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List: freedesktop-xdg
Subject: Re: continued: Common-VFS proposal
From: Waldo Bastian <bastian () suse ! com>
Date: 2005-01-20 16:38:12
Message-ID: 200501201738.12345.bastian () suse ! com
[Download RAW message or body]
On Thursday 20 January 2005 03:24, Sean Middleditch wrote:
> A client library is provided that offers basic VFS operations: open,
> read, write, rename, move, setattr, getattr, setaccess, getaccess, etc.
> The idea is to *not* model POSIX but instead model what real
> applications do. There's no "move" function in POSIX (rename is very
> different than a real move operation), but apps want to be able to move
> files. Therefor, move should be provided an actual function.
You may want to look at the API for KIO-slaves, attached for your convenience,
the virtual functions are the ones you are interested in.
As for multithreaded versus out of process. The nice thing about
out-of-process is that you can kill the process and everything gets cleaned
up for you. You will also have less interference between the main application
and whatever your VFS-handler is doing. If your VFS-handler is self-contained
it's usually not a problem, but if your VFS-handler needs to pull in
something like the samba libraries you suddenly start to add a lot of code
and extra symbols into the address space of random applications.
A drawback of out of process is that you lose some performance due to the IPC
overhead, with gigabit network speeds that becomes noticable. In practice
it's only an issue when you download files, so you should be cool if you let
the process handle saving to disk itself.
An interesting issue with Konqueror is that we want to initiate a file
transfer with Konqueror, but once we know the filetype we may decide to let
another application open the file. In such case we want to let the
application take over the file transfer that was initiated by Konqueror. Our
out-of-process approach makes that somewhat easy since we can just let the
download process disconnect from Konqueror and reconnect to the application.
Cheers,
Waldo
--
bastian@kde.org | Free Novell Linux Desktop 9 Evaluation Download
bastian@suse.com | http://www.novell.com/products/desktop/eval.html
["slavebase.h" (text/x-c++hdr)]
/*
Copyright (C) 2000 David Faure <faure@kde.org>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
#ifndef __slavebase_h
#define __slavebase_h
#include <kurl.h>
#include <kconfigbase.h>
#include <kio/global.h>
#include <kio/authinfo.h>
class DCOPClient;
class KRemoteEncoding;
namespace KIO {
class Connection;
class SlaveBasePrivate;
/**
* There are two classes that specifies the protocol between application (job)
* and kioslave. SlaveInterface is the class to use on the application end,
* SlaveBase is the one to use on the slave end.
*
* Slave implementations should simply inherit SlaveBase
*
* A call to foo() results in a call to slotFoo() on the other end.
*/
class KIO_EXPORT SlaveBase
{
public:
SlaveBase( const QCString &protocol, const QCString &pool_socket, const QCString \
&app_socket); virtual ~SlaveBase();
/**
* @internal
* Terminate the slave by calling the destructor and then ::exit()
*/
void exit();
/**
* @internal
*/
void dispatchLoop();
/**
* @internal
*/
void setConnection( Connection* connection ) { m_pConnection = connection; }
/**
* @internal
*/
Connection *connection() const { return m_pConnection; }
///////////
// Message Signals to send to the job
///////////
/**
* Sends data in the slave to the job (i.e. in get).
*
* To signal end of data, simply send an empty
* QByteArray().
*
* @param data the data read by the slave
*/
void data( const QByteArray &data );
/**
* Asks for data from the job.
* @see readData
*/
void dataReq( );
/**
* Call to signal an error.
* This also finishes the job, no need to call finished.
*
* If the Error code is KIO::ERR_SLAVE_DEFINED then the
* _text should contain the complete translated text of
* of the error message. This message will be displayed
* in an KTextBrowser which allows rich text complete
* with hyper links. Email links will call the default
* mailer, "exec:/command arg1 arg2" will be forked and
* all other links will call the default browser.
