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os::FSNode Class Reference

Lowlevel filesystem node class. More...

#include <fsnode.h>

Inheritance diagram for os::FSNode::

List of all members.

Public Methods
	FSNode ()
	Default contructor. More...
	FSNode (const std::string &cPath, int nOpenMode=O_RDONLY)
	Construct a FSNode from a file path. More...
	FSNode (const Directory &cDir, const std::string &cName, int nOpenMode=O_RDONLY)
	Construct a FSNode from directory and a name inside that directory. More...
	FSNode (const FileReference &cRef, int nOpenMode=O_RDONLY)
	Construct a FSNode from a file reference. More...
	FSNode (const FSNode &cNode)
	Copy contructor. More...
virtual	~FSNode ()
	Destructor. More...
virtual status_t	FDChanged (int nNewFD, const struct::stat &sStat)
virtual status_t	SetTo (const std::string &cPath, int nOpenMode=O_RDONLY)
	Open a node using a path. More...
virtual status_t	SetTo (const Directory &cDir, const std::string &cPath, int nOpenMode=O_RDONLY)
	Open a node using a dir/path pair. More...
virtual status_t	SetTo (const FileReference &cRef, int nOpenMode=O_RDONLY)
	Open the node referred to by the given os::FileReference. More...
virtual status_t	SetTo (const FSNode &cNode)
	Copy another FSNode. More...
virtual void	Unset ()
	Reset the FSNode. More...
virtual bool	IsValid () const
	Check if the node has been properly initialized. More...
virtual status_t	GetStat (struct::stat *psStat, bool bUpdateCache=true) const
virtual ino_t	GetInode () const
virtual dev_t	GetDev () const
virtual int	GetMode (bool bUpdateCache=true) const
virtual off_t	GetSize (bool bUpdateCache=true) const
virtual time_t	GetCTime (bool bUpdateCache=true) const
virtual time_t	GetMTime (bool bUpdateCache=true) const
virtual time_t	GetATime (bool bUpdateCache=true) const
virtual status_t	GetNextAttrName (std::string *pcName)
	Read the node's attribute directory. More...
virtual status_t	RewindAttrdir ()
	Reset the attribute directory iterator. More...
virtual ssize_t	WriteAttr (const std::string &cAttrName, int nFlags, int nType, const void *pBuffer, off_t nPos, size_t nLen)
	Add/update an attribute. More...
virtual ssize_t	ReadAttr (const std::string &cAttrName, int nType, void *pBuffer, off_t nPos, size_t nLen)
	Read the data held by an attribute. More...
virtual status_t	RemoveAttr (const std::string &cName)
	Remove an attribute from an FS node. More...
virtual status_t	StatAttr (const std::string &cName, struct::attr_info *psBuffer)
virtual int	GetFileDescriptor () const
Friends
class	Directory

Detailed Description

Description:: This class give access to the lowest level of a filesystem node. A node can be a directory, regular file, symlink or named pipe.

It give you access to stats that is common to all nodes in the filesystem like time-stamps, access-rights, inode and device numbers, and most imporant the file-attributes.

The native AtheOS filesystem (AFS) support "attributes" wich is extra data-streams associated with filesystem nodes. An attribute can have a specific type like int, float, string, etc etc, or it can be a untyped stream of data. Attributes can be used to store information associated by the file but that don't belong to file content itself (for example the file's icon-image and mime-type).

See also:: os::FileReference, os::File, os::Directory

Author:: Kurt Skauen ([email protected])

Constructor & Destructor Documentation

FSNode::FSNode ( )

Description:
Initiate the FSNode to a known but "invalid" state. The node must be initialize with one of the SetTo() members before any other members can be called.
Author:
Kurt Skauen ([email protected])

FSNode::FSNode ( const std::string & cPath,

int nOpenMode = O_RDONLY

)

Description:
See: SetTo( const std::string& cPath, int nOpenMode )
Note:
Since constructors can't return error codes it will throw an os::errno_exception in the case of failure. The error code can be retrieved from the exception object.

