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diff --git a/docs/htmldocs/Samba3-Developers-Guide/devprinting.html b/docs/htmldocs/Samba3-Developers-Guide/devprinting.html deleted file mode 100644 index a68530b16c..0000000000 --- a/docs/htmldocs/Samba3-Developers-Guide/devprinting.html +++ /dev/null @@ -1,215 +0,0 @@ -<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 15. Samba Printing Internals</title><link rel="stylesheet" href="../samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.75.2"><link rel="home" href="index.html" title="SAMBA Developers Guide"><link rel="up" href="pt04.html" title="Part IV. Debugging and tracing"><link rel="prev" href="tracing.html" title="Chapter 14. Tracing samba system calls"><link rel="next" href="pt05.html" title="Part V. Appendices"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 15. Samba Printing Internals</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="tracing.html">Prev</a> </td><th width="60%" align="center">Part IV. Debugging and tracing</th><td width="20%" align="right"> <a accesskey="n" href="pt05.html">Next</a></td></tr></table><hr></div><div class="chapter" title="Chapter 15. Samba Printing Internals"><div class="titlepage"><div><div><h2 class="title"><a name="devprinting"></a>Chapter 15. Samba Printing Internals</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Gerald</span> <span class="surname">Carter</span></h3></div></div><div><p class="pubdate">October 2002</p></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="devprinting.html#id332767">Abstract</a></span></dt><dt><span class="sect1"><a href="devprinting.html#id332778"> -Printing Interface to Various Back ends -</a></span></dt><dt><span class="sect1"><a href="devprinting.html#id332848"> -Print Queue TDB's -</a></span></dt><dt><span class="sect1"><a href="devprinting.html#id332986"> -ChangeID and Client Caching of Printer Information -</a></span></dt><dt><span class="sect1"><a href="devprinting.html#id332995"> -Windows NT/2K Printer Change Notify -</a></span></dt></dl></div><div class="sect1" title="Abstract"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id332767"></a>Abstract</h2></div></div></div><p> -The purpose of this document is to provide some insight into -Samba's printing functionality and also to describe the semantics -of certain features of Windows client printing. -</p></div><div class="sect1" title="Printing Interface to Various Back ends"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id332778"></a> -Printing Interface to Various Back ends -</h2></div></div></div><p> -Samba uses a table of function pointers to seven functions. The -function prototypes are defined in the <code class="varname">printif</code> structure declared -in <code class="filename">printing.h</code>. -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>retrieve the contents of a print queue</p></li><li class="listitem"><p>pause the print queue</p></li><li class="listitem"><p>resume a paused print queue</p></li><li class="listitem"><p>delete a job from the queue</p></li><li class="listitem"><p>pause a job in the print queue</p></li><li class="listitem"><p>result a paused print job in the queue</p></li><li class="listitem"><p>submit a job to the print queue</p></li></ul></div><p> -Currently there are only two printing back end implementations -defined. -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>a generic set of functions for working with standard UNIX - printing subsystems</p></li><li class="listitem"><p>a set of CUPS specific functions (this is only enabled if - the CUPS libraries were located at compile time).</p></li></ul></div></div><div class="sect1" title="Print Queue TDB's"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id332848"></a> -Print Queue TDB's -</h2></div></div></div><p> -Samba provides periodic caching of the output from the "lpq command" -for performance reasons. This cache time is configurable in seconds. -Obviously the longer the cache time the less often smbd will be -required to exec a copy of lpq. However, the accuracy of the print -queue contents displayed to clients will be diminished as well. -</p><p> -The list of currently opened print queue TDB's can be found -be examining the list of tdb_print_db structures ( see print_db_head -in printing.c ). A queue TDB is opened using the wrapper function -printing.c:get_print_db_byname(). The function ensures that smbd -does not open more than MAX_PRINT_DBS_OPEN in an effort to prevent -a large print server from exhausting all available file descriptors. -If the number of open queue TDB's exceeds the MAX_PRINT_DBS_OPEN -limit, smbd falls back to a most recently used algorithm for maintaining -a list of open TDB's. -</p><p> -There are two ways in which a a print job can be entered into -a print queue's TDB. The first is to submit the job from a Windows -client which will insert the job information directly into the TDB. -The second method is to have the print job picked up by executing the -"lpq command". -</p><pre class="programlisting"> -/* included from printing.h */ -struct printjob { - pid_t pid; /* which process launched the job */ - int sysjob; /* the system (lp) job number */ - int fd; /* file descriptor of open file if open */ - time_t starttime; /* when the job started spooling */ - int status; /* the status of this job */ - size_t size; /* the size of the job so far */ - int page_count; /* then number of pages so far */ - BOOL spooled; /* has it been sent to the spooler yet? */ - BOOL smbjob; /* set if the job is a SMB job */ - fstring filename; /* the filename used to spool the file */ - fstring jobname; /* the job name given to us by the client */ - fstring user; /* the user who started the job */ - fstring queuename; /* service number of printer for this job */ - NT_DEVICEMODE *nt_devmode; -}; -</pre><p> -The current manifestation of the printjob structure contains a field -for the UNIX job id returned from the "lpq command" and a Windows job -ID (32-bit bounded by PRINT_MAX_JOBID). When a print job is returned -by the "lpq command" that does not match an existing job in the queue's -TDB, a 32-bit job ID above the <*vance doesn't know what word is missing here*> is generating by adding UNIX_JOB_START to -the id reported by lpq. -</p><p> -In order to match a 32-bit Windows jobid onto a 16-bit lanman print job -id, smbd uses an in memory TDB to match the former to a number appropriate -for old lanman clients. -</p><p> -When updating a print queue, smbd will perform the following -steps ( refer to <code class="filename">print.c:print_queue_update()</code> ): -</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Check to see if another smbd is currently in - the process of updating the queue contents by checking the pid - stored in <code class="constant">LOCK/<em class="replaceable"><code>printer_name</code></em></code>. - If so, then do not update the TDB.</p></li><li class="listitem"><p>Lock the mutex entry in the TDB and store our own pid. - Check that this succeeded, else fail.</p></li><li class="listitem"><p>Store the updated time stamp for the new cache - listing</p></li><li class="listitem"><p>Retrieve the queue listing via "lpq command"</p></li><li class="listitem"><pre class="programlisting"> - foreach job in the queue - { - if the job is a UNIX job, create a new entry; - if the job has a Windows based jobid, then - { - Lookup the record by the jobid; - if the lookup failed, then - treat it as a UNIX job; - else - update the job status only - } - }</pre></li><li class="listitem"><p>Delete any jobs in the TDB that are not - in the in the lpq listing</p></li><li class="listitem"><p>Store the print queue status in the TDB</p></li><li class="listitem"><p>update the cache time stamp again</p></li></ol></div><p> -Note that it is the contents of this TDB that is returned to Windows -clients and not the actual listing from the "lpq command". -</p><p> -The NT_DEVICEMODE stored as part of the printjob structure is used to -store a pointer to a non-default DeviceMode associated with the print -job. The pointer will be non-null when the client included a Device -Mode in the OpenPrinterEx() call and subsequently submitted a job for -printing on that same handle. If the client did not include a Device -Mode in the OpenPrinterEx() request, the nt_devmode field is NULL -and the job has the printer's device mode associated with it by default. -</p><p> -Only non-default Device Mode are stored with print jobs in the print -queue TDB. Otherwise, the Device Mode is obtained from the printer -object when the client issues a GetJob(level == 2) request. -</p></div><div class="sect1" title="ChangeID and Client Caching of Printer Information"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id332986"></a> -ChangeID and Client Caching of Printer Information -</h2></div></div></div><p> -[To be filled in later] -</p></div><div class="sect1" title="Windows NT/2K Printer Change Notify"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id332995"></a> -Windows NT/2K Printer Change Notify -</h2></div></div></div><p> -When working with Windows NT+ clients, it is possible for a -print server to use RPC to send asynchronous change notification -events to clients for certain printer and print job attributes. -This can be useful when the client needs to know that a new -job has been added to the queue for a given printer or that the -driver for a printer has been changed. Note that this is done -entirely orthogonal to cache updates based on a new ChangeID for -a printer object. -</p><p> -The basic set of RPC's used to implement change notification are -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>RemoteFindFirstPrinterChangeNotifyEx ( RFFPCN )</p></li><li class="listitem"><p>RemoteFindNextPrinterChangeNotifyEx ( RFNPCN )</p></li><li class="listitem"><p>FindClosePrinterChangeNotify( FCPCN )</p></li><li class="listitem"><p>ReplyOpenPrinter</p></li><li class="listitem"><p>ReplyClosePrinter</p></li><li class="listitem"><p>RouteRefreshPrinterChangeNotify ( RRPCN )</p></li></ul></div><p> -One additional RPC is available to a server, but is never used by the -Windows spooler service: -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>RouteReplyPrinter()</p></li></ul></div><p> -The opnum for all of these RPC's are defined in include/rpc_spoolss.h -</p><p> -Windows NT print servers use a bizarre method of sending print -notification event to clients. The process of registering a new