inets,tftp: Break out TFTP from inets

- Create directory structure
- Move code, tests, documentation from inets
- Add inets_tftp_wrapper
- Add tftp app to run-dialyzer script

Change-Id: I6a142ae66cecb9a1821cbf9ea6a45f66a836763d

6 files changed, 4 insertions, 657 deletions

diff --git a/lib/inets/doc/src/Makefile b/lib/inets/doc/src/Makefile
index d66ef31ba6..90c1258d4a 100644
--- a/lib/inets/doc/src/Makefile
+++ b/lib/inets/doc/src/Makefile
@@ -47,7 +47,6 @@ XML_CHAPTER_FILES = \
 
 XML_REF3_FILES = \
 	inets.xml \
-	tftp.xml \
 	http_uri.xml\
 	httpc.xml\
 	httpd.xml \
diff --git a/lib/inets/doc/src/inets.xml b/lib/inets/doc/src/inets.xml
index 9b17567fd4..eb4e51584f 100644
--- a/lib/inets/doc/src/inets.xml
+++ b/lib/inets/doc/src/inets.xml
@@ -189,8 +189,8 @@
   <section>
     <title>SEE ALSO</title>
     <p><seealso marker="httpc">httpc(3)</seealso>,
-      <seealso marker="httpd">httpd(3)</seealso>,
-      <seealso marker="tftp">tftp(3)</seealso></p>
+    <seealso marker="httpd">httpd(3)</seealso>
+    </p>
   </section>
   
 </erlref>
diff --git a/lib/inets/doc/src/introduction.xml b/lib/inets/doc/src/introduction.xml
index c006599a21..faf911f188 100644
--- a/lib/inets/doc/src/introduction.xml
+++ b/lib/inets/doc/src/introduction.xml
@@ -37,7 +37,6 @@
     <p><c>Inets</c> is a container for Internet clients and servers
       including the following:</p>
       <list type="bulleted">
-       <item>A TFTP client and server</item>
        <item>An <term id="HTTP"></term> client and server</item>
      </list>
      <p>The HTTP client and server are HTTP 1.1 compliant as
@@ -49,7 +48,7 @@
     <title>Prerequisites</title>
     <p>It is assumed that the reader is familiar with the Erlang
       programming language, concepts of OTP, and has a basic
-      understanding of the TFTP and HTTP protocols.</p>
+      understanding of and HTTP protocol.</p>
   </section>
 </chapter>
 
diff --git a/lib/inets/doc/src/part.xml b/lib/inets/doc/src/part.xml
index e7a786d47b..b9c8ed674c 100644
--- a/lib/inets/doc/src/part.xml
+++ b/lib/inets/doc/src/part.xml
@@ -33,7 +33,6 @@
     <p>The <c>Inets</c> application provides a set of 
     Internet-related services as follows:</p>
       <list type="bulleted">
-       <item>A TFTP client and server</item>
        <item>An <term id="HTTP"></term> client and server</item>
      </list>
      <p>The HTTP client and server are HTTP 1.1 compliant as
diff --git a/lib/inets/doc/src/ref_man.xml b/lib/inets/doc/src/ref_man.xml
index 33886d1a41..58c1a651f9 100644
--- a/lib/inets/doc/src/ref_man.xml
+++ b/lib/inets/doc/src/ref_man.xml
@@ -30,12 +30,9 @@
     <file>ref_man.xml</file>
   </header>
   <description>
-    <p><c>Inets</c> is a container for Internet clients and
-    servers. An HTTP client and server, and
-    a TFTP client and server are incorporated in <c>Inets</c>.</p>
+    <p><c>Inets</c> is a container for an HTTP client and server.</p>
   </description>
   <xi:include href="inets.xml"/>
-  <xi:include href="tftp.xml"/>
   <xi:include href="httpc.xml"/>
   <xi:include href="httpd.xml"/>
   <xi:include href="httpd_custom_api.xml"/>
diff --git a/lib/inets/doc/src/tftp.xml b/lib/inets/doc/src/tftp.xml
deleted file mode 100644
index 10398f5088..0000000000
--- a/lib/inets/doc/src/tftp.xml
+++ /dev/null
@@ -1,647 +0,0 @@
-<?xml version="1.0" encoding="utf-8" ?>
-<!DOCTYPE erlref SYSTEM "erlref.dtd">
-
-<erlref>
-  <header>
-    <copyright>
-      <year>2006</year><year>2015</year>
-      <holder>Ericsson AB. All Rights Reserved.</holder>
-    </copyright>
-    <legalnotice>
-      Licensed under the Apache License, Version 2.0 (the "License");
-      you may not use this file except in compliance with the License.