Author:
Kurt Skauen ([email protected])

FSNode::FSNode ( const Directory & cDir,

const std::string & cPath,

int nOpenMode = O_RDONLY

)

Description:
See: SetTo( const Directory& cDir, const std::string& cPath, int nOpenMode )
Note:
Since constructors can't return error codes it will throw an os::errno_exception in the case of failure. The error code can be retrieved from the exception object.

Author:
Kurt Skauen ([email protected])

FSNode::FSNode ( const FileReference & cRef,

int nOpenMode = O_RDONLY

)

Description:
See: SetTo( const FileReference& cRef, int nOpenMode )
Note:
Since constructors can't return error codes it will throw an os::errno_exception in the case of failure. The error code can be retrieved from the exception object.

Author:
Kurt Skauen ([email protected])

FSNode::FSNode ( const FSNode & cNode )

Description:
Copy an existing node. If the node can't be copyed an os::errno_exception will be thrown. Each node consume a file-descriptor so running out of FD's will cause the copy to fail.
Note:
The attribute directory iterator will not be cloned so when FSNode::GetNextAttrName() is called for the first time it will return the first attribute name even if the iterator was not located at the beginning of the originals attribute directory.
Parameters:

cNode The node to copy.

Author:
Kurt Skauen ([email protected])

FSNode::~FSNode ( ) [virtual]

Description:
Will close the file descriptor and release other resources may consumed by the FSNode.
Author:
Kurt Skauen ([email protected])

Member Function Documentation

status_t FSNode::FDChanged ( int nNewFD,

const struct::stat & sStat

) [virtual]

Reimplemented in os::Directory, and os::File.

time_t FSNode::GetATime ( bool bUpdateCache = true ) const [virtual]

time_t FSNode::GetCTime ( bool bUpdateCache = true ) const [virtual]

dev_t FSNode::GetDev ( ) const [virtual]

int FSNode::GetFileDescriptor ( ) const [virtual]

ino_t FSNode::GetInode ( ) const [virtual]

time_t FSNode::GetMTime ( bool bUpdateCache = true ) const [virtual]

int FSNode::GetMode ( bool bUpdateCache = true ) const [virtual]

status_t FSNode::GetNextAttrName ( std::string * pcName ) [virtual]

Description:
Iterate over the node's "attribute directory". Call this member in sequence until it return "0" to iterate over all the attributes associated with the node. The attribute iterator can be reset to the first attribute with the RewindAttrdir() member.

More info about the returned attributes can be obtain with the StatAttr() member and the content of an attribute can be read with the ReadAttr() member.
Note:
Currently only the AtheOS native filesystem (AFS) support attributes so if the the file is not located on an AFS volume this member will fail.
Parameters:

pcName Pointer to an STL string that will receive the name.

Returns:
If a new name was successfully obtained 1 will be returned. If we reach the end of the attribute directory 0 will be returned. Any other errors will cause -1 to be returned and a error code will be stored in the global "errno" variable.
See also:
StatAttr(), ReadAttr(), WriteAttr()
Author:
Kurt Skauen ([email protected])

off_t FSNode::GetSize ( bool bUpdateCache = true ) const [virtual]

Reimplemented in os::File.

status_t FSNode::GetStat ( struct::stat * psStat,

bool bUpdateCache = true

) const [virtual]

bool FSNode::IsValid ( ) const [virtual]

Description:
Return true if the the object actually reference a real FS node. All other access functions will fail if the object is not fully initializesed eighter through one of the non-default constructors or with one of the SetTo() members.

Returns:
True if the object is fully initialized false otherwhice.
Author:
Kurt Skauen ([email protected])

ssize_t FSNode::ReadAttr ( const std::string & cAttrName,

int nType,

void * pBuffer,

off_t nPos,

size_t nLen

) [virtual]

Description:
Read an arbritary chunk of an attributes data. Both the name and the type must match for the operation so succede. If you don't know the type in advance it can be retrieved with the StatAttr() member.
Note:
Currently only the AtheOS native filesystem (AFS) support attributes so if the the file is not located on an AFS volume this member will fail.
Parameters:

cAttrName The name of the attribute to read.

nType The expected attribute type. The attribute must be of this type for the function to succede. See WriteAttr() for a more detailed descritpion of attribute types.

