include/wx/file.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/file.h
   3 // Purpose:     wxFile - encapsulates low-level "file descriptor"
   4 //              wxTempFile - safely replace the old file
   5 // Author:      Vadim Zeitlin
   6 // Modified by:
   7 // Created:     29/01/98
   8 // Copyright:   (c) 1998 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr>
   9 // Licence:     wxWindows licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 #ifndef _WX_FILEH__
  13 #define _WX_FILEH__
  14
  15 #include  "wx/defs.h"
  16
  17 #if wxUSE_FILE
  18
  19 #include  "wx/string.h"
  20 #include  "wx/filefn.h"
  21 #include  "wx/convauto.h"
  22
  23 // ----------------------------------------------------------------------------
  24 // class wxFile: raw file IO
  25 //
  26 // NB: for space efficiency this class has no virtual functions, including
  27 //     dtor which is _not_ virtual, so it shouldn't be used as a base class.
  28 // ----------------------------------------------------------------------------
  29
  30 class WXDLLIMPEXP_BASE wxFile
  31 {
  32 public:
  33   // more file constants
  34   // -------------------
  35     // opening mode
  36   enum OpenMode { read, write, read_write, write_append, write_excl };
  37     // standard values for file descriptor
  38   enum { fd_invalid = -1, fd_stdin, fd_stdout, fd_stderr };
  39
  40   // static functions
  41   // ----------------
  42     // check whether a regular file by this name exists
  43   static bool Exists(const wxString& name);
  44     // check whether we can access the given file in given mode
  45     // (only read and write make sense here)
  46   static bool Access(const wxString& name, OpenMode mode);
  47
  48   // ctors
  49   // -----
  50     // def ctor
  51   wxFile() { m_fd = fd_invalid; m_lasterror = 0; }
  52     // open specified file (may fail, use IsOpened())
  53   wxFile(const wxString& fileName, OpenMode mode = read);
  54     // attach to (already opened) file
  55   wxFile(int lfd) { m_fd = lfd; m_lasterror = 0; }
  56
  57   // open/close
  58     // create a new file (with the default value of bOverwrite, it will fail if
  59     // the file already exists, otherwise it will overwrite it and succeed)
  60   bool Create(const wxString& fileName, bool bOverwrite = false,
  61               int access = wxS_DEFAULT);
  62   bool Open(const wxString& fileName, OpenMode mode = read,
  63             int access = wxS_DEFAULT);
  64   bool Close();  // Close is a NOP if not opened
  65
  66   // assign an existing file descriptor and get it back from wxFile object
  67   void Attach(int lfd) { Close(); m_fd = lfd; m_lasterror = 0; }
  68   int  Detach() { int fdOld = m_fd; m_fd = fd_invalid; return fdOld; }
  69   int  fd() const { return m_fd; }
  70
  71   // read/write (unbuffered)
  72     // read all data from the file into a string (useful for text files)
  73   bool ReadAll(wxString *str, const wxMBConv& conv = wxConvAuto());
  74     // returns number of bytes read or wxInvalidOffset on error
  75   ssize_t Read(void *pBuf, size_t nCount);
  76     // returns the number of bytes written
  77   size_t Write(const void *pBuf, size_t nCount);
  78     // returns true on success
  79   bool Write(const wxString& s, const wxMBConv& conv = wxConvAuto());
  80     // flush data not yet written
  81   bool Flush();
  82
  83   // file pointer operations (return wxInvalidOffset on failure)
  84     // move ptr ofs bytes related to start/current offset/end of file
  85   wxFileOffset Seek(wxFileOffset ofs, wxSeekMode mode = wxFromStart);
  86     // move ptr to ofs bytes before the end
  87   wxFileOffset SeekEnd(wxFileOffset ofs = 0) { return Seek(ofs, wxFromEnd); }
  88     // get current offset
  89   wxFileOffset Tell() const;
  90     // get current file length
  91   wxFileOffset Length() const;
  92
  93   // simple accessors
  94     // is file opened?
