> I recently needed to watch the Midas messages for a particular error - and 
> thus needed a command to "get all the messages since a time t".
> 
> The documentation (https://midas.triumf.ca/MidasWiki/index.php/AJAX#jmsg) 
> documents a way to "get the most recent n messages" - but when I dug into the 
> code, I was delighted to find that the existing Midas code also supports the 
> "get all messages since t" query.
> 
> For the "get all messages since t" query, the parameter t should be the unix 
> timestamp in seconds, and the parameter n should be zero: curl -X GET 
> "http://localhost:8081/?cmd=jmsg&n=0&t=1473437918".
> 
> Pretty useful!  Perhaps this should be added to the AJAX documentation?

Thank you - I have added it to the documentation.

A link to an array variable such as

[local:npet:Stopped]/>ls /rcparams/ControlVariables/
TRFC:PB5 (V) -> /Equipment/Beamline/Variables/Demand[56]
                                17835

displays the whole Demand array on the mhttpd ODB page (see attachment)
rather than just the one element Demand[56].
This behaviour also occurs with older versions of mhttpd.
 
Not sure if it's a bug or a feature, but my suggestion is that it
ought to display the one element only (as odbedit does) and not the whole array.

Suzannah  

Further to my last message, I see that a midas version from 2013 does indeed display
links to arrays as I would expect (see attachment). Therefore the problem in later
versions  is a bug rather than a feature.


> A link to an array variable such as
> 
> [local:npet:Stopped]/>ls /rcparams/ControlVariables/
> TRFC:PB5 (V) -> /Equipment/Beamline/Variables/Demand[56]
>                                 17835
> 
> displays the whole Demand array on the mhttpd ODB page (see attachment)
> rather than just the one element Demand[56].
> This behaviour also occurs with older versions of mhttpd.
>  
> Not sure if it's a bug or a feature, but my suggestion is that it
> ought to display the one element only (as odbedit does) and not the whole array.
> 
> Suzannah  

> It might have worked some ~5 years ago, but it never really showed the target value of a link, just the 
> link itself. I reworked the code now to show both the link and the target of the link, so you can change 
> both in the mhttpd ODB page. Should be consistent now with odbedit. Have a look if it works for you.
> 
> Stefan

Thank you. That has solved the problem.
Suzannah 

I see two separate issues here. 

One is restricting the custom pages to ONE directory such as 
<exptab>/resources -> /home/users/exp/resources
and its subdirectories which seems like a good solution for all the
reasons you've mentioned. 

The other issue is the use of the "Path" key in /Custom, which is used to differentiate
between the "new" way (all resources served from the Path directory) 
and the original way where all the custom keys are specified with their full directories.

Recent versions of Midas had broken the original behaviour by insisting on the presence of the
"Path" key.  Konstantin fixed this by allowing the "Path" key to take the value "".  It is true
that some experiments currently may be serving resources from more than one directory tree, but changing
to storage of all custom pages in one directory (and its subdirectories) does not necessarily mean that
the original way of serving resources must be made obsolete.
 
I actually like the original way of specifying the custom keys for the pages and resources under /Custom, which
is presently selected  without the /Custom/Path key present at all (older versions) or with the
/Custom/Path key set to "" (latest versions). I like it for debugging, and I like to be able to see 
at a glance what resource files are in use from /Custom. 

I have a suggestion:

The resources could still be served from the /Custom directory if desired, except now mhttpd will ALWAYS add the 
fixed path in front of the given paths in /Custom. This would mean a fixed path and a minimal disruption to older pages 
(the <script> and <link> statements in the HTML code to include the resources would not need to be changed).
The "/Path" key is no longer be useful, since the resource path is now fixed. Instead a key e.g. "FlagRS"  could 
be used to select the desired behaviour,  with the default being the "new" (no key present).

For example, the full directory paths in /custom
ScanParams&                     /home/users/online/custom/scan/scan_select_popup.html
mpet.css!                       /home/users/online/custom/rs/mpet.css
scanvoltages!                   /home/users/online/custom/scan/scan_voltages.js

would become subdirectory path(s)
ScanParams&                     custom/scan/scan_select_popup.html
mpet.css!                       custom/rs/mpet.css
scanvoltages!                   custom/scan/scan_voltages.js
FlagRS                          y

The pages would be served from /home/users/exp/resources/custom/...

