X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/842d6c94bd9fedff4799fd8e54cdb48de2fa7aa3..156194e1d525407e90c21552f8f7aa05756e0ddc:/docs/latex/wx/file.tex diff --git a/docs/latex/wx/file.tex b/docs/latex/wx/file.tex index 655f48fcd4..427897947c 100644 --- a/docs/latex/wx/file.tex +++ b/docs/latex/wx/file.tex @@ -1,9 +1,23 @@ +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%% 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 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} @@ -17,7 +31,6 @@ None. wx/file.h defines the following constants: -{\small \begin{verbatim} #define wxS_IRUSR 00400 #define wxS_IWUSR 00200 @@ -34,13 +47,12 @@ 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} -} 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} @@ -51,7 +63,10 @@ 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 @@ -82,7 +97,7 @@ fail. \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} @@ -98,7 +113,7 @@ Opens a file with the given file descriptor, which has already been opened. 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} @@ -113,7 +128,7 @@ 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 -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. @@ -126,9 +141,9 @@ 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} @@ -136,7 +151,7 @@ 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 -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} @@ -148,18 +163,28 @@ Returns the file descriptor associated with the file. \constfunc{bool}{Eof}{\void} -Returns TRUE if the end of the file has been reached (the last byte has been read). +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 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. +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} @@ -175,7 +200,7 @@ due to a missing fsync function, which reduces the usefulness of this function \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} @@ -187,7 +212,7 @@ Returns the length of the file. \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} @@ -246,11 +271,11 @@ The actual offset position achieved, or wxInvalidOffset on failure. \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. @@ -262,205 +287,18 @@ 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. - -\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} - - - -\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}} - -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. +\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 wxWindows 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}.