The R13B03 release.OTP_R13B03

1 files changed, 637 insertions, 0 deletions

diff --git a/lib/inets/doc/src/tftp.xml b/lib/inets/doc/src/tftp.xml
new file mode 100644
index 0000000000..96d6ae0dd5
--- /dev/null
+++ b/lib/inets/doc/src/tftp.xml
@@ -0,0 +1,637 @@
+<?xml version="1.0" encoding="latin1" ?>
+<!DOCTYPE erlref SYSTEM "erlref.dtd">
+
+<erlref>
+  <header>
+    <copyright>
+      <year>2006</year><year>2009</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      The contents of this file are subject to the Erlang Public License,
+      Version 1.1, (the "License"); you may not use this file except in
+      compliance with the License. You should have received a copy of the
+      Erlang Public License along with this software. If not, it can be
+      retrieved online at http://www.erlang.org/.
+    
+      Software distributed under the License is distributed on an "AS IS"
+      basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+      the License for the specific language governing rights 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 in this release is
+      the "netascii" transfer mode.</p>
+    <p>The <seealso marker="#start/1">start/1</seealso> function starts
+      a daemon process which listens for UDP packets on a port. When it
+      receives a request for read or write it spawns a temporary server
+      process which handles the actual transfer of the file.</p>
+    <p>On the client side
+      the <seealso marker="#read_file/3">read_file/3</seealso>
+      and <seealso marker="#write_file/3">write_file/3</seealso>
+      functions spawns a temporary client process which establishes
+      contact with a TFTP daemon and performs the actual transfer of
+      the file.</p>
+    <p><c>tftp</c> uses a callback module to handle the actual 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
+      more information about these. The user can also implement own
+      callback modules, see <seealso marker="#tftp_callback">CALLBACK FUNCTIONS</seealso> below. A callback module provided by
+      the user is registered using the <c>callback</c> option, see
+      <seealso marker="#options">DATA TYPES</seealso> below.</p>
+  </description>
+  
+ <section>
+    <title>TFTP SERVER SERVICE START/STOP </title>
+    
+    <p>A TFTP server can be configured to start statically when starting
+      the Inets application. Alternatively it can be started dynamically
+      (when Inets already is started) by calling the Inets 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 below in
+      the <seealso marker="#options">COMMON 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 Inets service framework.</p>
+    
+  </section>
+  
+  <section>
+    <marker id="options"></marker>
+    <title>COMMON DATA TYPES</title>
+    <pre>
+      ServiceConfig = Options
+      Options = [option()]
+      option() -- see below
+    </pre>
+    <p>Most of the options are common for both the client and the server
+      side, but some of them differs a little. Here are the available
+      options:</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. The 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. It defaults to
+          the standardized number 69. On the server side it may
+          sometimes make sense to set it to 0, which means that
+          the daemon just will pick a free port (which one is
+          returned by the <c>info/1</c> function).</p>
+        <p>If a socket has somehow already has been connected, the
+          {udp, [{fd, integer()}]} option can be used to pass the
+          open file descriptor to gen_udp. This can be automated
+          a bit by using a command line argument stating the
+          prebound file descriptor number. For example, if the
+          Port is 69 and the file descriptor 22 has been opened by
+          setuid_socket_wrap. Then the command line argument
+          "-tftpd_69 22" will trigger the prebound file
+          descriptor 22 to be used instead of opening port 69.
+          The UDP option {udp, [{fd, 22}]} automatically be added.
