp-login-program'
    This specifies the name of the program to use for logging in to the
    remote host.  This may be the name of rsh or a workalike program,
    or the name of telnet or a workalike, or the name of su or a workalike.
  * `tramp-login-args'
    This specifies the list of arguments to pass to the above
    mentioned program.  Please note that this is a list of list of arguments,
    that is, normally you don't want to put \"-a -b\" or \"-f foo\"
    here.  Instead, you want a list (\"-a\" \"-b\"), or (\"-f\" \"foo\").
    There are some patterns: \"%h\" in this list is replaced by the host
    name, \"%u\" is replaced by the user name, \"%p\" is replaced by the
    port number, and \"%%\" can be used to obtain a literal percent character.
    If a list containing \"%h\", \"%u\" or \"%p\" is unchanged during
    expansion (i.e. no host or no user specified), this list is not used as
    argument.  By this, arguments like (\"-l\" \"%u\") are optional.
    \"%t\" is replaced by the temporary file name produced with
    `tramp-make-tramp-temp-file'.  \"%k\" indicates the keep-date
    parameter of a program, if exists.
  * `tramp-async-args'
    When an asynchronous process is started, we know already that
    the connection works.  Therefore, we can pass additional
    parameters to suppress diagnostic messages, in order not to
    tamper the process output.
  * `tramp-copy-program'
    This specifies the name of the program to use for remotely copying
    the file; this might be the absolute filename of rcp or the name of
    a workalike program.
  * `tramp-copy-args'
    This specifies the list of parameters to pass to the above mentioned
    program, the hints for `tramp-login-args' also apply here.
  * `tramp-copy-keep-date'
    This specifies whether the copying program when the preserves the
    timestamp of the original file.
  * `tramp-copy-keep-tmpfile'
    This specifies whether a temporary local file shall be kept
    for optimization reasons (useful for \"rsync\" methods).
  * `tramp-copy-recursive'
    Whether the operation copies directories recursively.
  * `tramp-default-port'
    The default port of a method is needed in case of gateway connections.
    Additionally, it is used as indication which method is prepared for
    passing gateways.
  * `tramp-gw-args'
    As the attribute name says, additional arguments are specified here
    when a method is applied via a gateway.
  * `tramp-password-end-of-line'
    This specifies the string to use for terminating the line after
    submitting the password.  If this method parameter is nil, then the
    value of the normal variable `tramp-default-password-end-of-line'
    is used.  This parameter is necessary because the \"plink\" program
    requires any two characters after sending the password.  These do
    not have to be newline or carriage return characters.  Other login
    programs are happy with just one character, the newline character.
    We use \"xy\" as the value for methods using \"plink\".
  * `tramp-tmpdir'
    A directory on the remote host for temporary files.  If not
    specified, \"/tmp\" is taken as default.

What does all this mean?  Well, you should specify `tramp-login-program'
for all methods; this program is used to log in to the remote site.  Then,
there are two ways to actually transfer the files between the local and the
remote side.  One way is using an additional rcp-like program.  If you want
to do this, set `tramp-copy-program' in the method.

Another possibility for file transfer is inline transfer, i.e. the
file is passed through the same buffer used by `tramp-login-program'.  In
this case, the file contents need to be protected since the
`tramp-login-program' might use escape codes or the connection might not
be eight-bit clean.  Therefore, file contents are encoded for transit.
See the variables `tramp-local-coding-commands' and
`tramp-remote-coding-commands' for details.

So, to summarize: if the method is an out-of-band method, then you
must specify `tramp-copy-program' and `tramp-copy-args'.  If it is an
inline method, then these two parameters should be nil.  Methods which
are fit for gateways must have `tramp-default-port' at least.

Notes:

When using `su' or `sudo' the phrase `open connection to a remote
host' sounds strange, but it is used nevertheless, for consistency.
No connection is opened to a remote host, but `su' or `sudo' is
started on the local host.  You should specify a remote host
`localhost' or the name of the local host.  Another host name is
useful only in combination with `tramp-default-proxies-alist'.")

(defun tramp-detect-ssh-controlmaster ()
  "Call ssh to detect whether it supports the ControlMaster argument.
This function may return nil when the argument is supported, but
shouldn't return t when it isn't."
  (ignore-errors
    (with-temp-buffer
      (call-process "ssh" nil t nil "-o" "ControlMaster")
      (goto-char (point-min))
      (search-forward-regexp "Missing ControlMaster argument" nil t))))

(defcustom tramp-default-method
  ;; An external copy method seems to be preferred, because it is much
  ;; more performant for large files, and it hasn't too serious delays
  ;; for small files.  But it must be ensured that there aren't
  ;; permanent password queries.  Either a password agent like
  ;; "ssh-agent" or "Pageant" shall run, or the optional
  ;; password-cache.el or auth-sources.el packages shall be active for
  ;; password caching.  "scpc" is chosen if we detect that the user is
  ;; running OpenSSH 4.0 or newer.
  (cond
   ;; PuTTY is installed.  We don't take it, if it is installed on a
   ;; non-windows system, or pscp from the pssh (parallel ssh) package
   ;; is found.
   ((and (eq system-type 'windows-nt)
         (executable-find "pscp"))
    (if (or (fboundp 'password-read)
            (fboundp 'auth-source-user-or-password)
            (fboundp 'auth-source-search)
            ;; Pageant is running.
            (tramp-compat-process-running-p "Pageant"))
        "pscp"
      "plink"))
   ;; There is an ssh installation.
   ((executable-find "scp")
    (cond
     ((tramp-detect-ssh-controlmaster) "scpc")
     ((or (fboundp 'password-read)
          (fboundp 'auth-source-user-or-password)
          (fboundp 'auth-source-search)
          ;; ssh-agent is running.
          (getenv "SSH_AUTH_SOCK")
          (getenv "SSH_AGENT_PID"))
      "scp")
     (t "ssh")))
   ;; Fallback.
   (t "ftp"))
  "*Default method to use for transferring files.
See `tramp-methods' for possibilities.
Also see `tramp-default-method-alist'."
  :group 'tramp
  :type 'string)

;;;###tramp-autoload
(defcustom tramp-default-method-alist nil
  "*Default method to use for specific host/user pairs.
This is an alist of items (HOST USER METHOD).  The first matching item
specifies the method to use for a file name which does not specify a
method.  HOST and USER are regular expressions or nil, which is
interpreted as a regular expression which always matches.  If no entry
matches, the variable `tramp-default-method' takes effect.

If the file name does not specify the user, lookup is done using the
empty string for the user name.

See `tramp-methods' for a list of possibilities for METHOD."
  :group 'tramp
  :type '(repeat (list (choice :tag "Host regexp" regexp sexp)
                       (choice :tag "User regexp" regexp sexp)
                       (choice :tag "Method name" string (const nil)))))

(defcustom tramp-default-user nil
  "*Default user to use for transferring files.
It is nil by default; otherwise settings in configuration files like
\"~/.ssh/config\" would be overwritten.  Also see `tramp-default-user-alist'.

This variable is regarded as obsolete, and will be removed soon."
  :group 'tramp
  :type '(choice (const nil) string))

;;;###tramp-autoload
(defcustom tramp-default-user-alist nil
  "*Default user to use for specific method/host pairs.
This is an alist of items (METHOD HOST USER).  The first matching item
specifies the user to use for a file name which does not specify a
user.  METHOD and USER are regular expressions or nil, which is
interpreted as a regular expression which always matches.  If no entry
matches, the variable `tramp-default-user' takes effect.

If the file name does not specify the method, lookup is done using the
empty string for the method name."
  :group 'tramp
  :type '(repeat (list (choice :tag "Method regexp" regexp sexp)
                       (choice :tag "  Host regexp" regexp sexp)
                       (choice :tag "    User name" string (const nil)))))

(defcustom tramp-default-host (system-name)
  "*Default host to use for transferring files.
Useful for su and sudo methods mostly."
  :group 'tramp
  :type 'string)

(defcustom tramp-default-proxies-alist nil
  "*Route to be followed for specific host/user pairs.
This is an alist of items (HOST USER PROXY).  The first matching
item specifies the proxy to be passed for a file name located on
a remote target matching USER@HOST.  HOST and USER are regular
expressions.  PROXY must be a Tramp filename without a localname
part.  Method and user name on PROXY are optional, which is
interpreted with the default values.  PROXY can contain the
patterns %h and %u, which are replaced by the strings matching
HOST or USER, respectively.

HOST, USER or PROXY could also be Lisp forms, which will be
evaluated.  The result must be a string or nil, which is
interpreted as a regular expression which always matches."
  :group 'tramp
  :type '(repeat (list (choice :tag "Host regexp" regexp sexp)
                       (choice :tag "User regexp" regexp sexp)
                       (choice :tag " Proxy name" string (const nil)))))

;;;###tramp-autoload
(defconst tramp-local-host-regexp
  (concat
   "\\`"
   (regexp-opt
    (list "localhost" "localhost6" (system-name) "127\.0\.0\.1" "::1") t)
   "\\'")
  "*Host names which are regarded as local host.")

(defvar tramp-completion-function-alist nil
  "*Alist of methods for remote files.
This is a list of entries of the form \(NAME PAIR1 PAIR2 ...\).
Each NAME stands for a remote access method.  Each PAIR is of the form
\(FUNCTION FILE\).  FUNCTION is responsible to extract user names and host
names from FILE for completion.  The following predefined FUNCTIONs exists:

 * `tramp-parse-rhosts'      for \"~/.rhosts\" like files,
 * `tramp-parse-shosts'      for \"~/.ssh/known_hosts\" like files,
 * `tramp-parse-sconfig'     for \"~/.ssh/config\" like files,
 * `tramp-parse-shostkeys'   for \"~/.ssh2/hostkeys/*\" like files,
 * `tramp-parse-sknownhosts' for \"~/.ssh2/knownhosts/*\" like files,
 * `tramp-parse-hosts'       for \"/etc/hosts\" like files,
 * `tramp-parse-passwd'      for \"/etc/passwd\" like files.
 * `tramp-parse-netrc'       for \"~/.netrc\" like files.
 * `tramp-parse-putty'       for PuTTY registry keys.

FUNCTION can also be a customer defined function.  For more details see
the info pages.")

(defconst tramp-echo-mark-marker "_echo"
  "String marker to surround echoed commands.")

(defconst tramp-echo-mark-marker-length (length tramp-echo-mark-marker)
  "String length of `tramp-echo-mark-marker'.")

(defconst tramp-echo-mark
  (concat tramp-echo-mark-marker
          (make-string tramp-echo-mark-marker-length ?\b))
  "String mark to be transmitted around shell commands.
Used to separate their echo from the output they produce.  This
will only be used if we cannot disable remote echo via stty.
This string must have no effect on the remote shell except for
producing some echo which can later be detected by
`tramp-echoed-echo-mark-regexp'.  Using `tramp-echo-mark-marker',
followed by an equal number of backspaces to erase them will
usually suffice.")

(defconst tramp-echoed-echo-mark-regexp
  (format "%s\\(\b\\( \b\\)?\\)\\{%d\\}"
          tramp-echo-mark-marker tramp-echo-mark-marker-length)
  "Regexp which matches `tramp-echo-mark' as it gets echoed by
the remote shell.")

(defcustom tramp-rsh-end-of-line "\n"
  "*String used for end of line in rsh connections.
I don't think this ever needs to be changed, so please tell me about it
if you need to change this.
Also see the method parameter `tramp-password-end-of-line' and the normal
variable `tramp-default-password-end-of-line'."
  :group 'tramp
  :type 'string)

(defcustom tramp-default-password-end-of-line
  tramp-rsh-end-of-line
  "*String used for end of line after sending a password.
This variable provides the default value for the method parameter
`tramp-password-end-of-line', see `tramp-methods' for more details.

It seems that people using plink under Windows need to send
\"\\r\\n\" (carriage-return, then newline) after a password, but just
\"\\n\" after all other lines.  This variable can be used for the
password, see `tramp-rsh-end-of-line' for the other cases.

The default value is to use the same value as `tramp-rsh-end-of-line'."
  :group 'tramp
  :type 'string)

(defcustom tramp-login-prompt-regexp
  ".*ogin\\( .*\\)?: *"
  "*Regexp matching login-like prompts.
The regexp should match at end of buffer.

Sometimes the prompt is reported to look like \"login as:\"."
  :group 'tramp
  :type 'regexp)

(defcustom tramp-shell-prompt-pattern
  ;; Allow a prompt to start right after a ^M since it indeed would be
  ;; displayed at the beginning of the line (and Zsh uses it).  This
  ;; regexp works only for GNU Emacs.
  (concat (if (featurep 'xemacs) "" "\\(?:^\\|\r\\)")
          "[^#$%>\n]*#?[#$%>] *\\(\e\\[[0-9;]*[a-zA-Z] *\\)*")
  "Regexp to match prompts from remote shell.
Normally, Tramp expects you to configure `shell-prompt-pattern'
correctly, but sometimes it happens that you are connecting to a
remote host which sends a different kind of shell prompt.  Therefore,
Tramp recognizes things matched by `shell-prompt-pattern' as prompt,
and also things matched by this variable.  The default value of this
variable is similar to the default value of `shell-prompt-pattern',
which should work well in many cases.

This regexp must match both `tramp-initial-end-of-output' and
`tramp-end-of-output'."
  :group 'tramp
  :type 'regexp)

(defcustom tramp-password-prompt-regexp
  "^.*\\([pP]assword\\|[pP]assphrase\\).*:\^@? *"
  "*Regexp matching password-like prompts.
The regexp should match at end of buffer.

The `sudo' program appears to insert a `^@' character into the prompt."
  :group 'tramp
  :type 'regexp)

(defcustom tramp-wrong-passwd-regexp
  (concat "^.*"
          ;; These strings should be on the last line
          (regexp-opt '("Permission denied"
                        "Login incorrect"
                        "Login Incorrect"
                        "Connection refused"
                        "Connection closed"
                        "Timeout, server not responding."
                        "Sorry, try again."
                        "Name or service not known"
                        "Host key verification failed."
                        "No supported authentication methods left to try!") t)
          ".*"
          "\\|"
          "^.*\\("
          ;; Here comes a list of regexes, separated by \\|
          "Received signal [0-9]+"
          "\\).*")
  "*Regexp matching a `login failed' message.
The regexp should match at end of buffer."
  :group 'tramp
  :type 'regexp)

(defcustom tramp-yesno-prompt-regexp
  (concat
   (regexp-opt '("Are you sure you want to continue connecting (yes/no)?") t)
   "\\s-*")
  "Regular expression matching all yes/no queries which need to be confirmed.
The confirmation should be done with yes or no.
The regexp should match at end of buffer.
See also `tramp-yn-prompt-regexp'."
  :group 'tramp
  :type 'regexp)

(defcustom tramp-yn-prompt-regexp
  (concat
   (regexp-opt '("Store key in cache? (y/n)"
                 "Update cached key? (y/n, Return cancels connection)") t)
   "\\s-*")
  "Regular expression matching all y/n queries which need to be confirmed.
The confirmation should be done with y or n.
The regexp should match at end of buffer.
See also `tramp-yesno-prompt-regexp'."
  :group 'tramp
  :type 'regexp)

(defcustom tramp-terminal-prompt-regexp
  (concat "\\("
          "TERM = (.*)"
          "\\|"
          "Terminal type\\? \\[.*\\]"
          "\\)\\s-*")
  "Regular expression matching all terminal setting prompts.
The regexp should match at end of buffer.
The answer will be provided by `tramp-action-terminal', which see."
  :group 'tramp
  :type 'regexp)

(defcustom tramp-operation-not-permitted-regexp
  (concat "\\(" "preserving times.*" "\\|" "set mode" "\\)" ":\\s-*"
          (regexp-opt '("Operation not permitted") t))
  "Regular expression matching keep-date problems in (s)cp operations.
Copying has been performed successfully already, so this message can
be ignored safely."
  :group 'tramp
  :type 'regexp)

(defcustom tramp-copy-failed-regexp
  (concat "\\(.+: "
          (regexp-opt '("Permission denied"
                        "not a regular file"
                        "is a directory"
                        "No such file or directory") t)
          "\\)\\s-*")
  "Regular expression matching copy problems in (s)cp operations."
  :group 'tramp
  :type 'regexp)

(defcustom tramp-process-alive-regexp
  ""
  "Regular expression indicating a process has finished.
In fact this expression is empty by intention, it will be used only to
check regularly the status of the associated process.
The answer will be provided by `tramp-action-process-alive',
`tramp-action-out-of-band', which see."
  :group 'tramp
  :type 'regexp)

(defconst tramp-temp-name-prefix "tramp."
  "*Prefix to use for temporary files.
If this is a relative file name (such as \"tramp.\"), it is considered
relative to the directory name returned by the function
`tramp-compat-temporary-file-directory' (which see).  It may also be an
absolute file name; don't forget to include a prefix for the filename
part, though.")

(defconst tramp-temp-buffer-name " *tramp temp*"
  "Buffer name for a temporary buffer.
It shall be used in combination with `generate-new-buffer-name'.")

(defvar tramp-temp-buffer-file-name nil
  "File name of a persistent local temporary file.
Useful for \"rsync\" like methods.")
(make-variable-buffer-local 'tramp-temp-buffer-file-name)
(put 'tramp-temp-buffer-file-name 'permanent-local t)

;; XEmacs is distributed with few Lisp packages.  Further packages are
;; installed using EFS.  If we use a unified filename format, then
;; Tramp is required in addition to EFS.  (But why can't Tramp just
;; disable EFS when Tramp is loaded?  Then XEmacs can ship with EFS
;; just like before.)  Another reason for using a separate filename
;; syntax on XEmacs is that EFS hooks into XEmacs in many places, but
;; Tramp only knows how to deal with `file-name-handler-alist', not
;; the other places.

;; Currently, we have the choice between 'ftp, 'sep, and 'url.
;;;###autoload
(defcustom tramp-syntax
  (if (featurep 'xemacs) 'sep 'ftp)
  "Tramp filename syntax to be used.

It can have the following values:

  'ftp -- Ange-FTP respective EFS like syntax (GNU Emacs default)
  'sep -- Syntax as defined for XEmacs (not available yet for GNU Emacs)
  'url -- URL-like syntax."
  :group 'tramp
  :type (if (featurep 'xemacs)
            '(choice (const :tag "EFS"    ftp)
                     (const :tag "XEmacs" sep)
                     (const :tag "URL"    url))
          '(choice (const :tag "Ange-FTP" ftp)
                   (const :tag "URL"      url))))

(defconst tramp-prefix-format
  (cond ((equal tramp-syntax 'ftp) "/")
        ((equal tramp-syntax 'sep) "/[")
        ((equal tramp-syntax 'url) "/")
        (t (error "Wrong `tramp-syntax' defined")))
  "*String matching the very beginning of Tramp file names.
Used in `tramp-make-tramp-file-name'.")

