Subj : Serial port query
To   : Darin McBride
From : Vitus Jensen
Date : Wed Aug 09 2000 08:23 pm

Moin Darin!

06.08.2000, Darin McBride wrote a message to Vitus Jensen:

....
 DM>>> Is there a way 1. to check the state of a port, 2. determine the
 DM>>> application using it?

 DM>>> By #1, I believe he means "determine if a comm port was in use".

 DM>>> Any ideas whatsoever would be appreciated.  I believe #1 can be done
 DM>>> by an attempt to open the port as a file in "DENY_ALL" mode - if it
 DM>>> fails, someone is using it.  I don't believe #2 is possible.  If I
 DM>>> could be corrected, that would be great.  :-)

 VJ>> Get OS2UNDOC from hobbes and have a look at the DosQuerySysState API. 
 VJ>> It will return infos about all open files of a single or all
 VJ>> processes.  There are problems when using it at certain fixpak
 VJ>> levels (older Warp 3 fixpaks).

 DM> Of course!  I forgot all about that.  I already use that call for a
 DM> number of things, so one more is no biggie.  :-)  Unfortunately, I
 DM> can't figure out how to trace back from the file to the process(es). 

Use the brute force method?  See below.


 DM> I've done some slight modifications to the sample programs given in
 DM> the undoc INF file, and I get:

 DM>     name: D:\BBS\MAIL\ECHO\FIDONET\BACKBONE\OS2PROG.SQD
 DM>  opencnt: 1
 DM>  sfn: e0
 DM>  refcnt: 1
 DM>  flags: 0
 DM>  accmode: c2
 DM>  filesize: 62315
 DM>  volhnd: 264
 DM>  attrib: 20 [A-----]

 DM> Now, *I* know which process this is:

 DM>     PID: 1736
 DM>  PPID: 30
 DM>  type: 3
 DM>  state: 10
 DM>  session id: 36
 DM>  mod handle: 1be8 (D:\BBS\FLEET\FLTSTRT.EXE)
 DM>  # of threads: 4
 DM> [...]

 DM> I just can't tell how to get from one to the other.
....

There is this lees-than-optimal solution but why not use it:

get a list of all running processes via DosQuerySysState
for every process ID
  get a list of all open files via DosQuerySysState
  for every open file
    check whether filename = COMx
    if identical 
      dump process info (DosQuerySysState)

I don't think it would be too slow to be usable.

Bye,
   Vitus

---
 * Origin: Of all the things I've lost, I miss my mind the most. (2:2474/424.1)

.