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<?php
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//$Header: /hl/cvsroots/gpl01/gpl01/webprojs/fboprime/sw/phplib/sguid.inc,v 1.4 2006/04/10 22:48:02 dashley Exp $
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//********************************************************************************
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//Copyright (C) 2006 David T. Ashley
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//********************************************************************************
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//This program or source file is free software; you can redistribute it and/or
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//modify it under the terms of the GNU General Public License as published by
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//the Free Software Foundation; either version 2 of the License, or (at your
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//option) any later version.
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//
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//This program or source file is distributed in the hope that it will
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//be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
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//MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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//GNU General Public License for more details.
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//
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//You may have received a copy of the GNU General Public License
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//along with this program; if not, write to the Free Software
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//Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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//********************************************************************************
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//Dave Ashley, 04/06
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//
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//This source file provides the code to create server globally-unique identifiers.
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//The rationale is that since no process can have the same PID at the same
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//time as another process, using the PID concatenated with a guaranteed
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//unique time should provide an identifier that can never recur in the lifetime
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//of the server.
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//
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//The format of the SGUID is documented in the FBO-Prime manual.
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//
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require_once("strfunc.inc"); //Necesssary for zero padding.
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require_once("timeraw.inc"); //Necessary to get raw time.
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//
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//
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//--------------------------------------------------------------------------------
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//Returns the full generated SGUID as described in the documentation.
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//
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//Unit-tested 20060408.
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//
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function SGUID_sguid()
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{
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return("SG" . SGUID_sguid_raw());
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}
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//
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//
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//--------------------------------------------------------------------------------
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//Returns the raw form of an SGUID (without the "SG" prefix).
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//
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//Unit-tested 20060408.
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//
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function SGUID_sguid_raw()
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{
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//Get the reference timestamp.
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$reftime = TIMERAW_time_precision_mixed_array_2();
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//Get the PID. This may also chew up some time and hopefully let the
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//server time change.
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$pid = getmypid();
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//Form the SGUID proper. Hopefully this will also chew up more time.
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$reftime_whole = $reftime[0];
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$reftime_frac = sprintf("%d", $reftime[1]);
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$pid_string = sprintf("%d", $pid );
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$rv = STRFUNC_pad_left_zero($reftime_whole, 11)
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. STRFUNC_pad_left_zero($reftime_frac, 9)
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. STRFUNC_pad_left_zero($pid_string, 10);
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//Spin-lock until the time has changed. With any luck, the statements
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//above have done that for us. It is hard to judge without some data
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//whether microsleep would make things more efficient ... let's just leave
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//it as a pure spin-lock.
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do
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{
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$comptime = TIMERAW_time_precision_mixed_array_2();
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}
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while (($reftime[1] == $comptime[1]) && ($reftime[0] == $comptime[0]));
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//Return the value to the caller.
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return($rv);
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}
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//
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//
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//--------------------------------------------------------------------------------
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//Returns the length of a SGUID (in characters).
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//
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//Unit-tested 20060408.
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//
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function SGUID_sguid_len()
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{
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return(32);
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}
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//
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//
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//--------------------------------------------------------------------------------
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//Returns 1 if the SGUID is syntactically valid or 0 otherwise.
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//
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//Unit-tested 20060408.
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//
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function SGUID_is_syntactically_valid($sguid_to_check)
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{
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//Must be a string data type.
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if (! is_string($sguid_to_check))
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return(0);
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//Must be of appropriate length.
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if (strlen($sguid_to_check) != 32)
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return(0);
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//First two characters must be "SG".
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if (substr($sguid_to_check, 0, 2) !== "SG")
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return(0);
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//The remainder of the string must be digits only.
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if (! STRFUNC_is_pure_digits(SubStr($sguid_to_check, 2, 30)))
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return(0);
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//If we're here, nothing obvious wrong with it.
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return(1);
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}
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//--------------------------------------------------------------------------------
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?>
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