Suzannah

 
> > Hi Stefan and Konstantin,
> > 
> > I think that this proposal sounds fairly reasonable.  I agree that we might as well move to a secure final solution at this point.  
> > 
> > One comment: since this change would break almost every experiment I have worked on for the last 4 years, it would be nice to add a command-line option to mhttpd that preserves the old /Custom/Path behavior.  This would allow experiments a transition 
> > period, so that they didn't immediately need to fix their setup.  The command-line option could be clearly marked as obsolete behaviour and could be removed within a year.
> > 
> > Cheers,
> > Thomas
> > 
> > 
> > 
> > > Parsing all URL in mhttpd to prevent /etc/passwd etc. to be returned is tricky, because people can use escape sequences etc. Therefore I think it is much better to restrict file access 
> > > on the file system level when opening a file. The only escape there one could have is "..", which can be tested easily. 
> > > 
> > > Therefore, I propose to restrict file access to two well-defined directories, which is one system directory and one user directory. The system directory should be defined via 
> > > $MIDASSYS/resources, and the user directory should be the experiment directory (as defined in exptab) followed by "resources". So if MIDASSYS equals to /usr/local/midas and the 
> > > experiment directory equals to /home/users/exp for example, we would only have these two directories (and of course the subdirectories within these) served by mhttpd:
> > > 
> > > $MIDASSYS/resource -> /usr/local/midas/resources
> > > <exptab>/resources -> /home/users/exp/resources
> > > 
> > > These directories should be hard-wired into mhttpd, and not go through and ODB entry, since otherwise one could manipulate the ODB entries (knowingly or unknowingly) and open a 
> > > back-door. 
> > > 
> > > If users need a more complex structure, they can put soft links into these directories.
> > > 
> > > The code which opens a resource file should then first evaluate $MIDASSYS, then add "/resources/", then add the requested file name, make sure that there is no ".." in the file name, 
> > > then open the file. If not existing, do the same for the <exptab>/resources/ directory.
> > > 
> > > This change will break most experiments, and forces people to move their custom pages to different directories, but I think it's the only clean solution and we just have to bite the 
> > > bullet.
> > > 
> > > Comments are welcome.
> > > 
> > > Stefan

Replacing the MIDAS status page with a custom status page documented at

https://midas.triumf.ca/MidasWiki/index.php/Custom_Page_Features#Replace_Status_Page_by_a_Custom_page

does not appear to be supported in the current MIDAS version. 

As two of my experiments use this feature may I suggest its reinstatement?

Suzannah

Thanks Stefan. 
Your fix works nicely with the start/stop buttons not returning to the same or to a
different web page.

However, it does not seem to have fixed the problem with the Customscript button. It does
not seem to pick up the redirect, nor do the Pause/Resume buttons (which are programmed to
appear when the run starts).


> To fix this problem, do the following:
> 
> - Update to the current SVN revision 4368 of mhttpd.c
> - Add following tag into your custom page:
> 
>   <input type=hidden name="redir" value="name">
> 
>   where "name" is the name of your custom page which follows the CS/ in the URL. Like 
> if you have a custom page which you access through httpd://localhost/CS/junk then the 
> tag would be 
> 
>   <input type=hidden name="redir" value="junk">
> 
> The "redir" parameter is now evaluated inside mhttpd and brings you back to the proper 
> custom page. You can also define another custom page as the target, if that makes 
> sense in your application.
> 
> Pierre: Would be nice to document this somewhere more officially.

Not sure if this is a bug or a feature:

Writing a boolean label on an image seems to produce rather strange behaviour.