(defconst tramp-prefix-regexp
  (concat "^" (regexp-quote tramp-prefix-format))
  "*Regexp matching the very beginning of Tramp file names.
Should always start with \"^\". Derived from `tramp-prefix-format'.")

(defconst tramp-method-regexp
  "[a-zA-Z_0-9-]+"
  "*Regexp matching methods identifiers.")

(defconst tramp-postfix-method-format
  (cond ((equal tramp-syntax 'ftp) ":")
        ((equal tramp-syntax 'sep) "/")
        ((equal tramp-syntax 'url) "://")
        (t (error "Wrong `tramp-syntax' defined")))
  "*String matching delimiter between method and user or host names.
Used in `tramp-make-tramp-file-name'.")

(defconst tramp-postfix-method-regexp
  (regexp-quote tramp-postfix-method-format)
  "*Regexp matching delimiter between method and user or host names.
Derived from `tramp-postfix-method-format'.")

(defconst tramp-user-regexp "[^:/ \t]+"
  "*Regexp matching user names.")

;;;###tramp-autoload
(defconst tramp-prefix-domain-format "%"
  "*String matching delimiter between user and domain names.")

;;;###tramp-autoload
(defconst tramp-prefix-domain-regexp
  (regexp-quote tramp-prefix-domain-format)
  "*Regexp matching delimiter between user and domain names.
Derived from `tramp-prefix-domain-format'.")

(defconst tramp-domain-regexp "[-a-zA-Z0-9_.]+"
  "*Regexp matching domain names.")

(defconst tramp-user-with-domain-regexp
  (concat "\\(" tramp-user-regexp "\\)"
                tramp-prefix-domain-regexp
          "\\(" tramp-domain-regexp "\\)")
  "*Regexp matching user names with domain names.")

(defconst tramp-postfix-user-format "@"
  "*String matching delimiter between user and host names.
Used in `tramp-make-tramp-file-name'.")

(defconst tramp-postfix-user-regexp
  (regexp-quote tramp-postfix-user-format)
  "*Regexp matching delimiter between user and host names.
Derived from `tramp-postfix-user-format'.")

(defconst tramp-host-regexp "[a-zA-Z0-9_.-]+"
  "*Regexp matching host names.")

(defconst tramp-prefix-ipv6-format
  (cond ((equal tramp-syntax 'ftp) "[")
        ((equal tramp-syntax 'sep) "")
        ((equal tramp-syntax 'url) "[")
        (t (error "Wrong `tramp-syntax' defined")))
  "*String matching left hand side of IPv6 addresses.
Used in `tramp-make-tramp-file-name'.")

(defconst tramp-prefix-ipv6-regexp
  (regexp-quote tramp-prefix-ipv6-format)
  "*Regexp matching left hand side of IPv6 addresses.
Derived from `tramp-prefix-ipv6-format'.")

;; The following regexp is a bit sloppy.  But it shall serve our
;; purposes.  It covers also IPv4 mapped IPv6 addresses, like in
;; "::ffff:192.168.0.1".
(defconst tramp-ipv6-regexp
  "\\(?:\\(?:[a-zA-Z0-9]+\\)?:\\)+[a-zA-Z0-9.]+"
  "*Regexp matching IPv6 addresses.")

(defconst tramp-postfix-ipv6-format
  (cond ((equal tramp-syntax 'ftp) "]")
        ((equal tramp-syntax 'sep) "")
        ((equal tramp-syntax 'url) "]")
        (t (error "Wrong `tramp-syntax' defined")))
  "*String matching right hand side of IPv6 addresses.
Used in `tramp-make-tramp-file-name'.")

(defconst tramp-postfix-ipv6-regexp
  (regexp-quote tramp-postfix-ipv6-format)
  "*Regexp matching right hand side of IPv6 addresses.
Derived from `tramp-postfix-ipv6-format'.")

(defconst tramp-prefix-port-format
  (cond ((equal tramp-syntax 'ftp) "#")
        ((equal tramp-syntax 'sep) "#")
        ((equal tramp-syntax 'url) ":")
        (t (error "Wrong `tramp-syntax' defined")))
  "*String matching delimiter between host names and port numbers.")

(defconst tramp-prefix-port-regexp
  (regexp-quote tramp-prefix-port-format)
  "*Regexp matching delimiter between host names and port numbers.
Derived from `tramp-prefix-port-format'.")

(defconst tramp-port-regexp "[0-9]+"
  "*Regexp matching port numbers.")

(defconst tramp-host-with-port-regexp
  (concat "\\(" tramp-host-regexp "\\)"
                tramp-prefix-port-regexp
          "\\(" tramp-port-regexp "\\)")
  "*Regexp matching host names with port numbers.")

(defconst tramp-postfix-host-format
  (cond ((equal tramp-syntax 'ftp) ":")
        ((equal tramp-syntax 'sep) "]")
        ((equal tramp-syntax 'url) "")
        (t (error "Wrong `tramp-syntax' defined")))
  "*String matching delimiter between host names and localnames.
Used in `tramp-make-tramp-file-name'.")

(defconst tramp-postfix-host-regexp
  (regexp-quote tramp-postfix-host-format)
  "*Regexp matching delimiter between host names and localnames.
Derived from `tramp-postfix-host-format'.")

(defconst tramp-localname-regexp ".*$"
  "*Regexp matching localnames.")

;;; File name format:

(defconst tramp-file-name-structure
  (list
   (concat
    tramp-prefix-regexp
    "\\(" "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp "\\)?"
    "\\(" "\\(" tramp-user-regexp "\\)"   tramp-postfix-user-regexp   "\\)?"
    "\\(" "\\(" tramp-host-regexp
                "\\|"
                tramp-prefix-ipv6-regexp  tramp-ipv6-regexp
                                          tramp-postfix-ipv6-regexp "\\)"
          "\\(" tramp-prefix-port-regexp  tramp-port-regexp "\\)?" "\\)?"
    tramp-postfix-host-regexp
    "\\(" tramp-localname-regexp "\\)")
   2 4 5 8)

  "*List of five elements (REGEXP METHOD USER HOST FILE), detailing \
the Tramp file name structure.

The first element REGEXP is a regular expression matching a Tramp file
name.  The regex should contain parentheses around the method name,
the user name, the host name, and the file name parts.

The second element METHOD is a number, saying which pair of
parentheses matches the method name.  The third element USER is
similar, but for the user name.  The fourth element HOST is similar,
but for the host name.  The fifth element FILE is for the file name.
These numbers are passed directly to `match-string', which see.  That
means the opening parentheses are counted to identify the pair.

See also `tramp-file-name-regexp'.")

;;;###autoload
(defconst tramp-file-name-regexp-unified
  (if (memq system-type '(cygwin windows-nt))
      "\\`/\\([^[/:]\\{2,\\}\\|[^/]\\{2,\\}]\\):"
    "\\`/\\([^[/:]+\\|[^/]+]\\):")
  "Value for `tramp-file-name-regexp' for unified remoting.
Emacs (not XEmacs) uses a unified filename syntax for Ange-FTP and
Tramp.  See `tramp-file-name-structure' for more explanations.

On W32 systems, the volume letter must be ignored.")

;;;###autoload
(defconst tramp-file-name-regexp-separate "\\`/\\[.*\\]"
  "Value for `tramp-file-name-regexp' for separate remoting.
XEmacs uses a separate filename syntax for Tramp and EFS.
See `tramp-file-name-structure' for more explanations.")

;;;###autoload
(defconst tramp-file-name-regexp-url "\\`/[^/:]+://"
  "Value for `tramp-file-name-regexp' for URL-like remoting.
See `tramp-file-name-structure' for more explanations.")

;;;###autoload
(defconst tramp-file-name-regexp
  (cond ((equal tramp-syntax 'ftp) tramp-file-name-regexp-unified)
        ((equal tramp-syntax 'sep) tramp-file-name-regexp-separate)
        ((equal tramp-syntax 'url) tramp-file-name-regexp-url)
        (t (error "Wrong `tramp-syntax' defined")))
  "*Regular expression matching file names handled by Tramp.
This regexp should match Tramp file names but no other file names.
When tramp.el is loaded, this regular expression is prepended to
`file-name-handler-alist', and that is searched sequentially.  Thus,
if the Tramp entry appears rather early in the `file-name-handler-alist'
and is a bit too general, then some files might be considered Tramp
files which are not really Tramp files.

Please note that the entry in `file-name-handler-alist' is made when
this file \(tramp.el\) is loaded.  This means that this variable must be set
before loading tramp.el.  Alternatively, `file-name-handler-alist' can be
updated after changing this variable.

Also see `tramp-file-name-structure'.")

;;;###autoload
(defconst tramp-completion-file-name-regexp-unified
  (if (memq system-type '(cygwin windows-nt))
      "\\`/[^/]\\{2,\\}\\'" "\\`/[^/]*\\'")
  "Value for `tramp-completion-file-name-regexp' for unified remoting.
GNU Emacs uses a unified filename syntax for Tramp and Ange-FTP.
See `tramp-file-name-structure' for more explanations.

On W32 systems, the volume letter must be ignored.")

;;;###autoload
(defconst tramp-completion-file-name-regexp-separate
  "\\`/\\([[][^]]*\\)?\\'"
  "Value for `tramp-completion-file-name-regexp' for separate remoting.
XEmacs uses a separate filename syntax for Tramp and EFS.
See `tramp-file-name-structure' for more explanations.")

;;;###autoload
(defconst tramp-completion-file-name-regexp-url
  "\\`/[^/:]+\\(:\\(/\\(/[^/]*\\)?\\)?\\)?\\'"
  "Value for `tramp-completion-file-name-regexp' for URL-like remoting.
See `tramp-file-name-structure' for more explanations.")

;;;###autoload
(defconst tramp-completion-file-name-regexp
  (cond ((equal tramp-syntax 'ftp) tramp-completion-file-name-regexp-unified)
        ((equal tramp-syntax 'sep) tramp-completion-file-name-regexp-separate)
        ((equal tramp-syntax 'url) tramp-completion-file-name-regexp-url)
        (t (error "Wrong `tramp-syntax' defined")))
  "*Regular expression matching file names handled by Tramp completion.
This regexp should match partial Tramp file names only.

Please note that the entry in `file-name-handler-alist' is made when
this file (tramp.el) is loaded.  This means that this variable must be set
before loading tramp.el.  Alternatively, `file-name-handler-alist' can be
updated after changing this variable.

Also see `tramp-file-name-structure'.")

;; Chunked sending kludge.  We set this to 500 for black-listed constellations
;; known to have a bug in `process-send-string'; some ssh connections appear
;; to drop bytes when data is sent too quickly.  There is also a connection
;; buffer local variable, which is computed depending on remote host properties
;; when `tramp-chunksize' is zero or nil.
(defcustom tramp-chunksize
  (when (and (not (featurep 'xemacs))
             (memq system-type '(hpux)))
    500)
;; Parentheses in docstring starting at beginning of line are escaped.
;; Fontification is messed up when
;; `open-paren-in-column-0-is-defun-start' set to t.
  "*If non-nil, chunksize for sending input to local process.
It is necessary only on systems which have a buggy `process-send-string'
implementation.  The necessity, whether this variable must be set, can be
checked via the following code:

  (with-temp-buffer
    (let* ((user \"xxx\") (host \"yyy\")
           (init 0) (step 50)
           (sent init) (received init))
      (while (= sent received)
        (setq sent (+ sent step))
        (erase-buffer)
        (let ((proc (start-process (buffer-name) (current-buffer)
                                   \"ssh\" \"-l\" user host \"wc\" \"-c\")))
          (when (memq (process-status proc) '(run open))
            (process-send-string proc (make-string sent ?\\ ))
            (process-send-eof proc)
            (process-send-eof proc))
          (while (not (progn (goto-char (point-min))
                             (re-search-forward \"\\\\w+\" (point-max) t)))
            (accept-process-output proc 1))
          (when (memq (process-status proc) '(run open))
            (setq received (string-to-number (match-string 0)))
            (delete-process proc)
            (message \"Bytes sent: %s\\tBytes received: %s\" sent received)
            (sit-for 0))))
      (if (> sent (+ init step))
          (message \"You should set `tramp-chunksize' to a maximum of %s\"
                   (- sent step))
        (message \"Test does not work\")
        (display-buffer (current-buffer))
        (sit-for 30))))

In the Emacs normally running Tramp, evaluate the above code
\(replace \"xxx\" and \"yyy\" by the remote user and host name,
respectively\).  You can do this, for example, by pasting it into
the `*scratch*' buffer and then hitting C-j with the cursor after the
last closing parenthesis.  Note that it works only if you have configured
\"ssh\" to run without password query, see ssh-agent\(1\).

You will see the number of bytes sent successfully to the remote host.
If that number exceeds 1000, you can stop the execution by hitting
C-g, because your Emacs is likely clean.

When it is necessary to set `tramp-chunksize', you might consider to
use an out-of-the-band method \(like \"scp\"\) instead of an internal one
\(like \"ssh\"\), because setting `tramp-chunksize' to non-nil decreases
performance.

If your Emacs is buggy, the code stops and gives you an indication
about the value `tramp-chunksize' should be set.  Maybe you could just
experiment a bit, e.g. changing the values of `init' and `step'
in the third line of the code.

Please raise a bug report via \"M-x tramp-bug\" if your system needs
this variable to be set as well."
  :group 'tramp
  :type '(choice (const nil) integer))

;; Logging in to a remote host normally requires obtaining a pty.  But
;; Emacs on MacOS X has process-connection-type set to nil by default,
;; so on those systems Tramp doesn't obtain a pty.  Here, we allow
;; for an override of the system default.
(defcustom tramp-process-connection-type t
  "Overrides `process-connection-type' for connections from Tramp.
Tramp binds process-connection-type to the value given here before
opening a connection to a remote host."
  :group 'tramp
  :type '(choice (const nil) (const t) (const pty)))

(defcustom tramp-completion-reread-directory-timeout 10
  "Defines seconds since last remote command before rereading a directory.
A remote directory might have changed its contents.  In order to
make it visible during file name completion in the minibuffer,
Tramp flushes its cache and rereads the directory contents when
more than `tramp-completion-reread-directory-timeout' seconds
have been gone since last remote command execution.  A value of `t'
would require an immediate reread during filename completion, `nil'
means to use always cached values for the directory contents."
  :group 'tramp
  :type '(choice (const nil) integer))

;;; Internal Variables:

(defvar tramp-current-method nil
  "Connection method for this *tramp* buffer.")

(defvar tramp-current-user nil
  "Remote login name for this *tramp* buffer.")

(defvar tramp-current-host nil
  "Remote host for this *tramp* buffer.")

;;;###autoload
(defconst tramp-completion-file-name-handler-alist
  '((file-name-all-completions . tramp-completion-handle-file-name-all-completions)
    (file-name-completion . tramp-completion-handle-file-name-completion))
  "Alist of completion handler functions.
Used for file names matching `tramp-file-name-regexp'. Operations
not mentioned here will be handled by Tramp's file name handler
functions, or the normal Emacs functions.")

;; Handlers for foreign methods, like FTP or SMB, shall be plugged here.
;;;###tramp-autoload
(defvar tramp-foreign-file-name-handler-alist nil
  "Alist of elements (FUNCTION . HANDLER) for foreign methods handled specially.
If (FUNCTION FILENAME) returns non-nil, then all I/O on that file is done by
calling HANDLER.")

;;; Internal functions which must come first:

;; Conversion functions between external representation and
;; internal data structure.  Convenience functions for internal
;; data structure.