change -notification handle is as follows. The 'C' is for client and the -'S' is for server. All error conditions have been eliminated. -</p><pre class="programlisting"> -C: Obtain handle to printer or to the printer - server via the standard OpenPrinterEx() call. -S: Respond with a valid handle to object - -C: Send a RFFPCN request with the previously obtained - handle with either (a) set of flags for change events - to monitor, or (b) a PRINTER_NOTIFY_OPTIONS structure - containing the event information to monitor. The windows - spooler has only been observed to use (b). -S: The <* another missing word*> opens a new TCP session to the client (thus requiring - all print clients to be CIFS servers as well) and sends - a ReplyOpenPrinter() request to the client. -C: The client responds with a printer handle that can be used to - send event notification messages. -S: The server replies success to the RFFPCN request. - -C: The windows spooler follows the RFFPCN with a RFNPCN - request to fetch the current values of all monitored - attributes. -S: The server replies with an array SPOOL_NOTIFY_INFO_DATA - structures (contained in a SPOOL_NOTIFY_INFO structure). - -C: If the change notification handle is ever released by the - client via a FCPCN request, the server sends a ReplyClosePrinter() - request back to the client first. However a request of this - nature from the client is often an indication that the previous - notification event was not marshalled correctly by the server - or a piece of data was wrong. -S: The server closes the internal change notification handle - (POLICY_HND) and does not send any further change notification - events to the client for that printer or job. -</pre><p> -The current list of notification events supported by Samba can be -found by examining the internal tables in srv_spoolss_nt.c -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>printer_notify_table[]</p></li><li class="listitem"><p>job_notify_table[]</p></li></ul></div><p> -When an event occurs that could be monitored, smbd sends a message -to itself about the change. The list of events to be transmitted -are queued by the smbd process sending the message to prevent an -overload of TDB usage and the internal message is sent during smbd's -idle loop (refer to printing/notify.c and the functions -send_spoolss_notify2_msg() and print_notify_send_messages() ). -</p><p> -The decision of whether or not the change is to be sent to connected -clients is made by the routine which actually sends the notification. -( refer to srv_spoolss_nt.c:recieve_notify2_message() ). -</p><p> -Because it possible to receive a listing of multiple changes for -multiple printers, the notification events must be split into -categories by the printer name. This makes it possible to group -multiple change events to be sent in a single RPC according to the -printer handle obtained via a ReplyOpenPrinter(). -</p><p> -The actual change notification is performed using the RRPCN request -RPC. This packet contains -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>the printer handle registered with the -client's spooler on which the change occurred</p></li><li class="listitem"><p>The change_low value which was sent as part -of the last RFNPCN request from the client</p></li><li class="listitem"><p>The SPOOL_NOTIFY_INFO container with the event -information</p></li></ul></div><p> -A <code class="varname">SPOOL_NOTIFY_INFO</code> contains: -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>the version and flags field are predefined -and should not be changed</p></li><li class="listitem"><p>The count field is the number of entries -in the SPOOL_NOTIFY_INFO_DATA array</p></li></ul></div><p> -The <code class="varname">SPOOL_NOTIFY_INFO_DATA</code> entries contain: -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The type defines whether or not this event -is for a printer or a print job</p></li><li class="listitem"><p>The field is the flag identifying the event</p></li><li class="listitem"><p>the notify_data union contains the new valuie of the -attribute</p></li><li class="listitem"><p>The enc_type defines the size of the structure for marshalling -and unmarshalling</p></li><li class="listitem"><p>(a) the id must be 0 for a printer event on a printer handle. -(b) the id must be the job id for an event on a printer job -(c) the id must be the matching number of the printer index used -in the response packet to the RFNPCN when using a print server -handle for notification. Samba currently uses the snum of -the printer for this which can break if the list of services -has been modified since the notification handle was registered.</p></li><li class="listitem"><p>The size is either (a) the string length in UNICODE for strings, -(b) the size in bytes of the security descriptor, or (c) 0 for -data values.</p></li></ul></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="tracing.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="pt04.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="pt05.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 14. Tracing samba system calls </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Part V. Appendices</td></tr></table></div></body></html> |