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[wxWidgets.git] / docs / latex / wx / file.tex

diff --git a/docs/latex/wx/file.tex b/docs/latex/wx/file.tex
index 73b55f5b24455bb0f781c4f4b8fe3c2fcbd42105..0972789d647c135abd0396d4496df70e77a036de 100644 (file)
--- a/docs/latex/wx/file.tex
+++ b/docs/latex/wx/file.tex
@@ -1,9 +1,27 @@
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% Name:        file.tex
+%% Purpose:     wxFile documentation
+%% Author:      Vadim Zeitlin
+%% Modified by:
+%% Created:     14.01.02 (extracted from file.tex)
+%% RCS-ID:      $Id$
+%% Copyright:   (c) Vadim Zeitlin
+%% License:     wxWidgets license
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+

 \section{\class{wxFile}}\label{wxfile}
 
 A wxFile performs raw file I/O. This is a very small class designed to
 minimize the overhead of using it - in fact, there is hardly any overhead at
 all, but using it brings you automatic error checking and hides differences
 \section{\class{wxFile}}\label{wxfile}
 
 A wxFile performs raw file I/O. This is a very small class designed to
 minimize the overhead of using it - in fact, there is hardly any overhead at
 all, but using it brings you automatic error checking and hides differences

-between platforms and compilers.
+between platforms and compilers. wxFile also automatically closes the file in
+its destructor making it unnecessary to worry about forgetting to do it.
+wxFile is a wrapper around {\tt file descriptor.} - see also 
+\helpref{wxFFile}{wxffile} for a wrapper around {\tt FILE} structure.
+
+{\tt wxFileOffset} is used by the wxFile functions which require offsets as 
+parameter or return them. If the platform supports it, wxFileOffset if a typedef
+for a native 64 bit integer, else a 32 bit integer is used for wxFileOffset.

 
 \wxheading{Derived from}
 
 
 \wxheading{Derived from}
 


@@ -17,7 +35,6 @@ None.
 
 wx/file.h defines the following constants:
 
 
 wx/file.h defines the following constants:
 

-{\small

 \begin{verbatim}
 #define wxS_IRUSR 00400
 #define wxS_IWUSR 00200
 \begin{verbatim}
 #define wxS_IRUSR 00400
 #define wxS_IWUSR 00200


@@ -34,13 +51,12 @@ wx/file.h defines the following constants:
 // default mode for the new files: corresponds to umask 022
 #define wxS_DEFAULT  (wxS_IRUSR | wxS_IWUSR | wxS_IRGRP | wxS_IWGRP | wxS_IROTH | wxS_IWOTH)
 \end{verbatim}
 // default mode for the new files: corresponds to umask 022
 #define wxS_DEFAULT  (wxS_IRUSR | wxS_IWUSR | wxS_IRGRP | wxS_IWGRP | wxS_IROTH | wxS_IWOTH)
 \end{verbatim}

-}

 
 These constants define the file access rights and are used with 
 \helpref{wxFile::Create}{wxfilecreate} and \helpref{wxFile::Open}{wxfileopen}.
 
 The {\it OpenMode} enumeration defines the different modes for opening a file,
 
 These constants define the file access rights and are used with 
 \helpref{wxFile::Create}{wxfilecreate} and \helpref{wxFile::Open}{wxfileopen}.
 
 The {\it OpenMode} enumeration defines the different modes for opening a file,

-it's defined inside wxFile class so its members should be specified with {\it wxFile::} scope
+it is defined inside wxFile class so its members should be specified with {\it wxFile::} scope

 resolution prefix. It is also used with \helpref{wxFile::Access}{wxfileaccess} function.
 
 \twocolwidtha{7cm}
 resolution prefix. It is also used with \helpref{wxFile::Access}{wxfileaccess} function.
 
