Description:
------------
I'm migrating a Wordpress site from one server another and I've run to to a problem with some of the images not being displayed. The images are being piped though a PHP script to dynamically resize them. After some investigation I've noticed that the issue is only effecting PNG images and found errors relating to gd-png in the webserver logs. As a test I created a simple php script which just opens a PNG with imagecreatefrompng and every time access the script via a browser I get the following errors...

PHP Warning:  imagecreatefrompng(): gd-png:  fatal libpng error: bad parameters to zlib in .../test.php on line 10

PHP Warning:  imagecreatefrompng(): gd-png error: setjmp returns error condition in .../test.php on line 10

PHP Warning:  imagecreatefrompng(): 'test.png' is not a valid PNG file in .../test.php on line 10

I have tried several different png's from several different sources in case the png's where the problem, but alias it seems to effect all png's regardless of origin.

Most interestingly, if I run the same script from the command line (su'd to the webserver user!) I do not get the errors (I get the raw PNG but that's expected).

I'm not sure if that makes it a PHP problem of an webserver problem, but I can't think of any reason why running the script via the webserver should cause such a problem. No permission issues are in play. 

I have two webservers setup very similar, both experience the same problem.

My apologies if this is not the correct place to report such a problem.

Note, I spent quite a few hours on this yesterday evening and was running PHP 5.6.11 but I have this morning upgraded to 5.6.12 and the problem persists. 

# uname -a
FreeBSD indigo 10.0-RELEASE-p17 FreeBSD 10.0-RELEASE-p17 #0: Tue Jan 27 13:45:18 UTC 2015

# httpd -V
Server version: Apache/2.4.16 (FreeBSD)
Server built:   Aug 14 2015 23:52:56
Server's Module Magic Number: 20120211:47
Server loaded:  APR 1.5.2, APR-UTIL 1.5.4
Compiled using: APR 1.5.2, APR-UTIL 1.5.4
Architecture:   64-bit
Server MPM:     prefork
  threaded:     no
    forked:     yes (variable process count)
Server compiled with....
 -D APR_HAS_SENDFILE
 -D APR_HAS_MMAP
 -D APR_HAVE_IPV6 (IPv4-mapped addresses disabled)
 -D APR_USE_FLOCK_SERIALIZE
 -D APR_USE_PTHREAD_SERIALIZE
 -D SINGLE_LISTEN_UNSERIALIZED_ACCEPT
 -D APR_HAS_OTHER_CHILD
 -D AP_HAVE_RELIABLE_PIPED_LOGS
 -D DYNAMIC_MODULE_LIMIT=256
 -D HTTPD_ROOT="/usr/local"
 -D SUEXEC_BIN="/usr/local/bin/suexec"
 -D DEFAULT_PIDLOG="/var/run/httpd.pid"
 -D DEFAULT_SCOREBOARD="/var/run/apache_runtime_status"
 -D DEFAULT_ERRORLOG="/var/log/httpd-error.log"
 -D AP_TYPES_CONFIG_FILE="etc/apache24/mime.types"
 -D SERVER_CONFIG_FILE="etc/apache24/httpd.conf"

# php -i
phpinfo()
PHP Version => 5.6.12

System => FreeBSD indigo 10.0-RELEASE-p17 FreeBSD 10.0-RELEASE-p17 #0: Tue Jan 27 13:45:18 UTC 2015     root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC amd64
Build Date => Aug 15 2015 12:38:40
Configure Command =>  './configure'  '--with-layout=GNU' '--localstatedir=/var' '--with-config-file-scan-dir=/usr/local/etc/php' '--disable-all' '--enable-libxml' '--enable-mysqlnd' '--with-libxml-dir=/usr/local' '--with-pcre-regex=/usr/local' '--with-zlib-dir=/usr' '--program-prefix=' '--enable-fpm' '--with-fpm-user=www' '--with-fpm-group=www' '--with-regex=php' '--with-zend-vm=CALL' '--prefix=/usr/local' '--mandir=/usr/local/man' '--infodir=/usr/local/info/' '--build=amd64-portbld-freebsd10.0' 'build_alias=amd64-portbld-freebsd10.0' 'CC=cc' 'CFLAGS=-O2 '-pipe' '-fstack-protector' '-fno-strict-aliasing'' 'LDFLAGS= '-fstack-protector'' 'LIBS=-lpthread' 'CPPFLAGS=' 'CPP=cpp' 'CXX=c++' 'CXXFLAGS=-O2 '-pipe' '-fstack-protector' '-fno-strict-aliasing''
Server API => Command Line Interface
Virtual Directory Support => disabled
Configuration File (php.ini) Path => /usr/local/etc
Loaded Configuration File => /usr/local/etc/php.ini
Scan this dir for additional .ini files => /usr/local/etc/php
Additional .ini files parsed => /usr/local/etc/php/extensions.ini

PHP API => 20131106
PHP Extension => 20131226
Zend Extension => 220131226
Zend Extension Build => API220131226,NTS
PHP Extension Build => API20131226,NTS
Debug Build => no
Thread Safety => disabled
Zend Signal Handling => disabled
Zend Memory Manager => enabled
Zend Multibyte Support => provided by mbstring
IPv6 Support => enabled
DTrace Support => disabled

Registered PHP Streams => compress.bzip2, php, file, glob, data, http, ftp, https, ftps, compress.zlib, zip, phar
Registered Stream Socket Transports => tcp, udp, unix, udg, ssl, sslv3, sslv2, tls, tlsv1.0, tlsv1.1, tlsv1.2
Registered Stream Filters => bzip2.*, string.rot13, string.toupper, string.tolower, string.strip_tags, convert.*, consumed, dechunk, convert.iconv.*, mcrypt.*, mdecrypt.*, zlib.*
...
...
...
gd

GD Support => enabled
GD Version => bundled (2.1.0 compatible)
FreeType Support => enabled
FreeType Linkage => with freetype
FreeType Version => 2.6.0
T1Lib Support => enabled
GIF Read Support => enabled
GIF Create Support => enabled
JPEG Support => enabled
libJPEG Version => 8
PNG Support => enabled
libPNG Version => 1.6.17
WBMP Support => enabled
XPM Support => enabled
libXpm Version => 30411
XBM Support => enabled
JIS-mapped Japanese Font Support => enabled
...
...
...
zlib

ZLib Support => enabled
Stream Wrapper => compress.zlib://
Stream Filter => zlib.inflate, zlib.deflate
Compiled Version => 1.2.8
Linked Version => 1.2.8

Any advice gratefully received!

Regards

Steve

Test script:
---------------
<?php
ini_set('display_errors',1);
ini_set('display_startup_errors',1);
error_reporting(-1);

function LoadPNG($imgname)
{
    /* Attempt to open */
    $im = imagecreatefrompng($imgname);

    /* See if it failed */
    if(!$im)
    {    // create error image
        $im  = imagecreatetruecolor(1500, 30);  $bgc = imagecolorallocate($im, 255, 255, 255);  $tc  = imagecolorallocate($im, 0, 0, 0);
        imagefilledrectangle($im, 0, 0, 1500, 30, $bgc);
        imagestring($im, 1, 5, 5, 'Error loading ' . $imgname, $tc);
    }

    return $im;
}

header('Content-Type: image/png');

$img = LoadPNG('test.png');

imagepng($img);
imagedestroy($img);
?>


Expected result:
----------------
I'd expect the script to open the images and display it in the web browser. It works for jpegs (using imagecreatefromjpeg obviously)