rm.h

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/* rm.h - include file for rm and undel facility
 *
 * Revision History:
 *  ??-???-???? ?? Created
 *  27-Dec-1989 SB Added new index file header stuff
 *
 * Index file format:
 *  The indexed file is composed of records of length RM_RECLEN.
 *	The old index file was composed of entries each the size of a record
 *  and composed of filename padded by NULs. The hash function mapped the
 *  Nth record (i.e. Nth INDEXED entry) to 'deleted.xxx', where, 'xxx' is (N+1)
 *  padded by leading zeroes.
 *	The new index file has an header record, rm_header, followed by entries
 *  of one or more records padded by NULs. Longfilenames occupy multiple
 *  records. The hash function maps the entry starting at Nth record to
 *  'deleted.xxx' where xxx is (N+1) padded by leading zeroes. This works out
 *  to be basically the same as that for the old format. The differences are :-
 *	-No entry is mapped to 'deleted.000'
 *	-Entries for filenames longer than (RM_RECLEN-1) bytes cause gaps in
 *	    mapping.
 *
 * Notes:
 *  RM/EXP/UNDEL work as follows:-
 *	    'RM foo' saves a copy of 'foo' and places it in an hidden
 *	sub-directory of RM_DIR (of foo) as file 'deleted.xxx', where, xxx is
 *	determined from the index file RM_IDX in RM_DIR. An entry is made in
 *	the index file for this.
 *	    'UNDEL foo' reads the index file in RM_DIR and determines xxx for
 *	foo and renames 'deleted.xxx' as foo. The entry for foo in the index
 *	file is filled with NULLs.
 *	    'EXP' picks up the index file from RM_DIR and deletes 'deleted.xxx'
 *	for each entry in the index file. It then deletes the index file and
 *	RM_DIR.
 *
 *  The new index file format can coexist with the old one because :-
 *	The header has a starting NULL which causes it to be ignored by
 *	    the old utilities,
 *	When the old utilities attempt to read in a long filename entry they
 *	fail without harm as the hashed 'deleted.xx' does not exist.
 */

#define RM_DIR	    "deleted."
#define RM_IDX	    "index."
#define RM_RECLEN   16

/* The header record in the index file has
 *	'\0IXn.nn\0' padded to RM_RECLEN bytes
 */

#define RM_SIG	    (char)0x00
#define RM_MAGIC    "IX"	  /* IX - IndeXed file */
#define RM_VER	    "1.01"
#define RM_NULL     '\0'

/* Forms header for Index file using RM_MAGIC, RM_VER and RM_NULL */

extern char rm_header[RM_RECLEN];

/* Function prototypes */

    // Converts Index file to the new format
int convertIdxFile (int fhidx, char *dir);

    // Determines if the record is a new index file header
flagType fIdxHdr (char *rec);

    // Reads an Index file record
int readIdxRec (int fhIdx, char *rec);

    // Reads index file records and returns INDEXED entry
int readNewIdxRec (int fhIdx, char *szRec, unsigned int cbMax);

    // Writes an new index file header
int writeIdxHdr (int fhIdx);

    // Writes an index file record
int writeIdxRec (int fhIdx, char *rec);

    // Indexes an entry into the Index file
int writeNewIdxRec (int fhIdx, char *szRec);