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Bug #48994 zlib.output_compression does not ouput HTTP headers when set to a string value
Submitted: 2009-07-21 02:48 UTC Modified: 2009-08-03 18:16 UTC
Avg. Score:3.0 ± 0.0
Reproduced:1 of 1 (100.0%)
Same Version:1 (100.0%)
Same OS:0 (0.0%)
From: jflatnes at vt dot edu Assigned: jani (profile)
Status: Closed Package: Zlib related
PHP Version: 5.2.10 OS: Linux 2.6.29
Private report: No CVE-ID: None
 [2009-07-21 02:48 UTC] jflatnes at vt dot edu
When the configuration option 'zlib.output_compression' is set to a boolean value, output is compressed and the appropriate HTTP headers are sent.  When the option is set to a string like 'true' or 'On', the output is compressed, but no headers are sent, causing browsers to fail to interpret the output as compressed.

Reproduce code:

ini_set('zlib.output_compression', 'On');

echo 'hello, world';


Expected result:
The output "hello, world" to be gzip/deflate compressed as appropriate for Accept-Encoding, and the Content-Encoding and Vary HTTP headers to be set.

Actual result:
Instead, the output is indeed gzip-compressed, but the Content-Encoding and Vary headers are not set.

The actual text that the browser prints is:

?&#65533;&#65533;&#65533;&#65533;&#65533;&#65533;?H????Q(?/?I&#65533;&#65533;&#65533;??&#65533;:r??&#65533;&#65533;&#65533;

Note, this works correctly with the an ini_set argument of the boolean value true.  The documentation claims that ini_set should take string arguments, though.  Even if a boolean/integer is required to activate output compression, the behavior should either be "all on" or "all off".


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 [2009-07-21 18:46 UTC]
Try this too:


var_dump(ini_set('zlib.output_compression', 'On'));


Also note that using "On" or "Off" or such with ini_set() does NOT work 
like they do when used in php.ini.
 [2009-07-21 19:03 UTC] jflatnes at vt dot edu
<?php var_dump(ini_set('zlib.output_compression', 'On')); ?>

Results in:

string(0) "" (meaning I had no previous setting for zlib.output_compression, I believe)


I am coming to understand that the string 'On' doesn't behave the same way in ini_set as in an ini file, as mentioned.  The issue I see here is that there are two options for zlib compression:

zlib.output_compression = false: no compression with no headers.

zlib.output_compression = true: compression with appropriate headers.

Passing a string to ini_set (other than the string '1') causes a third, undocumented behavior:

zlib.output_compression = 'On': compression without the headers.

Those three states describe the behavior I'm seeing, and the third state seems like a bug.  If 'On' is an invalid setting, shouldn't the compression simply not be activated?  Am I thinking about this correctly?)
 [2009-07-21 22:50 UTC]
There is something weird going on here, verified it now. Need to 
investigate more tomorrow. To reproduce on command line:

# HTTP_ACCEPT_ENCODING=gzip gdb --arg php-cgi test.php
 [2009-07-29 01:13 UTC] apinstein at mac dot com
I ran into this issue today as well... but I have more to add.

Using PHP 5.3 + zlib 1.2.3

I *cannot* get compression + headers. I can get no compression, or 
w/o headers, but never "working" compression+headers.

I have tried:


 php_flag zlib.output_compression On
 php_admin_flag zlib.output_compression On
 -> zip + no headers

 php_flag zlib.output_compression true
 php_admin_flag zlib.output_compression true
 -> not zipped

In app.php:

 ini_set('zlib.output_compression', true);
 ini_set('zlib.output_compression', "On");
 -> not zipped
 [2009-08-03 18:15 UTC]
Automatic comment from SVN on behalf of jani
Log: - Fixed bug #48994 (zlib.output_compression does not ouput HTTP headers when set to a string value)
# also fixes bug #35936 (ini.zlib.output-compression Documentation :)
 [2009-08-03 18:16 UTC]
This bug has been fixed in SVN.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
Thank you for the report, and for helping us make PHP better.

 [2009-08-17 17:30 UTC]
Automatic comment from SVN on behalf of jani
Log: - Fixed bug #49248 by fixing bug #48994 properly
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