+          See init:get_argument/ about command line arguments and
+          gen_udp:open/2 about UDP options.</p>
+      </item>
+      <tag><c>{port_policy, Policy}</c></tag>
+      <item>
+        <p><c>Policy = random | Port | {range, MinPort, MaxPort}</c>          <br></br>
+<c>Port = MinPort = MaxPort = int()</c></p>
+        <p>Policy for the selection of the temporary port which is used
+          by the server/client during the file transfer. It defaults to
+          <c>random</c> which is the standardized policy. With this
+          policy a randomized free port used. A single port or a range
+          of ports can be useful if the protocol should pass 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 usage of the <c>tsize</c> option. With
+          this set to true, the <c>write_file/3</c> client will
+          determine the filesize and send it to the server as
+          the standardized <c>tsize</c> option. A <c>read_file/3</c>
+          client will just acquire 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
+          will be aborted if the limit is exceeded. It defaults to
+          <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 will reject the setup of new connections if
+          the limit is exceeded. It defaults to <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>The 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>Control which features that should be rejected. This is
+          mostly useful for the server as it may restrict usage 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 will be matched to the regular
+          expressions of the registered callbacks. The first matching
+          callback will be used the 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,
+          <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 error, warning and
+	  info messages. >The callback module must implement the
+	  <c>tftp_logger</c> behavior,
+          <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 will try to resend a message up to
+	  <c>5</c> times when the timeout expires.</p>
+      </item>
+    </taglist>
+  </section>
+
+  <funcs>
+    <func>
+      <name>start(Options) -> {ok, Pid} | {error, Reason}</name>
+      <fsummary>Start a daemon process</fsummary>
+      <type>
+        <v>Options = [option()]</v>
+        <v>Pid = pid()</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Starts a daemon process which listens for udp packets on a
+          port. When it receives a request for read or write it spawns
+          a temporary server process which handles the actual transfer
+          of the (virtual) file.</p>
+      </desc>
+    </func>
+    <func>
+      <name>read_file(RemoteFilename, LocalFilename, Options) -> {ok, LastCallbackState} | {error, Reason}</name>
+      <fsummary>Read 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>write_file(RemoteFilename, LocalFilename, Options) -> {ok, LastCallbackState} | {error, Reason}</name>
+      <fsummary>Write 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>
+
+    <func>
+      <name>info(daemons) -> [{Pid, Options}]</name>
+      <fsummary>Return information about all daemons</fsummary>
+      <type>
+        <v>Pid = [pid()()]</v>
+        <v>Options = [option()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Returns info about all TFTP daemon processes.
+        </p>
+      </desc>
+    </func>
+
+    <func>
+      <name>info(servers) -> [{Pid, Options}]</name>
+      <fsummary>Return information about all servers</fsummary>
+      <type>
+        <v>Pid = [pid()()]</v>
+        <v>Options = [option()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Returns info about all TFTP server processes.
+        </p>
+      </desc>
+    </func>
+
+    <func>
+      <name>info(Pid) -> {ok, Options} | {error, Reason}</name>
+      <fsummary>Return information about a daemon, server or client process</fsummary>
+      <type>
+        <v>Options = [option()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Returns info about a TFTP daemon, server or client process.</p>
+      </desc>
+    </func>
+
+   <func>
+      <name>change_config(daemons, Options) -> [{Pid, Result}]</name>
+      <fsummary>Changes config 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 config for all TFTP daemon processes
+        </p>
+      </desc>
+    </func>
+
+    <func>
+      <name>change_config(servers, Options) -> [{Pid, Result}]</name>
+      <fsummary>Changes config 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 config for all TFTP server processes
+        </p>
+      </desc>
+    </func>
+
+    <func>
+      <name>change_config(Pid, Options) -> Result</name>
+      <fsummary>Changes config 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 config for a TFTP daemon, server or client process</p>
+      </desc>
+    </func>
+    <func>
+      <name>start() -> ok | {error, Reason}</name>
+      <fsummary>Start the Inets application</fsummary>
+      <type>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Starts the Inets application.</p>
+      </desc>
+    </func>
+  </funcs>
+
+  <section>
+    <marker id="tftp_callback"></marker>
+    <title>CALLBACK FUNCTIONS</title>
+    <p>A <c>tftp</c> callback module should be implemented as a
+      <c>tftp</c> behavior and export the functions listed below.</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
+      the <c>read/1</c> or <c>write/2</c> functions are invoked
+      repeatedly, once per transferred block. At each function call
+      the state returned from the previous call is obtained. When
+      the last block has been encountered the <c>read/1</c> or
+      <c>write/2</c> functions is expected to close the (virtual) file
+      and return its last state. The <c>abort/3</c> function is only
+      used in error situations. <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 return the subset of them that it
+      accepts. Then the options is sent to the server which will perform
+      the same TFTP option negotiation procedure. The options that are
+      accepted by the server are forwarded to the <c>open/5</c> function
+      on the client side. On the client side the <c>open/5</c> function
+      must accept all option as is or reject the transfer. Then
+      the callback interaction follows the same pattern as described
+      above 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 (which performs the file access
+    in the TFTP server) takes too long time (more than
+    the double TFTP timeout), the server will abort the
+    connection and send an error reply to the client.
