+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% 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: wxWindows license
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
\section{\class{wxFile}}\label{wxfile}
A wxFile performs raw file I/O. This is a very small class designed to
all, but using it brings you automatic error checking and hides differences
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}
wx/file.h defines the following constants:
-{\small
\begin{verbatim}
#define wxS_IRUSR 00400
#define wxS_IWUSR 00200
// 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,
-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}
\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
-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}
\latexignore{\rtfignore{\wxheading{Members}}}
-\membersection{wxFile::wxFile}\label{wxfileconstr}
+
+\membersection{wxFile::wxFile}\label{wxfilector}
\func{}{wxFile}{\void}
\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.
-NB: it is not virtual so you should use wxFile polymorphically.
+{\bf NB:} it is not virtual so you should not use wxFile polymorphically.
+
\membersection{wxFile::Access}\label{wxfileaccess}
This function verifies if we may access the given file in specified mode. Only
values of wxFile::read or wxFile::write really make sense here.
+
\membersection{wxFile::Attach}\label{wxfileattach}
\func{void}{Attach}{\param{int}{ fd}}
The descriptor should be already opened and it will be closed by wxFile
object.
+
\membersection{wxFile::Close}\label{wxfileclose}
\func{void}{Close}{\void}
Closes the file.
+
\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}
\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}
Returns the file descriptor associated with the file.
+
\membersection{wxFile::Eof}\label{wxfileeof}
\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
+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.
+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}}
-Returns TRUE if the given name specifies an existing regular file (not a
+Returns true if the given name specifies an existing regular file (not a
directory or a link)
+
\membersection{wxFile::Flush}\label{wxfileflush}
\func{bool}{Flush}{\void}
due to a missing fsync function, which reduces the usefulness of this function
(it can still be called but it will do nothing on unsupported compilers).
+
+\membersection{wxFile::GetKind}\label{wxfilegetfilekind}
+
+\constfunc{wxFileKind}{GetKind}{\void}
+
+Returns the type of the file. Possible return values are:
+
+\begin{verbatim}
+enum wxFileKind
+{
+ wxFILE_KIND_UNKNOWN,
+ wxFILE_KIND_DISK, // a file supporting seeking to arbitrary offsets
+ wxFILE_KIND_TERMINAL, // a tty
+ wxFILE_KIND_PIPE // a pipe
+};
+
+\end{verbatim}
+
+
\membersection{wxFile::IsOpened}\label{wxfileisopened}
\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}
-\constfunc{off\_t}{Length}{\void}
+\constfunc{wxFileOffset}{Length}{\void}
Returns the length of the file.
+
\membersection{wxFile::Open}\label{wxfileopen}
\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}
\docparam{mode}{The mode in which to open the file. May be one of {\bf wxFile::read}, {\bf wxFile::write} and {\bf wxFile::read\_write}.}
+
\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.
The number of bytes read, or the symbol {\bf wxInvalidOffset} (-1) if there was an error.
+
\membersection{wxFile::Seek}\label{wxfileseek}
-\func{off\_t}{Seek}{\param{off\_t }{ofs}, \param{wxSeekMode }{mode = wxFromStart}}
+\func{wxFileOffset}{Seek}{\param{wxFileOffset }{ofs}, \param{wxSeekMode }{mode = wxFromStart}}
Seeks to the specified position.
The actual offset position achieved, or wxInvalidOffset on failure.
+
\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 relative to the end of
+the file. For example, \texttt{SeekEnd($-5$)} would position the pointer $5$
+bytes before the end.
\wxheading{Parameters}
The actual offset position achieved, or wxInvalidOffset on failure.
+
\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
-error occured.
+error occurred.
+
\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{size\_t}{ count}}
Writes the specified number of bytes from a buffer.
\wxheading{Return value}
-TRUE if the operation was successful.
-
-\membersection{wxFile::Write}\label{wxfilewrites}
-
-\func{bool}{Write}{\param{const wxString\& }{s}}
-
-Writes the contents of the string to the file, returns TRUE on success.
-
-\section{\class{wxFFile}}\label{wxffile}
-
-A wxFFile 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.
-
-\wxheading{Derived from}
-
-None.
-
-\wxheading{Include files}
-
-<wx/ffile.h>
-
-\twocolwidtha{7cm}
-\begin{twocollist}\itemsep=0pt%
-\twocolitem{{\bf wxFromStart}}{Count offset from the start of the file}
-\twocolitem{{\bf wxFromCurrent}}{Count offset from the current position of the file pointer}
-\twocolitem{{\bf wxFromEnd}}{Count offset from the end of the file (backwards)}
-\end{twocollist}
-
-\latexignore{\rtfignore{\wxheading{Members}}}
-
-\membersection{wxFFile::wxFFile}\label{wxffileconstr}
-
-\func{}{wxFFile}{\void}
-
-Default constructor.
-
-\func{}{wxFFile}{\param{const char*}{ filename}, \param{const char*}{ mode = "r"}}
-
-Opens a file with the given mode. As there is no way to return whether the
-operation was successful or not from the constructor you should test the
-return value of \helpref{IsOpened}{wxffileisopened} to check that it didn't
-fail.