(defun tramp-file-name-p (vec)
  "Check, whether VEC is a Tramp object."
  (and (vectorp vec) (= 4 (length vec))))

(defun tramp-file-name-method (vec)
  "Return method component of VEC."
  (and (tramp-file-name-p vec) (aref vec 0)))

(defun tramp-file-name-user (vec)
  "Return user component of VEC."
  (and (tramp-file-name-p vec) (aref vec 1)))

(defun tramp-file-name-host (vec)
  "Return host component of VEC."
  (and (tramp-file-name-p vec) (aref vec 2)))

(defun tramp-file-name-localname (vec)
  "Return localname component of VEC."
  (and (tramp-file-name-p vec) (aref vec 3)))

;; The user part of a Tramp file name vector can be of kind
;; "user%domain".  Sometimes, we must extract these parts.
(defun tramp-file-name-real-user (vec)
  "Return the user name of VEC without domain."
  (save-match-data
    (let ((user (tramp-file-name-user vec)))
      (if (and (stringp user)
               (string-match tramp-user-with-domain-regexp user))
          (match-string 1 user)
        user))))

(defun tramp-file-name-domain (vec)
  "Return the domain name of VEC."
  (save-match-data
    (let ((user (tramp-file-name-user vec)))
      (and (stringp user)
           (string-match tramp-user-with-domain-regexp user)
           (match-string 2 user)))))

;; The host part of a Tramp file name vector can be of kind
;; "host#port".  Sometimes, we must extract these parts.
(defun tramp-file-name-real-host (vec)
  "Return the host name of VEC without port."
  (save-match-data
    (let ((host (tramp-file-name-host vec)))
      (if (and (stringp host)
               (string-match tramp-host-with-port-regexp host))
          (match-string 1 host)
        host))))

(defun tramp-file-name-port (vec)
  "Return the port number of VEC."
  (save-match-data
    (let ((method (tramp-file-name-method vec))
          (host (tramp-file-name-host vec)))
      (or (and (stringp host)
               (string-match tramp-host-with-port-regexp host)
               (string-to-number (match-string 2 host)))
          (tramp-get-method-parameter method 'tramp-default-port)))))

;;;###tramp-autoload
(defun tramp-tramp-file-p (name)
  "Return t if NAME is a string with Tramp file name syntax."
  (save-match-data
    (and (stringp name) (string-match tramp-file-name-regexp name))))

(defun tramp-find-method (method user host)
  "Return the right method string to use.
This is METHOD, if non-nil. Otherwise, do a lookup in
`tramp-default-method-alist'."
  (or method
      (let ((choices tramp-default-method-alist)
            lmethod item)
        (while choices
          (setq item (pop choices))
          (when (and (string-match (or (nth 0 item) "") (or host ""))
                     (string-match (or (nth 1 item) "") (or user "")))
            (setq lmethod (nth 2 item))
            (setq choices nil)))
        lmethod)
      tramp-default-method))

(defun tramp-find-user (method user host)
  "Return the right user string to use.
This is USER, if non-nil. Otherwise, do a lookup in
`tramp-default-user-alist'."
  (or user
      (let ((choices tramp-default-user-alist)
            luser item)
        (while choices
          (setq item (pop choices))
          (when (and (string-match (or (nth 0 item) "") (or method ""))
                     (string-match (or (nth 1 item) "") (or host "")))
            (setq luser (nth 2 item))
            (setq choices nil)))
        luser)
      tramp-default-user))

(defun tramp-find-host (method user host)
  "Return the right host string to use.
This is HOST, if non-nil. Otherwise, it is `tramp-default-host'."
  (or (and (> (length host) 0) host)
      tramp-default-host))

(defun tramp-dissect-file-name (name &optional nodefault)
  "Return a `tramp-file-name' structure.
The structure consists of remote method, remote user, remote host
and localname (file name on remote host).  If NODEFAULT is
non-nil, the file name parts are not expanded to their default
values."
  (save-match-data
    (let ((match (string-match (nth 0 tramp-file-name-structure) name)))
      (unless match (error "Not a Tramp file name: %s" name))
      (let ((method    (match-string (nth 1 tramp-file-name-structure) name))
            (user      (match-string (nth 2 tramp-file-name-structure) name))
            (host      (match-string (nth 3 tramp-file-name-structure) name))
            (localname (match-string (nth 4 tramp-file-name-structure) name)))
        (when host
          (when (string-match tramp-prefix-ipv6-regexp host)
            (setq host (replace-match "" nil t host)))
          (when (string-match tramp-postfix-ipv6-regexp host)
            (setq host (replace-match "" nil t host))))
        (if nodefault
            (vector method user host localname)
          (vector
           (tramp-find-method method user host)
           (tramp-find-user   method user host)
           (tramp-find-host   method user host)
           localname))))))

(defun tramp-buffer-name (vec)
  "A name for the connection buffer VEC."
  ;; We must use `tramp-file-name-real-host', because for gateway
  ;; methods the default port will be expanded later on, which would
  ;; tamper the name.
  (let ((method (tramp-file-name-method vec))
        (user   (tramp-file-name-user vec))
        (host   (tramp-file-name-real-host vec)))
    (if (not (zerop (length user)))
        (format "*tramp/%s %s@%s*" method user host)
      (format "*tramp/%s %s*" method host))))

(defun tramp-make-tramp-file-name (method user host localname)
  "Constructs a Tramp file name from METHOD, USER, HOST and LOCALNAME."
  (concat tramp-prefix-format
          (when (not (zerop (length method)))
            (concat method tramp-postfix-method-format))
          (when (not (zerop (length user)))
            (concat user tramp-postfix-user-format))
          (when host
            (if (string-match tramp-ipv6-regexp host)
                (concat tramp-prefix-ipv6-format host tramp-postfix-ipv6-format)
              host))
          tramp-postfix-host-format
          (when localname localname)))

(defun tramp-completion-make-tramp-file-name (method user host localname)
  "Constructs a Tramp file name from METHOD, USER, HOST and LOCALNAME.
It must not be a complete Tramp file name, but as long as there are
necessary only.  This function will be used in file name completion."
  (concat tramp-prefix-format
          (when (not (zerop (length method)))
            (concat method tramp-postfix-method-format))
          (when (not (zerop (length user)))
            (concat user tramp-postfix-user-format))
          (when (not (zerop (length host)))
            (concat
             (if (string-match tramp-ipv6-regexp host)
                 (concat
                  tramp-prefix-ipv6-format host tramp-postfix-ipv6-format)
               host)
             tramp-postfix-host-format))
          (when localname localname)))

(defun tramp-get-buffer (vec)
  "Get the connection buffer to be used for VEC."
  (or (get-buffer (tramp-buffer-name vec))
      (with-current-buffer (get-buffer-create (tramp-buffer-name vec))
        (setq buffer-undo-list t)
        (setq default-directory
              (tramp-make-tramp-file-name
               (tramp-file-name-method vec)
               (tramp-file-name-user vec)
               (tramp-file-name-host vec)
               "/"))
        (current-buffer))))

(defun tramp-get-connection-buffer (vec)
  "Get the connection buffer to be used for VEC.
In case a second asynchronous communication has been started, it is different
from `tramp-get-buffer'."
  (or (tramp-get-connection-property vec "process-buffer" nil)
      (tramp-get-buffer vec)))

(defun tramp-get-connection-name (vec)
  "Get the connection name to be used for VEC.
In case a second asynchronous communication has been started, it is different
from the default one."
  (or (tramp-get-connection-property vec "process-name" nil)
      (tramp-buffer-name vec)))

(defun tramp-get-connection-process (vec)
  "Get the connection process to be used for VEC.
In case a second asynchronous communication has been started, it is different
from the default one."
  (get-process (tramp-get-connection-name vec)))

(defun tramp-debug-buffer-name (vec)
  "A name for the debug buffer for VEC."
  ;; We must use `tramp-file-name-real-host', because for gateway
  ;; methods the default port will be expanded later on, which would
  ;; tamper the name.
  (let ((method (tramp-file-name-method vec))
        (user   (tramp-file-name-user vec))
        (host   (tramp-file-name-real-host vec)))
    (if (not (zerop (length user)))
        (format "*debug tramp/%s %s@%s*" method user host)
      (format "*debug tramp/%s %s*" method host))))

(defconst tramp-debug-outline-regexp
  "[0-9]+:[0-9]+:[0-9]+\\.[0-9]+ [a-z0-9-]+ (\\([0-9]+\\)) #"
  "Used for highlighting Tramp debug buffers in `outline-mode'.")

(defun tramp-debug-outline-level ()
  "Return the depth to which a statement is nested in the outline.
Point must be at the beginning of a header line.

The outline level is equal to the verbosity of the Tramp message."
  (1+ (string-to-number (match-string 1))))

(defun tramp-get-debug-buffer (vec)
  "Get the debug buffer for VEC."
  (with-current-buffer
      (get-buffer-create (tramp-debug-buffer-name vec))
    (when (bobp)
      (setq buffer-undo-list t)
      ;; Activate `outline-mode'.  This runs `text-mode-hook' and
      ;; `outline-mode-hook'.  We must prevent that local processes
      ;; die.  Yes: I've seen `flyspell-mode', which starts "ispell".
      ;; Furthermore, `outline-regexp' must have the correct value
      ;; already, because it is used by `font-lock-compile-keywords'.
      (let ((default-directory (tramp-compat-temporary-file-directory))
            (outline-regexp tramp-debug-outline-regexp))
        (outline-mode))
      (set (make-local-variable 'outline-regexp) tramp-debug-outline-regexp)
      (set (make-local-variable 'outline-level) 'tramp-debug-outline-level))
    (current-buffer)))

(defsubst tramp-debug-message (vec fmt-string &rest args)
  "Append message to debug buffer.
Message is formatted with FMT-STRING as control string and the remaining
ARGS to actually emit the message (if applicable)."
  (when (get-buffer (tramp-buffer-name vec))
    (with-current-buffer (tramp-get-debug-buffer vec)
      (goto-char (point-max))
      ;; Headline.
      (when (bobp)
        (insert
         (format
          ";; %sEmacs: %s Tramp: %s -*- mode: outline; -*-"
          (if (featurep 'sxemacs) "SX" (if (featurep 'xemacs) "X" "GNU "))
          emacs-version tramp-version)))
      (unless (bolp)
        (insert "\n"))
      ;; Timestamp.
      (let ((now (current-time)))
        (insert (format-time-string "%T." now))
        (insert (format "%06d " (nth 2 now))))
      ;; Calling Tramp function.  We suppress compat and trace
      ;; functions from being displayed.
      (let ((btn 1) btf fn)
        (while (not fn)
          (setq btf (nth 1 (backtrace-frame btn)))
          (if (not btf)
              (setq fn "")
            (when (symbolp btf)
              (setq fn (symbol-name btf))
              (unless
                  (and
                   (string-match "^tramp" fn)
                   (not
                    (string-match
                     (concat
                      "^"
                      (regexp-opt
                       '("tramp-compat-funcall"
                         "tramp-compat-with-temp-message"
                         "tramp-debug-message"
                         "tramp-error"
                         "tramp-error-with-buffer"
                         "tramp-message"
                         "tramp-with-progress-reporter")
                       t)
                      "$")
                     fn)))
                (setq fn nil)))
            (setq btn (1+ btn))))
        ;; The following code inserts filename and line number.
        ;; Should be deactivated by default, because it is time
        ;; consuming.
;       (let ((ffn (find-function-noselect (intern fn))))
;         (insert
;          (format
;           "%s:%d: "
;           (file-name-nondirectory (buffer-file-name (car ffn)))
;           (with-current-buffer (car ffn)
;             (1+ (count-lines (point-min) (cdr ffn)))))))
        (insert (format "%s " fn)))
      ;; The message.
      (insert (apply 'format fmt-string args)))))

(defvar tramp-message-show-message t
  "Show Tramp message in the minibuffer.
This variable is used to disable messages from `tramp-error'.
The messages are visible anyway, because an error is raised.")

(defsubst tramp-message (vec-or-proc level fmt-string &rest args)
  "Emit a message depending on verbosity level.
VEC-OR-PROC identifies the Tramp buffer to use.  It can be either a
vector or a process.  LEVEL says to be quiet if `tramp-verbose' is
less than LEVEL.  The message is emitted only if `tramp-verbose' is
greater than or equal to LEVEL.

The message is also logged into the debug buffer when `tramp-verbose'
is greater than or equal 4.

Calls functions `message' and `tramp-debug-message' with FMT-STRING as
control string and the remaining ARGS to actually emit the message (if
applicable)."
  (ignore-errors
    (when (<= level tramp-verbose)
      ;; Match data must be preserved!
      (save-match-data
        ;; Display only when there is a minimum level.
        (when (and tramp-message-show-message (<= level 3))
          (apply 'message
                 (concat
                  (cond
                   ((= level 0) "")
                   ((= level 1) "")
                   ((= level 2) "Warning: ")
                   (t           "Tramp: "))
                  fmt-string)
                 args))
        ;; Log only when there is a minimum level.
        (when (>= tramp-verbose 4)
          (when (and vec-or-proc
                     (processp vec-or-proc)
                     (buffer-name (process-buffer vec-or-proc)))
            (with-current-buffer (process-buffer vec-or-proc)
              ;; Translate proc to vec.
              (setq vec-or-proc (tramp-dissect-file-name default-directory))))
          (when (and vec-or-proc (vectorp vec-or-proc))
            (apply 'tramp-debug-message
                   vec-or-proc
                   (concat (format "(%d) # " level) fmt-string)
                   args)))))))

(defsubst tramp-error (vec-or-proc signal fmt-string &rest args)
  "Emit an error.
VEC-OR-PROC identifies the connection to use, SIGNAL is the
signal identifier to be raised, remaining args passed to
`tramp-message'.  Finally, signal SIGNAL is raised."
  (let (tramp-message-show-message)
    (tramp-message
     vec-or-proc 1 "%s"
     (error-message-string
      (list signal
            (get signal 'error-message)
            (apply 'format fmt-string args))))
    (signal signal (list (apply 'format fmt-string args)))))

(defsubst tramp-error-with-buffer
  (buffer vec-or-proc signal fmt-string &rest args)
  "Emit an error, and show BUFFER.
If BUFFER is nil, show the connection buffer.  Wait for 30\", or until
an input event arrives.  The other arguments are passed to `tramp-error'."
  (save-window-excursion
    (unwind-protect
        (apply 'tramp-error vec-or-proc signal fmt-string args)
      (when (and vec-or-proc
                 (not (zerop tramp-verbose))
                 (not (tramp-completion-mode-p)))
        (let ((enable-recursive-minibuffers t))
          (pop-to-buffer
           (or (and (bufferp buffer) buffer)
               (and (processp vec-or-proc) (process-buffer vec-or-proc))
               (tramp-get-buffer vec-or-proc)))
          (sit-for 30))))))

(defmacro with-parsed-tramp-file-name (filename var &rest body)
  "Parse a Tramp filename and make components available in the body.

First arg FILENAME is evaluated and dissected into its components.
Second arg VAR is a symbol.  It is used as a variable name to hold
the filename structure.  It is also used as a prefix for the variables
holding the components.  For example, if VAR is the symbol `foo', then
`foo' will be bound to the whole structure, `foo-method' will be bound to
the method component, and so on for `foo-user', `foo-host', `foo-localname'.

Remaining args are Lisp expressions to be evaluated (inside an implicit
`progn').

If VAR is nil, then we bind `v' to the structure and `method', `user',
`host', `localname' to the components."
  `(let* ((,(or var 'v) (tramp-dissect-file-name ,filename))
          (,(if var (intern (concat (symbol-name var) "-method")) 'method)
           (tramp-file-name-method ,(or var 'v)))
          (,(if var (intern (concat (symbol-name var) "-user")) 'user)
           (tramp-file-name-user ,(or var 'v)))
          (,(if var (intern (concat (symbol-name var) "-host")) 'host)
           (tramp-file-name-host ,(or var 'v)))
          (,(if var (intern (concat (symbol-name var) "-localname")) 'localname)
           (tramp-file-name-localname ,(or var 'v))))
     ,@body))

(put 'with-parsed-tramp-file-name 'lisp-indent-function 2)
(put 'with-parsed-tramp-file-name 'edebug-form-spec '(form symbolp body))
(tramp-compat-font-lock-add-keywords
 'emacs-lisp-mode '("\\<with-parsed-tramp-file-name\\>"))

(defun tramp-progress-reporter-update (reporter &optional value)
  (let* ((parameters (cdr reporter))
         (message (aref parameters 3)))
    (when (string-match message (or (current-message) ""))
      (tramp-compat-funcall 'progress-reporter-update reporter value))))

(defmacro tramp-with-progress-reporter (vec level message &rest body)
  "Executes BODY, spinning a progress reporter with MESSAGE.
If LEVEL does not fit for visible messages, or if this is a
nested call of the macro, there are only traces without a visible
progress reporter."
  (declare (indent 3) (debug t))
  `(let (pr tm)
     (tramp-message ,vec ,level "%s..." ,message)
     ;; We start a pulsing progress reporter after 3 seconds.  Feature
     ;; introduced in Emacs 24.1.
     (when (and tramp-message-show-message
                ;; Display only when there is a minimum level.
                (<= ,level (min tramp-verbose 3)))
       (ignore-errors
         (setq pr (tramp-compat-funcall 'make-progress-reporter ,message)
               tm (when pr
                    (run-at-time 3 0.1 'tramp-progress-reporter-update pr)))))
     (unwind-protect
         ;; Execute the body.  Unset `tramp-message-show-message' when
         ;; the timer object is created, in order to suppress
         ;; concurrent timers.
         (let ((tramp-message-show-message
                (and tramp-message-show-message (not tm))))
           ,@body)
       ;; Stop progress reporter.
       (if tm (tramp-compat-funcall 'cancel-timer tm))
       (tramp-message ,vec ,level "%s...done" ,message))))

(tramp-compat-font-lock-add-keywords
 'emacs-lisp-mode '("\\<tramp-with-progress-reporter\\>"))

(defalias 'tramp-drop-volume-letter
  (if (memq system-type '(cygwin windows-nt))
      (lambda (name)
        "Cut off unnecessary drive letter from file NAME.
The functions `tramp-*-handle-expand-file-name' call `expand-file-name'
locally on a remote file name.  When the local system is a W32 system
but the remote system is Unix, this introduces a superfluous drive
letter into the file name.  This function removes it."
        (save-match-data
          (if (string-match "\\`[a-zA-Z]:/" name)
              (replace-match "/" nil t name)
            name)))

    'identity))

;;; Config Manipulation Functions:

;;;###tramp-autoload
(defun tramp-set-completion-function (method function-list)
  "Sets the list of completion functions for METHOD.
FUNCTION-LIST is a list of entries of the form (FUNCTION FILE).
The FUNCTION is intended to parse FILE according its syntax.
It might be a predefined FUNCTION, or a user defined FUNCTION.
Predefined FUNCTIONs are `tramp-parse-rhosts', `tramp-parse-shosts',
`tramp-parse-sconfig', `tramp-parse-hosts', `tramp-parse-passwd',
and `tramp-parse-netrc'.