-      You may obtain a copy of the License at
- 
-          http://www.apache.org/licenses/LICENSE-2.0
-
-      Unless required by applicable law or agreed to in writing, software
-      distributed under the License is distributed on an "AS IS" BASIS,
-      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-      See the License for the specific language governing permissions and
-      limitations under the License.
-    
-    </legalnotice>
-
-    <title>tftp</title>
-    <prepared></prepared>
-    <docno></docno>
-    <date></date>
-    <rev></rev>
-  </header>
-  <module>tftp</module>
-  <modulesummary>Trivial FTP.</modulesummary>
-  <description>
-    <p>This is a complete implementation of the following IETF standards:</p>
-    <list type="bulleted">
-      <item>RFC 1350, The TFTP Protocol (revision 2)</item>
-      <item>RFC 2347, TFTP Option Extension</item>
-      <item>RFC 2348, TFTP Blocksize Option</item>
-      <item>RFC 2349, TFTP Timeout Interval and Transfer Size Options</item>
-    </list>
-    <p>The only feature that not is implemented is
-      the "netascii" transfer mode.</p>
-    <p>The <seealso marker="#start/1">start/1</seealso> function starts
-      a daemon process listening for UDP packets on a port. When it
-      receives a request for read or write, it spawns a temporary server
-      process handling the transfer.</p>
-    <p>On the client side,
-      function <seealso marker="#read_file/3">read_file/3</seealso>
-      and <seealso marker="#write_file/3">write_file/3</seealso>
-      spawn a temporary client process establishing
-      contact with a TFTP daemon and perform the file transfer.</p>
-    <p><c>tftp</c> uses a callback module to handle the file
-      transfer. Two such callback modules are provided,
-      <c>tftp_binary</c> and <c>tftp_file</c>. See
-      <seealso marker="#read_file/3">read_file/3</seealso> and
-      <seealso marker="#write_file/3">write_file/3</seealso> for details.
-      You can also implement your own callback modules, see 
-      <seealso marker="#tftp_callback">CALLBACK FUNCTIONS</seealso>. 
-      A callback module provided by
-      the user is registered using option <c>callback</c>, see
-      <seealso marker="#options">DATA TYPES</seealso>.</p>
-  </description>
-  
- <section>
-    <title>TFTP SERVER SERVICE START/STOP</title>
-    
-    <p>A TFTP server can be configured to start statically when starting
-      the <c>Inets</c> application. Alternatively, it can be started dynamically
-      (when <c>Inets</c> is already started) by calling the <c>Inets</c> application 
-      API <c>inets:start(tftpd, ServiceConfig)</c> or
-      <c>inets:start(tftpd, ServiceConfig, How)</c>,
-      see <seealso marker="inets">inets(3)</seealso> for details.
-      The <c>ServiceConfig</c> for TFTP is described in
-      the <seealso marker="#options">DATA TYPES</seealso>
-      section.</p>
-    
-    <p>The TFTP server can be stopped using <c>inets:stop(tftpd, Pid)</c>,
-      see <seealso marker="inets">inets(3)</seealso> for details.</p>
-
-    <p>The TPFT client is of such a temporary nature that it is not
-      handled as a service in the <c>Inets</c> service framework.</p>
-    
-  </section>
-  
-  <section>
-    <marker id="options"></marker>
-    <title>DATA TYPES</title>
-    <p><c>ServiceConfig = Options</c></p>
-    <p><c>Options = [option()]</c></p>
-    <p>Most of the options are common for both the client and the server
-      side, but some of them differs a little. 
-      The available <c>option()</c>s are as follows:</p>
-    <taglist>
-      <tag><c>{debug, Level}</c></tag>
-      <item>
-        <p><c>Level = none | error | warning | brief | normal | verbose | all</c></p>
-        <p>Controls the level of debug printouts. 