 \twocolwidtha{7cm}


@@ -51,11 +67,14 @@ or test if it can be opened for writing with Access()}
 \twocolitem{{\bf wxFile::read\_write}}{Open file for reading and writing; can not be used with Access()}
 \twocolitem{{\bf wxFile::write\_append}}{Open file for appending: the file is opened for writing, but the old
 contents of the file is not erased and the file pointer is initially placed at the end of the file;
 \twocolitem{{\bf wxFile::read\_write}}{Open file for reading and writing; can not be used with Access()}
 \twocolitem{{\bf wxFile::write\_append}}{Open file for appending: the file is opened for writing, but the old
 contents of the file is not erased and the file pointer is initially placed at the end of the file;

-can not be used with Access()}
+can not be used with Access(). This is the same as {\bf wxFile::write} if the
+file doesn't exist.}
+\twocolitem{{\bf wxFile::write\_excl}}{Open the file securely for writing (Uses O\_EXCL | O\_CREAT).
+Will fail if the file already exists, else create and open it atomically.  Useful for opening temporary files without being vulnerable to race exploits.}

 \end{twocollist}
 
 Other constants defined elsewhere but used by wxFile functions are wxInvalidOffset which represents an
 \end{twocollist}
 
 Other constants defined elsewhere but used by wxFile functions are wxInvalidOffset which represents an

-invalid value of type {\it off\_t} and is returned by functions returning {\it off\_t} on error and the seek
+invalid value of type {\it wxFileOffset} and is returned by functions returning {\it wxFileOffset} on error and the seek

 mode constants used with \helpref{Seek()}{wxfileseek}:
 
 \twocolwidtha{7cm}
 mode constants used with \helpref{Seek()}{wxfileseek}:
 
 \twocolwidtha{7cm}


@@ -67,7 +86,7 @@ mode constants used with \helpref{Seek()}{wxfileseek}:
 
 \latexignore{\rtfignore{\wxheading{Members}}}
 
 
 \latexignore{\rtfignore{\wxheading{Members}}}
 

-\membersection{wxFile::wxFile}\label{wxfileconstr}
+\membersection{wxFile::wxFile}\label{wxfilector}

 
 \func{}{wxFile}{\void}
 
 
 \func{}{wxFile}{\void}
 


@@ -82,7 +101,7 @@ fail.
 
 \func{}{wxFile}{\param{int}{ fd}}
 
 
 \func{}{wxFile}{\param{int}{ fd}}
 

-Opens a file with the given file descriptor, which has already been opened.
+Associates the file with the given file descriptor, which has already been opened.

 
 \wxheading{Parameters}
 
 
 \wxheading{Parameters}
 


@@ -92,13 +111,13 @@ Opens a file with the given file descriptor, which has already been opened.
 
 \docparam{fd}{An existing file descriptor (see \helpref{Attach()}{wxfileattach} for the list of predefined descriptors)}
 
 
 \docparam{fd}{An existing file descriptor (see \helpref{Attach()}{wxfileattach} for the list of predefined descriptors)}
 

-\membersection{wxFile::\destruct{wxFile}}
+\membersection{wxFile::\destruct{wxFile}}\label{wxfiledtor}

 
 \func{}{\destruct{wxFile}}{\void}
 
 Destructor will close the file.
 
 
 \func{}{\destruct{wxFile}}{\void}
 
 Destructor will close the file.
 

-NB: it is not virtual so you should {\it not} derive from wxFile!
+{\bf NB:} it is not virtual so you should not use wxFile polymorphically.

 
 \membersection{wxFile::Access}\label{wxfileaccess}
 
 
 \membersection{wxFile::Access}\label{wxfileaccess}
 


@@ -113,7 +132,7 @@ values of wxFile::read or wxFile::write really make sense here.
 
 Attaches an existing file descriptor to the wxFile object. Example of predefined
 file descriptors are 0, 1 and 2 which correspond to stdin, stdout and stderr (and
 
 Attaches an existing file descriptor to the wxFile object. Example of predefined
 file descriptors are 0, 1 and 2 which correspond to stdin, stdout and stderr (and

-have symbolic names of wxFile::fd\_stdin, wxFile::fd\_stdout and wxFile::fd\_stderr).
+have symbolic names of {\bf wxFile::fd\_stdin}, {\bf wxFile::fd\_stdout} and {\bf wxFile::fd\_stderr}).

 
 The descriptor should be already opened and it will be closed by wxFile
 object.
 
 The descriptor should be already opened and it will be closed by wxFile
 object.


@@ -126,9 +145,9 @@ Closes the file.
 