  95   bool IsOpened() const { return m_fd != fd_invalid; }
  96     // is end of file reached?
  97   bool Eof() const;
  98     // has an error occurred?
  99   bool Error() const { return m_lasterror != 0; }
 100     // get last errno
 101   int GetLastError() const { return m_lasterror; }
 102     // reset error state
 103   void ClearLastError() { m_lasterror = 0; }
 104     // type such as disk or pipe
 105   wxFileKind GetKind() const { return wxGetFileKind(m_fd); }
 106
 107
 108   // dtor closes the file if opened
 109   ~wxFile() { Close(); }
 110
 111 private:
 112   // copy ctor and assignment operator are private because
 113   // it doesn't make sense to copy files this way:
 114   // attempt to do it will provoke a compile-time error.
 115   wxFile(const wxFile&);
 116   wxFile& operator=(const wxFile&);
 117
 118   // Copy the value of errno into m_lasterror if rc == -1 and return true in
 119   // this case (indicating that we've got an error). Otherwise return false.
 120   //
 121   // Notice that we use the possibly 64 bit wxFileOffset instead of int here so
 122   // that it works for checking the result of functions such as tell() too.
 123   bool CheckForError(wxFileOffset rc) const;
 124
 125
 126   int m_fd; // file descriptor or INVALID_FD if not opened
 127   int m_lasterror; // errno value of last error
 128 };
 129
 130 // ----------------------------------------------------------------------------
 131 // class wxTempFile: if you want to replace another file, create an instance
 132 // of wxTempFile passing the name of the file to be replaced to the ctor. Then
 133 // you can write to wxTempFile and call Commit() function to replace the old
 134 // file (and close this one) or call Discard() to cancel the modification. If
 135 // you call neither of them, dtor will call Discard().
 136 // ----------------------------------------------------------------------------
 137
 138 class WXDLLIMPEXP_BASE wxTempFile
 139 {
 140 public:
 141   // ctors
 142     // default
 143   wxTempFile() { }
 144     // associates the temp file with the file to be replaced and opens it
 145   wxTempFile(const wxString& strName);
 146
 147   // open the temp file (strName is the name of file to be replaced)
 148   bool Open(const wxString& strName);
 149
 150   // is the file opened?
 151   bool IsOpened() const { return m_file.IsOpened(); }
 152     // get current file length
 153   wxFileOffset Length() const { return m_file.Length(); }
 154     // move ptr ofs bytes related to start/current offset/end of file
 155   wxFileOffset Seek(wxFileOffset ofs, wxSeekMode mode = wxFromStart)
 156     { return m_file.Seek(ofs, mode); }
 157     // get current offset
 158   wxFileOffset Tell() const { return m_file.Tell(); }
 159
 160   // I/O (both functions return true on success, false on failure)
 161   bool Write(const void *p, size_t n) { return m_file.Write(p, n) == n; }
 162   bool Write(const wxString& str, const wxMBConv& conv = wxMBConvUTF8())
 163     { return m_file.Write(str, conv); }
 164
 165   // flush data: can be called before closing file to ensure that data was
 166   // correctly written out
 167   bool Flush() { return m_file.Flush(); }
 168
 169   // different ways to close the file
 170     // validate changes and delete the old file of name m_strName
 171   bool Commit();
 172     // discard changes
 173   void Discard();
 174
 175   // dtor calls Discard() if file is still opened
 176  ~wxTempFile();
 177
 178 private:
 179   // no copy ctor/assignment operator
 180   wxTempFile(const wxTempFile&);
 181   wxTempFile& operator=(const wxTempFile&);
 182
 183   wxString  m_strName,  // name of the file to replace in Commit()
 184             m_strTemp;  // temporary file name
 185   wxFile    m_file;     // the temporary file
 186 };
 187
 188 #endif // wxUSE_FILE
 189
 190 #endif // _WX_FILEH__