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Inside Macintosh: PowerPC System Software /

Chapter 3 - Code Fragment Manager / Code Fragment Manager Reference

Data Structures

Disk Location Record

For fragments located in the data fork of a file on disk, the onDisk field of a fragment location record contains a disk location record, which specifies the location of the fragment. A disk location record is defined by the DiskFragment data type.

struct DiskFragment {
   FSSpecPtr               fileSpec;      /*pointer to FSSpec*/
   long                    offset;        /*offset to start of fragment*/
   long                    length;        /*length of fragment*/
};
typedef struct DiskFragment DiskFragment;

Field Description

fileSpec

A pointer to a file specification record (a data structure of type FSSpec) for the data fork of a file. This pointer is valid only while the initialization routine is executing. If you need to access the information in the file specification record at any later time, you must make a copy of that record.

offset

The offset, in bytes, from the beginning of the file's data fork to the beginning of the fragment.

length

The length, in bytes, of the fragment. If this field contains the value 0, the fragment extends to the end-of-file.

IMPORTANT

The fields of a disk location record are aligned in memory in accordance with 680x0 alignment conventions.