#59 No error message on dba open failure

[Geoffrey T. Dairiki]

In the dba (and dbm, too, I think) backend, error
messages which occur when the database files are opened
are supressed.

If PhpWiki is miscuonfigured in such a way that the dba
open fails, no indication as to the reason for the
failure is given to the user.

This commonly happens in the case that the users PHP4
has dba support, but does not include support the gdbm
driver. In this case index.php (with default
lib/config.php) produces a blank page. (In this case
the fix is probably to use the 'db2' driver instead of
the gdbm driver --- this currently requires editing
line 42 of lib/dbalib.php.)

What should (probably) be done:

1. PhpWiki should produce an error message when
   dba_open() fails.

2. The choice of backend type should be moved into
   lib/config.php. (Perhaps the appropriate backend could
   be automatically deduced?)

3. The installation docs should make some mention of
   this problem, as it seems to have become a FAQ.

[Steve Wainstead]

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I've updated the INSTALL, lib/config.php and lib/dbalib.php
files. There is a constant now in config.php, DBM_FILE_TYPE
which is 'gdbm' by default. The INSTALL notes that if the
user gets a blank page on startup, this might be the problem.

~swain

[Steve Wainstead]

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Also... the problem with dba_lib() is: it will fail if
someone else has the file open. This is why I used the '@'
to supress the error message. Without the '@' the user might
see 20 or so error messages and then the page will display
when the file is opened after the other process closes it.

It returns 'false' for any error it encounters. There is no
way, it seems, to tell a "file was in use" error from "this
OS doesn't support that file type."

[Jude Walker]

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user_id=366797

Also, it's possible (as it was in my case) that the
PHP installation is missing DBA support totally. You
sort of alluded to that already, but it's important
to verify that DBA support is enabled by looking at
?phpinfo() right away. Thanks for the comments and help.