-	Default is <c>none</c>.</p>
-      </item>
-      <tag><c>{host, Host}</c></tag>
-      <item>
-        <p><c>Host = hostname()</c>, see
-          <seealso marker="kernel:inet">inet(3)</seealso>.</p>
-        <p>The name or IP address of the host where the TFTP daemon
-          resides. This option is only used by the client.</p>
-      </item>
-      <tag><c>{port, Port}</c></tag>
-      <item>
-        <p><c>Port = int()</c></p>
-        <p>The TFTP port where the daemon listens. Defaults is
-          the standardized number 69. On the server side, it can
-          sometimes make sense to set it to 0, meaning that
-          the daemon just picks a free port (which one is
-          returned by function <c>info/1</c>).</p>
-        <p>If a socket is connected already, option
-          <c>{udp, [{fd, integer()}]}</c> can be used to pass the
-          open file descriptor to <c>gen_udp</c>. This can be automated
-          by using a command-line argument stating the
-          prebound file descriptor number. For example, if the
-          port is 69 and file descriptor 22 is opened by
-          <c>setuid_socket_wrap</c>, the command-line argument
-          "-tftpd_69 22" triggers the prebound file
-          descriptor 22 to be used instead of opening port 69.
-          The UDP option <c>{udp, [{fd, 22}]}</c> is automatically added.
-          See <c>init:get_argument/</c> about command-line arguments and
-          <c>gen_udp:open/2</c> about UDP options.</p>
-      </item>
-      <tag><c>{port_policy, Policy}</c></tag>
-      <item>
-        <p><c>Policy = random | Port | {range, MinPort, MaxPort}</c></p>
-	<p><c>Port = MinPort = MaxPort = int()</c></p>
-        <p>Policy for the selection of the temporary port that is used
-          by the server/client during the file transfer. Default is
-          <c>random</c>, which is the standardized policy. With this
-          policy a randomized free port is used. A single port or a range
-          of ports can be useful if the protocol passes through a
-          firewall.</p>
-      </item>
-      <tag><c>{udp, Options}</c></tag>
-      <item>
-        <p><c>Options = [Opt]</c>, see
-          <seealso marker="kernel:gen_udp#open/1">gen_udp:open/2</seealso>.</p>
-      </item>
-      <tag><c>{use_tsize, Bool}</c></tag>
-      <item>
-        <p><c>Bool = bool()</c></p>
-        <p>Flag for automated use of option <c>tsize</c>. With
-          this set to <c>true</c>, the <c>write_file/3</c> client
-          determines the filesize and sends it to the server as
-          the standardized <c>tsize</c> option. A <c>read_file/3</c>
-          client acquires only a filesize from the server by sending
-          a zero <c>tsize</c>.</p>
-      </item>
-      <tag><c>{max_tsize, MaxTsize}</c></tag>
-      <item>
-        <p><c>MaxTsize = int() | infinity</c></p>
-        <p>Threshold for the maximal filesize in bytes. The transfer
-          is aborted if the limit is exceeded. 
-	  Default is <c>infinity</c>.</p>
-      </item>
-      <tag><c>{max_conn, MaxConn}</c></tag>
-      <item>
-        <p><c>MaxConn = int() | infinity</c></p>
-        <p>Threshold for the maximal number of active connections.
-          The daemon rejects the setup of new connections if
-          the limit is exceeded. Default is <c>infinity</c>.</p>
-      </item>
-      <tag><c>{TftpKey, TftpVal}</c></tag>
-      <item>
-        <p><c>TftpKey = string()</c>          <br></br>
-<c>TftpVal = string()</c></p>
-        <p>Name and value of a TFTP option.</p>
-      </item>
-      <tag><c>{reject, Feature}</c></tag>
-      <item>
-        <p><c>Feature = Mode | TftpKey</c>          <br></br>
-<c>&nbsp;Mode = read | write</c>          <br></br>
-<c>&nbsp;TftpKey = string()</c></p>
-        <p>Controls which features to reject. This is
-          mostly useful for the server as it can restrict the use
-	  of certain TFTP options or read/write access.</p>
-      </item>
-      <tag><c>{callback, {RegExp, Module, State}}</c></tag>
-      <item>
-        <p><c>RegExp = string()</c>          <br></br>
-<c>Module = atom()</c>          <br></br>
-<c>State = term()</c></p>
-        <p>Registration of a callback module. When a file is to be
-          transferred, its local filename is matched to the regular
-          expressions of the registered callbacks. The first matching
-          callback is used during the transfer. See
-          <seealso marker="#read_file/3">read_file/3</seealso> and
-          <seealso marker="#write_file/3">write_file/3</seealso>.
