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.
\wxheading{Derived from}
None.
+\wxheading{Include files}
+
+<wx/file.h>
+
\wxheading{Constants}
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 resolution prefix. It is also used with
-\helpref{wxFile::Access}{wxfileaccess} function.
+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}%
-\begin{twocollist}\itemsep=0pt
+\twocolwidtha{7cm}
+\begin{twocollist}\itemsep=0pt%
\twocolitem{{\bf wxFile::read}}{Open file for reading or test if it can be opened for reading with Access()}
\twocolitem{{\bf wxFile::write}}{Open file for writing deleting the contents of the file if it already exists
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;
-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
mode constants used with \helpref{Seek()}{wxfileseek}:
\twocolwidtha{7cm}
-\begin{twocollist}\itemsep=0pt
+\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)}
\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}
Destructor will close the file.
-NB: it is not virtual so you should {\it not} derive from wxFile!
+NB: it is not virtual so you should use wxFile polymorphically.
\membersection{wxFile::Access}\label{wxfileaccess}
-\func{static bool}{Access}{\param{const char *}{ name}, \param{OpenMode}{ mode}
+
+\func{static bool}{Access}{\param{const char *}{ name}, \param{OpenMode}{ mode}}
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}}
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.
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().
\membersection{wxFile::fd}\label{wxfilefd}
+
\constfunc{int}{fd}{\void}
Returns the file descriptor associated with the file.
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}}
-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::Seek}\label{wxfileseek}
-\func{off\_t}{Seek}{\param{off\_t }{ofs}, \param{wxFile::SeekMode }{mode = wxFile::FromStart}}
+\func{off\_t}{Seek}{\param{off\_t }{ofs}, \param{wxSeekMode }{mode = wxFromStart}}
Seeks to the specified position.
\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}
\constfunc{off\_t}{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{off\_t}{ count}}
Writes the specified number of bytes from a buffer.
\wxheading{Return value}
-TRUE if the operation was successful.
+the number of bytes actually written
\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
+\func{bool}{Write}{\param{const wxString\& }{s}, \param{wxMBConv&}{ conv = wxConvLibc}}
+
+Writes the contents of the string to the file, returns TRUE on success.
+
+The second argument is only meaningful in Unicode build of wxWindows when
+{\it conv} is used to convert {\it s} to multibyte representation.
+
+\section{\class{wxFFile}}\label{wxffile}
+
+wxFFile implements buffered 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. It wraps inside it a {\tt FILE *} handle used
+by standard C IO library (also known as {\tt stdio}).
+
+\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.
+Note that you should use {\tt "b"} flag if you use binary files under Windows
+or the results might be unexpected due to automatic newline conversion done
+for the text files.}
+
+\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}}
+
+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}
+
+Number of bytes written.
+
+\membersection{wxFFile::Write}\label{wxffilewrites}
+
+\func{bool}{Write}{\param{const wxString\& }{s}, \param{wxMBConv&}{ conv = wxConvLibc}}
+
+Writes the contents of the string to the file, returns TRUE on success.
+
+The second argument is only meaningful in Unicode build of wxWindows when
+{\it conv} is used to convert {\it s} to multibyte representation.
+
projects / wxWidgets.git / blobdiff