Example:

    (tramp-set-completion-function
     \"ssh\"
     '((tramp-parse-sconfig \"/etc/ssh_config\")
       (tramp-parse-sconfig \"~/.ssh/config\")))"

  (let ((r function-list)
        (v function-list))
    (setq tramp-completion-function-alist
          (delete (assoc method tramp-completion-function-alist)
                  tramp-completion-function-alist))

    (while v
      ;; Remove double entries.
      (when (member (car v) (cdr v))
        (setcdr v (delete (car v) (cdr v))))
      ;; Check for function and file or registry key.
      (unless (and (functionp (nth 0 (car v)))
                   (if (string-match "^HKEY_CURRENT_USER" (nth 1 (car v)))
                       ;; Windows registry.
                       (and (memq system-type '(cygwin windows-nt))
                            (zerop
                             (tramp-compat-call-process
                              "reg" nil nil nil "query" (nth 1 (car v)))))
                     ;; Configuration file.
                     (file-exists-p (nth 1 (car v)))))
        (setq r (delete (car v) r)))
      (setq v (cdr v)))

    (when r
      (add-to-list 'tramp-completion-function-alist
                   (cons method r)))))

(defun tramp-get-completion-function (method)
  "Returns a list of completion functions for METHOD.
For definition of that list see `tramp-set-completion-function'."
  (cons
   ;; Hosts visited once shall be remembered.
   `(tramp-parse-connection-properties ,method)
   ;; The method related defaults.
   (cdr (assoc method tramp-completion-function-alist))))


;;; Fontification of `read-file-name':

;; rfn-eshadow.el is part of Emacs 22.  It is autoloaded.
(defvar tramp-rfn-eshadow-overlay)
(make-variable-buffer-local 'tramp-rfn-eshadow-overlay)

(defun tramp-rfn-eshadow-setup-minibuffer ()
  "Set up a minibuffer for `file-name-shadow-mode'.
Adds another overlay hiding filename parts according to Tramp's
special handling of `substitute-in-file-name'."
  (when (symbol-value 'minibuffer-completing-file-name)
    (setq tramp-rfn-eshadow-overlay
          (tramp-compat-funcall
           'make-overlay
           (tramp-compat-funcall 'minibuffer-prompt-end)
           (tramp-compat-funcall 'minibuffer-prompt-end)))
    ;; Copy rfn-eshadow-overlay properties.
    (let ((props (tramp-compat-funcall
                  'overlay-properties (symbol-value 'rfn-eshadow-overlay))))
      (while props
        ;; The `field' property prevents correct minibuffer
        ;; completion; we exclude it.
        (if (not (eq (car props) 'field))
            (tramp-compat-funcall
             'overlay-put tramp-rfn-eshadow-overlay (pop props) (pop props))
          (pop props) (pop props))))))

(when (boundp 'rfn-eshadow-setup-minibuffer-hook)
  (add-hook 'rfn-eshadow-setup-minibuffer-hook
            'tramp-rfn-eshadow-setup-minibuffer)
  (add-hook 'tramp-unload-hook
            (lambda ()
              (remove-hook 'rfn-eshadow-setup-minibuffer-hook
                           'tramp-rfn-eshadow-setup-minibuffer))))

(defconst tramp-rfn-eshadow-update-overlay-regexp
  (format "[^%s/~]*\\(/\\|~\\)" tramp-postfix-host-format))

(defun tramp-rfn-eshadow-update-overlay ()
  "Update `rfn-eshadow-overlay' to cover shadowed part of minibuffer input.
This is intended to be used as a minibuffer `post-command-hook' for
`file-name-shadow-mode'; the minibuffer should have already
been set up by `rfn-eshadow-setup-minibuffer'."
  ;; In remote files name, there is a shadowing just for the local part.
  (ignore-errors
    (let ((end (or (tramp-compat-funcall
                    'overlay-end (symbol-value 'rfn-eshadow-overlay))
                   (tramp-compat-funcall 'minibuffer-prompt-end))))
      (when
          (file-remote-p
           (tramp-compat-funcall
            'buffer-substring-no-properties end (point-max)))
        (save-excursion
          (save-restriction
            (narrow-to-region
             (1+ (or (string-match
                      tramp-rfn-eshadow-update-overlay-regexp
                      (buffer-string) end)
                     end))
             (point-max))
            (let ((rfn-eshadow-overlay tramp-rfn-eshadow-overlay)
                  (rfn-eshadow-update-overlay-hook nil)
                  file-name-handler-alist)
              (tramp-compat-funcall
               'move-overlay rfn-eshadow-overlay (point-max) (point-max))
              (tramp-compat-funcall 'rfn-eshadow-update-overlay))))))))

(when (boundp 'rfn-eshadow-update-overlay-hook)
  (add-hook 'rfn-eshadow-update-overlay-hook
            'tramp-rfn-eshadow-update-overlay)
  (add-hook 'tramp-unload-hook
            (lambda ()
              (remove-hook 'rfn-eshadow-update-overlay-hook
                           'tramp-rfn-eshadow-update-overlay))))

;; Inodes don't exist for some file systems.  Therefore we must
;; generate virtual ones.  Used in `find-buffer-visiting'.  The method
;; applied might be not so efficient (Ange-FTP uses hashes). But
;; performance isn't the major issue given that file transfer will
;; take time.
(defvar tramp-inodes nil
  "Keeps virtual inodes numbers.")

;; Devices must distinguish physical file systems.  The device numbers
;; provided by "lstat" aren't unique, because we operate on different hosts.
;; So we use virtual device numbers, generated by Tramp.  Both Ange-FTP and
;; EFS use device number "-1".  In order to be different, we use device number
;; (-1 . x), whereby "x" is unique for a given (method user host).
(defvar tramp-devices nil
  "Keeps virtual device numbers.")

(defun tramp-default-file-modes (filename)
  "Return file modes of FILENAME as integer.
If the file modes of FILENAME cannot be determined, return the
value of `default-file-modes', without execute permissions."
  (or (file-modes filename)
      (logand (default-file-modes) (tramp-compat-octal-to-decimal "0666"))))

(defun tramp-replace-environment-variables (filename)
  "Replace environment variables in FILENAME.
Return the string with the replaced variables."
  (save-match-data
    (let ((idx (string-match "$\\(\\w+\\)" filename)))
      ;; `$' is coded as `$$'.
      (when (and idx
                 (or (zerop idx) (not (eq ?$ (aref filename (1- idx)))))
                 (getenv (match-string 1 filename)))
        (setq filename
              (replace-match
               (substitute-in-file-name (match-string 0 filename))
               t nil filename)))
      filename)))

;; In XEmacs, electricity is implemented via a key map for ?/ and ?~,
;; which calls corresponding functions (see minibuf.el).
(when (fboundp 'minibuffer-electric-separator)
  (mapc
   (lambda (x)
     (eval
      `(defadvice ,x
         (around ,(intern (format "tramp-advice-%s" x)) activate)
         "Invoke `substitute-in-file-name' for Tramp files."
         (if (and (symbol-value 'minibuffer-electric-file-name-behavior)
                  (tramp-tramp-file-p (buffer-substring)))
             ;; We don't need to handle `last-input-event', because
             ;; due to the key map we know it must be ?/ or ?~.
             (let ((s (concat (buffer-substring (point-min) (point))
                              (string last-command-char))))
               (delete-region (point-min) (point))
               (insert (substitute-in-file-name s))
               (setq ad-return-value last-command-char))
           ad-do-it)))
     (eval
      `(add-hook
        'tramp-unload-hook
        (lambda ()
          (ad-remove-advice ',x 'around ',(intern (format "tramp-advice-%s" x)))
          (ad-activate ',x)))))

   '(minibuffer-electric-separator
     minibuffer-electric-tilde)))

(defun tramp-find-file-name-coding-system-alist (filename tmpname)
  "Like `find-operation-coding-system' for Tramp filenames.
Tramp's `insert-file-contents' and `write-region' work over
temporary file names.  If `file-coding-system-alist' contains an
expression, which matches more than the file name suffix, the
coding system might not be determined.  This function repairs it."
  (let (result)
    (dolist (elt file-coding-system-alist result)
      (when (and (consp elt) (string-match (car elt) filename))
        ;; We found a matching entry in `file-coding-system-alist'.
        ;; So we add a similar entry, but with the temporary file name
        ;; as regexp.
        (add-to-list
         'result (cons (regexp-quote tmpname) (cdr elt)) 'append)))))

;;;###autoload
(progn (defun tramp-run-real-handler (operation args)
  "Invoke normal file name handler for OPERATION.
First arg specifies the OPERATION, second arg is a list of arguments to
pass to the OPERATION."
  (let* ((inhibit-file-name-handlers
          `(tramp-file-name-handler
            tramp-vc-file-name-handler
            tramp-completion-file-name-handler
            cygwin-mount-name-hook-function
            cygwin-mount-map-drive-hook-function
            .
            ,(and (eq inhibit-file-name-operation operation)
                  inhibit-file-name-handlers)))
         (inhibit-file-name-operation operation))
    (apply operation args))))

;;;###autoload
(progn (defun tramp-completion-run-real-handler (operation args)
  "Invoke `tramp-file-name-handler' for OPERATION.
First arg specifies the OPERATION, second arg is a list of arguments to
pass to the OPERATION."
  (let* ((inhibit-file-name-handlers
          `(tramp-completion-file-name-handler
            cygwin-mount-name-hook-function
            cygwin-mount-map-drive-hook-function
            .
            ,(and (eq inhibit-file-name-operation operation)
                  inhibit-file-name-handlers)))
         (inhibit-file-name-operation operation))
    (apply operation args))))

;; We handle here all file primitives.  Most of them have the file
;; name as first parameter; nevertheless we check for them explicitly
;; in order to be signaled if a new primitive appears.  This
;; scenario is needed because there isn't a way to decide by
;; syntactical means whether a foreign method must be called.  It would
;; ease the life if `file-name-handler-alist' would support a decision
;; function as well but regexp only.
(defun tramp-file-name-for-operation (operation &rest args)
  "Return file name related to OPERATION file primitive.
ARGS are the arguments OPERATION has been called with."
  (cond
   ;; FILE resp DIRECTORY.
   ((member operation
            (list 'access-file 'byte-compiler-base-file-name 'delete-directory
                  'delete-file 'diff-latest-backup-file 'directory-file-name
                  'directory-files 'directory-files-and-attributes
                  'dired-compress-file 'dired-uncache
                  'file-accessible-directory-p 'file-attributes
                  'file-directory-p 'file-executable-p 'file-exists-p
                  'file-local-copy 'file-remote-p 'file-modes
                  'file-name-as-directory 'file-name-directory
                  'file-name-nondirectory 'file-name-sans-versions
                  'file-ownership-preserved-p 'file-readable-p
                  'file-regular-p 'file-symlink-p 'file-truename
                  'file-writable-p 'find-backup-file-name 'find-file-noselect
                  'get-file-buffer 'insert-directory 'insert-file-contents
                  'load 'make-directory 'make-directory-internal
                  'set-file-modes 'substitute-in-file-name
                  'unhandled-file-name-directory 'vc-registered
                  ;; Emacs 22+ only.
                  'set-file-times
                  ;; Emacs 24+ only.
                  'file-selinux-context 'set-file-selinux-context
                  ;; XEmacs only.
                  'abbreviate-file-name 'create-file-buffer
                  'dired-file-modtime 'dired-make-compressed-filename
                  'dired-recursive-delete-directory 'dired-set-file-modtime
                  'dired-shell-unhandle-file-name 'dired-uucode-file
                  'insert-file-contents-literally 'make-temp-name 'recover-file
                  'vm-imap-check-mail 'vm-pop-check-mail 'vm-spool-check-mail))
    (if (file-name-absolute-p (nth 0 args))
        (nth 0 args)
      (expand-file-name (nth 0 args))))
   ;; FILE DIRECTORY resp FILE1 FILE2.
   ((member operation
            (list 'add-name-to-file 'copy-file 'expand-file-name
                  'file-name-all-completions 'file-name-completion
                  'file-newer-than-file-p 'make-symbolic-link 'rename-file
                  ;; Emacs 23+ only.
                  'copy-directory
                  ;; XEmacs only.
                  'dired-make-relative-symlink
                  'vm-imap-move-mail 'vm-pop-move-mail 'vm-spool-move-mail))
    (save-match-data
      (cond
       ((string-match tramp-file-name-regexp (nth 0 args)) (nth 0 args))
       ((string-match tramp-file-name-regexp (nth 1 args)) (nth 1 args))
       (t (buffer-file-name (current-buffer))))))
   ;; START END FILE.
   ((eq operation 'write-region)
    (nth 2 args))
   ;; BUFFER.
   ((member operation
            (list 'set-visited-file-modtime 'verify-visited-file-modtime
                  ;; Emacs 22+ only.
                  'make-auto-save-file-name
                  ;; XEmacs only.
                  'backup-buffer))
    (buffer-file-name
     (if (bufferp (nth 0 args)) (nth 0 args) (current-buffer))))
   ;; COMMAND.
   ((member operation
            (list ;; not in Emacs 23+.
                  'dired-call-process
                  ;; Emacs only.
                  'shell-command
                  ;; Emacs 22+ only.
                  'process-file
                  ;; Emacs 23+ only.
                  'start-file-process
                  ;; XEmacs only.
                  'dired-print-file 'dired-shell-call-process
                  ;; nowhere yet.
                  'executable-find 'start-process
                  'call-process 'call-process-region))
    default-directory)
   ;; Unknown file primitive.
   (t (error "unknown file I/O primitive: %s" operation))))

(defun tramp-find-foreign-file-name-handler (filename)
  "Return foreign file name handler if exists."
  (when (tramp-tramp-file-p filename)
    (let ((v (tramp-dissect-file-name filename t))
          (handler tramp-foreign-file-name-handler-alist)
          elt res)
      ;; When we are not fully sure that filename completion is safe,
      ;; we should not return a handler.
      (when (or (tramp-file-name-method v) (tramp-file-name-user v)
                (and (tramp-file-name-host v)
                     (not (member (tramp-file-name-host v)
                                  (mapcar 'car tramp-methods))))
                (not (tramp-completion-mode-p)))
        (while handler
          (setq elt (car handler)
                handler (cdr handler))
          (when (funcall (car elt) filename)
            (setq handler nil
                  res (cdr elt))))
        res))))

;; Main function.
;;;###autoload
(defun tramp-file-name-handler (operation &rest args)
  "Invoke Tramp file name handler.
Falls back to normal file name handler if no Tramp file name handler exists."
  (if tramp-mode
      (save-match-data
        (let* ((filename
                (tramp-replace-environment-variables
                 (apply 'tramp-file-name-for-operation operation args)))
               (completion (tramp-completion-mode-p))
               (foreign (tramp-find-foreign-file-name-handler filename)))
          (with-parsed-tramp-file-name filename nil
            ;; Call the backend function.
            (if foreign
                (condition-case err
                    (let ((sf (symbol-function foreign)))
                      ;; Some packages set the default directory to a
                      ;; remote path, before respective Tramp packages
                      ;; are already loaded.  This results in
                      ;; recursive loading.  Therefore, we load the
                      ;; Tramp packages locally.
                      (when (and (listp sf) (eq (car sf) 'autoload))
                        (let ((default-directory
                                (tramp-compat-temporary-file-directory)))
                          (load (cadr sf) 'noerror 'nomessage)))
                      (apply foreign operation args))

                  ;; Trace that somebody has interrupted the operation.
                  ((debug quit)
                   (let (tramp-message-show-message)
                     (tramp-message
                      v 1 "Interrupt received in operation %s"
                      (append (list operation) args)))
                   ;; Propagate the quit signal.
                   (signal (car err) (cdr err)))

                  ;; When we are in completion mode, some failed
                  ;; operations shall return at least a default value
                  ;; in order to give the user a chance to correct the
                  ;; file name in the minibuffer.
                  ;; We cannot use 'debug as error handler.  In order
                  ;; to get a full backtrace, one could apply
                  ;;   (setq debug-on-error t debug-on-signal t)
                  (error
                   (cond
                    ((and completion (zerop (length localname))
                          (memq operation '(file-exists-p file-directory-p)))
                     t)
                    ((and completion (zerop (length localname))
                          (memq operation
                                '(expand-file-name file-name-as-directory)))
                     filename)
                    ;; Propagate the error.
                    (t (signal (car err) (cdr err))))))

              ;; Nothing to do for us.
              (tramp-run-real-handler operation args)))))

    ;; When `tramp-mode' is not enabled, we don't do anything.
    (tramp-run-real-handler operation args)))

;; In Emacs, there is some concurrency due to timers.  If a timer
;; interrupts Tramp and wishes to use the same connection buffer as
;; the "main" Emacs, then garbage might occur in the connection
;; buffer.  Therefore, we need to make sure that a timer does not use
;; the same connection buffer as the "main" Emacs.  We implement a
;; cheap global lock, instead of locking each connection buffer
;; separately.  The global lock is based on two variables,
;; `tramp-locked' and `tramp-locker'.  `tramp-locked' is set to true
;; (with setq) to indicate a lock.  But Tramp also calls itself during
;; processing of a single file operation, so we need to allow
;; recursive calls.  That's where the `tramp-locker' variable comes in
;; -- it is let-bound to t during the execution of the current
;; handler.  So if `tramp-locked' is t and `tramp-locker' is also t,
;; then we should just proceed because we have been called
;; recursively.  But if `tramp-locker' is nil, then we are a timer
;; interrupting the "main" Emacs, and then we signal an error.

(defvar tramp-locked nil
  "If non-nil, then Tramp is currently busy.
Together with `tramp-locker', this implements a locking mechanism
preventing reentrant calls of Tramp.")

(defvar tramp-locker nil
  "If non-nil, then a caller has locked Tramp.
Together with `tramp-locked', this implements a locking mechanism
preventing reentrant calls of Tramp.")

;;;###autoload
(progn (defun tramp-completion-file-name-handler (operation &rest args)
  "Invoke Tramp file name completion handler.
Falls back to normal file name handler if no Tramp file name handler exists."
  ;; We bind `directory-sep-char' here for XEmacs on Windows, which
  ;; would otherwise use backslash.
  (let ((directory-sep-char ?/)
        (fn (assoc operation tramp-completion-file-name-handler-alist)))
    (if (and
         ;; When `tramp-mode' is not enabled, we don't do anything.
         fn tramp-mode
         ;; For other syntaxes than `sep', the regexp matches many common
         ;; situations where the user doesn't actually want to use Tramp.
         ;; So to avoid autoloading Tramp after typing just "/s", we
         ;; disable this part of the completion, unless the user implicitly
         ;; indicated his interest in using a fancier completion system.
         (or (eq tramp-syntax 'sep)
             (featurep 'tramp) ;; If it's loaded, we may as well use it.
             ;; `partial-completion-mode' does not exist in XEmacs.
             ;; It is obsoleted with Emacs 24.1.
             (and (boundp 'partial-completion-mode)
                  (symbol-value 'partial-completion-mode))
             ;; FIXME: These may have been loaded even if the user never
             ;; intended to use them.
             (featurep 'ido)
             (featurep 'icicles)))
        (save-match-data (apply (cdr fn) args))
      (tramp-completion-run-real-handler operation args)))))

;;;###autoload
(progn (defun tramp-register-file-name-handlers ()
  "Add Tramp file name handlers to `file-name-handler-alist'."
  ;; Remove autoloaded handlers from file name handler alist.  Useful,
  ;; if `tramp-syntax' has been changed.
  (let ((a1 (rassq 'tramp-file-name-handler file-name-handler-alist)))
    (setq file-name-handler-alist (delq a1 file-name-handler-alist)))
  (let ((a1 (rassq
             'tramp-completion-file-name-handler file-name-handler-alist)))
    (setq file-name-handler-alist (delq a1 file-name-handler-alist)))
  ;; Add the handlers.
  (add-to-list 'file-name-handler-alist
               (cons tramp-file-name-regexp 'tramp-file-name-handler))
  (put 'tramp-file-name-handler 'safe-magic t)
  (add-to-list 'file-name-handler-alist
               (cons tramp-completion-file-name-regexp
                     'tramp-completion-file-name-handler))
  (put 'tramp-completion-file-name-handler 'safe-magic t)
  ;; If jka-compr or epa-file are already loaded, move them to the
  ;; front of `file-name-handler-alist'.
  (dolist (fnh '(epa-file-handler jka-compr-handler))
    (let ((entry (rassoc fnh file-name-handler-alist)))
      (when entry
        (setq file-name-handler-alist
              (cons entry (delete entry file-name-handler-alist))))))))

;; `tramp-file-name-handler' must be registered before evaluation of
;; site-start and init files, because there might exist remote files
;; already, f.e. files kept via recentf-mode.
;;;###autoload
(tramp-register-file-name-handlers)

(defun tramp-exists-file-name-handler (operation &rest args)
  "Check, whether OPERATION runs a file name handler."
  ;; The file name handler is determined on base of either an
  ;; argument, `buffer-file-name', or `default-directory'.
  (ignore-errors
    (let* ((buffer-file-name "/")
           (default-directory "/")
           (fnha file-name-handler-alist)
           (check-file-name-operation operation)
           (file-name-handler-alist
            (list
             (cons "/"
                   (lambda (operation &rest args)
                     "Returns OPERATION if it is the one to be checked."
                     (if (equal check-file-name-operation operation)
                         operation
                       (let ((file-name-handler-alist fnha))
                         (apply operation args))))))))
      (equal (apply operation args) operation))))

;;;###autoload
(defun tramp-unload-file-name-handlers ()
  (setq file-name-handler-alist
        (delete (rassoc 'tramp-file-name-handler
                        file-name-handler-alist)
                (delete (rassoc 'tramp-completion-file-name-handler
                                file-name-handler-alist)
                        file-name-handler-alist))))

(add-hook 'tramp-unload-hook 'tramp-unload-file-name-handlers)

;;; File name handler functions for completion mode:

(defvar tramp-completion-mode nil
  "If non-nil, external packages signal that they are in file name completion.

