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Entry  19 Jun 2017, Thomas Lindner, Bug Report, mhttpd ODB editor changes string length, breaks  
    Reply  21 Jun 2017, Thomas Lindner, Bug Report, mhttpd ODB editor changes string length, breaks  
Message ID: 1301     Entry time: 19 Jun 2017     Reply to this: 1303
Author: Thomas Lindner 
Topic: Bug Report 
Subject: mhttpd ODB editor changes string length, breaks  
I guess this might be related to the changes in the last elog conversation; but
I'll break it out as a separate problem.

The new mhttpd ODB editor seems to resize all strings (not just strings that are
greater than 256 characters).  So, when I change some string with the mhttpd ODB
editor to 'ffffff', then I find that the string size is now ~7 characters.

This might be fine in general; but it seems to cause a problem when dealing with
alarms.  In particular, I find that if I try to set (through mhttpd) the
"execute command" for an alarm class or the "condition" for an alarm, then I get
into lots of trouble.  For instance, I changed the "execute command" for my
alarm class through mhttpd; when associated alarms were triggered, I got errors

21:58:12 [feSourceEpics,ERROR] [odb.c:9133:db_get_record,ERROR] struct size
mismatch for "/Alarms/Classes/Alarm" (expected size: 348, size in ODB: 100)
21:58:12 [feSourceEpics,ERROR] [alarm.c:379:al_trigger_class,ERROR] Cannot get
alarm class record

This makes sense, since ALARM_CLASS has a fixed size

typedef struct {
   BOOL write_system_message;
   char execute_command[256];
   char display_fgcolor[32];

so problems will clearly occur when I change the size and try to grab it:

   status = db_get_record1(hDB, hkeyclass, &ac, &size, 0, strcomb(alarm_class_str));
I guess that similar problems also occur if you edit the string for ALARM or
PROGRAM_INFO instances.  These problems do not occur when I change my strings
with odbedit, which doesn't resize strings below 256.

I'm not sure what the proper solution is.  A temporary solution is that the
mhttpd ODB editor shouldn't resize strings if the new size is less than 256
characters; in that case the size should be left as 256 characters.

This test was done with MIDAS git repository as of today:
commit 45a90dc329554f528485da121501daf6ecde100d
ELOG V3.1.4-2e1708b5