Returns:
On success the number of bytes actually read is returned. On failure -1 is returned and the error code is stored in the global variable "errno".

See also:
WriteAttr(), StatAttr()
Author:
Kurt Skauen ([email protected])

status_t FSNode::RemoveAttr ( const std::string & cName ) [virtual]

Description:
This will remove the named attribute from the node itself and if the attribute has been indexed it will also be removed from the index.
Note:
Currently only the AtheOS native filesystem (AFS) support attributes so if the the file is not located on an AFS volume this member will fail.
Parameters:

cName Name of the attribute to remove.

Returns:
On success 0 is returned. On failure -1 is returned and the error code is stored in the global variable "errno".
See also:
WriteAttr(), ReadAttr()
Author:
Kurt Skauen ([email protected])

status_t FSNode::RewindAttrdir ( ) [virtual]

Description:
RewindAttrdir() will cause the next GetNextAttrName() call to return the name of the first attribute associated with this node.
Note:
Currently only the AtheOS native filesystem (AFS) support attributes so if the the file is not located on an AFS volume this member will fail.
Returns:
0 on success. On failure -1 is returned and a error code is stored in the global variable "errno".
See also:
GetNextAttrName()
Author:
Kurt Skauen ([email protected])

status_t FSNode::SetTo ( const FSNode & cNode ) [virtual]

Description:
Make this node a clone of cNode.
Note:
If this call fail the old state of the FSNode will remain unchanged
Parameters:

cNode The FSNode to copy.

Returns:
On success 0 is returned. On error -1 is returned and a error code is assigned to the global variable "errno". The error code can be any of the errors returned by the open() POSIX function.
See also:

Author:
Kurt Skauen ([email protected])

Reimplemented in os::SymLink.

status_t FSNode::SetTo ( const FileReference & cRef,

int nOpenMode = O_RDONLY

) [virtual]

Description:
Same semantics SetTo( const std::string& cPath, int nOpenMode ) except that the node to open is targeted by a file reference rather than a regular path.
Note:
If this call fail the old state of the FSNode will remain unchanged
Returns:
On success 0 is returned. On error -1 is returned and a error code is assigned to the global variable "errno". The error code can be any of the errors returned by the open() POSIX function.
See also:
SetTo( const std::string& cPath, int nOpenMode )
Author:
Kurt Skauen ([email protected])

Reimplemented in os::SymLink.

status_t FSNode::SetTo ( const Directory & cDir,

const std::string & cPath,

int nOpenMode = O_RDONLY

) [virtual]

Description:
Open a node by using a directory and a path relative to that directory.

The path can eighter be absolute (cDir will then be ignored) or it can be relative to cDir. This have much the same semantics as setting the current working directory to cDir and then open the node by calling SetTo( const std::string& cPath, int nOpenMode ) with the path. The main advantage with this function is that it is thread-safe. You don't get any races while temporarily changing the current working directory.
For a more detailed description look at: SetTo( const std::string& cPath, int nOpenMode )

Note:
If this call fail the old state of the FSNode will remain unchanged
Parameters:

cDir A valid directory from which the cPath is relative to.

cPath The file path relative to cDir. The path can eighter be absoulute (in which case cDir is ignored) or it can be relative to cDir.

nOpenMode Flags controlling how to open the node. See SetTo( const std::string& cPath, int nOpenMode ) for a full description of the various flags.

Returns:
On success 0 is returned. On error -1 is returned and a error code is assigned to the global variable "errno". The error code can be any of the errors returned by the open() POSIX function.

See also:
FSNode( const std::string& cPath, int nOpenMode )
Author:
Kurt Skauen ([email protected])

Reimplemented in os::SymLink.

status_t FSNode::SetTo ( const std::string & cPath,

int nOpenMode = O_RDONLY

) [virtual]

Description:
Open a node by path. The path must be valid and the process must have access to it but it can point to any kind of FS-node (file, directory, symlink).

