From: valyala at tut dot by Operating system: any PHP version: 4.3.7 PHP Bug Type: Documentation problem Bug description: The example PHP code in docs http://php.net/gmp/ crashes PHP
Description: ------------ The following example code, which "will calculate factorial of 1000 (pretty big number) very fast" on documentation page http://php.net/gmp/ crashes PHP. ------------------------------- <?php function fact($x) { if ($x <= 1) { return 1; } else { return gmp_mul($x, fact($x-1)); } } echo gmp_strval(fact(1000)) . "\n"; ?> ------------------------------- The next PHP code avoids the crash: ------------------------------- <?php function fact($x) { $result = 1; while ($x > 1) { $result = gmp_mul($result, $x--); } return $result; } echo gmp_strval(fact(1000)) . "\n"; } ?> ------------------------------- This bug related to the following bugs: #7720, #15522, #26212. It seems that PHP4.3.7 (and older) don't handle stack overflow during function calls. You can find the maximum recursion depth for your version of PHP independently. Just play with $rec_depth number in the following script: --------------------------- <?php function f($n) { if (--$n) f($n); } /* adjust this number to find the maximum recursion depth */ $rec_depth = 1000; f($rec_depth); ?> --------------------------- p.s. Are the volunteers in PHP developement team, who wanted to track stack overflow problem? Reproduce code: --------------- see above Expected result: ---------------- decimal view of 1000! Actual result: -------------- PHP crash -- Edit bug report at http://bugs.php.net/?id=28827&edit=1 -- Try a CVS snapshot (php4): http://bugs.php.net/fix.php?id=28827&r=trysnapshot4 Try a CVS snapshot (php5): http://bugs.php.net/fix.php?id=28827&r=trysnapshot5 Fixed in CVS: http://bugs.php.net/fix.php?id=28827&r=fixedcvs Fixed in release: http://bugs.php.net/fix.php?id=28827&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=28827&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=28827&r=needscript Try newer version: http://bugs.php.net/fix.php?id=28827&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=28827&r=support Expected behavior: http://bugs.php.net/fix.php?id=28827&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=28827&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=28827&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=28827&r=globals PHP 3 support discontinued: http://bugs.php.net/fix.php?id=28827&r=php3 Daylight Savings: http://bugs.php.net/fix.php?id=28827&r=dst IIS Stability: http://bugs.php.net/fix.php?id=28827&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=28827&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=28827&r=float
