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<?php
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//------------------------------------------------------------------------
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//Marshall Aviation Center FBO Management Software
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//Copyright (C)2005 David T. Ashley
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//
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//This program is free software; you can redistribute it and/or
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//modify it under the terms of the GNU General Public License
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//as published by the Free Software Foundation; either version 2
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//of the License, or (at your option) any later version.
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//
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//This program is distributed in the hope that it will be useful,
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//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 should 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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//The author (David T. Ashley) may be contacted by e-mail at dta@e3ft.com
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//and by postal mail at P.O. Box 918, Marshall MI 49068.
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//------------------------------------------------------------------------
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//Functions for server-unique identifiers.
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//
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//A server-unique identifier is something guaranteed to be unique for the
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//life of the server. These are the basis for session IDs, etc.
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//------------------------------------------------------------------------
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//Gets a unique integer whole time and microtime. The time is
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//guaranteed unique because this function implements a spinlock
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//until the time changes.
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function suid_uniquetime(&$whole_time, &$micro_time)
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{
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list($usec_reference, $sec_reference) = explode(" ", microtime());
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$usec_reference = (int)($usec_reference * 1000000.0);
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$exit_condition = 0;
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while (!$exit_condition)
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{
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list($usec, $sec) = explode(" ", microtime());
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$usec = (int)($usec * 1000000.0);
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if (($usec == $usec_reference) && ($sec == $sec_reference))
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{
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//The time has not changed. Use usleep() to try to
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//give a time breather without chewing CPU time.
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usleep(100);
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}
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else
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{
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//The time has changed. We can leave the loop.
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$exit_condition = 1;
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}
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}
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//Assign the values for the caller.
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$whole_time = $sec_reference;
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$micro_time = $usec_reference;
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}
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//------------------------------------------------------------------------
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//Returns a SUID as documented. Format will be:
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// PID -- 8 hexadecimal digits.
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// WHOLE TIME -- 10 hexadecimal digits.
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// NANO TIME -- 8 hexadecimal digits.
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//
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function suid_suid()
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{
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$pidstring = sprintf("0000%04X", getmypid());
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suid_uniquetime($secs_out, $usecs_out);
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$wholestring = sprintf("%010X", $secs_out);
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$usecs_out = $usecs_out * 1000;
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$fracstring = sprintf("%08X", $usecs_out);
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return($pidstring . $wholestring . $fracstring);
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}
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//------------------------------------------------------------------------
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?>
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