+    This implies that the server will release 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
+    will simply ignore the new request if the request is
+    equal with 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 will
+    consumer lesser resources.
+    </p>
+  </section>
+
+  <funcs>
+    <func>
+      <name>prepare(Peer, Access, Filename, Mode, SuggestedOptions, InitialState) -> {ok, AcceptedOptions, NewState} | {error, {Code, Text}}</name>
+      <fsummary>Prepare 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 may be added, but the ones that are present in
+          <c>SuggestedOptions</c> may be omitted or replaced with new
+          values in <c>AcceptedOptions</c>.</p>
+        <p>Will be 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 those options that it
+          accepts. These will be forwarded to <c>open/4</c> as
+          <c>SuggestedOptions</c>.</p>
+      </desc>
+    </func>
+    <func>
+      <name>open(Peer, Access, Filename, Mode, SuggestedOptions, State) -> {ok, AcceptedOptions, NewState} | {error, {Code, Text}}</name>
+      <fsummary>Open 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 may be added, but
+          the ones that are present in <c>SuggestedOptions</c> may be
+          omitted or replaced with new values in <c>AcceptedOptions</c>.</p>
+      </desc>
+    </func>
+    <func>
+      <name>read(State) -> {more, Bin, NewState} | {last, Bin, FileSize} | {error, {Code, Text}}</name>
+      <fsummary>Read 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>Read 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 etc. In both
+          cases there will be no more calls to any of
+          the callback functions.</p>
+      </desc>
+    </func>
+    <func>
+      <name>write(Bin, State) -> {more, NewState} | {last, FileSize} | {error, {Code, Text}}</name>
+      <fsummary>Write 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>Write 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 etc. In both
+          cases there will be no more calls to any of
+          the callback functions.</p>
+      </desc>
+    </func>
+    <func>
+      <name>abort(Code, Text, State) -> ok</name>
+      <fsummary>Abort 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 etc. The function will not be
+          invoked if any of the other callback
+          functions returns an error, as it is
+          expected that they already have cleaned up
+          the necessary resources. It will however be
+          invoked if the functions fails (crashes).</p>
+      </desc>
+    </func>
+  </funcs>
+  
+  <section>
+    <marker id="tftp_logger"></marker>
+    <title>LOGGER FUNCTIONS</title>
+    
+    <p>A <c>tftp_logger</c> callback module should be implemented as a
+      <c>tftp_logger</c> behavior and export the functions listed below.</p>
+    </section>
+
+  <funcs>
+    <func>
+      <name>error_msg(Format, Data) -> ok | exit(Reason)</name>
+      <fsummary>Log an error message</fsummary>
+      <type>
+        <v>Format = string()</v>
+        <v>Data = [term()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Log an error message. See <c>error_logger:error_msg/2 for details.</c> </p>
+      </desc>
+    </func>
+
+    <func>
+      <name>warning_msg(Format, Data) -> ok | exit(Reason)</name>
+      <fsummary>Log an error message</fsummary>
+      <type>
+        <v>Format = string()</v>
+        <v>Data = [term()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Log a warning message. See <c>error_logger:warning_msg/2 for details.</c> </p>
+      </desc>
+    </func>
+
+    <func>
+      <name>info_msg(Format, Data) -> ok | exit(Reason)</name>
+      <fsummary>Log an error message</fsummary>
+      <type>
+        <v>Format = string()</v>
+        <v>Data = [term()]</v>
+        <v>Reason = term()</v>
+      </type>
+      <desc>
+        <p>Log an info message. See <c>error_logger:info_msg/2 for details.</c> </p>
+      </desc>
+    </func>
+  </funcs>
+</erlref>
+
+