*
* @see KIO::Error
* @see KTextBrowser
* @param _errid the error code from KIO::Error
* @param _text the rich text error message
*/
void error( int _errid, const QString &_text );
/**
* Call in openConnection, if you reimplement it, when you're done.
*/
void connected();
/**
* Call to signal successful completion of any command
* (besides openConnection and closeConnection)
*/
void finished();
/**
* Call to signal that data from the sub-URL is needed
*/
void needSubURLData();
/**
* Used to report the status of the slave.
* @param host the slave is currently connected to. (Should be
* empty if not connected)
* @param connected Whether an actual network connection exists.
**/
void slaveStatus(const QString &host, bool connected);
/**
* Call this from stat() to express details about an object, the
* UDSEntry customarily contains the atoms describing file name, size,
* mimetype, etc.
* @param _entry The UDSEntry containing all of the object attributes.
*/
void statEntry( const UDSEntry& _entry );
/**
* Call this in listDir, each time you have a bunch of entries
* to report.
*/
void listEntries( const UDSEntryList& _entry );
/**
* Call this at the beginning of put(), to give the size of the existing
* partial file, if there is one. The @p offset argument notifies the
* other job (the one that gets the data) about the offset to use.
* In this case, the boolean returns whether we can indeed resume or not
* (we can't if the protocol doing the get() doesn't support setting an offset)
*/
bool canResume( KIO::filesize_t offset );
/*
* Call this at the beginning of get(), if the "resume" metadata was set
* and resuming is implemented by this protocol.
*/
void canResume();
///////////
// Info Signals to send to the job
///////////
/**
* Call this in get and copy, to give the total size
* of the file
* Call in listDir too, when you know the total number of items.
*/
void totalSize( KIO::filesize_t _bytes );
/**
* Call this during get and copy, once in a while,
* to give some info about the current state.
* Don't emit it in listDir, listEntries speaks for itself.
*/
void processedSize( KIO::filesize_t _bytes );
/**
* Only use this if you can't know in advance the size of the
* copied data. For example, if you're doing variable bitrate
* compression of the source.
*
* STUB ! Currently unimplemented. Here now for binary compatibility.
*
* Call this during get and copy, once in a while,
* to give some info about the current state.
* Don't emit it in listDir, listEntries speaks for itself.
*/
void processedPercent( float percent );
/**
* Call this in get and copy, to give the current transfer
* speed, but only if it can't be calculated out of the size you
* passed to processedSize (in most cases you don't want to call it)
*/
void speed( unsigned long _bytes_per_second );
/**
* Call this to signal a redirection
* The job will take care of going to that url.
*/
void redirection( const KURL &_url );
/**
* Tell that we will only get an error page here.
* This means: the data you'll get isn't the data you requested,
* but an error page (usually HTML) that describes an error.
*/
void errorPage();
/**
* Call this in mimetype() and in get(), when you know the mimetype.
* See mimetype about other ways to implement it.
*/
void mimeType( const QString &_type );
/**
* Call to signal a warning, to be displayed in a dialog box.
*/
void warning( const QString &msg );
/**
* Call to signal a message, to be displayed if the application wants to,
* for instance in a status bar. Usual examples are "connecting to host xyz", \
etc.
*/
void infoMessage( const QString &msg );
enum MessageBoxType { QuestionYesNo = 1, WarningYesNo = 2, WarningContinueCancel \
= 3, WarningYesNoCancel = 4, Information = 5, SSLMessageBox = 6 };
/**
* Call this to show a message box from the slave
* @param type type of message box: QuestionYesNo, WarningYesNo, \
WarningContinueCancel...
* @param text Message string. May contain newlines.
* @param caption Message box title.
* @param buttonYes The text for the first button.
* The default is i18n("&Yes").
* @param buttonNo The text for the second button.
* The default is i18n("&No").
* Note: for ContinueCancel, buttonYes is the continue button and buttonNo is \
unused.
* and for Information, none is used.
* @return a button code, as defined in KMessageBox, or 0 on communication error.