This is necessary, because Tramp uses a heuristic depending on last
input event.  This fails when external packages use other characters
but <TAB>, <SPACE> or ?\\? for file name completion.  This variable
should never be set globally, the intention is to let-bind it.")

;; Necessary because `tramp-file-name-regexp-unified' and
;; `tramp-completion-file-name-regexp-unified' aren't different.  If
;; nil, `tramp-completion-run-real-handler' is called (i.e. forwarding
;; to `tramp-file-name-handler'). Otherwise, it takes
;; `tramp-run-real-handler'.  Using `last-input-event' is a little bit
;; risky, because completing a file might require loading other files,
;; like "~/.netrc", and for them it shouldn't be decided based on that
;; variable. On the other hand, those files shouldn't have partial
;; Tramp file name syntax. Maybe another variable should be introduced
;; overwriting this check in such cases. Or we change Tramp file name
;; syntax in order to avoid ambiguities, like in XEmacs ...
;;;###tramp-autoload
(defun tramp-completion-mode-p ()
  "Check, whether method / user name / host name completion is active."
  (or
   ;; Signal from outside.  `non-essential' has been introduced in Emacs 24.
   (and (boundp 'non-essential) (symbol-value 'non-essential))
   tramp-completion-mode
   ;; Emacs.
   (equal last-input-event 'tab)
   (and (natnump last-input-event)
        (or
         ;; ?\t has event-modifier 'control.
         (equal last-input-event ?\t)
         (and (not (event-modifiers last-input-event))
              (or (equal last-input-event ?\?)
                  (equal last-input-event ?\ )))))
   ;; XEmacs.
   (and (featurep 'xemacs)
        ;; `last-input-event' might be nil.
        (not (null last-input-event))
        ;; `last-input-event' may have no character approximation.
        (tramp-compat-funcall 'event-to-character last-input-event)
        (or
         ;; ?\t has event-modifier 'control.
         (equal
          (tramp-compat-funcall 'event-to-character last-input-event) ?\t)
         (and (not (event-modifiers last-input-event))
              (or (equal
                   (tramp-compat-funcall 'event-to-character last-input-event)
                   ?\?)
                  (equal
                   (tramp-compat-funcall 'event-to-character last-input-event)
                   ?\ )))))))

(defun tramp-connectable-p (filename)
  "Check, whether it is possible to connect the remote host w/o side-effects.
This is true, if either the remote host is already connected, or if we are
not in completion mode."
  (and (tramp-tramp-file-p filename)
       (with-parsed-tramp-file-name filename nil
         (or (not (tramp-completion-mode-p))
             (let ((p (tramp-get-connection-process v)))
               (and p (processp p) (memq (process-status p) '(run open))))))))

;; Method, host name and user name completion.
;; `tramp-completion-dissect-file-name' returns a list of
;; tramp-file-name structures. For all of them we return possible completions.
;;;###autoload
(defun tramp-completion-handle-file-name-all-completions (filename directory)
  "Like `file-name-all-completions' for partial Tramp files."

  (let* ((fullname (tramp-drop-volume-letter
                    (expand-file-name filename directory)))
         ;; Possible completion structures.
         (v (tramp-completion-dissect-file-name fullname))
         result result1)

    (while v
      (let* ((car (car v))
             (method (tramp-file-name-method car))
             (user (tramp-file-name-user car))
             (host (tramp-file-name-host car))
             (localname (tramp-file-name-localname car))
             (m (tramp-find-method method user host))
             (tramp-current-user user) ; see `tramp-parse-passwd'
             all-user-hosts)

        (unless localname        ;; Nothing to complete.

          (if (or user host)

              ;; Method dependent user / host combinations.
              (progn
                (mapc
                 (lambda (x)
                   (setq all-user-hosts
                         (append all-user-hosts
                                 (funcall (nth 0 x) (nth 1 x)))))
                 (tramp-get-completion-function m))

                (setq result
                      (append result
                              (mapcar
                               (lambda (x)
                                 (tramp-get-completion-user-host
                                  method user host (nth 0 x) (nth 1 x)))
                               (delq nil all-user-hosts)))))

            ;; Possible methods.
            (setq result
                  (append result (tramp-get-completion-methods m)))))

        (setq v (cdr v))))

    ;; Unify list, remove nil elements.
    (while result
      (let ((car (car result)))
        (when car
          (add-to-list
           'result1
           (substring car (length (tramp-drop-volume-letter directory)))))
        (setq result (cdr result))))

    ;; Complete local parts.
    (append
     result1
     (ignore-errors
       (apply (if (tramp-connectable-p fullname)
                  'tramp-completion-run-real-handler
                'tramp-run-real-handler)
              'file-name-all-completions (list (list filename directory)))))))

;; Method, host name and user name completion for a file.
;;;###autoload
(defun tramp-completion-handle-file-name-completion
  (filename directory &optional predicate)
  "Like `file-name-completion' for Tramp files."
  (try-completion
   filename
   (mapcar 'list (file-name-all-completions filename directory))
   (when (and predicate
              (tramp-connectable-p (expand-file-name filename directory)))
     (lambda (x) (funcall predicate (expand-file-name (car x) directory))))))

;; I misuse a little bit the tramp-file-name structure in order to handle
;; completion possibilities for partial methods / user names / host names.
;; Return value is a list of tramp-file-name structures according to possible
;; completions. If "localname" is non-nil it means there
;; shouldn't be a completion anymore.

;; Expected results:

;; "/x" "/[x"           "/x@" "/[x@"         "/x@y" "/[x@y"
;; [nil nil "x" nil]    [nil "x" nil nil]    [nil "x" "y" nil]
;; [nil "x" nil nil]
;; ["x" nil nil nil]

;; "/x:"                "/x:y"               "/x:y:"
;; [nil nil "x" ""]     [nil nil "x" "y"]    ["x" nil "y" ""]
;; "/[x/"               "/[x/y"
;; ["x" nil "" nil]     ["x" nil "y" nil]
;; ["x" "" nil nil]     ["x" "y" nil nil]

;; "/x:y@"              "/x:y@z"             "/x:y@z:"
;; [nil nil "x" "y@"]   [nil nil "x" "y@z"]  ["x" "y" "z" ""]
;; "/[x/y@"             "/[x/y@z"
;; ["x" nil "y" nil]    ["x" "y" "z" nil]
(defun tramp-completion-dissect-file-name (name)
  "Returns a list of `tramp-file-name' structures.
They are collected by `tramp-completion-dissect-file-name1'."

  (let* ((result)
         (x-nil "\\|\\(\\)")
         (tramp-completion-ipv6-regexp
          (format
           "[^%s]*"
           (if (zerop (length tramp-postfix-ipv6-format))
               tramp-postfix-host-format
             tramp-postfix-ipv6-format)))
         ;; "/method" "/[method"
         (tramp-completion-file-name-structure1
          (list (concat tramp-prefix-regexp "\\(" tramp-method-regexp x-nil "\\)$")
                1 nil nil nil))
         ;; "/user" "/[user"
         (tramp-completion-file-name-structure2
          (list (concat tramp-prefix-regexp "\\(" tramp-user-regexp x-nil   "\\)$")
                nil 1 nil nil))
         ;; "/host" "/[host"
         (tramp-completion-file-name-structure3
          (list (concat tramp-prefix-regexp "\\(" tramp-host-regexp x-nil   "\\)$")
                nil nil 1 nil))
         ;; "/[ipv6" "/[ipv6"
         (tramp-completion-file-name-structure4
          (list (concat tramp-prefix-regexp
                        tramp-prefix-ipv6-regexp
                        "\\(" tramp-completion-ipv6-regexp x-nil   "\\)$")
                nil nil 1 nil))
         ;; "/user@host" "/[user@host"
         (tramp-completion-file-name-structure5
          (list (concat tramp-prefix-regexp
                        "\\(" tramp-user-regexp "\\)"   tramp-postfix-user-regexp
                        "\\(" tramp-host-regexp x-nil   "\\)$")
                nil 1 2 nil))
         ;; "/user@[ipv6" "/[user@ipv6"
         (tramp-completion-file-name-structure6
          (list (concat tramp-prefix-regexp
                        "\\(" tramp-user-regexp "\\)"   tramp-postfix-user-regexp
                        tramp-prefix-ipv6-regexp
                        "\\(" tramp-completion-ipv6-regexp x-nil   "\\)$")
                nil 1 2 nil))
         ;; "/method:user" "/[method/user" "/method://user"
         (tramp-completion-file-name-structure7
          (list (concat tramp-prefix-regexp
                        "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp
                        "\\(" tramp-user-regexp x-nil   "\\)$")
                1 2 nil nil))
         ;; "/method:host" "/[method/host" "/method://host"
         (tramp-completion-file-name-structure8
          (list (concat tramp-prefix-regexp
                        "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp
                        "\\(" tramp-host-regexp x-nil   "\\)$")
                1 nil 2 nil))
         ;; "/method:[ipv6" "/[method/ipv6" "/method://[ipv6"
         (tramp-completion-file-name-structure9
          (list (concat tramp-prefix-regexp
                        "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp
                        tramp-prefix-ipv6-regexp
                        "\\(" tramp-completion-ipv6-regexp x-nil   "\\)$")
                1 nil 2 nil))
         ;; "/method:user@host" "/[method/user@host" "/method://user@host"
         (tramp-completion-file-name-structure10
          (list (concat tramp-prefix-regexp
                        "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp
                        "\\(" tramp-user-regexp "\\)"   tramp-postfix-user-regexp
                        "\\(" tramp-host-regexp x-nil   "\\)$")
                1 2 3 nil))
         ;; "/method:user@[ipv6" "/[method/user@ipv6" "/method://user@[ipv6"
         (tramp-completion-file-name-structure11
          (list (concat tramp-prefix-regexp
                        "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp
                        "\\(" tramp-user-regexp "\\)"   tramp-postfix-user-regexp
                        tramp-prefix-ipv6-regexp
                        "\\(" tramp-completion-ipv6-regexp x-nil   "\\)$")
                1 2 3 nil))
         ;; "/method: "/method:/"
         (tramp-completion-file-name-structure12
          (list
           (if (equal tramp-syntax 'url)
               (concat tramp-prefix-regexp
                       "\\(" tramp-method-regexp "\\)"
                       "\\(" (substring tramp-postfix-method-regexp 0 1)
                       "\\|" (substring tramp-postfix-method-regexp 1 2) "\\)"
                       "\\(" "\\)$")
             ;; Should not match if not URL syntax.
             (concat tramp-prefix-regexp "/$"))
           1 3 nil nil))
         ;; "/method: "/method:/"
         (tramp-completion-file-name-structure13
          (list
           (if (equal tramp-syntax 'url)
               (concat tramp-prefix-regexp
                       "\\(" tramp-method-regexp "\\)"
                       "\\(" (substring tramp-postfix-method-regexp 0 1)
                       "\\|" (substring tramp-postfix-method-regexp 1 2) "\\)"
                       "\\(" "\\)$")
             ;; Should not match if not URL syntax.
             (concat tramp-prefix-regexp "/$"))
           1 nil 3 nil)))

    (mapc (lambda (regexp)
      (add-to-list 'result
        (tramp-completion-dissect-file-name1 regexp name)))
      (list
       tramp-completion-file-name-structure1
       tramp-completion-file-name-structure2
       tramp-completion-file-name-structure3
       tramp-completion-file-name-structure4
       tramp-completion-file-name-structure5
       tramp-completion-file-name-structure6
       tramp-completion-file-name-structure7
       tramp-completion-file-name-structure8
       tramp-completion-file-name-structure9
       tramp-completion-file-name-structure10
       tramp-completion-file-name-structure11
       tramp-completion-file-name-structure12
       tramp-completion-file-name-structure13
       tramp-file-name-structure))

    (delq nil result)))

(defun tramp-completion-dissect-file-name1 (structure name)
  "Returns a `tramp-file-name' structure matching STRUCTURE.
The structure consists of remote method, remote user,
remote host and localname (filename on remote host)."

  (save-match-data
    (when (string-match (nth 0 structure) name)
      (let ((method    (and (nth 1 structure)
                            (match-string (nth 1 structure) name)))
            (user      (and (nth 2 structure)
                            (match-string (nth 2 structure) name)))
            (host      (and (nth 3 structure)
                            (match-string (nth 3 structure) name)))
            (localname (and (nth 4 structure)
                            (match-string (nth 4 structure) name))))
        (vector method user host localname)))))

;; This function returns all possible method completions, adding the
;; trailing method delimiter.
(defun tramp-get-completion-methods (partial-method)
  "Returns all method completions for PARTIAL-METHOD."
  (mapcar
   (lambda (method)
     (and method
          (string-match (concat "^" (regexp-quote partial-method)) method)
          (tramp-completion-make-tramp-file-name method nil nil nil)))
   (mapcar 'car tramp-methods)))

;; Compares partial user and host names with possible completions.
(defun tramp-get-completion-user-host (method partial-user partial-host user host)
  "Returns the most expanded string for user and host name completion.
PARTIAL-USER must match USER, PARTIAL-HOST must match HOST."
  (cond

   ((and partial-user partial-host)
    (if (and host
             (string-match (concat "^" (regexp-quote partial-host)) host)
             (string-equal partial-user (or user partial-user)))
        (setq user partial-user)
      (setq user nil
            host nil)))

   (partial-user
    (setq host nil)
    (unless
        (and user (string-match (concat "^" (regexp-quote partial-user)) user))
      (setq user nil)))

   (partial-host
    (setq user nil)
    (unless
        (and host (string-match (concat "^" (regexp-quote partial-host)) host))
      (setq host nil)))

   (t (setq user nil
            host nil)))

  (unless (zerop (+ (length user) (length host)))
    (tramp-completion-make-tramp-file-name method user host nil)))

;;;###tramp-autoload
(defun tramp-parse-rhosts (filename)
  "Return a list of (user host) tuples allowed to access.
Either user or host may be nil."
  ;; On Windows, there are problems in completion when
  ;; `default-directory' is remote.
  (let ((default-directory (tramp-compat-temporary-file-directory))
        res)
    (when (file-readable-p filename)
      (with-temp-buffer
        (insert-file-contents filename)
        (goto-char (point-min))
        (while (not (eobp))
          (push (tramp-parse-rhosts-group) res))))
    res))

(defun tramp-parse-rhosts-group ()
   "Return a (user host) tuple allowed to access.
Either user or host may be nil."
   (let ((result)
         (regexp
          (concat
           "^\\(" tramp-host-regexp "\\)"
           "\\([ \t]+" "\\(" tramp-user-regexp "\\)" "\\)?")))
     (narrow-to-region (point) (point-at-eol))
     (when (re-search-forward regexp nil t)
       (setq result (append (list (match-string 3) (match-string 1)))))
     (widen)
     (forward-line 1)
     result))

;;;###tramp-autoload
(defun tramp-parse-shosts (filename)
  "Return a list of (user host) tuples allowed to access.
User is always nil."
  ;; On Windows, there are problems in completion when
  ;; `default-directory' is remote.
  (let ((default-directory (tramp-compat-temporary-file-directory))
        res)
    (when (file-readable-p filename)
      (with-temp-buffer
        (insert-file-contents filename)
        (goto-char (point-min))
        (while (not (eobp))
          (push (tramp-parse-shosts-group) res))))
    res))

(defun tramp-parse-shosts-group ()
   "Return a (user host) tuple allowed to access.
User is always nil."
   (let ((result)
         (regexp (concat "^\\(" tramp-host-regexp "\\)")))
     (narrow-to-region (point) (point-at-eol))
     (when (re-search-forward regexp nil t)
       (setq result (list nil (match-string 1))))
     (widen)
     (or
      (> (skip-chars-forward ",") 0)
      (forward-line 1))
     result))

;;;###tramp-autoload
(defun tramp-parse-sconfig (filename)
  "Return a list of (user host) tuples allowed to access.
User is always nil."
  ;; On Windows, there are problems in completion when
  ;; `default-directory' is remote.
  (let ((default-directory (tramp-compat-temporary-file-directory))
        res)
    (when (file-readable-p filename)
      (with-temp-buffer
        (insert-file-contents filename)
        (goto-char (point-min))
        (while (not (eobp))
          (push (tramp-parse-sconfig-group) res))))
    res))

(defun tramp-parse-sconfig-group ()
   "Return a (user host) tuple allowed to access.
User is always nil."
   (let ((result)
         (regexp (concat "^[ \t]*Host[ \t]+" "\\(" tramp-host-regexp "\\)")))
     (narrow-to-region (point) (point-at-eol))
     (when (re-search-forward regexp nil t)
       (setq result (list nil (match-string 1))))
     (widen)
     (or
      (> (skip-chars-forward ",") 0)
      (forward-line 1))
     result))

;;;###tramp-autoload
(defun tramp-parse-shostkeys (dirname)
  "Return a list of (user host) tuples allowed to access.
User is always nil."
  ;; On Windows, there are problems in completion when
  ;; `default-directory' is remote.
  (let* ((default-directory (tramp-compat-temporary-file-directory))
         (regexp (concat "^key_[0-9]+_\\(" tramp-host-regexp "\\)\\.pub$"))
         (files (when (file-directory-p dirname) (directory-files dirname)))
         result)
    (while files
      (when (string-match regexp (car files))
        (push (list nil (match-string 1 (car files))) result))
      (setq files (cdr files)))
    result))

