*  FUNCTION: ApptChangeRecord
 *  DESCRIPTION: Change a record in the Appointment Database
 *  PARAMETERS: database pointer
 * database index
 * database record
 * changed fields
 *  RETURNS: ##0 if successful, errorcode if not
 *  CREATED: 1/25/95 
 *  BY: Roger Flores
 *COMMENTS:Records are not stored with extra padding - they
 *are always resized to their exact storage space.  This avoids
 *a database compression issue.  The code works as follows:
 *1)get the size of the new record
 *2)make the new record
 *3)pack the packed record plus the changes into the new record
 *4)if the sort position is changes move to the new position
 *5)attach in position
Err ApptChangeRecord(DmOpenRef dbP, UInt16 *index, ApptDBRecordPtr r, 
		     ApptDBRecordFlags changedFields)
  Err result;
  Int16 newIndex;
  UInt16 attributes;
  Boolean dontMove;
  MemHandle oldH;
  MemHandle srcH;
  MemHandle dstH;
  ApptDBRecordType src;
  ApptPackedDBRecordPtr dst;
  ApptPackedDBRecordPtr cmp;
  // We do not assume that r is completely valid so we get a valid
  // ApptDBRecordPtr...
  if ((result = ApptGetRecord(dbP, *index, &src, &srcH)) != 0)
    return result;
  // and we apply the changes to it.
  if (changedFields.when) 
    src.when = r->when;
  if (changedFields.alarm) 
    src.alarm = r->alarm;
  if (changedFields.repeat)
    src.repeat = r->repeat;
  if (changedFields.exceptions)
    src.exceptions = r->exceptions;
  if (changedFields.description)
    src.description = r->description;
  if (changedFields.note)
    src.note = r->note;

  // Allocate a new chunk with the correct size and pack the data from 
  // the unpacked record into it.
  dstH = DmNewHandle(dbP, (UInt32) ApptPackedSize(&src));
  if (dstH)
      dst = MemHandleLock (dstH);
      ApptPack (&src, dst);

  MemHandleUnlock (srcH);
  if (dstH == NULL)
    return dmErrMemError;

  // If the sort position is changed move to the new position.
  // Check if any of the key fields have changed. 
  if ((!changedFields.when) && (! changedFields.repeat))
    goto attachRecord;// repeating events aren't in sorted order
  // Make sure *index-1 < *index < *index+1, if so it's in sorted 
  // order.  Leave it there.
  if (*index > 0)
      // This record wasn't deleted and deleted records are at the end of the
      // database so the prior record may not be deleted!
      cmp = MemHandleLock (DmQueryRecord(dbP, *index-1));
      dontMove = (ApptComparePackedRecords (cmp, dst, 0, NULL, NULL, 0) <= 0);
      MemPtrUnlock (cmp);
    dontMove = true;

  if (dontMove && (*index+1 < DmNumRecords (dbP)))
      DmRecordInfo(dbP, *index+1, &attributes, NULL, NULL);
      if ( ! (attributes & dmRecAttrDelete) )
	  cmp = MemHandleLock (DmQueryRecord(dbP, *index+1));
	  dontMove = dontMove && ApptComparePackedRecords (dst, cmp, 0, NULL, NULL, 0) <= 0;
	  MemPtrUnlock (cmp);
  if (dontMove)
    goto attachRecord;
  // The record isn't in the right position.  Move it.
  newIndex = ApptFindSortPosition (dbP, dst);
  DmMoveRecord (dbP, *index, newIndex);
  if (newIndex > *index) newIndex--;
  *index = newIndex;// return new position

  // Attach the new record to the old index,  the preserves the 
  // category and record id.
  result = DmAttachRecord (dbP, index, dstH, &oldH);

  if (result) return result;


  ECApptDBValidate (dbP);

  return 0;

 *  FUNCTION: ApptNewRecord
 *  DESCRIPTION: Create a new packed record in sorted position
 *  PARAMETERS: database pointer
 *database record
 *  RETURNS: ##0 if successful, error code if not
 *  CREATED: 1/25/95 
 *  BY: Roger Flores
Err ApptNewRecord(DmOpenRef dbP, ApptDBRecordPtr r, UInt16 *index)
  MemHandle recordH;
  ApptPackedDBRecordPtr recordP;
  UInt16 newIndex;
  Err err;