-          </p>
-        <p>The callback module must implement the <c>tftp</c> behavior, see
-          <seealso marker="#tftp_callback">CALLBACK FUNCTIONS</seealso>.</p>
-      </item>
-
-   <tag><c>{logger, Module}</c></tag>
-      <item>
-        <p><c>Module = module()()</c></p>
-
-        <p>Callback module for customized logging of errors, warnings, and
-	  info messages. The callback module must implement the
-	  <c>tftp_logger</c> behavior, see
-          <seealso marker="#tftp_logger">LOGGER FUNCTIONS</seealso>.
-          The default module is <c>tftp_logger</c>.</p>
-      </item>
-
-      <tag><c>{max_retries, MaxRetries}</c></tag>
-      <item>
-        <p><c>MaxRetries = int()</c></p>
-
-        <p>Threshold for the maximal number of retries. By default
-	  the server/client tries to resend a message up to
-	  five times when the time-out expires.</p>
-      </item>
-    </taglist>
-  </section>
-
-  <funcs>
-    <func>
-      <name>change_config(daemons, Options) -> [{Pid, Result}]</name>
-      <fsummary>Changes configuration for all daemons.
-      </fsummary>
-      <type>
-        <v>Options = [option()]</v>
-        <v>Pid = pid()</v>
-        <v>Result = ok | {error, Reason}</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Changes configuration for all TFTP daemon processes. </p>
-      </desc>
-    </func>
-
-    <func>
-      <name>change_config(servers, Options) -> [{Pid, Result}]</name>
-      <fsummary>Changes configuration for all servers.
-      </fsummary>
-      <type>
-        <v>Options = [option()]</v>
-        <v>Pid = pid()</v>
-        <v>Result = ok | {error, Reason}</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Changes configuration for all TFTP server processes.</p>
-      </desc>
-    </func>
-
-    <func>
-      <name>change_config(Pid, Options) -> Result</name>
-      <fsummary>Changes configuration for a TFTP daemon, server, 
-      or client process.</fsummary>
-      <type>
-        <v>Pid = pid()</v>
-        <v>Options = [option()]</v>
-        <v>Result = ok | {error, Reason}</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Changes configuration for a TFTP daemon, server, or client process.</p>
-      </desc>
-    </func>
-    
-    <func>
-      <name>info(daemons) -> [{Pid, Options}]</name>
-      <fsummary>Returns information about all daemons.</fsummary>
-      <type>
-        <v>Pid = [pid()()]</v>
-        <v>Options = [option()]</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Returns information about all TFTP daemon processes.</p>
-      </desc>
-    </func>
-
-    <func>
-      <name>info(servers) -> [{Pid, Options}]</name>
-      <fsummary>Returns information about all servers.</fsummary>
-      <type>
-        <v>Pid = [pid()()]</v>
-        <v>Options = [option()]</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Returns information about all TFTP server processes. </p>
-      </desc>
-    </func>
-
-    <func>
-      <name>info(Pid) -> {ok, Options} | {error, Reason}</name>
-      <fsummary>Returns information about a daemon, server, or client process.</fsummary>
-      <type>
-        <v>Options = [option()]</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Returns information about a TFTP daemon, server, or client process.</p>
-      </desc>
-    </func>
-       
-    <func>
-      <name>read_file(RemoteFilename, LocalFilename, Options) -> {ok, LastCallbackState} | {error, Reason}</name>
-      <fsummary>Reads a (virtual) file from a TFTP server.</fsummary>
-      <type>
-        <v>RemoteFilename = string()</v>
-        <v>LocalFilename = binary | string()</v>
-        <v>Options = [option()]</v>
-        <v>LastCallbackState = term()</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Reads a (virtual) file <c>RemoteFilename</c> from a TFTP
-	server.</p>
-	<p>If <c>LocalFilename</c> is the atom <c>binary</c>,
-	<c>tftp_binary</c> is used as callback module. It concatenates
-	all transferred blocks and returns them as one single binary
-	in <c>LastCallbackState</c>.</p>
-	<p>If <c>LocalFilename</c> is a string and there are no
-	registered callback modules, <c>tftp_file</c> is used as
-	callback module. It writes each transferred block to the file
-	named <c>LocalFilename</c> and returns the number of
-	transferred bytes in <c>LastCallbackState</c>.</p>
-	<p>If <c>LocalFilename</c> is a string and there are registered
-	callback modules, <c>LocalFilename</c> is tested against
-	the regexps of these and the callback module corresponding to
-	the first match is used, or an error tuple is returned if no
