Chapter 3KcsChunkSet Class
This chapter describes the KCMS framework KcsChunkSet class. You can manage blocks (or chunks) of data arranged in
tagged file format with Chunk classes. The ICC profile format is directly
analogous to the KcsChunkSet. The KcsChunkSet class is derived from the KcsShareable
class. See Chapter 1, KcsShareable Class for a description of the KcsShareable class.
As you read this chapter, you will find it helpful to have access to
the following header files:
kcsshare.h
kcsio.h and kcsmblk.h
kcschu.h and kcschunk.h
Note - It is highly recommended that you do not
use any of the variables and functions for handle-based memory in the these
header files. Handle-based memory is not required on the Solaris system.
The header file for the class is kcschunk.h. The
constant and #define identifiers for this class are defined
in the kcsids.h header file as:
const KcsId KcsSharChkSId = {(0x43686B53UL)}; /* 'ChkS' */
#define KcsSharChkSIdd (0x43686B53UL) /* 'ChkS' */ |
In addition to the KcsShareable methods overridden
by this class, there are methods for managing chunks of data. The protected
and public members are described.
Protected Members
The KcsChunkSet class has the following protected
members.
Table 3-1 KcsChunkSet Protected Members
Protected Member | Description |
|---|
virtual KcsStatus
readChunkBuffer(const KcsChunkId aChunkId,
void *aChunk,unsigned long *aSizeRead,
unsigned long aSizeWanted = 0); |
| Reads a chunk of bytes indicated by a chunk
Id. KCS_CHUNK_ID_ERR is returned if no
chunk Ids match in the profile. Assumes the aChunk buffer
is allocated. Get the buffer size with getChunkSize()
which is defined in Table 3-2. |
virtual KcsStatus
writeChunkBuffer(const KcsChunkId aChunkId,
void *aChunk, const unsigned long aSize,
KcsCompressBoolean aCompress = KcsCompress,
KcsLocationEnum aLocationEnum =
KcsLocationUnspecified,
long aOffset = KcsNoOffsetSpecified); |
| Writes a chunk of bytes to a new chunk in
the profile, given a void *. Returns a new chunk Id. If
a particular location or offset is specified, other chunks are moved to write
this chunk at the specified location. |
Public Members
The KcsChunkSet class has the following public
members.
Table 3-2 KcsChunkSet Public Members
Public Member | Description |
|---|
virtual KcsStatus
createChunkId(KcsChunkId *aNewChunkId,
unsigned long aChunkSize = 0,
KcsLocationEnum aLocationEnum =
aKcsLocationUnspecified,
long aChunkOffset = KcsNoOffsetSpecified,
KcsRegisterBoolean aRegister =
KcsIgnoreIdSpecified); |
| Allocates aNewChunkId for a chunk introduced
to the data type. Puts a new entry into the chunk map. The size of the chunk
can be specified, or by default equals 0. The chunk location
can be specified in aLocationEnum and aChunkOffset or defaults can be used. Creates specific chunk ids with aRegister. |
virtual KcsStatus
deleteChunk(const long aChunkId); |
| Deletes the chunk (and its chunk map entry)
identified by a chunkId. You are required to check whether
any other objects are using this chunk. |
virtual unsigned long
getChunkSetLength(KcsStatus *aStatus); |
| Returns the length of the domain of the chunk
set. |
virtual long
getChunkSetOffset(KcsStatus *aStatus); |
| Returns the offset of the beginning of the
domain of the chunk set. |
virtual unsigned long
getChunkSize(KcsStatus *aStatus,
KcsChunkId aChunkId); |
| Returns the chunk size identified by aChunkId. If the chunk is compressed, returns the uncompressed chunk size. |
| Returns the chunk set's I/O object. |
virtual KcsChunkId
getTopChunkId(KcsStatus *aStatus,
unsigned long aSize = 0,
long aOffset = KcsNoOffsetSpecified); |
| Returns the chunk Id of the top chunk which stores information about other
chunks. Read this chunk first because it tells what is contained in the other
chunks. Or you can specify the size of the chunk and the chunk's offset; by
default, aSize = 0 and aOffset = KcsNoOffsetSpecified. If no top chunk exists
, call createChunkId(). |
virtual Boolean
isEqual(KcsChunkSet *aNotherCS); |
| Checks if this chunk set is the same as another chunk set. |
KcsChunkSet(KcsStatus *aStatus); |
| Constructor without an I/O object. |
KcsChunkSet(KcsStatus *aStatus,
KcsIO *aIoObj,
unsigned long aChunkSetLength = KcsUseEOF,
KcsSaveBoolean aSaveMapping =
KcsSaveChunkSet,
int Format = 0); |
| Constructor of a chunk set instance based on an I/O object. aChunkSetLength can be set to the length of
the static store managed by the chunk set if not equal to the length managed
by the I/O object. Otherwise, by default, aChunkSetLength
is set to the end of the static store managed by the I/O object. When a particular file format does not allow writing out the chunk map, aSaveMapping is False; otherwise, aSaveMapping is, by default, True indicating that the chunk
containing the chunk map should be saved. |
| Destructor. |
KcsStatus
readChunk(const KcsChunkId aChunkId, void *aChunk,
unsigned long *aSizeRead,
unsigned long aSizeWanted = 0); |
| Reads a chunk set. |
virtual KcsStatus
setChunkSetOffset(long aOffset); |
| Sets aOffset to the beginning
of the domain of the chunk set. |
virtual KcsStatus
setChunkSetPrivateOffset(const long aOffset) |
| Sets the chunk set's private offset. |
virtual KcsStatus
setIO(KcsIO *aIoObj); |
| Sets the chunk set's
I/O object. |
virtual unsigned long
updateChunkUseCount(KcsStatus *aStatus,
KcsChunkId aChunkId, long aDelta,
unsigned long aComparisonCount); |
| Calls the ChunkMap object
to change the use count of a particular chunk. Compares the use count with
an expected value, aComparisonCount. |
KcsStatus
writeChunk(KcsChunkId aChunkId,
void *aChunk,
const unsigned long aSize,
KcsCompressBoolean aCompress = KcsCompress,
KcsLocationEnum aLocationEnum =
KcsLocationUnspecified,
long aOffset = KcsNoOffsetSpecified); |
| Writes a chunk set. |
Example
The following code shows you some examples of how to use these KcsChunkSet class member functions: getChunkSet(), getChunkSize(), readChunk(), and writeChunk().
Example 3-1 Getting, Reading and Writing a Chunk
KcsChunkId myChunkId;
KcsStatus aStat;
KcsChunkSet* chunkSet;
char* mftData;
u_long mftSize;
u_long mftWanted;
// Get the chunk data
chunkSet = getChunkSet();
if (chunkSet == NULL)
return (KCS_INTERNAL_CLASS_CORRUPTED);
//Get the size
mftSize = chunkSet->getChunkSize(&aStat, myChunkId);
if (aStat != KCS_SUCCESS)
return(aStat);
//Make space for the data
mftData = NULL;
if ((mftData = malloc((u_int)mftSize)) == NULL) {
return (KCS_MEM_ALLOC_ERR);
}
//Read it
aStat = chunkSet->readChunk(myChunkId, mftData, &mftWanted,
mftSize);
if (aStat != KCS_SUCCESS)
return (aStat);
//Zero it out and write it back
memset(mftData, 0, mftSize);
aStat = chunkSet->writeChunk(myChunkId, mftData, mftSize);
if (aStat != KCS_SUCCESS)
return (aStat);
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