Allocates and deallocates storage in a disk file, much like a "freestore" manager. More...

#include <rw/filemgr.h>

Inheritance diagram for RWFileManager:

Public Member Functions
	RWFileManager (const char filename, const char mode=rwnil)

	~RWFileManager ()

RWoffset	allocate (RWspace s)

void	deallocate (RWoffset t)

RWoffset	endData () const

RWoffset	start () const

Public Member Functions inherited from RWFile
	RWFile (const char filename, const char mode=0, bool large_file=false)

	~RWFile ()

const char *	Access () const

void	ClearErr ()

RWoffset	CurOffset () const

RWoffset64	CurOffset64 () const

bool	Eof () const

bool	eof () const

bool	Erase ()

bool	Error () const

bool	Exists () const

bool	Flush ()

const char *	GetName () const

FILE *	GetStream () const

bool	good () const

bool	IsEmpty () const

bool	isValid () const

bool	Read (bool &i)

bool	Read (bool i, size_t n, size_t count=0)

bool	Read (char &c)

bool	Read (char i, size_t n, int delim, size_t count=0)

bool	Read (char i, size_t n, size_t count=0)

bool	Read (char *string)

bool	Read (double &s)

bool	Read (double i, size_t n, size_t count=0)

bool	Read (float &f)

bool	Read (float i, size_t n, size_t count=0)

bool	Read (int &i)

bool	Read (int i, size_t n, size_t count=0)

bool	Read (long &i)

bool	Read (long i, size_t n, size_t count=0)

bool	Read (long double &d)

bool	Read (long double i, size_t n, size_t count=0)

bool	Read (long long &i)

bool	Read (long long i, size_t n, size_t count=0)

bool	Read (short &i)

bool	Read (short i, size_t n, size_t count=0)

bool	Read (unsigned char &c)

bool	Read (unsigned char c, size_t n, size_t count=0)

bool	Read (unsigned int &i)

bool	Read (unsigned int i, size_t n, size_t count=0)

bool	Read (unsigned long &i)

bool	Read (unsigned long i, size_t n, size_t count=0)

bool	Read (unsigned long long &i)

bool	Read (unsigned long long i, size_t n, size_t count=0)

bool	Read (unsigned short &i)

bool	Read (unsigned short i, size_t n, size_t count=0)

bool	Read (wchar_t &w)

bool	Read (wchar_t i, size_t n, size_t count=0)

bool	SeekTo (RWoffset offset)

bool	SeekTo64 (RWoffset64 offset)

bool	SeekToBegin ()

bool	SeekToEnd ()

bool	Write (bool i)

bool	Write (char i)

bool	Write (const bool *i, size_t count)

bool	Write (const char *string)

bool	Write (const char *string, size_t)

bool	Write (const double *i, size_t count)

bool	Write (const float *i, size_t count)

bool	Write (const int *i, size_t count)

bool	Write (const long *i, size_t count)

bool	Write (const long double *i, size_t count)

bool	Write (const long long *i, size_t count)

bool	Write (const short *i, size_t count)

bool	Write (const unsigned char *c, size_t N)

bool	Write (const unsigned int *i, size_t N)

bool	Write (const unsigned long *i, size_t N)

bool	Write (const unsigned long long *i, size_t count)

bool	Write (const unsigned short *i, size_t N)

bool	Write (const wchar_t *i, size_t count)

bool	Write (double d)

bool	Write (float f)

bool	Write (int i)

bool	Write (long double d)

bool	Write (long i)

bool	Write (long long i)

bool	Write (short i)

bool	Write (unsigned char i)

bool	Write (unsigned int i)

bool	Write (unsigned long i)

bool	Write (unsigned long long i)

bool	Write (unsigned short i)

bool	Write (wchar_t i)

Additional Inherited Members
Static Public Member Functions inherited from RWFile
static bool	Exists (const char *filename)

static bool	Exists (const char *filename, int mode)

Detailed Description

Class RWFileManager allocates and deallocates storage in a disk file, much like a "freestore" manager. It does this by maintaining a linked list of free space within the file.

Note: Class RWFileManager inherits class RWFile as a public base class; hence all the public member functions of RWFile are visible to RWFileManager. They are not listed here.

If a file is managed by an RWFileManager, then reading or writing to unallocated space in the file has undefined results. In particular, overwriting the end of allocated space is a common problem which usually results in corrupted data. One way to encounter this problem is to use binaryStoreSize() to discover the amount of space needed to store an RWCollection. For most purposes, the storage size of an RWCollection is found using the RWCollectable method recursiveStoreSize().

Synopsis: typedef long RWoffset;

typedef unsigned long RWspace; // (typically)

#include <rw/filemgr.h>

RWFileManager f("file.dat");

RWFileManager
Allocates and deallocates storage in a disk file, much like a "freestore" manager.
Definition filemgr.h:66

RWoffset
unspecified_type RWoffset
Definition compat.h:506

Persistence: None

Constructor & Destructor Documentation

◆ RWFileManager()

RWFileManager::RWFileManager	(	const char *	filename,
		const char *	mode = rwnil )

explicit

Constructs an RWFileManager for the file with path name filename using mode mode. The mode is as given by the C Standard Library function fopen(). If mode is zero (the default), then the constructor attempts to open an existing file with the given filename for update (mode "rb+"). If this is not possible, then it attempts to create a new file with the given filename (mode "wb+"). If the file exists and is not empty, then the constructor assumes it contains an existing file manager; other contents cause the function to throw an exception of type RWExternalErr. If no file exists or if an existing file is empty, then the constructor attempts to create the file (if necessary) and initialize it with a new file manager. The resultant object should be checked for validity using function isValid(). RWFileErr is a possible exception that could be thrown.

◆ ~RWFileManager()

RWFileManager::~RWFileManager ( )

Empty Destructor.

Member Function Documentation

◆ allocate()

RWoffset RWFileManager::allocate ( RWspace s )

Allocates s bytes of storage in the file. Returns the offset to the start of the storage location. The very first allocation for the file is considered "special" and can be returned at any later time by the function start(). RWFileErr is a possible exception that could be thrown.

◆ deallocate()

void RWFileManager::deallocate ( RWoffset t )

Deallocates (frees) the storage space starting at offset t. This space must have been previously allocated by a call to allocate(). The very first allocation ever made in the file is considered "special" and cannot be deallocated. RWFileErr is a possible exception that could be thrown.

◆ endData()

RWoffset RWFileManager::endData ( ) const

inline

Returns an offset just past the end of the file.

◆ start()

RWoffset RWFileManager::start ( ) const