Description:
------------
When a PHP/PHTML file (a file getting parsed by PHP) contains a leading UTF-8 Byte Order Mark (BOM), EF BB BF in hex, the character encoding of the output varies.


Possibly relevant PHP configuration snippets from httpd.conf:

php_value default_charset none
php_value default_mimetype "text/html"
php_admin_value output_buffering 4096
php_admin_value output_handler none


PHP configuration flags (from config.nice):

CPPFLAGS='-I/usr/local/include' \
LDFLAGS='-L/lib -L/opt/freeware/lib -L/usr/local/lib' \
CC='/usr/local/bin/gcc' \
'./configure' \
'--enable-bcmath' \
'--enable-calendar' \
'--enable-dba' \
'--enable-dbase' \
'--enable-dbx' \
'--enable-debug' \
'--enable-dio' \
'--enable-exif' \
'--enable-embedded-mysqli' \
'--enable-filepro' \
'--enable-ftp' \
'--enable-gd-jis-conv' \
'--enable-gd-native-ttf' \
'--enable-mbstring' \
'--enable-memory-limit' \
'--enable-shmop' \
'--enable-soap' \
'--enable-sockets' \
'--enable-sysvmsg' \
'--enable-sysvsem' \
'--enable-sysvshm' \
'--enable-yp' \
'--enable-zend-multibyte' \
'--prefix=/apache/php' \
'--with-apxs2=/apache/bin/apxs' \
'--with-bz2' \
'--with-freetype-dir' \
'--with-gd' \
'--with-gdbm' \
'--with-gettext' \
'--with-inifile' \
'--with-jpeg-dir' \
'--with-ldap' \
'--with-libxml-dir' \
'--with-mime-magic' \
'--with-mysql=/usr/local/mysql' \
'--with-openssl=/opt/freeware' \
'--with-png-dir' \
'--with-tiff-dir' \
'--with-ttf' \
'--with-xpm-dir' \
'--with-zlib' \
'--with-zlib-dir' \
"$@"

Reproduce code:
---------------
Source code with leading BOM: http://www.anst.uu.se/bwiberg/php/utf8_bug.php.txt

Corresponding page yielding varying result:
http://www.anst.uu.se/bwiberg/php/utf8_bug.php

(Use telnet or other "dumb" tool to dump the results; it appears that the result varies by server process that handles the request. We're using the Apache 2 prefork MPM.)

Example of incorrect result, here we get ISO-8859-1 encoded output:

http://www.anst.uu.se/bwiberg/php/utf8_bug_result1.txt


Expected result:
----------------
Example of correct result, here we get UTF-8 encoded output:

http://www.anst.uu.se/bwiberg/php/utf8_bug_result2.txt


Actual result:
--------------
Varies between the two examples. Make sure to close the connection in between (or the same server process will serve your multiple requests).

Restarting the web server does not help.

Changing the PHP settings for default character set (default_charset) and default MIME type (default_mimetype) does not help; I have tried all combinations.

Turning off output buffering (php_admin_flag output_buffering off) does not help.