-*-text-*-
$Header: /CVSROOT/public/scylla-charybdis/md5backup/doc/internals.txt,v 1.2 2004/07/05 23:53:52 tino Exp $

md5backup works as follows:

Traverse the directories given (stay in the same filesystem).
If an ignored directory is found, it is skipped (recoursively).
For all files found:
	Check if the file is ignored, if so, skip this file.
	Locate the file in the database.
	If not there
		Do a backup of this file
	else
		Consult the modification timestamp.
		If newer do a backup of this file

Backup is done as follows:

Append a log entry.
Write the file into tmp/ directory.
Record md5 while written.
Append the result to the md5 file (md5/ directory).
Loop a counter counting from 0
	if md5 file in the files/ hierarchy with the count exists:
		compare the temporary with it
		If equal:
			delete temporary file
			break out of loop
	else
		move temporary to files/ hierarchily as md5 file with count
		and hardlink these file to the = targets as well.
		break out of loop
Update the database
Append apropriate log entry.

Note that usually count will be 0, as currently there are no files
known which have the same MD5 sum but different contents.
If there is trouble with the = targets, count will go to infinity,
thus md5backup will starve looping in the count.  Yes, this is a bug,
but will not be solved in the next time I think.
(Note that I think I fixed the bug already arround 0.3.3.)

$Log: internals.txt,v $
Revision 1.2  2004/07/05 23:53:52  tino
va_copy not defined in all systems

Revision 1.1  2004/05/09 23:18:48  tino
copied from README