*/
int messageBox( MessageBoxType type, const QString &text,
const QString &caption = QString::null,
const QString &buttonYes = QString::null,
const QString &buttonNo = QString::null );
/**
* Call this to show a message box from the slave
* @param text Message string. May contain newlines.
* @param type type of message box: QuestionYesNo, WarningYesNo, \
WarningContinueCancel...
* @param caption Message box title.
* @param buttonYes The text for the first button.
* The default is i18n("&Yes").
* @param buttonNo The text for the second button.
* The default is i18n("&No").
* Note: for ContinueCancel, buttonYes is the continue button and buttonNo is \
unused.
* and for Information, none is used.
* @param dontAskAgainName A checkbox is added with which further confirmation \
can be turned off.
* The string is used to lookup and store the setting in kioslaverc.
* @return a button code, as defined in KMessageBox, or 0 on communication error.
* @since 3.3
*/
int messageBox( const QString &text, MessageBoxType type,
const QString &caption = QString::null,
const QString &buttonYes = QString::null,
const QString &buttonNo = QString::null,
const QString &dontAskAgainName = QString::null );
/**
* Sets meta-data to be send to the application before the first
* data() or finished() signal.
*/
void setMetaData(const QString &key, const QString &value);
/**
* Queries for the existence of a certain config/meta-data entry
* send by the application to the slave.
* @since 3.2
*/
bool hasMetaData(const QString &key) const;
/**
* Queries for config/meta-data send by the application to the slave.
* @since 3.2
*/
QString metaData(const QString &key) const;
/**
* @obsolete kept for binary compatibility
* Queries for the existence of a certain config/meta-data entry
* send by the application to the slave.
*/
bool hasMetaData(const QString &key);
/**
* @obsolete kept for binary compatibility
* Queries for config/meta-data send by the application to the slave.
*/
QString metaData(const QString &key);
/**
* Returns a configuration object to query config/meta-data information
* from.
*
* The application provides the slave with all configuration information
* relevant for the current protocol and host.
*/
KConfigBase* config();
/**
* Returns an object that can translate remote filenames into proper
* Unicode forms. This encoding can be set by the user.
*
* @since 3.3
*/
KRemoteEncoding* remoteEncoding();
///////////
// Commands sent by the job, the slave has to
// override what it wants to implement
///////////
/**
* Set the host
* @param host
* @param port
* @param user
* @param pass
* Called directly by createSlave, this is why there is no equivalent in
* SlaveInterface, unlike the other methods.
*
* This method is called whenever a change in host, port or user occurs.
*/
virtual void setHost(const QString& host, int port, const QString& user, const \
QString& pass);
/**
* Prepare slave for streaming operation
*/
virtual void setSubURL(const KURL&url);
/**
* Opens the connection (forced)
* When this function gets called the slave is operating in
* connection-oriented mode.
* When a connection gets lost while the slave operates in
* connection oriented mode, the slave should report
* ERR_CONNECTION_BROKEN instead of reconnecting. The user is
* expected to disconnect the slave in the error handler.
*/
virtual void openConnection();
/**
* Closes the connection (forced)
* Called when the application disconnects the slave to close
* any open network connections.
*
* When the slave was operating in connection-oriented mode,
* it should reset itself to connectionless (default) mode.
*/
virtual void closeConnection();
/**
* get, aka read.
* @param url the full url for this request. Host, port and user of the URL
* can be assumed to be the same as in the last setHost() call.
* The slave emits the data through data
*/
virtual void get( const KURL& url );
/**
* put, aka write.
* @param url where to write the file (decoded)
* @param permissions may be -1. In this case no special permission mode is set.
* @param overwrite if true, any existing file will be overwritten.
* If the file indeed already exists, the slave should NOT apply the
* permissions change to it.
* @param resume
*/
virtual void put( const KURL& url, int permissions, bool overwrite, bool resume \
);
/**
* Finds all details for one file or directory.
* The information returned is the same as what listDir returns,
* but only for one file or directory.
