Edit report at http://bugs.php.net/bug.php?id=34906&edit=1
ID: 34906
Updated by: tony2...@php.net
Reported by: feldgendler at mail dot ru
Summary: mysql: no way to get errno for a failed secondary
connection attempt
Status: Assigned
Type: Feature/Change Request
Package: MySQL related
Operating System: *
PHP Version: 5CVS-2005-10-19 (cvs)
-Assigned To: georg
+Assigned To: johannes
Block user comment: N
Private report: N
New Comment:
Reassigned to Johannes.
The patch is still available here:
http://dev.daylessday.org/diff/bug34906.diff
Previous Comments:
------------------------------------------------------------------------
[2005-10-18 13:51:40] feldgendler at mail dot ru
About the patch: I think it's not enough. Once a connection attempt has
failed, conect_errno will be nonzero, and mysql_errno() without
arguments always will return this value. This will be too much deviation
from the current behavior -- in fact, many always call mysql_errno()
without arguments. Here is a typical script which will be broken:
if (!mysql_connect('dbhost', 'user', 'pass')) {
mysql_connect('backup-dbhost', 'user', 'pass');
}
// ...
if (!mysql_query("...")) {
echo mysql_errno(); // This will print connect_errno!
}
I think that connect_errno should be reset to zero somewhere, but I
don't know where it would be appropriate. mysql_errno() shouldn't reset
connect_errno because mysql_error() and mysql_errno() are expected to be
idempotent.
------------------------------------------------------------------------
[2005-10-18 13:43:11] tony2...@php.net
Assigned to the maintainer.
Georg, please check the patch:
http://tony2001.phpclub.net/dev/tmp/bug34906.diff
------------------------------------------------------------------------
[2005-10-18 13:19:52] feldgendler at mail dot ru
Description:
------------
This is actually a bug in the well-defined and documented API, so there
is no reproduce code here.
After successfully establishing a connection, when an attempt to create
another connection fails, there is no way to find out the errno. This is
because mysql_errno() always uses an established link, either the one
passed as the argument or the default one. There is just no way to find
out why the second connection failed.
// assume this one succeeds
$first_connection = mysql_connect($host1, $u1, $p1);
// at this point, $first_connection is the default link
// assume this one fails
$second_connection = mysql_connect($host2, $u2, $p2);
// $second_connection is false,
// $first_connection is still the default link
echo mysql_errno();
// 0 is printed because there is no error
// on $first_connection
Before stamping "Bogus" on this bug, please note the following:
1. I have read the manual about mysql_errno() and mysql_connect(). Every
word of it. Even more, I think that PHP currently behaves as documented.
But it's just wrong because there is no way to find out why a connection
has failed.
2. I have read other bug reports about mysql_errno(). They are actually
about other issues, or they don't state this problem clearly enough, so
I'm filing this bug report to make it clear what the problem is.
3. I have read the source code of the mysql extension. From the source,
I've found out that the error code and message from a failed connection
attempt is really stored in mysql_globals (connect_errno and
connect_error), but mysql_errno() PHP function only returns
MySG(connect_errno) when the function is invoked without arguments AND
there is no default link. If there is a default link, and an attempt to
establish a second one has failed, there isn't a way to have
MySG(connect_errno) returned to the PHP program.
It is not obvious how to fix this bug, because it isn't a deviation from
the documented behavior, but rather an incompleteness of the API. Two of
the possible approaches are proposed here:
http://www.mail-archive.com/internals@lists.php.net/msg02524.html
------------------------------------------------------------------------
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