For example,
odb>ls /Equipment/gas/settings/my_bool -lt
Key name                        Type    #Val  Size  Last Opn Mode Value
---------------------------------------------------------------------------
my_bool                         BOOL    1     4     14m  0   RWD  y


odb>cd /custom/images/my_image.gif/labels
odb>ls
Src                             /Equipment/gas/settings/my_bool
Format                          val: %d (bool)
Font                            Medium
X                               10
Y                               10
Align                           0
FGColor                         FFFFFF
BGColor                         FF8800

Instead of the expected string "val: y (bool)", only the value of the key
appears, i.e. "y". 
The behaviour is the same whether I use %d, %u, %s, %c etc as the format character. 

Hello,

Just did a fresh install of MIDAS from the SVN repository under CentOS and
everything compiles fine, but when I go to run the frontend (using dio), I get
the following error message:

Connect to experiment ...[odb.c:868:db_open_database] Different database format:
 Shared memory is 14, program is 2
[midas.c:1763:cm_connect_experiment1] cannot open database


Any ideas on what the problem could be, or how to fix it?  


~Steve

Thanks for your help.  I tried again and it got me back to the initial problem I had.
 The frontend will start, and the analyzer starts (complains about there not being a
last.root, but other than that it's fine), and then when starting mlogger, I get:

[odb.c:860:db_validate_db] Warning: database corruption, first_free_key 0x0001A4
04
[odb.c:3666:db_get_key] invalid key handle
[midas.c:1970:cm_check_client] cannot delete client info
[odb.c:3666:db_get_key] invalid key handle
[midas.c:1970:cm_check_client] cannot delete client info
[odb.c:3666:db_get_key] invalid key handle


And it continues to shoot out error messages about invalid key handles until I kill
it.  Then trying to start the frontend again fails until I remove the .ODB.SHM file. 
Any other ideas?

> > Hello,
> > 
> > Just did a fresh install of MIDAS from the SVN repository under CentOS and
> > everything compiles fine, but when I go to run the frontend (using dio), I get
> > the following error message:
> > 
> > Connect to experiment ...[odb.c:868:db_open_database] Different database format:
> >  Shared memory is 14, program is 2
> > [midas.c:1763:cm_connect_experiment1] cannot open database
> > 
> > 
> > Any ideas on what the problem could be, or how to fix it?  
> 
> You have an old .ODB.SHM from a previous version in your directoy (note the '.' in
> front, so you need a 'ls -alg' to see it). Delete that file and try again.

Dear all,

we are experiencing a connection problem to the MySQL server that we use to log informations. Is there an 
option to retry multiple times the I/O on the MySQL?

The error we are experiencing is the following (hiding the IP address):

[Logger,ERROR] [mlogger.cxx:2455:write_runlog_sql,ERROR] Failed to connect to database: Error: Can't 
connect to MySQL server on 'xxx.xxx.xxx.xxx:6033' (110)

Then the logger stops, and must be restarted. This eventually happens only during the BOR or the EOR.

Best,
Stefano.

> > Dear all,
> > 
> > we are experiencing a connection problem to the MySQL server that we use to log informations. Is there an 
> > option to retry multiple times the I/O on the MySQL?
> > 
> > The error we are experiencing is the following (hiding the IP address):
> > 
> > [Logger,ERROR] [mlogger.cxx:2455:write_runlog_sql,ERROR] Failed to connect to database: Error: Can't 
> > connect to MySQL server on 'xxx.xxx.xxx.xxx:6033' (110)
> > 
> > Then the logger stops, and must be restarted. This eventually happens only during the BOR or the EOR.
> 
> What would you propose? If the connection does not work, most likely the server is down or busy. If we retry, 
> the connection still might not work. If we retry many times, people will complain that the run start or stop 
> takes very long. If we then just continue (without stopping the logger), the MySQL database will miss important 
> information and the runs probably cannot be analyzed later. So I believe it's better to really stop the logger 
> so that people get aware that there is a problem and fix the source, rather than curing the symptoms.
> 
> In the MEG experiment at PSI we run the logger with a MySQL database and we never see any connection issue, 
> except when the MySQL server gets in maintenance (once a year), but usually we don't take data then. Since we 
> use the same logger code, it cannot be a problem there. So I would try to fix the problem on the MySQL side.
> 
> Best,
> Stefan


Dear Stefan,

a possible solution could be to define the number of times to retry as a parameter that is 0 by default, as well as a wait time between two subsequent tries. This 
would leave the decision on how to handle a possible failed connection to the user. In our case, for example, we would prefer to not stop the acquisition in case 
of a failed connection to the external SQL. In addition, we have other software that, with a retry procedure, doesn’t fail: with 1 re-try and a sleep time of 0.5 s 
we already recover 100% of the faults.