-	matching regexp is found.</p>
-      </desc>	
-    </func>
-    
-    <func>
-       <name>start(Options) -> {ok, Pid} | {error, Reason}</name>
-      <fsummary>Starts a daemon process.</fsummary>
-      <type>
-        <v>Options = [option()]</v>
-        <v>Pid = pid()</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Starts a daemon process listening for UDP packets on a
-	port. When it receives a request for read or write, it spawns
-	a temporary server process handling the actual transfer
-	of the (virtual) file.</p>
-      </desc>
-    </func>
-
-    <func>
-      <name>write_file(RemoteFilename, LocalFilename, Options) -> {ok, LastCallbackState} | {error, Reason}</name>
-      <fsummary>Writes a (virtual) file to a TFTP server.</fsummary>
-      <type>
-        <v>RemoteFilename = string()</v>
-        <v>LocalFilename = binary() | string()</v>
-        <v>Options = [option()]</v>
-        <v>LastCallbackState = term()</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Writes a (virtual) file <c>RemoteFilename</c> to a TFTP
-          server.</p>
-        <p>If <c>LocalFilename</c> is a binary, <c>tftp_binary</c> is
-          used as callback module. The binary is transferred block by
-          block and the number of transferred bytes is returned in
-          <c>LastCallbackState</c>.</p>
-        <p>If <c>LocalFilename</c> is a string and there are no
-          registered callback modules, <c>tftp_file</c> is used as
-          callback module. It reads the file named <c>LocalFilename</c>
-          block by block and returns the number of transferred bytes
-          in <c>LastCallbackState</c>.</p>
-        <p>If <c>LocalFilename</c> is a string and there are registered
-	callback modules, <c>LocalFilename</c> is tested against
-	the regexps of these and the callback module corresponding to
-	the first match is used, or an error tuple is returned if no
-	matching regexp is found.</p>
-      </desc>
-    </func>
-  </funcs>
-
-  <section>
-    <marker id="tftp_callback"></marker>
-    <title>CALLBACK FUNCTIONS</title>
-    <p>A <c>tftp</c> callback module is to be implemented as a
-      <c>tftp</c> behavior and export the functions listed
-      in the following.</p>
-    <p>On the server side, the callback interaction starts with a call to
-      <c>open/5</c> with the registered initial callback state.
-      <c>open/5</c> is expected to open the (virtual) file. Then either
-      function <c>read/1</c> or <c>write/2</c> is invoked
-      repeatedly, once per transferred block. At each function call,
-      the state returned from the previous call is obtained. When
-      the last block is encountered, function <c>read/1</c> or
-      <c>write/2</c> is expected to close the (virtual) file
-      and return its last state. Function <c>abort/3</c> is only
-      used in error situations. Function <c>prepare/5</c> is not used on
-      the server side.</p>
-    <p>On the client side, the callback interaction is the same, but it
-      starts and ends a bit differently. It starts with a call to
-      <c>prepare/5</c> with the same arguments as <c>open/5</c> takes.
-      <c>prepare/5</c> is expected to validate the TFTP options
-      suggested by the user and to return the subset of them that it
-      accepts. Then the options are sent to the server, which performs
-      the same TFTP option negotiation procedure. The options that are
-      accepted by the server are forwarded to function <c>open/5</c>
-      on the client side. On the client side, function <c>open/5</c>
-      must accept all option as-is or reject the transfer. Then
-      the callback interaction follows the same pattern as described
-      for the server side. When the last block is encountered in
-      <c>read/1</c> or <c>write/2</c>, the returned state is forwarded to
-      the user and returned from <c>read_file</c>/3 or
-      <c>write_file/3</c>.</p>
-
-    <p> If a callback (performing the file access
-    in the TFTP server) takes too long time (more than
-    the double TFTP time-out), the server aborts the
-    connection and sends an error reply to the client.
-    This implies that the server releases resources
-    attached to the connection faster than before. The
-    server simply assumes that the client has given
-    up.</p>
-
-    <p>If the TFTP server receives yet another request from
-    the same client (same host and port) while it
-    already has an active connection to the client, it
-    ignores the new request if the request is
-    equal to the first one (same filename and options).
