# enhance PHP syslog support

- Thread: https://externals.io/message/51373
- Original archive: https://news-web.php.net/php.internals/51373
- Started by jerome@loyet.net on 2011-01-30T13:34:18+00:00
- Messages: 1
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## #51373 — jerome@loyet.net — 2011-01-30T13:34:18+00:00

URL: https://externals.io/message/51373#51373

Hi guys,

I was looking at bugs #51118 and #52052. Both are related to syslog
(one from a user PHP script and the other within FPM).

I think syslog is not handled correctely by PHP. Let me explain:

There is basically 3 functions provided by the syslog library:

       void openlog(const char *ident, int option, int facility);
       void syslog(int priority, const char *format, ...);
       void closelog(void);

If syslog(...) is only used, messages are logged with default
facility, ident and option.
If openlog(...) is called before syslog(...), default facility, ident
and option are replaced.
 `closelog()` restores default facility, ident and option.

These 3 options (facility, ident and option) visibility is global to a process.

So if independent parts of a program are calling `openlog()`, `syslog()`
and `closelog()` on their sides, it will affect others. This typically
happens in PHP.

here is an example running with php-cli (in order not to think with
forks and threads):
<?php
        trigger_error("PHP error #1 (logged by PHP core) ".getmypid());
        openlog("custom ident", LOG_PID, LOG_LOCAL0);
        syslog(LOG_ALERT, "message from PHP script ".getmypid());
        trigger_error("PHP error #2 (logged by PHP core) ".getmypid());
?>

I've added the 2 following lines to my /etc/syslog.conf in order to
send `LOG_USER` and LOG_LOCAL0 to different files:
local0.*        /var/log/local0.log
user.*  /var/log/loguser.log

I ran ./sapi/cli/php -d error_reporting=E_ALL -d log_errors=On -d
error_log=syslog test.php

and the results:

==> /var/log/loguser.log <==
Jan 29 16:56:16 wild php: PHP Notice:  PHP error #1 (logged by PHP
core) 28503 in /LIBRE/dev/php-src/trunk/test.php on line 2

==> /var/log/local0.log <==
Jan 29 16:56:16 wild custom ident[28503]: message from PHP script 28503
Jan 29 16:56:16 wild custom ident[28503]: PHP Notice:  PHP error #2
(logged by PHP core) 28503 in /LIBRE/dev/php-src/trunk/test.php on
line 5

The first trigger_error is sent correctely with facility `LOG_USER` (the
default one, as php core does not call openlog) and the name of the
process for the ident.
The `syslog()` calls from my php script, is sent correctely to
LOG_LOCAL0 (as set with the previous `openlog()` call)
But the last trigger_error is also sent to LOG_LOCAL0 which is wrong
as it should have been sent to LOCAL_USER

Now, we can imagine the switching errors it can cause on a multiple
vhost shared prefork apache .

I've been working the following patch (attached in bug #51118)
http://bugs.php.net/patch-display.php?bug_id=51118&patch=php-syslog.patch&revision=1296394262&download=1

What's been done :
- add error_log_facility and error_log_ident variables to php.ini
- add main/php_syslog.c file with :
  - php_openlog: save ident, facility and option in its global context
before calling openlog
  - php_closelog: clear global context before calling closelog
  - php_syslog_get_ident: returns the ident global context
  - php_syslog_get_facility: returns the facility global context
  - php_syslog_get_option: returns the option global context
  - php_syslog2() is quite the same as php_syslog with
ident/facility/option arguments added. Thoses are compared to the
syslog global context, and openlog is called if they don't match.

- php_syslog remains #defined to syslog
- in main/main.c:
  - if error_log is set to "syslog", call php_syslog2() with
error_log_ident/facility instead of php_syslog()
- in ext/standard/syslog.c
  - now `openlog()` returns a ressource which contains ident/option/facility
  - now `syslog()` and `closelog()` takes an optional ressource parameter
(returned from openlog)
  - use php_syslog2,php_openlog and php_closelog
- in sapi/milter/php_milter.c
  - use php_syslog2 in place of previous openlog/syslog

what guys do you think ?

++ Jerome