 \membersection{wxFile::Create}\label{wxfilecreate}
 
 
 \membersection{wxFile::Create}\label{wxfilecreate}
 

-\func{bool}{Create}{\param{const char*}{ filename}, \param{bool}{ overwrite = FALSE}, \param{int }{access = wxS\_DEFAULT}}
+\func{bool}{Create}{\param{const char*}{ filename}, \param{bool}{ overwrite = false}, \param{int }{access = wxS\_DEFAULT}}

 
 

-Creates a file for writing. If the file already exists, setting {\bf overwrite} to TRUE
+Creates a file for writing. If the file already exists, setting {\bf overwrite} to true

 will ensure it is overwritten.
 
 \membersection{wxFile::Detach}\label{wxfiledetach}
 will ensure it is overwritten.
 
 \membersection{wxFile::Detach}\label{wxfiledetach}


@@ -136,7 +155,7 @@ will ensure it is overwritten.
 \func{void}{Detach}{\void}
 
 Get back a file descriptor from wxFile object - the caller is responsible for closing the file if this
 \func{void}{Detach}{\void}
 
 Get back a file descriptor from wxFile object - the caller is responsible for closing the file if this

-descriptor is opened. \helpref{IsOpened()}{wxfileisopened} will return FALSE after call to Detach().
+descriptor is opened. \helpref{IsOpened()}{wxfileisopened} will return false after call to Detach().

 
 \membersection{wxFile::fd}\label{wxfilefd}
 
 
 \membersection{wxFile::fd}\label{wxfilefd}
 


@@ -148,13 +167,28 @@ Returns the file descriptor associated with the file.
 
 \constfunc{bool}{Eof}{\void}
 
 
 \constfunc{bool}{Eof}{\void}
 

-Returns TRUE if the end of the file has been reached.
+Returns true if the end of the file has been reached.
+
+Note that the behaviour of the file pointer based class 
+\helpref{wxFFile}{wxffile} is different as \helpref{wxFFile::Eof}{wxffileeof} 
+will return true here only if an attempt has been made to read 
+{\it past} the last byte of the file, while wxFile::Eof() will return true
+even before such attempt is made if the file pointer is at the last position
+in the file.
+
+Note also that this function doesn't work on unseekable file descriptors
+(examples include pipes, terminals and sockets under Unix) and an attempt to
+use it will result in an error message in such case. So, to read the entire
+file into memory, you should write a loop which uses 
+\helpref{Read}{wxfileread} repeatedly and tests its return condition instead
+of using Eof() as this will not work for special files under Unix.

 
 \membersection{wxFile::Exists}\label{wxfileexists}
 
 \func{static bool}{Exists}{\param{const char*}{ filename}}
 
 
 \membersection{wxFile::Exists}\label{wxfileexists}
 
 \func{static bool}{Exists}{\param{const char*}{ filename}}
 

-Returns TRUE if the given name specifies an existing regular file.
+Returns true if the given name specifies an existing regular file (not a
+directory or a link)

 
 \membersection{wxFile::Flush}\label{wxfileflush}
 
 
 \membersection{wxFile::Flush}\label{wxfileflush}
 


@@ -170,11 +204,11 @@ due to a missing fsync function, which reduces the usefulness of this function
 
 \constfunc{bool}{IsOpened}{\void}
 
 
 \constfunc{bool}{IsOpened}{\void}
 

-Returns TRUE if the file has been opened.
+Returns true if the file has been opened.

 
 \membersection{wxFile::Length}\label{wxfilelength}
 
 
 \membersection{wxFile::Length}\label{wxfilelength}
 

-\constfunc{off\_t}{Length}{\void}
+\constfunc{wxFileOffset}{Length}{\void}

 
 Returns the length of the file.
 
 
 Returns the length of the file.
 


@@ -182,7 +216,7 @@ Returns the length of the file.
 
 \func{bool}{Open}{\param{const char*}{ filename}, \param{wxFile::OpenMode}{ mode = wxFile::read}}
 
 
 \func{bool}{Open}{\param{const char*}{ filename}, \param{wxFile::OpenMode}{ mode = wxFile::read}}
 

-Opens the file, returning TRUE if successful.
+Opens the file, returning true if successful.

 
 \wxheading{Parameters}
 
 
 \wxheading{Parameters}
 


@@ -192,7 +226,7 @@ Opens the file, returning TRUE if successful.
 