The nOpenMode should be a compination of any of the O_* flags defined in <fcntl.h>. Their meaning is the same as when opening a file with the open() POSIX function except you can not create a file by setting the O_CREAT flag.
The following flags are accepted:

O_RDONLY open the node read-only
O_WRONLY open the node write-only
O_RDWR open the node for both reading and writing
O_TRUNC trunate the size to 0 (only valid for files)
O_APPEND automatically move the file-pointer to the end of the file before each write (only valid for files)
O_NONBLOCK open the file in non-blocking mode
O_DIRECTORY fail if cPath don't point at a directory
O_NOTRAVERSE open the symlink it self rather than it's target if cPath points at a symlink

Note:
If this call fail the old state of the FSNode will remain unchanged
Parameters:

cPath Path pointing at the node to open.

nOpenMode Flags controlling how to open the node.

Returns:
On success 0 is returned. On error -1 is returned and a error code is assigned to the global variable "errno". The error code can be any of the errors returned by the open() POSIX function.
Author:
Kurt Skauen ([email protected])

Reimplemented in os::SymLink.

virtual status_t os::FSNode::StatAttr ( const std::string & cName,

struct::attr_info * psBuffer

) [virtual]

void FSNode::Unset ( ) [virtual]

Description:
Will close the file descriptor and other resources may consumed by the FSNode. The IsValid() member will return false until the node is reinitialized with one of the SetTo() members.

Author:
Kurt Skauen ([email protected])

ssize_t FSNode::WriteAttr ( const std::string & cAttrName,

int nFlags,

int nType,

const void * pBuffer,

off_t nPos,

size_t nLen

) [virtual]

Description:
WriteAttr() is used to create new attributes and update existing attributes. A attribute is simply a chunc of data that is associated with the file but that is not part of the files regular data-stream. Attributes can be added to all kind's of FS nodes like regular files, directories, and symlinks.

A attribute can contain a untyped stream of data of an arbritary length or it can contain typed data like integers, floats, strings, etc etc. The reason for having typed data is to be able to make a search index that can be used to for efficient search for files based on their attributes. The indexing system is not fully implemented yet but will be part of AtheOS in the future.
Note:
Currently only the AtheOS native filesystem (AFS) support attributes so if the the file is not located on an AFS volume this member will fail.
Parameters:

cAttrName The name of the attribute. The name must be unique inside the scope of the node it belongs to. If an attribute already exists with that name it will be overwritten.

nFlags Currently only O_TRUNC is accepted. If you pass in O_TRUNC and a attribute with the same name already exists it will be truncated to a size of 0 before the new attribute data is written. By passing in 0 you can update parts of or extend an existing attribute.

nType The data-type of the attribute. This should be one of the ATTR_TYPE_* types defined in <atheos/filesystem.h>.

ATTR_TYPE_NONE, Untyped "raw" data of any size.
ATTR_TYPE_INT32, 32-bit integer value (the size must be exactly 4 bytes).
ATTR_TYPE_INT64, 64-bit integer value often used for time-values (the size must be exactly 8 bytes).
ATTR_TYPE_FLOAT, 32-bit floating point value (the size must be exactly 4 bytes).
ATTR_TYPE_DOUBLE, 64-bit floating point value (the size must be exactly 8 bytes).
ATTR_TYPE_STRING, UTF8 string. The string should not be NUL terminated.
Parameters:

pBuffer Pointer to the data to be written.

nPos The offset into the attribute where the data will be written.

nLen Number of bytes to be written.

Returns:
On success the number of bytes actually written is returned. On failure -1 is returned and the error code is stored in the global variable "errno"

See also:
ReadAttr(), StatAttr()
Author:
Kurt Skauen ([email protected])

Friends And Related Function Documentation

friend class Directory [friend]

Generated at Tue Sep 11 15:27:48 2001 for AtheOS higlevel API by

os::FSNode Class Reference

Public Methods

Friends

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation