dir(4CDFS)                    (CD-ROM)                    dir(4CDFS)


       NAME
             dir (cdfs) - format of CD-ROM file system (cdfs) directory
             data structure

       SYNOPSIS
             #include <sys/fs/iso9660.h>
             #include <sys/fs/cdfs_inode.h>

       DESCRIPTION
             In a cdfs file system, the contents of a file or directory are
             stored in contiguous physical sectors called an extent.  The
             contents of a directory are stored in a single extent.  The
             contents of a file may be stored in multiple non-adjacent
             extents.  More than one file can share the same extent.  The
             first sector of each extent may contain an Extended Attribute
             Record (XAR) that describes additional attributes of the file
             or directory (such as the User ID, Group ID, permissions).

             Each directory in a cdfs filesystem contains two or more
             Directory Records.  These directory records identify the file
             and subdirectories owned by the directory.  For each file or
             subdirectory in the directory, there will exist one Directory
             Record for each extent belonging to that file/subdirectory.
             Each Directory Record is of variable length and contains
             information such as:

                   the name of the file or subdirectory

                   the location and size of its extent

                   a System Use Area

             Note: For a multi-extent file, there will be one directory
             record for each extent in the file.

             Each Directory Record has a System Use Area (SUA) that stores
             information about other operating system standards, such as
             additional file-related information not defined by the ISO-
             9660 specification.  The SUA can be used to store information
             required to support POSIX standards.  For example, the SUA can
             contain the device file major/minor numbers, which are defined
             by the POSIX standard.  The System Use Sharing Protocol (SUSP)
             defines how the information in the SUA is defined.





                           Copyright 1994 Novell, Inc.               Page 1

      dir(4CDFS)                    (CD-ROM)                    dir(4CDFS)


            The Directory Record data structure is defined in the
            iso9660.h header file.  For each cdfs file and directory
            currently being referenced, an in-core data structure, struct
            cdfs_drec, is used to store the relevant portions of all of
            the Directory Records belonging to that file or directory.
            Each cdfs_drec also stores other information relating to the
            extent and/or Directory Record.  The cdfs_drec structure is
            defined in the cdfs_inode.h header file.

            The cdfs_drec structure is as follows:
            struct cdfs_drec {
              struct cdfs_drec       *drec_NextDR;/* Pointer to next Dir Rec */
              struct cdfs_drec       *drec_PrevDR;/* Pointer to previous Dir Rec */
              uint_t     drec_Loc;   /* Loc of media DREC (L-Sec #) */
              uint_t     drec_Offset;/* # bytes from L-sec start */
              uint_t     drec_Len;   /* Len of media Dir Rec (Bytes) */
              uint_t     drec_XarLen;/* Len of media XAR (Log Blk) */
              daddr_t    drec_ExtLoc;/* Location of Extent (L-Blk #) */
              uint_t     drec_DataLen;/* Len of File Sec data */
              timestruc_t            drec_Date;/* Recording date and time */
              uint_t     drec_Flags; /* Flags - See below */
              uint_t     drec_UnitSz;/* File Unit Size */
              uint_t     drec_Interleave;/* Interleave Gap Size */
              uint_t     drec_VolSeqNum;/* Volume Sequence Number */
              uint_t     drec_FileIDLen;/* Len of File ID String */
              uint_t     drec_FileIDOff;/* Dir Rec offset of File ID */
              uint_t     drec_SysUseOff;/* Dir Rec offset of Sys Use Area */
              uint_t     drec_SysUseSz;/* Size of Sys Use Area */
            };

      REFERENCES
            cdfs-specific fs(4CDFS), cdfs-specific inode(4CDFS)
            System Use Sharing Protocol and Rock Ridge Interchange
            Protocol from Rock Ridge Technical Working Group, ISO 9660
            Specification ISO 9660:1988(E), Working Paper for Information
            Processing: Volume and File Structure of CD-ROM Information
             Interchange" in Optical Information Systems magazine,
            January/February 1987










                          Copyright 1994 Novell, Inc.               Page 2