#36741 [Fbk->Opn]: userstreams testcase have off-by-one error on fseek()

ID: 36741 User updated by: elliot dot li at gmail dot com Reported By: elliot dot li at gmail dot com -Status: Feedback +Status: Open Bug Type: Streams related Operating System: Linux PHP Version: 5.1.2 New Comment: Well, this is my patch. (sorry, I don't know how to append an attachment) ===== php-5.1.2-userstreams.test.patch FOLLOWS ===== diff -Nur php-5.1.2/ext/standard/tests/file/userstreams.phpt php-5.1.2.my/ext/standard/tests/file/userstreams.phpt --- php-5.1.2/ext/standard/tests/file/userstreams.phpt 2003-11-30 21:57:17.000000000 +0800 +++ php-5.1.2.my/ext/standard/tests/file/userstreams.phpt 2006-03-20 08:32:10.000000000 +0800 @@ -211,15 +211,15 @@ $whence = $whence_map[array_rand($whence_map, 1)]; switch($whence) { case SEEK_SET: - $offset = rand(0, $DATALEN); + $offset = rand(0, $DATALEN-1); $position = $offset; break; case SEEK_END: - $offset = -rand(0, $DATALEN); + $offset = -rand(0, $DATALEN-1); $position = $DATALEN + $offset; break; case SEEK_CUR: - $offset = rand(0, $DATALEN); + $offset = rand(0, $DATALEN-1); $offset -= $position; $position += $offset; break; ===== php-5.1.2-userstreams.test.patch ABOVE ===== Previous Comments: ------------------------------------------------------------------------ [2006-03-18 21:57:31] tony2001@php.net Do you have a patch? (unified diff, please) ------------------------------------------------------------------------ [2006-03-15 05:58:13] elliot dot li at gmail dot com Description: ------------ This case(php-5.1.2/ext/standard/tests/file/userstreams.phpt) generates a bunch of random numbers and use them as offsets for fseek() test on a userstream. However, the range of these random numbers is [0, $DATALEN](rand(0, $DATALEN)), which should be [0, $DATALEN). ======== CODE SNIP FOLLOWS ======== /* generate some random seek offsets */ $position = 0; for ($i = 0; $i < 256; $i++) { $whence = $whence_map[array_rand($whence_map, 1)]; switch($whence) { case SEEK_SET: $offset = rand(0, $DATALEN); $position = $offset; break; case SEEK_END: $offset = -rand(0, $DATALEN); $position = $DATALEN + $offset; break; case SEEK_CUR: $offset = rand(0, $DATALEN); $offset -= $position; $position += $offset; break; } $seeks[] = array($whence, $offset, $position); } ======== CODE SNIP ABOVE ======== Reproduce code: --------------- Run this case on and on for a while, you can encounter this problem. I found this problem during a regression test, and reproduced it on my PC(Pentium 4 2.6GHz) within one day. Expected result: ---------------- No error should be reported if everything goes OK. Actual result: -------------- ========= LOG SNIP FOLLOWS ========= --[34] whence=SEEK_SET offset=32550 line_length=1024 position_should_be=32550 -- REAL: pos=(29175,32550,32550) ret=0 line[0]=`' USER: pos=(29175,29175,29175) ret=0 line[16]=`zl urnq vf ubzr ' ###################################### FAIL! ========= LOG SNIP ABOVE ========= 32550 is the total length of the userstream, so fseek($fp, 32550, SEEK_SET) must fail. I noticed another problem: mystream.stream_seek() would return a false on this condition, but the return value of fseek() is still 0! This would lead to the result that the failure of seeking in a userstream couldn't be noticed by the main program. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=36741&edit=1