*/
virtual void stat( const KURL& url );
/**
* Finds mimetype for one file or directory.
*
* This method should either emit 'mimeType' or it
* should send a block of data big enough to be able
* to determine the mimetype.
*
* If the slave doesn't reimplement it, a get will
* be issued, i.e. the whole file will be downloaded before
* determining the mimetype on it - this is obviously not a
* good thing in most cases.
*/
virtual void mimetype( const KURL& url );
/**
* Lists the contents of @p url.
* The slave should emit ERR_CANNOT_ENTER_DIRECTORY if it doesn't exist,
* if we don't have enough permissions, or if it is a file
* It should also emit totalFiles as soon as it knows how many
* files it will list.
*/
virtual void listDir( const KURL& url );
/**
* Create a directory
* @param url path to the directory to create
* @param permissions the permissions to set after creating the directory
* (-1 if no permissions to be set)
* The slave emits ERR_COULD_NOT_MKDIR if failure.
*/
virtual void mkdir( const KURL&url, int permissions );
/**
* Rename @p oldname into @p newname.
* If the slave returns an error ERR_UNSUPPORTED_ACTION, the job will
* ask for copy + del instead.
* @param src where to move the file from
* @param dest where to move the file to
* @param overwrite if true, any existing file will be overwritten
*/
virtual void rename( const KURL& src, const KURL& dest, bool overwrite );
/**
* Creates a symbolic link named @p dest, pointing to @p target, which
* may be a relative or an absolute path.
* @param target The string that will become the "target" of the link (can be \
relative)
* @param dest The symlink to create.
* @param overwrite whether to automatically overwrite if the dest exists
*/
virtual void symlink( const QString& target, const KURL& dest, bool overwrite );
/**
* Change permissions on @p path
* The slave emits ERR_DOES_NOT_EXIST or ERR_CANNOT_CHMOD
*/
virtual void chmod( const KURL& url, int permissions );
/**
* Copy @p src into @p dest.
* If the slave returns an error ERR_UNSUPPORTED_ACTION, the job will
* ask for get + put instead.
* @param src where to copy the file from (decoded)
* @param dest where to copy the file to (decoded)
* @param permissions may be -1. In this case no special permission mode is set.
* @param overwrite if true, any existing file will be overwritten
*
*/
virtual void copy( const KURL &src, const KURL &dest, int permissions, bool \
overwrite );
/**
* Delete a file or directory.
* @param url file/directory to delete
* @param isfile if true, a file should be deleted.
* if false, a directory should be deleted.
*/
virtual void del( const KURL &url, bool isfile);
/**
* Used for any command that is specific to this slave (protocol)
* Examples are : HTTP POST, mount and unmount (kio_file)
*
* @param data packed data; the meaning is completely dependent on the
* slave, but usually starts with an int for the command number.
* Document your slave's commands, at least in its header file.
*/
virtual void special( const QByteArray & data );
/**
* Used for multiple get. Currently only used foir HTTP pielining
* support.
*
* @param data packed data; Contains number of URLs to fetch, and for
* each URL the URL itself and its associated MetaData.
*/
virtual void multiGet( const QByteArray & data );
/**
* Called to get the status of the slave. Slave should respond
* by calling slaveStatus(...)
*/
virtual void slave_status();
/**
* Called by the scheduler to tell the slave that the configuration
* changed (i.e. proxy settings) .
*/
virtual void reparseConfiguration();
/**
* @return timeout value for connecting to remote host.
*/
int connectTimeout();
/**
* @return timeout value for connecting to proxy in secs.
*/
int proxyConnectTimeout();
/**
* @return timeout value for read from first data from
* remote host in seconds.
*/
int responseTimeout();
/**
* @return timeout value for read from subsequent data from
* remote host in secs.
*/
int readTimeout();
/**
* This function sets a timeout of @p timeout seconds and calls
* special(data) when the timeout occurs as if it was called by the
* application.