(defun tramp-parse-sknownhosts (dirname)
  "Return a list of (user host) tuples allowed to access.
User is always nil."
  ;; On Windows, there are problems in completion when
  ;; `default-directory' is remote.
  (let* ((default-directory (tramp-compat-temporary-file-directory))
         (regexp (concat "^\\(" tramp-host-regexp
                         "\\)\\.ssh-\\(dss\\|rsa\\)\\.pub$"))
         (files (when (file-directory-p dirname) (directory-files dirname)))
         result)
    (while files
      (when (string-match regexp (car files))
        (push (list nil (match-string 1 (car files))) result))
      (setq files (cdr files)))
    result))

;;;###tramp-autoload
(defun tramp-parse-hosts (filename)
  "Return a list of (user host) tuples allowed to access.
User is always nil."
  ;; On Windows, there are problems in completion when
  ;; `default-directory' is remote.
  (let ((default-directory (tramp-compat-temporary-file-directory))
        res)
    (when (file-readable-p filename)
      (with-temp-buffer
        (insert-file-contents filename)
        (goto-char (point-min))
        (while (not (eobp))
          (push (tramp-parse-hosts-group) res))))
    res))

(defun tramp-parse-hosts-group ()
   "Return a (user host) tuple allowed to access.
User is always nil."
   (let ((result)
         (regexp
          (concat "^\\(" tramp-ipv6-regexp "\\|" tramp-host-regexp "\\)")))
     (narrow-to-region (point) (point-at-eol))
     (when (re-search-forward regexp nil t)
       (setq result (list nil (match-string 1))))
     (widen)
     (or
      (> (skip-chars-forward " \t") 0)
      (forward-line 1))
     result))

;; For su-alike methods it would be desirable to return "root@localhost"
;; as default.  Unfortunately, we have no information whether any user name
;; has been typed already.  So we use `tramp-current-user' as indication,
;; assuming it is set in `tramp-completion-handle-file-name-all-completions'.
;;;###tramp-autoload
(defun tramp-parse-passwd (filename)
  "Return a list of (user host) tuples allowed to access.
Host is always \"localhost\"."
  ;; On Windows, there are problems in completion when
  ;; `default-directory' is remote.
  (let ((default-directory (tramp-compat-temporary-file-directory))
        res)
    (if (zerop (length tramp-current-user))
        '(("root" nil))
      (when (file-readable-p filename)
        (with-temp-buffer
          (insert-file-contents filename)
          (goto-char (point-min))
          (while (not (eobp))
            (push (tramp-parse-passwd-group) res))))
      res)))

(defun tramp-parse-passwd-group ()
   "Return a (user host) tuple allowed to access.
Host is always \"localhost\"."
   (let ((result)
         (regexp (concat "^\\(" tramp-user-regexp "\\):")))
     (narrow-to-region (point) (point-at-eol))
     (when (re-search-forward regexp nil t)
       (setq result (list (match-string 1) "localhost")))
     (widen)
     (forward-line 1)
     result))

;;;###tramp-autoload
(defun tramp-parse-netrc (filename)
  "Return a list of (user host) tuples allowed to access.
User may be nil."
  ;; On Windows, there are problems in completion when
  ;; `default-directory' is remote.
  (let ((default-directory (tramp-compat-temporary-file-directory))
        res)
    (when (file-readable-p filename)
      (with-temp-buffer
        (insert-file-contents filename)
        (goto-char (point-min))
        (while (not (eobp))
          (push (tramp-parse-netrc-group) res))))
    res))

(defun tramp-parse-netrc-group ()
   "Return a (user host) tuple allowed to access.
User may be nil."
   (let ((result)
         (regexp
          (concat
           "^[ \t]*machine[ \t]+" "\\(" tramp-host-regexp "\\)"
           "\\([ \t]+login[ \t]+" "\\(" tramp-user-regexp "\\)" "\\)?")))
     (narrow-to-region (point) (point-at-eol))
     (when (re-search-forward regexp nil t)
       (setq result (list (match-string 3) (match-string 1))))
     (widen)
     (forward-line 1)
     result))

;;;###tramp-autoload
(defun tramp-parse-putty (registry)
  "Return a list of (user host) tuples allowed to access.
User is always nil."
  ;; On Windows, there are problems in completion when
  ;; `default-directory' is remote.
  (let ((default-directory (tramp-compat-temporary-file-directory))
        res)
    (with-temp-buffer
      (when (zerop (tramp-compat-call-process "reg" nil t nil "query" registry))
        (goto-char (point-min))
        (while (not (eobp))
          (push (tramp-parse-putty-group registry) res))))
    res))

(defun tramp-parse-putty-group (registry)
   "Return a (user host) tuple allowed to access.
User is always nil."
   (let ((result)
         (regexp (concat (regexp-quote registry) "\\\\\\(.+\\)")))
     (narrow-to-region (point) (point-at-eol))
     (when (re-search-forward regexp nil t)
       (setq result (list nil (match-string 1))))
     (widen)
     (forward-line 1)
     result))

;;; Common file name handler functions for different backends:

(defvar tramp-handle-file-local-copy-hook nil
  "Normal hook to be run at the end of `tramp-*-handle-file-local-copy'.")

(defvar tramp-handle-write-region-hook nil
  "Normal hook to be run at the end of `tramp-*-handle-write-region'.")

(defun tramp-handle-directory-file-name (directory)
  "Like `directory-file-name' for Tramp files."
  ;; If localname component of filename is "/", leave it unchanged.
  ;; Otherwise, remove any trailing slash from localname component.
  ;; Method, host, etc, are unchanged.  Does it make sense to try
  ;; to avoid parsing the filename?
  (with-parsed-tramp-file-name directory nil
    (if (and (not (zerop (length localname)))
             (eq (aref localname (1- (length localname))) ?/)
             (not (string= localname "/")))
        (substring directory 0 -1)
      directory)))

(defun tramp-handle-directory-files
  (directory &optional full match nosort files-only)
  "Like `directory-files' for Tramp files."
  ;; FILES-ONLY is valid for XEmacs only.
  (when (file-directory-p directory)
    (setq directory (file-name-as-directory (expand-file-name directory)))
    (let ((temp (nreverse (file-name-all-completions "" directory)))
          result item)

      (while temp
        (setq item (directory-file-name (pop temp)))
        (when (and (or (null match) (string-match match item))
                   (or (null files-only)
                       ;; Files only.
                       (and (equal files-only t) (file-regular-p item))
                       ;; Directories only.
                       (file-directory-p item)))
          (push (if full (concat directory item) item)
                result)))
      (if nosort result (sort result 'string<)))))

(defun tramp-handle-directory-files-and-attributes
  (directory &optional full match nosort id-format)
  "Like `directory-files-and-attributes' for Tramp files."
  (mapcar
   (lambda (x)
     (cons x (tramp-compat-file-attributes
              (if full x (expand-file-name x directory)) id-format)))
   (directory-files directory full match nosort)))

(defun tramp-handle-dired-uncache (dir &optional dir-p)
  "Like `dired-uncache' for Tramp files."
  ;; DIR-P is valid for XEmacs only.
  (with-parsed-tramp-file-name
      (if (or dir-p (file-directory-p dir)) dir (file-name-directory dir)) nil
    (tramp-flush-directory-property v localname)))

(defun tramp-handle-file-exists-p (filename)
  "Like `file-exists-p' for Tramp files."
  (not (null (file-attributes filename))))

(defun tramp-handle-file-modes (filename)
  "Like `file-modes' for Tramp files."
  (let ((truename (or (file-truename filename) filename)))
    (when (file-exists-p truename)
      (tramp-mode-string-to-int (nth 8 (file-attributes truename))))))

;; Localname manipulation functions that grok Tramp localnames...
(defun tramp-handle-file-name-as-directory (file)
  "Like `file-name-as-directory' but aware of Tramp files."
  ;; `file-name-as-directory' would be sufficient except localname is
  ;; the empty string.
  (let ((v (tramp-dissect-file-name file t)))
    ;; Run the command on the localname portion only.
    (tramp-make-tramp-file-name
     (tramp-file-name-method v)
     (tramp-file-name-user v)
     (tramp-file-name-host v)
     (tramp-run-real-handler
      'file-name-as-directory (list (or (tramp-file-name-localname v) ""))))))

(defun tramp-handle-file-name-completion
  (filename directory &optional predicate)
  "Like `file-name-completion' for Tramp files."
  (unless (tramp-tramp-file-p directory)
    (error
     "tramp-handle-file-name-completion invoked on non-tramp directory `%s'"
     directory))
  (try-completion
   filename
   (mapcar 'list (file-name-all-completions filename directory))
   (when predicate
     (lambda (x) (funcall predicate (expand-file-name (car x) directory))))))

(defun tramp-handle-file-name-directory (file)
  "Like `file-name-directory' but aware of Tramp files."
  ;; Everything except the last filename thing is the directory.  We
  ;; cannot apply `with-parsed-tramp-file-name', because this expands
  ;; the remote file name parts.  This is a problem when we are in
  ;; file name completion.
  (let ((v (tramp-dissect-file-name file t)))
    ;; Run the command on the localname portion only.
    (tramp-make-tramp-file-name
     (tramp-file-name-method v)
     (tramp-file-name-user v)
     (tramp-file-name-host v)
     (tramp-run-real-handler
      'file-name-directory (list (or (tramp-file-name-localname v) ""))))))

(defun tramp-handle-file-name-nondirectory (file)
  "Like `file-name-nondirectory' but aware of Tramp files."
  (with-parsed-tramp-file-name file nil
    (tramp-run-real-handler 'file-name-nondirectory (list localname))))

(defun tramp-handle-file-newer-than-file-p (file1 file2)
  "Like `file-newer-than-file-p' for Tramp files."
  (cond
   ((not (file-exists-p file1)) nil)
   ((not (file-exists-p file2)) t)
   (t (tramp-time-less-p (nth 5 (file-attributes file2))
                         (nth 5 (file-attributes file1))))))

(defun tramp-handle-file-regular-p (filename)
  "Like `file-regular-p' for Tramp files."
  (and (file-exists-p filename)
       (eq ?- (aref (nth 8 (file-attributes filename)) 0))))

(defun tramp-handle-file-remote-p (filename &optional identification connected)
  "Like `file-remote-p' for Tramp files."
  (let ((tramp-verbose 3))
    (when (tramp-tramp-file-p filename)
      (let* ((v (tramp-dissect-file-name filename))
             (p (tramp-get-connection-process v))
             (c (and p (processp p) (memq (process-status p) '(run open)))))
        ;; We expand the file name only, if there is already a connection.
        (with-parsed-tramp-file-name
            (if c (expand-file-name filename) filename) nil
          (and (or (not connected) c)
               (cond
                ((eq identification 'method) method)
                ((eq identification 'user) user)
                ((eq identification 'host) host)
                ((eq identification 'localname) localname)
                (t (tramp-make-tramp-file-name method user host "")))))))))

(defun tramp-handle-file-symlink-p (filename)
  "Like `file-symlink-p' for Tramp files."
  (with-parsed-tramp-file-name filename nil
    (let ((x (car (file-attributes filename))))
      (when (stringp x)
        ;; When Tramp is running on VMS, then `file-name-absolute-p'
        ;; might do weird things.
        (if (file-name-absolute-p x)
            (tramp-make-tramp-file-name method user host x)
          x)))))

(defun tramp-handle-find-backup-file-name (filename)
  "Like `find-backup-file-name' for Tramp files."
  (with-parsed-tramp-file-name filename nil
    ;; We set both variables. It doesn't matter whether it is
    ;; Emacs or XEmacs.
    (let ((backup-directory-alist
           ;; Emacs case.
           (when (boundp 'backup-directory-alist)
             (if (symbol-value 'tramp-backup-directory-alist)
                 (mapcar
                  (lambda (x)
                    (cons
                     (car x)
                     (if (and (stringp (cdr x))
                              (file-name-absolute-p (cdr x))
                              (not (tramp-file-name-p (cdr x))))
                         (tramp-make-tramp-file-name method user host (cdr x))
                       (cdr x))))
                  (symbol-value 'tramp-backup-directory-alist))
               (symbol-value 'backup-directory-alist))))

          (bkup-backup-directory-info
           ;; XEmacs case.
           (when (boundp 'bkup-backup-directory-info)
             (if (symbol-value 'tramp-bkup-backup-directory-info)
                 (mapcar
                  (lambda (x)
                    (nconc
                     (list (car x))
                     (list
                      (if (and (stringp (car (cdr x)))
                               (file-name-absolute-p (car (cdr x)))
                               (not (tramp-file-name-p (car (cdr x)))))
                          (tramp-make-tramp-file-name
                           method user host (car (cdr x)))
                        (car (cdr x))))
                     (cdr (cdr x))))
                  (symbol-value 'tramp-bkup-backup-directory-info))
               (symbol-value 'bkup-backup-directory-info)))))

      (tramp-run-real-handler 'find-backup-file-name (list filename)))))

(defun tramp-handle-insert-file-contents
  (filename &optional visit beg end replace)
  "Like `insert-file-contents' for Tramp files."
  (barf-if-buffer-read-only)
  (setq filename (expand-file-name filename))
  (let (result local-copy remote-copy)
    (with-parsed-tramp-file-name filename nil
      (unwind-protect
          (if (not (file-exists-p filename))
              ;; We don't raise a Tramp error, because it might be
              ;; suppressed, like in `find-file-noselect-1'.
              (signal 'file-error
                      (list "File not found on remote host" filename))

            (if (and (tramp-local-host-p v)
                     (let (file-name-handler-alist)
                       (file-readable-p localname)))
                ;; Short track: if we are on the local host, we can
                ;; run directly.
                (setq result
                      (tramp-run-real-handler
                       'insert-file-contents
                       (list localname visit beg end replace)))

              ;; When we shall insert only a part of the file, we copy
              ;; this part.
              (when (or beg end)
                (setq remote-copy (tramp-make-tramp-temp-file v))
                ;; This is defined in tramp-sh.el.  Let's assume this
                ;; is loaded already.
                (tramp-compat-funcall 'tramp-send-command
                 v
                 (cond
                  ((and beg end)
                   (format "dd bs=1 skip=%d if=%s count=%d of=%s"
                           beg (tramp-shell-quote-argument localname)
                           (- end beg) remote-copy))
                  (beg
                   (format "dd bs=1 skip=%d if=%s of=%s"
                           beg (tramp-shell-quote-argument localname)
                           remote-copy))
                  (end
                   (format "dd bs=1 count=%d if=%s of=%s"
                           end (tramp-shell-quote-argument localname)
                           remote-copy)))))

              ;; `insert-file-contents-literally' takes care to avoid
              ;; calling jka-compr.  By let-binding
              ;; `inhibit-file-name-operation', we propagate that care
              ;; to the `file-local-copy' operation.
              (setq local-copy
                    (let ((inhibit-file-name-operation
                           (when (eq inhibit-file-name-operation
                                     'insert-file-contents)
                             'file-local-copy)))
                      (cond
                       ((stringp remote-copy)
                        (file-local-copy
                         (tramp-make-tramp-file-name
                          method user host remote-copy)))
                       ((stringp tramp-temp-buffer-file-name)
                        (copy-file filename tramp-temp-buffer-file-name 'ok)
                        tramp-temp-buffer-file-name)
                       (t (file-local-copy filename)))))

              ;; When the file is not readable for the owner, it
              ;; cannot be inserted, even if it is readable for the
              ;; group or for everybody.
              (set-file-modes local-copy (tramp-compat-octal-to-decimal "0600"))

              (when (and (null remote-copy)
                         (tramp-get-method-parameter
                          method 'tramp-copy-keep-tmpfile))
                ;; We keep the local file for performance reasons,
                ;; useful for "rsync".
                (setq tramp-temp-buffer-file-name local-copy))

              (tramp-with-progress-reporter
                  v 3 (format "Inserting local temp file `%s'" local-copy)
                ;; We must ensure that `file-coding-system-alist'
                ;; matches `local-copy'.
                (let ((file-coding-system-alist
                       (tramp-find-file-name-coding-system-alist
                        filename local-copy)))
                  (setq result
                        (insert-file-contents
                         local-copy nil nil nil replace))))))

        ;; Save exit.
        (progn
          (when visit
            (setq buffer-file-name filename)
            (setq buffer-read-only (not (file-writable-p filename)))
            (set-visited-file-modtime)
            (set-buffer-modified-p nil))
          (when (and (stringp local-copy)
                     (or remote-copy (null tramp-temp-buffer-file-name)))
            (delete-file local-copy))
          (when (stringp remote-copy)
            (delete-file
             (tramp-make-tramp-file-name method user host remote-copy))))))

    ;; Result.
    (list (expand-file-name filename)
          (cadr result))))

(defun tramp-handle-load (file &optional noerror nomessage nosuffix must-suffix)
  "Like `load' for Tramp files."
  (with-parsed-tramp-file-name (expand-file-name file) nil
    (unless nosuffix
      (cond ((file-exists-p (concat file ".elc"))
             (setq file (concat file ".elc")))
            ((file-exists-p (concat file ".el"))
             (setq file (concat file ".el")))))
    (when must-suffix
      ;; The first condition is always true for absolute file names.
      ;; Included for safety's sake.
      (unless (or (file-name-directory file)
                  (string-match "\\.elc?\\'" file))
        (tramp-error
         v 'file-error
         "File `%s' does not include a `.el' or `.elc' suffix" file)))
    (unless noerror
      (when (not (file-exists-p file))
        (tramp-error v 'file-error "Cannot load nonexistent file `%s'" file)))
    (if (not (file-exists-p file))
        nil
      (let ((tramp-message-show-message (not nomessage)))
        (tramp-with-progress-reporter v 0 (format "Loading %s" file)
          (let ((local-copy (file-local-copy file)))
            ;; MUST-SUFFIX doesn't exist on XEmacs, so let it default to nil.
            (unwind-protect
                (load local-copy noerror t t)
              (delete-file local-copy)))))
      t)))