Anyway, we implemented a local database, which is a mirror of the external one, and the problems disappeared.

Thanks,
Stefano.

I have added ROOT support to midas\examples\experiment\makefile.nt. To 
compile the example experiment under Windows, one needs

1) Installed version of ROOT
2) Having ROOTSYS environment variable defined
3) Invoke "nmake -f makefile.nt" in the midas\examples\experiment directory

Please note that in the current release 3.05 of ROOT, sockets are not yet 
working under Windows, so the histogram server built into the analyzer 
cannot be accessed. It is however possible to output the analyzed data into 
a .root file and visualize it with the root browser like

analyzer -i run00001.mid -o run00001.root

> > While adding new functionality to submit_elog() (add the message text to 
the
> > outgoing email), I noticed that the email text is being stored into an 
array
> > of size 256, mail_text[256], without any checks for array overrun. This
> > cannot be good. How should this be corrected?
> > K.O.
> 
> Similar problem exists in midas.c::el_submit(). The array "message[10000]" 
is
> easy to overrun by submitting a long elog message.
> 
> K.O.

The whole elog functionality in mhttpd will be replaced (sometime) by the 
standalone ELOG package, linked against mhttpd. The ELOG functionality is 
much richer and does not conatin all the mentioned problems which have been 
fixed there some time ago. For the time being it might however be worth to 
fix the mentioned problems, but without spending too much time on it.

> around to implement it, until now. I also added assert() traps for the most
> common array overruns in the Elog code.

In addition to the assert() one should use strlcat() and strlcpy() all over 
the code to avoid buffer overruns. The ELOG standalone code does that already 
properly.

- Stefan

> > > around to implement it, until now. I also added assert() traps for the 
most
> > > common array overruns in the Elog code.
> > 
> > In addition to the assert() one should use strlcat() and strlcpy() all 
over 
> > the code to avoid buffer overruns. The ELOG standalone code does that 
already 
> > properly.
> > 
> > - Stefan
> 
> Yes, the original authors should have used strlcat(). Now that I uncovered 
this source of mhttpd 
> memory corruption, maybe some volunteer will fix it up properly.
> 
> K.O.

I am the original author and will fix all that once I merged mhttpd and elog. 
Due to my current task list, this will happen probably in November.

- Stefan

> > test
> > test
> > test
> 
> another test
> 
> K.O.

I got the two email notifications, if you have tried that...

> ss_thread_create now returns the thread ID on success, and zero on failure.
> Previously returned SS_SUCCESS or SS_NO_THREAD. User must now test the
> return value to determine result.
> 
> ss_thread_kill added to kill the passed thread ID. Returns SS_SUCCESS or
> SS_NO_THREAD.
> 
> Any thread creation must be verified now, and old code must be examined to
> ensure the return value is checked.

Thank you for that post. Internally, threads are not use in midas, so there 
should be no problem. Only experiments using threads explicitly should take 
care.

I had to add a 'umask' opiton to the loggers (lazy and mlogger) for the new 
PSI archive. One can now put a filename into the settings like:

archive,21,user,pw,dir,run%05d.mid,026

where the optional last parameter is used for a "umask 026" command just 
sent to the FTP server after the connection has been established. This 
changes the mode bits of the newly transferred file. We needed that so that 
the files are group readable, since several people from one group want to 
read the data.

I committed mlogger.c and ybos.c which contains the ftp code (should 
actually go into lazylogger.c instead of ybos.c).

I just realized that db_set_value, db_set_data, db_set_num_values and 
db_merge_data do not check for num_values == 0. With such a parameter the 
ODB can become corrupted, since zero length ODB entries are not allowed. I 
fixed the according places in odb.c and committed the changes. Everyone 
with ODB corruption problems should update that code.