*
* A timeout can only occur when the slave is waiting for a command
* from the application.
*
* Specifying a negative timeout cancels a pending timeout.
*
* Only one timeout at a time is supported, setting a timeout
* cancels any pending timeout.
* @since 3.1
*/
void setTimeoutSpecialCommand(int timeout, const QByteArray &data=QByteArray());
/**
* @internal
*/
static void sigsegv_handler(int);
/**
* @internal
*/
static void sigpipe_handler(int);
/////////////////
// Dispatching (internal)
////////////////
/**
* @internal
*/
virtual bool dispatch();
/**
* @internal
*/
virtual void dispatch( int command, const QByteArray &data );
/**
* Read data send by the job, after a dataReq
*
* @param buffer buffer where data is stored
* @return 0 on end of data,
* > 0 bytes read
* < 0 error
**/
int readData( QByteArray &buffer );
/**
* internal function to be called by the slave.
* It collects entries and emits them via listEntries
* when enough of them are there or a certain time
* frame exceeded (to make sure the app gets some
* items in time but not too many items one by one
* as this will cause a drastic performance penalty)
* @param ready set to true after emitting all items. _entry is not
* used in this case
*/
void listEntry( const UDSEntry& _entry, bool ready);
/**
* internal function to connect a slave to/ disconnect from
* either the slave pool or the application
*/
void connectSlave(const QString& path);
void disconnectSlave();
/**
* Prompt the user for Authorization info (login & password).
*
* Use this function to request authorization information from
* the end user. You can also pass an error message which explains
* why a previous authorization attempt failed. Here is a very
* simple example:
*
* \code
* KIO::AuthInfo authInfo;
* if ( openPassDlg( authInfo ) )
* {
* kdDebug() << QString::fromLatin1("User: ")
* << authInfo.username << endl;
* kdDebug() << QString::fromLatin1("Password: ")
* << QString::fromLatin1("Not displayed here!") << endl;
* }
* \endcode
*
* You can also preset some values like the username, caption or
* comment as follows:
*
* \code
* KIO::AuthInfo authInfo;
* authInfo.caption= "Acme Password Dialog";
* authInfo.username= "Wile E. Coyote";
* QString errorMsg = "You entered an incorrect password.";
* if ( openPassDlg( authInfo, errorMsg ) )
* {
* kdDebug() << QString::fromLatin1("User: ")
* << authInfo.username << endl;
* kdDebug() << QString::fromLatin1("Password: ")
* << QString::fromLatin1("Not displayed here!") << endl;
* }
* \endcode
*
* NOTE: A call to this function can fail and return @p false,
* if the UIServer could not be started for whatever reason.
*
* @param info See AuthInfo.
* @param errorMsg Error message to show
* @return @p true if user clicks on "OK", @p false otherwsie.
* @since 3.1
*/
bool openPassDlg( KIO::AuthInfo& info, const QString &errorMsg );
/**
* Same as above function except it does not need error message.
* BIC: Combine this function with the above for KDE4.
*/
bool openPassDlg( KIO::AuthInfo& info );
/**
* Checks for cached authentication based on parameters
* given by @p info.
*
* Use this function to check if any cached password exists
* for the URL given by @p info. If @p AuthInfo::realmValue
* and/or @p AuthInfo::verifyPath flag is specified, then
* they will also be factored in determining the presence
* of a cached password. Note that @p Auth::url is a required
* parameter when attempting to check for cached authorization
* info. Here is a simple example:
*
* \code
* AuthInfo info;
* info.url = KURL("http://www.foobar.org/foo/bar");
* info.username = "somename";
* info.verifyPath = true;
* if ( !checkCachedAuthentication( info ) )
* {
* if ( !openPassDlg(info) )
* ....
* }
* \endcode
*
* @param info See AuthInfo.
* @return @p true if cached Authorization is found, false otherwise.
*/
bool checkCachedAuthentication( AuthInfo& info );
/**
* Explicitly store authentication information. openPassDlg already
* stores password information automatically, you only need to call
* this function if you want to store authentication information that
* is different from the information returned by openPassDlg.