-    This implies that the (new) client will be served
-    by the already ongoing connection on the server
-    side. By not setting up yet another connection, in
-    parallel with the ongoing one, the server
-    consumes less resources.</p>
-    
-    <marker id="prepare"></marker>
-  </section>
-
-  <funcs>
-     <func>
-      <name>Module:abort(Code, Text, State) -> ok</name>
-      <fsummary>Aborts the file transfer.</fsummary>
-      <type>
-        <v>Code = undef | enoent | eacces | enospc</v>
-        <v>&nbsp;&nbsp;| badop | eexist | baduser | badopt</v>
-        <v>&nbsp;&nbsp;| int()</v>
-        <v>Text = string()</v>
-        <v>State = term()</v>
-      </type>
-      <desc>
-        <p>Invoked when the file transfer is aborted.</p>
-        <p>The callback function is expected to clean
-	up its used resources after the aborted file
-	transfer, such as closing open file
-	descriptors and so on. The function is not
-	invoked if any of the other callback
-	functions returns an error, as it is
-	expected that they already have cleaned up
-	the necessary resources. However, it is
-	invoked if the functions fail (crash).</p>
-      </desc>
-    </func>
-    
-      <func>
-      <name>Module:open(Peer, Access, Filename, Mode, SuggestedOptions, State) -> {ok, AcceptedOptions, NewState} | {error, {Code, Text}}</name>
-      <fsummary>Opens a file for read or write access.</fsummary>
-      <type>
-        <v>Peer = {PeerType, PeerHost, PeerPort}</v>
-        <v>PeerType = inet | inet6</v>
-        <v>PeerHost = ip_address()</v>
-        <v>PeerPort = integer()</v>
-        <v>Access = read | write</v>
-        <v>Filename = string()</v>
-        <v>Mode = string()</v>
-        <v>SuggestedOptions = AcceptedOptions = [{Key, Value}]</v>
-        <v>&nbsp;Key = Value = string()</v>
-        <v>State = InitialState | term()</v>
-        <v>&nbsp;InitialState = [] | [{root_dir, string()}]</v>
-        <v>NewState = term()</v>
-        <v>Code = undef | enoent | eacces | enospc</v>
-        <v>&nbsp;&nbsp;| badop | eexist | baduser | badopt</v>
-        <v>&nbsp;&nbsp;| int()</v>
-        <v>Text = string()</v>
-      </type>
-      <desc>
-        <p>Opens a file for read or write access.</p>
-        <p>On the client side, where the <c>open/5</c> call has been
-	preceded by a call to <c>prepare/5</c>, all options must be
-	accepted or rejected.</p>
-	<p>On the server side, where there is no preceding
-	<c>prepare/5</c> call, no new options can be added, but
-	those present in <c>SuggestedOptions</c> can be
-	omitted or replaced with new values in <c>AcceptedOptions</c>.</p>
-    
-	<marker id="read"></marker>
-      </desc>
-    </func>
-    
-    <func>
-      <name>Module:prepare(Peer, Access, Filename, Mode, SuggestedOptions, InitialState) -> {ok, AcceptedOptions, NewState} | {error, {Code, Text}}</name>
-      <fsummary>Prepares to open a file on the client side.</fsummary>
-      <type>
-        <v>Peer = {PeerType, PeerHost, PeerPort}</v>
-        <v>PeerType = inet | inet6</v>
-        <v>PeerHost = ip_address()</v>
-        <v>PeerPort = integer()</v>
-        <v>Access = read | write</v>
-        <v>Filename = string()</v>
-        <v>Mode = string()</v>
-        <v>SuggestedOptions = AcceptedOptions = [{Key, Value}]</v>
-        <v>&nbsp;Key = Value = string()</v>
-        <v>InitialState = [] | [{root_dir, string()}]</v>
-        <v>NewState = term()</v>
-        <v>Code = undef | enoent | eacces | enospc</v>
-        <v>&nbsp;&nbsp;| badop | eexist | baduser | badopt</v>
-        <v>&nbsp;&nbsp;| int()</v>
-        <v>Text = string()</v>
-      </type>
-      <desc>
-	<p>Prepares to open a file on the client side.</p>
-	<p>No new options can be added, but those present in
-	<c>SuggestedOptions</c> can be omitted or replaced with new
-	values in <c>AcceptedOptions</c>.</p>
