include/wx/file.h

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