*/
bool cacheAuthentication( const AuthInfo& info );
/**
* @obsolete as of 3.1.
* TODO: Remove before KDE 4.0
*/
bool pingCacheDaemon() const;
/**
* @obsolete as of 3.1. Use openPassDlg instead.
* TODO: Remove before KDE 4.0
* Creates a basic key to be used to cache the password.
* @param url the url from which the key is supposed to be generated
*/
QString createAuthCacheKey( const KURL& url );
/**
* @obsolete as of 3.1. Use openPassDlg instead.
* TODO: Remove before KDE 4.0
*
* Cache authentication information is now stored automatically
* by openPassDlg.
*/
void sendAuthenticationKey( const QCString& gKey, const QCString& key, bool keep \
);
/**
* @obsolete as of 3.1. Use openPassDlg instead.
* TODO: Remove before KDE 4.0
*
* Cached authentication information is now session based and
* removed automatically when a given session ends, i.e. the
* application is closed.
*/
void delCachedAuthentication( const QString& key );
/**
* @obsolete as of 3.1. Use openPassDlg instead.
* TODO: Remove before KDE 4.0
*/
void setMultipleAuthCaching( bool ) {};
/**
* @obsolete as of 3.1. Use openPassDlg instead.
* TODO: Remove before KDE 4.0
*/
bool multipleAuthCaching() const { return false; }
/**
* Used by the slave to check if it can connect
* to a given host. This should be called where the slave is ready
* to do a ::connect() on a socket. For each call to
* requestNetwork must exist a matching call to
* dropNetwork, or the system will stay online until
* KNetMgr gets closed (or the SlaveBase gets destructed)!
*
* If KNetMgr is not running, then this is a no-op and returns true
*
* @param host tells the netmgr the host the slave wants to connect
* to. As this could also be a proxy, we can't just take
* the host currenctly connected to (but that's the default
* value)
*
* @return true in theorie, the host is reachable
* false the system is offline and the host is in a remote network.
*/
bool requestNetwork(const QString& host = QString::null);
/**
* Used by the slave to withdraw a connection requested by
* requestNetwork. This function cancels the last call to
* requestNetwork. If a client uses more than one internet
* connection, it must use dropNetwork(host) to
* stop each request.
*
* If KNetMgr is not running, then this is a no-op.
*
* @param host the host passed to requestNetwork
*
* A slave should call this function every time it disconnect from a host.
* */
void dropNetwork(const QString& host = QString::null);
/**
* Return the dcop client used by this slave.
* @since 3.1
*/
DCOPClient *dcopClient();
/**
* Wait for an answer to our request, until we get @p expected1 or @p expected2
* @return the result from readData, as well as the cmd in *pCmd if set, and the \
data in @p data
*/
int waitForAnswer( int expected1, int expected2, QByteArray & data, int * pCmd = \
0 );
/**
* Internal function to transmit meta data to the application.
*/
void sendMetaData();
/**
* Name of the protocol supported by this slave
*/
QCString mProtocol;
Connection * m_pConnection;
MetaData mOutgoingMetaData;
MetaData mIncomingMetaData;
/** If your ioslave was killed by a signal, wasKilled() returns true.
Check it regularly in lengthy functions (e.g. in get();) and return
as fast as possible from this function if wasKilled() returns true.
This will ensure that your slave destructor will be called correctly.
@since 3.1
*/
bool wasKilled() const;
/** Internally used.
* @internal
* @since 3.1
*/
void setKillFlag();
protected:
UDSEntryList pendingListEntries;
uint listEntryCurrentSize;
long listEntry_sec, listEntry_usec;
Connection *appconn;
QString mPoolSocket;
QString mAppSocket;
bool mConnectedToApp;
static long s_seqNr;
virtual void virtual_hook( int id, void* data );
private:
SlaveBasePrivate *d;
};
}
#endif
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