 \membersection{wxFile::Read}\label{wxfileread}
 
 
 \membersection{wxFile::Read}\label{wxfileread}
 

-\func{off\_t}{Read}{\param{void*}{ buffer}, \param{off\_t}{ count}}
+\func{size\_t}{Read}{\param{void*}{ buffer}, \param{size\_t}{ count}}

 
 Reads the specified number of bytes into a buffer, returning the actual number read.
 
 
 Reads the specified number of bytes into a buffer, returning the actual number read.
 


@@ -208,7 +242,7 @@ The number of bytes read, or the symbol {\bf wxInvalidOffset} (-1) if there was
 
 \membersection{wxFile::Seek}\label{wxfileseek}
 
 
 \membersection{wxFile::Seek}\label{wxfileseek}
 

-\func{off\_t}{Seek}{\param{off\_t }{ofs}, \param{wxFile::SeekMode }{mode = wxFile::FromStart}}
+\func{wxFileOffset}{Seek}{\param{wxFileOffset }{ofs}, \param{wxSeekMode }{mode = wxFromStart}}

 
 Seeks to the specified position.
 
 
 Seeks to the specified position.
 


@@ -216,7 +250,7 @@ Seeks to the specified position.
 
 \docparam{ofs}{Offset to seek to.}
 
 
 \docparam{ofs}{Offset to seek to.}
 

-\docparam{mode}{One of {\bf wxFile::FromStart}, {\bf wxFile::FromEnd}, {\bf wxFile::FromCurrent}.}
+\docparam{mode}{One of {\bf wxFromStart}, {\bf wxFromEnd}, {\bf wxFromCurrent}.}

 
 \wxheading{Return value}
 
 
 \wxheading{Return value}
 


@@ -224,7 +258,7 @@ The actual offset position achieved, or wxInvalidOffset on failure.
 
 \membersection{wxFile::SeekEnd}\label{wxfileseekend}
 
 
 \membersection{wxFile::SeekEnd}\label{wxfileseekend}
 

-\func{off\_t}{SeekEnd}{\param{off\_t }{ofs = 0}}
+\func{wxFileOffset}{SeekEnd}{\param{wxFileOffset }{ofs = 0}}

 
 Moves the file pointer to the specified number of bytes before the end of the file.
 
 
 Moves the file pointer to the specified number of bytes before the end of the file.
 


@@ -238,14 +272,14 @@ The actual offset position achieved, or wxInvalidOffset on failure.
 
 \membersection{wxFile::Tell}\label{wxfiletell}
 
 
 \membersection{wxFile::Tell}\label{wxfiletell}
 

-\constfunc{off\_t}{Tell}{\void}
+\constfunc{wxFileOffset}{Tell}{\void}

 
 Returns the current position or wxInvalidOffset if file is not opened or if another
 
 Returns the current position or wxInvalidOffset if file is not opened or if another

-error occured.
+error occurred.

 
 \membersection{wxFile::Write}\label{wxfilewrite}
 
 
 \membersection{wxFile::Write}\label{wxfilewrite}
 

-\func{bool}{Write}{\param{const void*}{ buffer}, \param{off\_t}{ count}}
+\func{size\_t}{Write}{\param{const void*}{ buffer}, \param{wxFileOffset}{ count}}

 
 Writes the specified number of bytes from a buffer.
 
 
 Writes the specified number of bytes from a buffer.
 


@@ -257,11 +291,18 @@ Writes the specified number of bytes from a buffer.
 
 \wxheading{Return value}
 
 
 \wxheading{Return value}
 

-TRUE if the operation was successful.
+the number of bytes actually written

 
 \membersection{wxFile::Write}\label{wxfilewrites}
 
 
 \membersection{wxFile::Write}\label{wxfilewrites}
 

-\func{bool}{Write}{\param{const wxString\& }{s}}
+\func{bool}{Write}{\param{const wxString\& }{s}, \param{wxMBConv\&}{ conv = wxConvUTF8}}
+
+Writes the contents of the string to the file, returns true on success.
+
+The second argument is only meaningful in Unicode build of wxWidgets when
+{\it conv} is used to convert {\it s} to multibyte representation.

 
 

-Writes the contents of the string to the file, returns TRUE on success.
+Note that this method only works with {\tt NUL}-terminated strings, if you want
+to write data with embedded {\tt NUL}s to the file you should use the other 
+\helpref{Write() overload}{wxfilewrite}.