(defun tramp-handle-shell-command
  (command &optional output-buffer error-buffer)
  "Like `shell-command' for Tramp files."
  (let* ((asynchronous (string-match "[ \t]*&[ \t]*\\'" command))
         ;; We cannot use `shell-file-name' and `shell-command-switch',
         ;; they are variables of the local host.
         (args (append
                (cons
                 (tramp-get-method-parameter
                  (tramp-file-name-method
                   (tramp-dissect-file-name default-directory))
                  'tramp-remote-shell)
                 (tramp-get-method-parameter
                  (tramp-file-name-method
                   (tramp-dissect-file-name default-directory))
                  'tramp-remote-shell-args))
                (list (substring command 0 asynchronous))))
         current-buffer-p
         (output-buffer
          (cond
           ((bufferp output-buffer) output-buffer)
           ((stringp output-buffer) (get-buffer-create output-buffer))
           (output-buffer
            (setq current-buffer-p t)
            (current-buffer))
           (t (get-buffer-create
               (if asynchronous
                   "*Async Shell Command*"
                 "*Shell Command Output*")))))
         (error-buffer
          (cond
           ((bufferp error-buffer) error-buffer)
           ((stringp error-buffer) (get-buffer-create error-buffer))))
         (buffer
          (if (and (not asynchronous) error-buffer)
              (with-parsed-tramp-file-name default-directory nil
                (list output-buffer (tramp-make-tramp-temp-file v)))
            output-buffer))
         (p (get-buffer-process output-buffer)))

    ;; Check whether there is another process running.  Tramp does not
    ;; support 2 (asynchronous) processes in parallel.
    (when p
      (if (yes-or-no-p "A command is running.  Kill it? ")
          (ignore-errors (kill-process p))
        (error "Shell command in progress")))

    (if current-buffer-p
        (progn
          (barf-if-buffer-read-only)
          (push-mark nil t))
      (with-current-buffer output-buffer
        (setq buffer-read-only nil)
        (erase-buffer)))

    (if (and (not current-buffer-p) (integerp asynchronous))
        (prog1
            ;; Run the process.
            (setq p (apply 'start-file-process "*Async Shell*" buffer args))
          ;; Display output.
          (pop-to-buffer output-buffer)
          (setq mode-line-process '(":%s"))
          (shell-mode)
          (set-process-sentinel p 'shell-command-sentinel)
          (set-process-filter p 'comint-output-filter))

      (prog1
          ;; Run the process.
          (apply 'process-file (car args) nil buffer nil (cdr args))
        ;; Insert error messages if they were separated.
        (when (listp buffer)
          (with-current-buffer error-buffer
            (insert-file-contents (cadr buffer)))
          (delete-file (cadr buffer)))
        (if current-buffer-p
            ;; This is like exchange-point-and-mark, but doesn't
            ;; activate the mark.  It is cleaner to avoid activation,
            ;; even though the command loop would deactivate the mark
            ;; because we inserted text.
            (goto-char (prog1 (mark t)
                         (set-marker (mark-marker) (point)
                                     (current-buffer))))
          ;; There's some output, display it.
          (when (with-current-buffer output-buffer (> (point-max) (point-min)))
            (if (functionp 'display-message-or-buffer)
                (tramp-compat-funcall 'display-message-or-buffer output-buffer)
              (pop-to-buffer output-buffer))))))))

(defun tramp-handle-substitute-in-file-name (filename)
  "Like `substitute-in-file-name' for Tramp files.
\"//\" and \"/~\" substitute only in the local filename part.
If the URL Tramp syntax is chosen, \"//\" as method delimiter and \"/~\" at
beginning of local filename are not substituted."
  ;; First, we must replace environment variables.
  (setq filename (tramp-replace-environment-variables filename))
  (with-parsed-tramp-file-name filename nil
    (if (equal tramp-syntax 'url)
        ;; We need to check localname only.  The other parts cannot contain
        ;; "//" or "/~".
        (if (and (> (length localname) 1)
                 (or (string-match "//" localname)
                     (string-match "/~" localname 1)))
            (tramp-run-real-handler 'substitute-in-file-name (list filename))
          (tramp-make-tramp-file-name
           (when method (substitute-in-file-name method))
           (when user (substitute-in-file-name user))
           (when host (substitute-in-file-name host))
           (when localname
             (tramp-run-real-handler
              'substitute-in-file-name (list localname)))))
      ;; Ignore in LOCALNAME everything before "//" or "/~".
      (when (and (stringp localname) (string-match ".+?/\\(/\\|~\\)" localname))
        (setq filename
              (concat (file-remote-p filename)
                      (replace-match "\\1" nil nil localname)))
        ;; "/m:h:~" does not work for completion.  We use "/m:h:~/".
        (when (string-match "~$" filename)
          (setq filename (concat filename "/"))))
      (tramp-run-real-handler 'substitute-in-file-name (list filename)))))

(defun tramp-handle-unhandled-file-name-directory (filename)
  "Like `unhandled-file-name-directory' for Tramp files."
  ;; With Emacs 23, we could simply return `nil'.  But we must keep it
  ;; for backward compatibility.
  (expand-file-name "~/"))

;;; Functions for establishing connection:

;; The following functions are actions to be taken when seeing certain
;; prompts from the remote host.  See the variable
;; `tramp-actions-before-shell' for usage of these functions.

(defun tramp-action-login (proc vec)
  "Send the login name."
  (when (not (stringp tramp-current-user))
    (save-window-excursion
      (let ((enable-recursive-minibuffers t))
        (pop-to-buffer (tramp-get-connection-buffer vec))
        (setq tramp-current-user (read-string (match-string 0))))))
  (tramp-message vec 3 "Sending login name `%s'" tramp-current-user)
  (with-current-buffer (tramp-get-connection-buffer vec)
    (tramp-message vec 6 "\n%s" (buffer-string)))
  (tramp-send-string vec tramp-current-user))

(defun tramp-action-password (proc vec)
  "Query the user for a password."
  (with-current-buffer (process-buffer proc)
    (tramp-check-for-regexp proc tramp-password-prompt-regexp)
    (tramp-message vec 3 "Sending %s" (match-string 1))
    (tramp-enter-password proc)
    ;; Hide password prompt.
    (narrow-to-region (point-max) (point-max))))

(defun tramp-action-succeed (proc vec)
  "Signal success in finding shell prompt."
  (throw 'tramp-action 'ok))

(defun tramp-action-permission-denied (proc vec)
  "Signal permission denied."
  (kill-process proc)
  (throw 'tramp-action 'permission-denied))

(defun tramp-action-yesno (proc vec)
  "Ask the user for confirmation using `yes-or-no-p'.
Send \"yes\" to remote process on confirmation, abort otherwise.
See also `tramp-action-yn'."
  (save-window-excursion
    (let ((enable-recursive-minibuffers t))
      (save-match-data (pop-to-buffer (tramp-get-connection-buffer vec)))
      (unless (yes-or-no-p (match-string 0))
        (kill-process proc)
        (throw 'tramp-action 'permission-denied))
      (with-current-buffer (tramp-get-connection-buffer vec)
        (tramp-message vec 6 "\n%s" (buffer-string)))
      (tramp-send-string vec "yes"))))

(defun tramp-action-yn (proc vec)
  "Ask the user for confirmation using `y-or-n-p'.
Send \"y\" to remote process on confirmation, abort otherwise.
See also `tramp-action-yesno'."
  (save-window-excursion
    (let ((enable-recursive-minibuffers t))
      (save-match-data (pop-to-buffer (tramp-get-connection-buffer vec)))
      (unless (y-or-n-p (match-string 0))
        (kill-process proc)
        (throw 'tramp-action 'permission-denied))
      (with-current-buffer (tramp-get-connection-buffer vec)
        (tramp-message vec 6 "\n%s" (buffer-string)))
      (tramp-send-string vec "y"))))

(defun tramp-action-terminal (proc vec)
  "Tell the remote host which terminal type to use.
The terminal type can be configured with `tramp-terminal-type'."
  (tramp-message vec 5 "Setting `%s' as terminal type." tramp-terminal-type)
  (with-current-buffer (tramp-get-connection-buffer vec)
    (tramp-message vec 6 "\n%s" (buffer-string)))
  (tramp-send-string vec tramp-terminal-type))

(defun tramp-action-process-alive (proc vec)
  "Check, whether a process has finished."
  (unless (memq (process-status proc) '(run open))
    (throw 'tramp-action 'process-died)))

(defun tramp-action-out-of-band (proc vec)
  "Check, whether an out-of-band copy has finished."
  (cond ((and (memq (process-status proc) '(stop exit))
              (zerop (process-exit-status proc)))
         (tramp-message vec 3 "Process has finished.")
         (throw 'tramp-action 'ok))
        ((or (and (memq (process-status proc) '(stop exit))
                  (not (zerop (process-exit-status proc))))
             (memq (process-status proc) '(signal)))
         ;; `scp' could have copied correctly, but set modes could have failed.
         ;; This can be ignored.
         (with-current-buffer (process-buffer proc)
           (goto-char (point-min))
           (if (re-search-forward tramp-operation-not-permitted-regexp nil t)
               (progn
                 (tramp-message vec 5 "'set mode' error ignored.")
                 (tramp-message vec 3 "Process has finished.")
                 (throw 'tramp-action 'ok))
             (tramp-message vec 3 "Process has died.")
             (throw 'tramp-action 'process-died))))
        (t nil)))

;;; Functions for processing the actions:

(defun tramp-process-one-action (proc vec actions)
  "Wait for output from the shell and perform one action."
  (let (found todo item pattern action)
    (while (not found)
      ;; Reread output once all actions have been performed.
      ;; Obviously, the output was not complete.
      (tramp-accept-process-output proc 1)
      (setq todo actions)
      (while todo
        (setq item (pop todo))
        (setq pattern (format "\\(%s\\)\\'" (symbol-value (nth 0 item))))
        (setq action (nth 1 item))
        (tramp-message
         vec 5 "Looking for regexp \"%s\" from remote shell" pattern)
        (when (tramp-check-for-regexp proc pattern)
          (tramp-message vec 5 "Call `%s'" (symbol-name action))
          (setq found (funcall action proc vec)))))
    found))

(defun tramp-process-actions (proc vec pos actions &optional timeout)
  "Perform ACTIONS until success or TIMEOUT.
PROC and VEC indicate the remote connection to be used.  POS, if
set, is the starting point of the region to be deleted in the
connection buffer."
  ;; Preserve message for `progress-reporter'.
  (tramp-compat-with-temp-message ""
    ;; Enable auth-source and password-cache.  We must use
    ;; tramp-current-* variables in case we have several hops.
    (tramp-set-connection-property
     (tramp-dissect-file-name
      (tramp-make-tramp-file-name
       tramp-current-method tramp-current-user tramp-current-host ""))
     "first-password-request" t)
    (save-restriction
      (let (exit)
        (while (not exit)
          (tramp-message proc 3 "Waiting for prompts from remote shell")
          (setq exit
                (catch 'tramp-action
                  (if timeout
                      (with-timeout (timeout)
                        (tramp-process-one-action proc vec actions))
                    (tramp-process-one-action proc vec actions)))))
        (with-current-buffer (tramp-get-connection-buffer vec)
          (widen)
          (tramp-message vec 6 "\n%s" (buffer-string)))
        (unless (eq exit 'ok)
          (tramp-clear-passwd vec)
          (tramp-error-with-buffer
           nil vec 'file-error
           (cond
            ((eq exit 'permission-denied) "Permission denied")
            ((eq exit 'process-died) "Process died")
            (t "Login failed"))))
        (when (numberp pos)
          (with-current-buffer (tramp-get-connection-buffer vec)
            (let (buffer-read-only) (delete-region pos (point)))))))))

:;; Utility functions:

(defun tramp-accept-process-output (&optional proc timeout timeout-msecs)
  "Like `accept-process-output' for Tramp processes.
This is needed in order to hide `last-coding-system-used', which is set
for process communication also."
  (with-current-buffer (process-buffer proc)
    (tramp-message proc 10 "%s %s" proc (process-status proc))
    (let (buffer-read-only last-coding-system-used)
      ;; Under Windows XP, accept-process-output doesn't return
      ;; sometimes.  So we add an additional timeout.
      (with-timeout ((or timeout 1))
        (accept-process-output proc timeout timeout-msecs)))
    (tramp-message proc 10 "\n%s" (buffer-string))))

(defun tramp-check-for-regexp (proc regexp)
  "Check, whether REGEXP is contained in process buffer of PROC.
Erase echoed commands if exists."
  (with-current-buffer (process-buffer proc)
    (goto-char (point-min))

    ;; Check whether we need to remove echo output.
    (when (and (tramp-get-connection-property proc "check-remote-echo" nil)
               (re-search-forward tramp-echoed-echo-mark-regexp nil t))
      (let ((begin (match-beginning 0)))
        (when (re-search-forward tramp-echoed-echo-mark-regexp nil t)
          ;; Discard echo from remote output.
          (tramp-set-connection-property proc "check-remote-echo" nil)
          (tramp-message proc 5 "echo-mark found")
          (forward-line 1)
          (delete-region begin (point))
          (goto-char (point-min)))))

    (when (or (not (tramp-get-connection-property proc "check-remote-echo" nil))
              ;; Sometimes, the echo string is suppressed on the remote side.
              (not (string-equal
                    (tramp-compat-funcall
                     'substring-no-properties tramp-echo-mark-marker
                     0 (min tramp-echo-mark-marker-length (1- (point-max))))
                    (tramp-compat-funcall
                     'buffer-substring-no-properties
                     1 (min (1+ tramp-echo-mark-marker-length) (point-max))))))
      ;; No echo to be handled, now we can look for the regexp.
      (goto-char (point-min))
      (re-search-forward regexp nil t))))

(defun tramp-wait-for-regexp (proc timeout regexp)
  "Wait for a REGEXP to appear from process PROC within TIMEOUT seconds.
Expects the output of PROC to be sent to the current buffer.  Returns
the string that matched, or nil.  Waits indefinitely if TIMEOUT is
nil."
  (with-current-buffer (process-buffer proc)
    (let ((found (tramp-check-for-regexp proc regexp))
          (start-time (current-time)))
      (cond (timeout
             ;; Work around a bug in XEmacs 21, where the timeout
             ;; expires faster than it should.  This degenerates
             ;; to polling for buggy XEmacsen, but oh, well.
             (while (and (not found)
                         (< (tramp-time-diff (current-time) start-time)
                            timeout))
               (with-timeout (timeout)
                 (while (not found)
                   (tramp-accept-process-output proc 1)
                   (unless (memq (process-status proc) '(run open))
                     (tramp-error-with-buffer
                      nil proc 'file-error "Process has died"))
                   (setq found (tramp-check-for-regexp proc regexp))))))
            (t
             (while (not found)
               (tramp-accept-process-output proc 1)
               (unless (memq (process-status proc) '(run open))
                 (tramp-error-with-buffer
                  nil proc 'file-error "Process has died"))
               (setq found (tramp-check-for-regexp proc regexp)))))
      (tramp-message proc 6 "\n%s" (buffer-string))
      (when (not found)
        (if timeout
            (tramp-error
             proc 'file-error "[[Regexp `%s' not found in %d secs]]"
             regexp timeout)
          (tramp-error proc 'file-error "[[Regexp `%s' not found]]" regexp)))
      found)))

;; We don't call `tramp-send-string' in order to hide the password
;; from the debug buffer, and because end-of-line handling of the
;; string.
(defun tramp-enter-password (proc)
  "Prompt for a password and send it to the remote end."
  (process-send-string
   proc (concat (tramp-read-passwd proc)
                (or (tramp-get-method-parameter
                     tramp-current-method
                     'tramp-password-end-of-line)
                    tramp-default-password-end-of-line))))

;; It seems that Tru64 Unix does not like it if long strings are sent
;; to it in one go.  (This happens when sending the Perl
;; `file-attributes' implementation, for instance.)  Therefore, we
;; have this function which sends the string in chunks.
(defun tramp-send-string (vec string)
  "Send the STRING via connection VEC.

The STRING is expected to use Unix line-endings, but the lines sent to
the remote host use line-endings as defined in the variable
`tramp-rsh-end-of-line'.  The communication buffer is erased before sending."
  (let* ((p (tramp-get-connection-process vec))
         (chunksize (tramp-get-connection-property p "chunksize" nil)))
    (unless p
      (tramp-error
       vec 'file-error "Can't send string to remote host -- not logged in"))
    (tramp-set-connection-property p "last-cmd-time" (current-time))
    (tramp-message vec 10 "%s" string)
    (with-current-buffer (tramp-get-connection-buffer vec)
      ;; Clean up the buffer.  We cannot call `erase-buffer' because
      ;; narrowing might be in effect.
      (let (buffer-read-only) (delete-region (point-min) (point-max)))
      ;; Replace "\n" by `tramp-rsh-end-of-line'.
      (setq string
            (mapconcat 'identity
                       (tramp-compat-split-string string "\n")
                       tramp-rsh-end-of-line))
      (unless (or (string= string "")
                  (string-equal (substring string -1) tramp-rsh-end-of-line))
        (setq string (concat string tramp-rsh-end-of-line)))
      ;; Send the string.
      (if (and chunksize (not (zerop chunksize)))
          (let ((pos 0)
                (end (length string)))
            (while (< pos end)
              (tramp-message
               vec 10 "Sending chunk from %s to %s"
               pos (min (+ pos chunksize) end))
              (process-send-string
               p (substring string pos (min (+ pos chunksize) end)))
              (setq pos (+ pos chunksize))))
        (process-send-string p string)))))

(defun tramp-get-inode (vec)
  "Returns the virtual inode number.
If it doesn't exist, generate a new one."
  (let ((string (tramp-make-tramp-file-name
                 (tramp-file-name-method vec)
                 (tramp-file-name-user vec)
                 (tramp-file-name-host vec)
                 "")))
    (unless (assoc string tramp-inodes)
      (add-to-list 'tramp-inodes
                   (list string (length tramp-inodes))))
    (nth 1 (assoc string tramp-inodes))))

(defun tramp-get-device (vec)
  "Returns the virtual device number.
If it doesn't exist, generate a new one."
  (let ((string (tramp-make-tramp-file-name
                 (tramp-file-name-method vec)
                 (tramp-file-name-user vec)
                 (tramp-file-name-host vec)
                 "")))
    (unless (assoc string tramp-devices)
      (add-to-list 'tramp-devices
                   (list string (length tramp-devices))))
    (cons -1 (nth 1 (assoc string tramp-devices)))))

(defun tramp-equal-remote (file1 file2)
  "Check, whether the remote parts of FILE1 and FILE2 are identical.
The check depends on method, user and host name of the files.  If
one of the components is missing, the default values are used.
The local file name parts of FILE1 and FILE2 are not taken into
account.