-	<p>This is followed by a call to <c>open/4</c> before any
-	read/write access is performed. <c>AcceptedOptions</c> is
-	sent to the server, which replies with the options that it
-	accepts. These are then forwarded to <c>open/4</c> as
-	<c>SuggestedOptions</c>.</p>
-    
-	<marker id="open"></marker>
-      </desc>
-    </func>
-
-    <func>
-      <name>Module:read(State) -> {more, Bin, NewState} | {last, Bin, FileSize} | {error, {Code, Text}}</name>
-      <fsummary>Reads a chunk from the file.</fsummary>
-      <type>
-        <v>State = NewState = term()</v>
-        <v>Bin = binary()</v>
-        <v>FileSize = int()</v>
-        <v>Code = undef | enoent | eacces | enospc</v>
-        <v>&nbsp;&nbsp;| badop | eexist | baduser | badopt</v>
-        <v>&nbsp;&nbsp;| int()</v>
-        <v>Text = string()</v>
-      </type>
-      <desc>
-        <p>Reads a chunk from the file.</p>
-        <p>The callback function is expected to close
-	the file when the last file chunk is
-	encountered. When an error is encountered,
-	the callback function is expected to clean
-	up after the aborted file transfer, such as
-	closing open file descriptors, and so on. In both
-	cases there will be no more calls to any of
-	the callback functions.</p>
-    
-	<marker id="write"></marker>
-      </desc>
-    </func>
-
-    <func>
-      <name>Module:write(Bin, State) -> {more, NewState} | {last, FileSize} | {error, {Code, Text}}</name>
-      <fsummary>Writes a chunk to the file.</fsummary>
-      <type>
-        <v>Bin = binary()</v>
-        <v>State = NewState = term()</v>
-        <v>FileSize = int()</v>
-        <v>Code = undef | enoent | eacces | enospc</v>
-        <v>&nbsp;&nbsp;| badop | eexist | baduser | badopt</v>
-        <v>&nbsp;&nbsp;| int()</v>
-        <v>Text = string()</v>
-      </type>
-      <desc>
-        <p>Writes a chunk to the file.</p>
-        <p>The callback function is expected to close
-	the file when the last file chunk is
-	encountered. When an error is encountered,
-	the callback function is expected to clean
-	up after the aborted file transfer, such as
-	closing open file descriptors, and so on. In both
-	cases there will be no more calls to any of
-	the callback functions.</p>
-    
-	<marker id="abort"></marker>
-      </desc>
-    </func>
-  </funcs>
-  
-  <section>
-    <marker id="tftp_logger"></marker>
-    <title>LOGGER FUNCTIONS</title>
-    
-    <p>A <c>tftp_logger</c> callback module is to be implemented as a
-    <c>tftp_logger</c> behavior and export the following functions:</p>
-    
-    <marker id="error_msg"></marker>
-    </section>
-
-  <funcs>
-    <func>
-      <name>Logger:error_msg(Format, Data) -> ok | exit(Reason)</name>
-      <fsummary>Logs an error message.</fsummary>
-      <type>
-        <v>Format = string()</v>
-        <v>Data = [term()]</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-	<p>Logs an error message. 
-	See <c>error_logger:error_msg/2</c> for details.</p>
-	
-	<marker id="warning_msg"></marker>
-      </desc>
-    </func>
-
-    <func>
-      <name>Logger:info_msg(Format, Data) -> ok | exit(Reason)</name>
-      <fsummary>Logs an info message.</fsummary>
-      <type>
-        <v>Format = string()</v>
-        <v>Data = [term()]</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Logs an info message. 
-	See <c>error_logger:info_msg/2</c>  for details.</p>
-      </desc>
-    </func>
-    
-    <func>
-      <name>Logger:warning_msg(Format, Data) -> ok | exit(Reason)</name>
-      <fsummary>Logs a warning message.</fsummary>
-      <type>
-        <v>Format = string()</v>
-        <v>Data = [term()]</v>
-        <v>Reason = term()</v>
-      </type>
-      <desc>
-        <p>Logs a warning message. 
-	See <c>error_logger:warning_msg/2</c> for details.</p>
-	
-	<marker id="info_msg"></marker>
-      </desc>
-    </func>
-  </funcs>
-</erlref>
-
-