Initial import of htcd system 1.0

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

1 files changed, 154 insertions, 0 deletions

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+/*************************************************************************
+ *
+ * HTCd - Copyright (C) 1998-2006 Henrik Rydberg
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+HDB/1.2 FILE FORMAT SPECIFICATION Sat Feb 24 18:38:25 MET 2001
+
+MT AND MP SAFE
+
+One single format utilizing memory maps, and which is designed to
+work safely between processes and within a multi-threading process.
+To accomplish this, there are two types of locking mechanisms -
+one inter-process lock in the file header, and one MT lock implemented
+the usual way.
+
+The format is robust within each thread, except for changes in the
+table structure, which generates fatal error_t errors.
+
+The format includes a finite (32) number of tables, which should not
+be a real problem. Besides, a possible change is to move the frame
+pointer to a position inside, so that additional header could be
+added if needed.
+
+FILEFORMAT in HDB/1.2
+
+BYTES 1.2          NAME         DESCRIPTION
+32                 IDENT        Identification header
+4                  LOCK         Inter-process lock
+4                  MINOR        Minor modification state number
+4                  MAJOR        Major modification state number
+4                  FATAL        Fatal modification state number
+4                  FILESIZE     Size of file
+4                  FILETOP      Size of used part
+4                  TABLES       Number of table name strings
+4                  INDEX        Which column is the order column.
+32                 COMPNAME     Comparison name
+32*32              TABLENAMES   Table names
+4                  FRAME        Start of record data
+*                  RECORDS      Record list
+  4                mem          amount of memory for this record
+  4                caps         the capacity of this record - 0 means deleted
+  mem-8            data         The data follows
+0                  ZEROS        The rest of the file is padded with zeros.
+
+The records are always staying where they land; a minor change means
+a change in-place, a major change means a change leading to an index
+update, which could be a deletion, an insertion. Those are updated at
+will, and not seen until wanted. A fatal change is a change in the
+table structure, i.e., an insertion or deletion of a table. Also a
+table name change counts as fatal. The filesize used to be (earlier
+versions) a state needing attention as well, but not anymore.
+
+--
+
+HDB/1.11 FILE FORMAT SPECIFICATION Mon Jan 29 03:51:41 MET 2001
+
+STATIC/DYNAMIC mapping
+
+The header field determines whether the mapping is dynamic or static,
+i.e., static mapping creates a shared mmap and edits the records
+directly, whereas the dynamic mapping creates a private map and
+stores the changes on save only.
+
+The format changed quite a lot after all...
+
+FILEFORMAT in HDB/1.11
+
+BYTES 1.11         NAME         DESCRIPTION
+32                 IDENT        Identification header
+4                  MODNUM       Modification number
+4                  LOCK         Soft lock
+4                  FILESIZE     Size of file
+4                  FILETOP      Size of used part
+4                  FIXED        Whether fixed mapping or not
+4                  TABLES       Number of table name strings
+4                  INDEX        Which column is the order column.
+32                 COMPNAME     Comparison name
+4                  RECORDS      Number of records in file.
+                   tables
+  4,*              name         table name
+  4,*              defaults     default string
+  4                caps         default sizes
+    [4],*          records      TABLES[RECORDS]
+
+Size info [4] always refers to the stringref-size, but the number of
+bytes actually written is as follows: for fixed maps, it is tabs[].caps,
+and for dynamic maps, it is capsize(), which is defined as (n=stringref-size)
+(4+n)&~3.
+
+--
+
+HDB/1.10 FILE FORMAT SPECIFICATION Thu Jan 25 00:42:49 MET 2001
+
+The HDB/1.0 format has been used widely in the software
+for our group (MST) during the last three years of so.
+The HDB/1.1 file format is binary compatible with 1.0,
+and merely consists of a formalization, along with a
+change in the internal manipulation scheme and a new
+hdb editor.
+
+FILE FORMAT IN 1.0 and 1.1
+
+BYTES 1.0/1.1      NAME         DESCRIPTION
+32/variable        HEAD         Identification header.
+                                Used to be exactly 32 bytes,
+                                but see no point in that.
+4                  TABLES       Number of table name strings
+  4                dim          bytes in string
+  *                data         string data
+4                  DEFAULTS     Number of default strings
+  4                dim          bytes in string
+  *                data         string data
+4                  ORDERBY      Which column is the order column.
+4                  dim          Number of bytes in compname.
+*                  data         string data
+4                  RECORDS      Number of records in file.
+  4                tables
+    4              dim
+    *              data
+0/variable         FOOTER       File ends. Simple Footer.
+
+ADDITIONAL CHANGES BETWEEN 1.0 and 1.1
+
+The major difference - and the rationale for 1.1 - is
+the possiblity to edit files directly, as in mmap.
+To be able to do this, there is a need to force a minimum
+size to each field. This is done by padding the data
+with trailing zeros. This is ok since only string data
+is stored in the fields, and never binary data. Just think
+of it; if it was binary data, it would not be replaced
+by something the same size anyways, so thats forbidden
+in the direct-editing mode. It makes no difference to
+the normal operation.
+
+The default sizes for new fields are taken from the defaults
+table, which again is completely compatible. The only
+difference is that the zeros are stored as well, and hence
+cannot be defined just by the default string, but need an editor
+that specifies the sizes.
+