  // Make a new chunk with the correct size.
  recordH = DmNewHandle (dbP, (UInt32) ApptPackedSize(r));
  if (recordH == NULL)
    return dmErrMemError;

  recordP = MemHandleLock (recordH);
  // Copy the data from the unpacked record to the packed one.
  ApptPack (r, recordP);

  newIndex = ApptFindSortPosition(dbP, recordP);

  MemPtrUnlock (recordP);

  // 4) attach in place
  err = DmAttachRecord(dbP, &newIndex, recordH, 0);
  if (err) 
    *index = newIndex;
  return err;


Linux System Admin Tips: There are over 200 Linux tips and tricks in this article. That is over 100 pages covering everything from NTP, setting up 2 IP address on one NIC, sharing directories among several users, putting running jobs in the background, find out who is doing what on your system by examining open sockets and the ps command, how to watch a file, how to prevent even root from deleting a file, tape commands, setting up cron jobs, using rsync, using screen conveniently with emacs, how to kill every process for a user, security tips and a lot more. These tip grow weekly. The above link will download the text version for easy grep searching. There is also an html version here.

Breaking Firewalls with OpenSSH and PuTTY: If the system administrator deliberately filters out all traffic except port 22 (ssh), to a single server, it is very likely that you can still gain access other computers behind the firewall. This article shows how remote Linux and Windows users can gain access to firewalled samba, mail, and http servers. In essence, it shows how openSSH and Putty can be used as a VPN solution for your home or workplace.

MySQL Tips and Tricks: Find out who is doing what in MySQL and how to kill the process, create binary log files, connect, create and select with Perl and Java, remove duplicates in a table with the index command, rollback and how to apply, merging several tables into one, updating foreign keys, monitor port 3306 with the tcpdump command, creating a C API, complex selects, and much more.

Create a Live Linux CD - BusyBox and OpenSSH Included: These steps will show you how to create a functioning Linux system, with the latest 2.6 kernel compiled from source, and how to integrate the BusyBox utilities including the installation of DHCP. Plus, how to compile in the OpenSSH package on this CD based system. On system boot-up a filesystem will be created and the contents from the CD will be uncompressed and completely loaded into RAM -- the CD could be removed at this point for boot-up on a second computer. The remaining functioning system will have full ssh capabilities. You can take over any PC assuming, of course, you have configured the kernel with the appropriate drivers and the PC can boot from a CD. This tutorial steps you through the whole processes.

SQLite Tutorial : This article explores the power and simplicity of sqlite3, first by starting with common commands and triggers, then the attach statement with the union operation is introduced in a way that allows multiple tables, in separate databases, to be combined as one virtual table, without the overhead of copying or moving data. Next, the simple sign function and the amazingly powerful trick of using this function in SQL select statements to solve complex queries with a single pass through the data is demonstrated, after making a brief mathematical case for how the sign function defines the absolute value and IF conditions.

The Lemon Parser Tutorial: This article explains how to build grammars and programs using the lemon parser, which is faster than yacc. And, unlike yacc, it is thread safe.

How to Compile the 2.6 kernel for Red Hat 9 and 8.0 and get Fedora Updates: This is a step by step tutorial on how to compile the 2.6 kernel from source.

Virtual Filesystem: Building A Linux Filesystem From An Ordinary File. You can take a disk file, format it as ext2, ext3, or reiser filesystem and then mount it, just like a physical drive. Yes, it then possible to read and write files to this newly mounted device. You can also copy the complete filesystem, since it is just a file, to another computer. If security is an issue, read on. This article will show you how to encrypt the filesystem, and mount it with ACL (Access Control Lists), which give you rights beyond the traditional read (r) write (w) and execute (x) for the 3 user groups file, owner and other.

Working With Time: What? There are 61 seconds in a minute? We can go back in time? We still tell time by the sun?

Chirico img Mike Chirico, a father of triplets (all girls) lives outside of Philadelphia, PA, USA. He has worked with Linux since 1996, has a Masters in Computer Science and Mathematics from Villanova University, and has worked in computer-related jobs from Wall Street to the University of Pennsylvania. His hero is Paul Erdos, a brilliant number theorist who was known for his open collaboration with others.

Mike's notes page is souptonuts. For open source consulting needs, please send an email to All consulting work must include a donation to Logo Logo