Example:

  (tramp-equal-remote \"/ssh::/etc\" \"/<your host name>:/home\")

would yield `t'.  On the other hand, the following check results in nil:

  (tramp-equal-remote \"/sudo::/etc\" \"/su::/etc\")"
  (and (stringp (file-remote-p file1))
       (stringp (file-remote-p file2))
       (string-equal (file-remote-p file1) (file-remote-p file2))))

(defun tramp-get-method-parameter (method param)
  "Return the method parameter PARAM.
If the `tramp-methods' entry does not exist, return nil."
  (let ((entry (assoc param (assoc method tramp-methods))))
    (when entry (cadr entry))))

(defun tramp-mode-string-to-int (mode-string)
  "Converts a ten-letter `drwxrwxrwx'-style mode string into mode bits."
  (let* (case-fold-search
         (mode-chars (string-to-vector mode-string))
         (owner-read (aref mode-chars 1))
         (owner-write (aref mode-chars 2))
         (owner-execute-or-setid (aref mode-chars 3))
         (group-read (aref mode-chars 4))
         (group-write (aref mode-chars 5))
         (group-execute-or-setid (aref mode-chars 6))
         (other-read (aref mode-chars 7))
         (other-write (aref mode-chars 8))
         (other-execute-or-sticky (aref mode-chars 9)))
    (save-match-data
      (logior
       (cond
        ((char-equal owner-read ?r) (tramp-compat-octal-to-decimal "00400"))
        ((char-equal owner-read ?-) 0)
        (t (error "Second char `%c' must be one of `r-'" owner-read)))
       (cond
        ((char-equal owner-write ?w) (tramp-compat-octal-to-decimal "00200"))
        ((char-equal owner-write ?-) 0)
        (t (error "Third char `%c' must be one of `w-'" owner-write)))
       (cond
        ((char-equal owner-execute-or-setid ?x)
         (tramp-compat-octal-to-decimal "00100"))
        ((char-equal owner-execute-or-setid ?S)
         (tramp-compat-octal-to-decimal "04000"))
        ((char-equal owner-execute-or-setid ?s)
         (tramp-compat-octal-to-decimal "04100"))
        ((char-equal owner-execute-or-setid ?-) 0)
        (t (error "Fourth char `%c' must be one of `xsS-'"
                  owner-execute-or-setid)))
       (cond
        ((char-equal group-read ?r) (tramp-compat-octal-to-decimal "00040"))
        ((char-equal group-read ?-) 0)
        (t (error "Fifth char `%c' must be one of `r-'" group-read)))
       (cond
        ((char-equal group-write ?w) (tramp-compat-octal-to-decimal "00020"))
        ((char-equal group-write ?-) 0)
        (t (error "Sixth char `%c' must be one of `w-'" group-write)))
       (cond
        ((char-equal group-execute-or-setid ?x)
         (tramp-compat-octal-to-decimal "00010"))
        ((char-equal group-execute-or-setid ?S)
         (tramp-compat-octal-to-decimal "02000"))
        ((char-equal group-execute-or-setid ?s)
         (tramp-compat-octal-to-decimal "02010"))
        ((char-equal group-execute-or-setid ?-) 0)
        (t (error "Seventh char `%c' must be one of `xsS-'"
                  group-execute-or-setid)))
       (cond
        ((char-equal other-read ?r)
         (tramp-compat-octal-to-decimal "00004"))
        ((char-equal other-read ?-) 0)
        (t (error "Eighth char `%c' must be one of `r-'" other-read)))
       (cond
         ((char-equal other-write ?w) (tramp-compat-octal-to-decimal "00002"))
         ((char-equal other-write ?-) 0)
         (t (error "Nineth char `%c' must be one of `w-'" other-write)))
       (cond
        ((char-equal other-execute-or-sticky ?x)
         (tramp-compat-octal-to-decimal "00001"))
        ((char-equal other-execute-or-sticky ?T)
         (tramp-compat-octal-to-decimal "01000"))
        ((char-equal other-execute-or-sticky ?t)
         (tramp-compat-octal-to-decimal "01001"))
        ((char-equal other-execute-or-sticky ?-) 0)
        (t (error "Tenth char `%c' must be one of `xtT-'"
                  other-execute-or-sticky)))))))

(defun tramp-local-host-p (vec)
  "Return t if this points to the local host, nil otherwise."
  ;; We cannot use `tramp-file-name-real-host'.  A port is an
  ;; indication for an ssh tunnel or alike.
  (let ((host (tramp-file-name-host vec)))
    (and
     (stringp host)
     (string-match tramp-local-host-regexp host)
     ;; The method shall be applied to one of the shell file name
     ;; handler.  `tramp-local-host-p' is also called for "smb" and
     ;; alike, where it must fail.
     (tramp-get-method-parameter
      (tramp-file-name-method vec) 'tramp-login-program)
     ;; The local temp directory must be writable for the other user.
     (file-writable-p
      (tramp-make-tramp-file-name
       (tramp-file-name-method vec)
       (tramp-file-name-user vec)
       host
       (tramp-compat-temporary-file-directory)))
     ;; On some systems, chown runs only for root.
     (or (zerop (user-uid))
         ;; This is defined in tramp-sh.el.  Let's assume this is
         ;; loaded already.
         (zerop (tramp-compat-funcall 'tramp-get-remote-uid vec 'integer))))))

(defun tramp-get-remote-tmpdir (vec)
  "Return directory for temporary files on the remote host identified by VEC."
  (with-connection-property vec "tmpdir"
    (let ((dir (tramp-make-tramp-file-name
                (tramp-file-name-method vec)
                (tramp-file-name-user vec)
                (tramp-file-name-host vec)
                (or
                 (tramp-get-method-parameter
                  (tramp-file-name-method vec) 'tramp-tmpdir)
                 "/tmp"))))
      (if (and (file-directory-p dir) (file-writable-p dir))
          dir
        (tramp-error vec 'file-error "Directory %s not accessible" dir)))))

(defun tramp-make-tramp-temp-file (vec)
  "Create a temporary file on the remote host identified by VEC.
Return the local name of the temporary file."
  (let ((prefix (expand-file-name
                 tramp-temp-name-prefix (tramp-get-remote-tmpdir vec)))
        result)
    (while (not result)
      ;; `make-temp-file' would be the natural choice for
      ;; implementation.  But it calls `write-region' internally,
      ;; which also needs a temporary file - we would end in an
      ;; infinite loop.
      (setq result (make-temp-name prefix))
      (if (file-exists-p result)
          (setq result nil)
        ;; This creates the file by side effect.
        (set-file-times result)
        (set-file-modes result (tramp-compat-octal-to-decimal "0700"))))

    ;; Return the local part.
    (with-parsed-tramp-file-name result nil localname)))

(defun tramp-delete-temp-file-function ()
  "Remove temporary files related to current buffer."
  (when (stringp tramp-temp-buffer-file-name)
    (ignore-errors (delete-file tramp-temp-buffer-file-name))))

(add-hook 'kill-buffer-hook 'tramp-delete-temp-file-function)
(add-hook 'tramp-unload-hook
          (lambda ()
            (remove-hook 'kill-buffer-hook
                         'tramp-delete-temp-file-function)))

;;; Auto saving to a special directory:

(unless (tramp-exists-file-name-handler 'make-auto-save-file-name)
  (defadvice make-auto-save-file-name
    (around tramp-advice-make-auto-save-file-name () activate)
    "Invoke `tramp-*-handle-make-auto-save-file-name' for Tramp files."
    (if (tramp-tramp-file-p (buffer-file-name))
        ;; We cannot call `tramp-handle-make-auto-save-file-name'
        ;; directly, because this would bypass the locking mechanism.
        (setq ad-return-value
              (tramp-file-name-handler 'make-auto-save-file-name))
      ad-do-it))
  (add-hook
   'tramp-unload-hook
   (lambda ()
     (ad-remove-advice
      'make-auto-save-file-name
      'around 'tramp-advice-make-auto-save-file-name)
     (ad-activate 'make-auto-save-file-name))))

;; In XEmacs < 21.5, autosaved remote files have permission 0666 minus
;; umask. This is a security threat.

(defun tramp-set-auto-save-file-modes ()
  "Set permissions of autosaved remote files to the original permissions."
  (let ((bfn (buffer-file-name)))
    (when (and (tramp-tramp-file-p bfn)
               (buffer-modified-p)
               (stringp buffer-auto-save-file-name)
               (not (equal bfn buffer-auto-save-file-name)))
      (unless (file-exists-p buffer-auto-save-file-name)
        (write-region "" nil buffer-auto-save-file-name))
      ;; Permissions should be set always, because there might be an old
      ;; auto-saved file belonging to another original file.  This could
      ;; be a security threat.
      (set-file-modes
       buffer-auto-save-file-name
       (or (file-modes bfn) (tramp-compat-octal-to-decimal "0600"))))))

(unless (and (featurep 'xemacs)
             (= emacs-major-version 21)
             (> emacs-minor-version 4))
  (add-hook 'auto-save-hook 'tramp-set-auto-save-file-modes)
  (add-hook 'tramp-unload-hook
            (lambda ()
              (remove-hook 'auto-save-hook 'tramp-set-auto-save-file-modes))))

(defun tramp-subst-strs-in-string (alist string)
  "Replace all occurrences of the string FROM with TO in STRING.
ALIST is of the form ((FROM . TO) ...)."
  (save-match-data
    (while alist
      (let* ((pr (car alist))
             (from (car pr))
             (to (cdr pr)))
        (while (string-match (regexp-quote from) string)
          (setq string (replace-match to t t string)))
        (setq alist (cdr alist))))
    string))

;;; Compatibility functions section:

(defun tramp-read-passwd (proc &optional prompt)
  "Read a password from user (compat function).
Consults the auth-source package.
Invokes `password-read' if available, `read-passwd' else."
  (let* ((key (tramp-make-tramp-file-name
               tramp-current-method tramp-current-user
               tramp-current-host ""))
         (pw-prompt
          (or prompt
              (with-current-buffer (process-buffer proc)
                (tramp-check-for-regexp proc tramp-password-prompt-regexp)
                (format "%s for %s " (capitalize (match-string 1)) key))))
         auth-info auth-passwd)
    (with-parsed-tramp-file-name key nil
      (prog1
          (or
           ;; See if auth-sources contains something useful, if it's
           ;; bound.  `auth-source-user-or-password' is an obsoleted
           ;; function, it has been replaced by `auth-source-search'.
           (and (boundp 'auth-sources)
                (tramp-get-connection-property v "first-password-request" nil)
                ;; Try with Tramp's current method.
                (if (fboundp 'auth-source-search)
                    (setq auth-info
                          (tramp-compat-funcall
                           'auth-source-search
                           :max 1
                           :user (or tramp-current-user t)
                           :host tramp-current-host
                           :port tramp-current-method)
                          auth-passwd (plist-get (nth 0 auth-info) :secret)
                          auth-passwd (if (functionp auth-passwd)
                                          (funcall auth-passwd)
                                        auth-passwd))
                  (tramp-compat-funcall
                   'auth-source-user-or-password
                   "password" tramp-current-host tramp-current-method)))
           ;; Try the password cache.
           (when (functionp 'password-read)
             (unless (tramp-get-connection-property
                      v "first-password-request" nil)
               (tramp-compat-funcall 'password-cache-remove key))
             (let ((password
                    (tramp-compat-funcall 'password-read pw-prompt key)))
               (tramp-compat-funcall 'password-cache-add key password)
               password))
           ;; Else, get the password interactively.
           (read-passwd pw-prompt))
        (tramp-set-connection-property v "first-password-request" nil)))))

(defun tramp-clear-passwd (vec)
  "Clear password cache for connection related to VEC."
  (tramp-compat-funcall
   'password-cache-remove
   (tramp-make-tramp-file-name
    (tramp-file-name-method vec)
    (tramp-file-name-user vec)
    (tramp-file-name-host vec)
    "")))

;; Snarfed code from time-date.el and parse-time.el

(defconst tramp-half-a-year '(241 17024)
"Evaluated by \"(days-to-time 183)\".")

(defconst tramp-parse-time-months
  '(("jan" . 1) ("feb" . 2) ("mar" . 3)
    ("apr" . 4) ("may" . 5) ("jun" . 6)
    ("jul" . 7) ("aug" . 8) ("sep" . 9)
    ("oct" . 10) ("nov" . 11) ("dec" . 12))
  "Alist mapping month names to integers.")

(defun tramp-time-less-p (t1 t2)
  "Say whether time value T1 is less than time value T2."
  (unless t1 (setq t1 '(0 0)))
  (unless t2 (setq t2 '(0 0)))
  (or (< (car t1) (car t2))
      (and (= (car t1) (car t2))
           (< (nth 1 t1) (nth 1 t2)))))

(defun tramp-time-subtract (t1 t2)
  "Subtract two time values.
Return the difference in the format of a time value."
  (unless t1 (setq t1 '(0 0)))
  (unless t2 (setq t2 '(0 0)))
  (let ((borrow (< (cadr t1) (cadr t2))))
    (list (- (car t1) (car t2) (if borrow 1 0))
          (- (+ (if borrow 65536 0) (cadr t1)) (cadr t2)))))

(defun tramp-time-diff (t1 t2)
  "Return the difference between the two times, in seconds.
T1 and T2 are time values (as returned by `current-time' for example)."
  (cond ((and (fboundp 'subtract-time)
              (fboundp 'float-time))
         (tramp-compat-funcall
          'float-time (tramp-compat-funcall 'subtract-time t1 t2)))
        ((and (fboundp 'subtract-time)
              (fboundp 'time-to-seconds))
         (tramp-compat-funcall
          'time-to-seconds (tramp-compat-funcall 'subtract-time t1 t2)))
        ((fboundp 'itimer-time-difference)
         (tramp-compat-funcall
          'itimer-time-difference
          (if (< (length t1) 3) (append t1 '(0)) t1)
          (if (< (length t2) 3) (append t2 '(0)) t2)))
        (t
         (let ((time (tramp-time-subtract t1 t2)))
           (+ (* (car time) 65536.0)
              (cadr time)
              (/ (or (nth 2 time) 0) 1000000.0))))))

;; Currently (as of Emacs 20.5), the function `shell-quote-argument'
;; does not deal well with newline characters.  Newline is replaced by
;; backslash newline.  But if, say, the string `a backslash newline b'
;; is passed to a shell, the shell will expand this into "ab",
;; completely omitting the newline.  This is not what was intended.
;; It does not appear to be possible to make the function
;; `shell-quote-argument' work with newlines without making it
;; dependent on the shell used.  But within this package, we know that
;; we will always use a Bourne-like shell, so we use an approach which
;; groks newlines.
;;
;; The approach is simple: we call `shell-quote-argument', then
;; massage the newline part of the result.
;;
;; This function should produce a string which is grokked by a Unix
;; shell, even if the Emacs is running on Windows.  Since this is the
;; kludges section, we bind `system-type' in such a way that
;; `shell-quote-arguments'  behaves as if on Unix.
;;
;; Thanks to Mario DeWeerd for the hint that it is sufficient for this
;; function to work with Bourne-like shells.
;;
;; CCC: This function should be rewritten so that
;; `shell-quote-argument' is not used.  This way, we are safe from
;; changes in `shell-quote-argument'.
;;;###tramp-autoload
(defun tramp-shell-quote-argument (s)
  "Similar to `shell-quote-argument', but groks newlines.
Only works for Bourne-like shells."
  (let ((system-type 'not-windows))
    (save-match-data
      (let ((result (shell-quote-argument s))
            (nl (regexp-quote (format "\\%s" tramp-rsh-end-of-line))))
        (when (and (>= (length result) 2)
                   (string= (substring result 0 2) "\\~"))
          (setq result (substring result 1)))
        (while (string-match nl result)
          (setq result (replace-match (format "'%s'" tramp-rsh-end-of-line)
                                      t t result)))
        result))))

;; Checklist for `tramp-unload-hook'
;; - Unload all `tramp-*' packages
;; - Reset `file-name-handler-alist'
;; - Cleanup hooks where Tramp functions are in
;; - Cleanup advised functions
;; - Cleanup autoloads
;;;###autoload
(defun tramp-unload-tramp ()
  "Discard Tramp from loading remote files."
  (interactive)
  ;; ange-ftp settings must be enabled.
  (tramp-compat-funcall 'tramp-ftp-enable-ange-ftp)
  ;; Maybe it's not loaded yet.
  (ignore-errors (unload-feature 'tramp 'force)))

(provide 'tramp)

;;; TODO:

;; * Rewrite `tramp-shell-quote-argument' to abstain from using
;;   `shell-quote-argument'.
;; * In Emacs 21, `insert-directory' shows total number of bytes used
;;   by the files in that directory.  Add this here.
;; * Avoid screen blanking when hitting `g' in dired.  (Eli Tziperman)
;; * Make ffap.el grok Tramp filenames.  (Eli Tziperman)
;; * abbreviate-file-name
;; * Better error checking.  At least whenever we see something
;;   strange when doing zerop, we should kill the process and start
;;   again.  (Greg Stark)
;; * Username and hostname completion.
;; ** Try to avoid usage of `last-input-event' in `tramp-completion-mode-p'.
;; ** Unify `tramp-parse-{rhosts,shosts,sconfig,hosts,passwd,netrc}'.
;;    Code is nearly identical.
;; * Make `tramp-default-user' obsolete.
;; * Implement a general server-local-variable mechanism, as there are
;;   probably other variables that need different values for different
;;   servers too.  The user could then configure a variable (such as
;;   tramp-server-local-variable-alist) to define any such variables
;;   that they need to, which would then be let bound as appropriate
;;   in tramp functions.  (Jason Rumney)
;; * IMHO, it's a drawback that currently Tramp doesn't support
;;   Unicode in Dired file names by default.  Is it possible to
;;   improve Tramp to set LC_ALL to "C" only for commands where Tramp
;;   expects English?  Or just to set LC_MESSAGES to "C" if Tramp
;;   expects only English messages?  (Juri Linkov)
;; * Make shadowfile.el grok Tramp filenames.  (Bug#4526, Bug#4846)
;; * I was wondering if it would be possible to use tramp even if I'm
;;   actually using sshfs.  But when I launch a command I would like
;;   to get it executed on the remote machine where the files really
;;   are.  (Andrea Crotti)
;; * Run emerge on two remote files.  Bug is described here:
;;   <http://www.mail-archive.com/tramp-devel@nongnu.org/msg01041.html>.
;;   (Bug#6850)
;; * It would be very useful if it were possible to load or save a
;;   buffer using Tramp in a non-blocking way so that use of Emacs on
;;   other buffers could continue.  (Bug#9617)

;;; tramp.el ends here

;; Local Variables:
;; mode: Emacs-Lisp
;; coding: utf-8
;; End: