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_error = false; }
  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_error = false; }
  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_error = false; }
  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_error; }
  99     // type such as disk or pipe
 100   wxFileKind GetKind() const { return wxGetFileKind(m_fd); }
 101
 102   // dtor closes the file if opened
 103   ~wxFile() { Close(); }
 104
 105 private:
 106   // copy ctor and assignment operator are private because
 107   // it doesn't make sense to copy files this way:
 108   // attempt to do it will provoke a compile-time error.
 109   wxFile(const wxFile&);
 110   wxFile& operator=(const wxFile&);
 111
 112   int m_fd; // file descriptor or INVALID_FD if not opened
 113   bool m_error; // error memory
 114 };
 115
 116 // ----------------------------------------------------------------------------
 117 // class wxTempFile: if you want to replace another file, create an instance
 118 // of wxTempFile passing the name of the file to be replaced to the ctor. Then
 119 // you can write to wxTempFile and call Commit() function to replace the old
 120 // file (and close this one) or call Discard() to cancel the modification. If
 121 // you call neither of them, dtor will call Discard().
 122 // ----------------------------------------------------------------------------
 123
 124 class WXDLLIMPEXP_BASE wxTempFile
 125 {
 126 public:
 127   // ctors
 128     // default
 129   wxTempFile() { }
 130     // associates the temp file with the file to be replaced and opens it
 131   wxTempFile(const wxString& strName);
 132
 133   // open the temp file (strName is the name of file to be replaced)
 134   bool Open(const wxString& strName);
 135
 136   // is the file opened?
 137   bool IsOpened() const { return m_file.IsOpened(); }
 138     // get current file length
 139   wxFileOffset Length() const { return m_file.Length(); }
 140     // move ptr ofs bytes related to start/current offset/end of file
 141   wxFileOffset Seek(wxFileOffset ofs, wxSeekMode mode = wxFromStart)
 142     { return m_file.Seek(ofs, mode); }
 143     // get current offset
 144   wxFileOffset Tell() const { return m_file.Tell(); }
 145
 146   // I/O (both functions return true on success, false on failure)
 147   bool Write(const void *p, size_t n) { return m_file.Write(p, n) == n; }
 148   bool Write(const wxString& str, const wxMBConv& conv = wxMBConvUTF8())
 149     { return m_file.Write(str, conv); }
 150
 151   // flush data: can be called before closing file to ensure that data was
 152   // correctly written out
 153   bool Flush() { return m_file.Flush(); }
 154
 155   // different ways to close the file
 156     // validate changes and delete the old file of name m_strName
 157   bool Commit();
 158     // discard changes
 159   void Discard();
 160
 161   // dtor calls Discard() if file is still opened
 162  ~wxTempFile();
 163
 164 private:
 165   // no copy ctor/assignment operator
 166   wxTempFile(const wxTempFile&);
 167   wxTempFile& operator=(const wxTempFile&);
 168
 169   wxString  m_strName,  // name of the file to replace in Commit()
 170             m_strTemp;  // temporary file name
 171   wxFile    m_file;     // the temporary file
 172 };
 173
 174 #endif // wxUSE_FILE
 175
 176 #endif // _WX_FILEH__