Bug #11678 Updated: ob_get_contents in ob_start() callback causes infinite loop

ID: 11678 User Update by: rick@eastcore.net Status: Open Bug Type: Scripting Engine problem Operating system: Linux w/ 2.4.4 kernel PHP Version: 4.0.4pl1 Description: ob_get_contents in ob_start() callback causes infinite loop The occurrence of $baz should be $bar in function my_callback (this doesn't change the bug, just points out my mad typ1ng skillz, etc.). Previous Comments: --------------------------------------------------------------------------- [2001-06-25 20:54:06] rick@eastcore.net SCRIPT: ob_start("my_callback"); echo "foo<br>n"; ob_end_flush(); function my_callback($buffer) { ob_start(); echo "bar<br>n"; $bar = ob_get_contents(); ob_end_clean(); $buffer .= $baz; } BEHAVIOR: PHP (static command-line, or as an Apache module) goes into some sort of loop (I can guess which sort, see below) and begins sucking CPU like a cyber-hooker. CONFIGURE: './configure' '--prefix=/d/test_make/php' '--with-config-file-path=/d/test_make/php' '--with-apache=/home/rick/corengine-2.0.1pre1/src/apache_1.3.12' '--with-mysql=/usr' Looks to me like some sort of scoping/context issue (can't start a new buffer inside the callback) -- in the callback ob_start is getting called but when ob_end_clean is called I'd guess that the state (the callback == "my_callback") has not been properly restricted to the enclosing buffering (does that sentence parse?) and the callback from the outer buffering is applied to the inner. When that happens... infinite loop (and depending upon how it's implemented it may not even be grabbing stack space which would make it truly a CPU-sucker). Why did this come up? I had some object functionality with a "render" method which simply printed out its output. I moved a system to using buffered output and found that it would be more efficient to call the object->render() method after the buffering was done (with a search & replace) since I then had more information and could do less computation. So, rather than rewrite the render method to return its output I decided to nest a buffer and just capture the output (the render method delegates to other objects which makes buffering even more attractive in this case). Since the best time to capture the buffer is when I'm cleaning up the other one... boom I hit this bug. I currently do not have PHP > 4.0.4pl1 installed so this bug may be present in later releases I just haven't been able to check yet. --------------------------------------------------------------------------- Full Bug description available at: http://bugs.php.net/?id=11678