-
-\func{}{wxFFile}{\param{FILE*}{ fp}}
-
-Opens a file with the given file pointer, which has already been opened.
-
-\wxheading{Parameters}
-
-\docparam{filename}{The filename.}
-
-\docparam{mode}{The mode in which to open the file using standard C strings.}
-
-\docparam{fp}{An existing file descriptor, such as stderr.}
-
-\membersection{wxFFile::\destruct{wxFFile}}
-
-\func{}{\destruct{wxFFile}}{\void}
-
-Destructor will close the file.
-
-NB: it is not virtual so you should {\it not} derive from wxFFile!
-
-\membersection{wxFFile::Attach}\label{wxffileattach}
-
-\func{void}{Attach}{\param{FILE*}{ fp}}
-
-Attaches an existing file pointer to the wxFFile object.
-
-The descriptor should be already opened and it will be closed by wxFFile
-object.
-
-\membersection{wxFFile::Close}\label{wxffileclose}
-
-\func{bool}{Close}{\void}
-
-Closes the file and returns TRUE on success.
-
-\membersection{wxFFile::Detach}\label{wxffiledetach}
-
-\func{void}{Detach}{\void}
-
-Get back a file pointer from wxFFile object - the caller is responsible for closing the file if this
-descriptor is opened. \helpref{IsOpened()}{wxffileisopened} will return FALSE after call to Detach().
-
-\membersection{wxFFile::fp}\label{wxffilefp}
-
-\constfunc{FILE *}{fp}{\void}
-
-Returns the file pointer associated with the file.
-
-\membersection{wxFFile::Eof}\label{wxffileeof}
-
-\constfunc{bool}{Eof}{\void}
-
-Returns TRUE if the an attempt has been made to read {\it past}
-the end of the file.
-
-Note that the behaviour of the file descriptor based class
-\helpref{wxFile}{wxfile} is different as \helpref{wxFile::Eof}{wxfileeof}
-will return TRUE here as soon as the last byte of the file has been
-read.
-
-\membersection{wxFFile::Flush}\label{wxffileflush}
-
-\func{bool}{Flush}{\void}
-
-Flushes the file and returns TRUE on success.
-
-\membersection{wxFFile::IsOpened}\label{wxffileisopened}
-
-\constfunc{bool}{IsOpened}{\void}
-
-Returns TRUE if the file has been opened.
-
-\membersection{wxFFile::Length}\label{wxffilelength}
-
-\constfunc{size\_t}{Length}{\void}
-
-Returns the length of the file.
-
-\membersection{wxFFile::Open}\label{wxffileopen}
-
-\func{bool}{Open}{\param{const char*}{ filename}, \param{const char*}{ mode = "r"}}
-
-Opens the file, returning TRUE if successful.
-
-\wxheading{Parameters}
-
-\docparam{filename}{The filename.}
-
-\docparam{mode}{The mode in which to open the file.}
-
-\membersection{wxFFile::Read}\label{wxffileread}
-
-\func{size\_t}{Read}{\param{void*}{ buffer}, \param{off\_t}{ count}}
-
-Reads the specified number of bytes into a buffer, returning the actual number read.
-
-\wxheading{Parameters}
-
-\docparam{buffer}{A buffer to receive the data.}
-
-\docparam{count}{The number of bytes to read.}
-
-\wxheading{Return value}
-
-The number of bytes read.
-
-\membersection{wxFFile::Seek}\label{wxffileseek}
-
-\func{bool}{Seek}{\param{long }{ofs}, \param{wxSeekMode }{mode = wxFromStart}}
-
-Seeks to the specified position and returs TRUE on success.
-
-\wxheading{Parameters}
-
-\docparam{ofs}{Offset to seek to.}
-
-\docparam{mode}{One of {\bf wxFromStart}, {\bf wxFromEnd}, {\bf wxFromCurrent}.}
-
-\membersection{wxFFile::SeekEnd}\label{wxffileseekend}
-
-\func{bool}{SeekEnd}{\param{long }{ofs = 0}}
+the number of bytes actually written
-Moves the file pointer to the specified number of bytes before the end of the file
-and returns TRUE on success.
-\wxheading{Parameters}
-
-\docparam{ofs}{Number of bytes before the end of the file.}
-
-\membersection{wxFFile::Tell}\label{wxffiletell}
-
-\constfunc{size\_t}{Tell}{\void}
-
-Returns the current position.
-
-\membersection{wxFFile::Write}\label{wxffilewrite}
-
-\func{size_t}{Write}{\param{const void*}{ buffer}, \param{size\_t}{ count}}
-
-Writes the specified number of bytes from a buffer.
-
-\wxheading{Parameters}
-
-\docparam{buffer}{A buffer containing the data.}
-
-\docparam{count}{The number of bytes to write.}
-
-\wxheading{Return value}
+\membersection{wxFile::Write}\label{wxfilewrites}
-Number of bytes written.
+\func{bool}{Write}{\param{const wxString\& }{s}, \param{wxMBConv\&}{ conv = wxConvUTF8}}
-\membersection{wxFFile::Write}\label{wxffilewrites}
+Writes the contents of the string to the file, returns true on success.
-\func{bool}{Write}{\param{const wxString\& }{s}}
+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}.
projects / wxWidgets.git / blobdiff