Volume Operations

Five general operations can be performed on a volume:

A volume can be opened (mounted). During the opening of a volume, file system control structures are read from the underlying device, parsed and verified.

Files can be accessed on a volume. A file is a linear data sequence (‘file contents’) associated with some logical, typically human-readable identifier (‘file name’). Additional properties, such as size, update date/time and access mode (e.g., read-only, write-only, read-write) may be associated with a file. File accesses constitute reading data from files, writing data to files, creating new files, renaming files, copying files, etc. File access is accomplished via file module-level functions, which are covered in Chapter 8, “Files”.

Directories can be accessed on a volume. A directory is a container for files and other directories. Operations include iterating through the contents of the directory, creating new directories, renaming directories, etc. Directory access is accomplished via directory module-level functions, which are covered in Chapter 9, “Directories”.

A volume can be formatted. (More specifically, high-level formatted.) Formatting writes the control information for a file system to the partition on which a volume is located.

A volume can be closed (unmounted). During the closing of a volume, any cached data is written to the underlying device and associated structures are freed.

For information about using volume names, see section 4-2 “μ C/FS Device and Volume Names”. For FAT-specific volume functions, see Chapter 4, “File Systems: FAT”.

Function	Description	Valid for Unmounted Volume?
FSVol_CacheAssign()	Assign cache to volume.	Yes
FSVol_CacheInvalidate()	Invalidate cache for volume.	No
FSVol_CacheFlush()	Flush cache for volume.	No
FSVol_Close()	Close (unmount) volume.	Yes
FSVol_Fmt()	Format volume.	Yes
FSVol_IsMounted()	Determine whether volume is mounted.	Yes
FSVol_LabelGet()	Get volume label.	No
FSVol_LabelSet()	Set volume label.	No
FSVol_Open()	Open (mount) volume.	-----
FSVol_Query()	Get volume information.	Yes
FSVol_Rd()	Read sector on volume.	No
FSVol_Refresh()	Refresh a volume.	No
FSVol_Wr()	Write sector on volume.	No

Table 7-2 Volume API functions