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 license
  11 /////////////////////////////////////////////////////////////////////////////
  12
  13 #ifndef _WX_FILEH__
  14 #define _WX_FILEH__
  15
  16 #ifdef __GNUG__
  17 #pragma interface "file.h"
  18 #endif
  19
  20 #ifndef WX_PRECOMP
  21   #include  "wx/string.h"
  22   #include  "wx/filefn.h"
  23 #endif
  24
  25 #if wxUSE_FILE
  26
  27 // ----------------------------------------------------------------------------
  28 // constants
  29 // ----------------------------------------------------------------------------
  30
  31 // we redefine these constants here because S_IREAD &c are _not_ standard
  32 // however, we do assume that the values correspond to the Unix umask bits
  33 #define wxS_IRUSR 00400
  34 #define wxS_IWUSR 00200
  35 #define wxS_IXUSR 00100
  36
  37 #define wxS_IRGRP 00040
  38 #define wxS_IWGRP 00020
  39 #define wxS_IXGRP 00010
  40
  41 #define wxS_IROTH 00004
  42 #define wxS_IWOTH 00002
  43 #define wxS_IXOTH 00001
  44
  45 // default mode for the new files: corresponds to umask 022
  46 #define wxS_DEFAULT   (wxS_IRUSR | wxS_IWUSR | wxS_IRGRP | wxS_IWGRP |\
  47                        wxS_IROTH | wxS_IWOTH)
  48
  49 // ----------------------------------------------------------------------------
  50 // class wxFile: raw file IO
  51 //
  52 // NB: for space efficiency this class has no virtual functions, including
  53 //     dtor which is _not_ virtual, so it shouldn't be used as a base class.
  54 // ----------------------------------------------------------------------------
  55 class WXDLLEXPORT wxFile
  56 {
  57 public:
  58   // more file constants
  59   // -------------------
  60     // opening mode
  61   enum OpenMode { read, write, read_write, write_append };
  62     // standard values for file descriptor
  63   enum { fd_invalid = -1, fd_stdin, fd_stdout, fd_stderr };
  64
  65   // static functions
  66   // ----------------
  67     // check whether a regular file by this name exists
  68   static bool Exists(const wxChar *name);
  69     // check whetther we can access the given file in given mode
  70     // (only read and write make sense here)
  71   static bool Access(const wxChar *name, OpenMode mode);
  72
  73   // ctors
  74   // -----
  75     // def ctor
  76   wxFile() { m_fd = fd_invalid; }
  77     // open specified file (may fail, use IsOpened())
  78   wxFile(const wxChar *szFileName, OpenMode mode = read);
  79     // attach to (already opened) file
  80   wxFile(int fd) { m_fd = fd; }
  81
  82   // open/close
  83     // create a new file (with the default value of bOverwrite, it will fail if
  84     // the file already exists, otherwise it will overwrite it and succeed)
  85   bool Create(const wxChar *szFileName, bool bOverwrite = FALSE,
  86               int access = wxS_DEFAULT);
  87   bool Open(const wxChar *szFileName, OpenMode mode = read,
  88             int access = wxS_DEFAULT);
  89   bool Close();  // Close is a NOP if not opened
  90
  91   // assign an existing file descriptor and get it back from wxFile object
  92   void Attach(int fd) { Close(); m_fd = fd; }
  93   void Detach()       { m_fd = fd_invalid;  }
  94   int  fd() const { return m_fd; }
  95
  96   // read/write (unbuffered)
  97     // returns number of bytes read or ofsInvalid on error
  98   off_t Read(void *pBuf, off_t nCount);
  99     // returns the number of bytes written
 100   size_t Write(const void *pBuf, size_t nCount);
 101     // returns true on success
 102   bool Write(const wxString& s)
 103   {
 104       size_t size = s.Len()*sizeof(wxChar);
 105       return Write(s.c_str(), size) == size;
 106   }
 107     // flush data not yet written
 108   bool Flush();
 109
 110   // file pointer operations (return ofsInvalid on failure)
 111     // move ptr ofs bytes related to start/current off_t/end of file
 112   off_t Seek(off_t ofs, wxSeekMode mode = wxFromStart);
 113     // move ptr to ofs bytes before the end
 114   off_t SeekEnd(off_t ofs = 0) { return Seek(ofs, wxFromEnd); }
 115     // get current off_t
 116   off_t Tell() const;
 117     // get current file length
 118   off_t Length() const;
 119
 120   // simple accessors
 121     // is file opened?
 122   bool IsOpened() const { return m_fd != fd_invalid; }
 123     // is end of file reached?
 124   bool Eof() const;
 125     // has an error occured?
 126   bool Error() const { return m_error; }
 127
 128   // dtor closes the file if opened
 129   ~wxFile() { Close(); }
 130
 131 private:
 132   // copy ctor and assignment operator are private because
 133   // it doesn't make sense to copy files this way:
 134   // attempt to do it will provoke a compile-time error.
 135   wxFile(const wxFile&);
 136   wxFile& operator=(const wxFile&);
 137
 138   int m_fd; // file descriptor or INVALID_FD if not opened
 139   bool m_error; // error memory
 140 };
 141
 142 // ----------------------------------------------------------------------------
 143 // class wxTempFile: if you want to replace another file, create an instance
 144 // of wxTempFile passing the name of the file to be replaced to the ctor. Then
 145 // you can write to wxTempFile and call Commit() function to replace the old
 146 // file (and close this one) or call Discard() to cancel the modification. If
 147 // you call neither of them, dtor will call Discard().
 148 // ----------------------------------------------------------------------------
 149 class WXDLLEXPORT wxTempFile
 150 {
 151 public:
 152   // ctors
 153     // default
 154   wxTempFile() { }
 155     // associates the temp file with the file to be replaced and opens it
 156   wxTempFile(const wxString& strName);
 157
 158   // open the temp file (strName is the name of file to be replaced)
 159   bool Open(const wxString& strName);
 160
 161   // is the file opened?
 162   bool IsOpened() const { return m_file.IsOpened(); }
 163
 164   // I/O (both functions return true on success, false on failure)
 165   bool Write(const void *p, size_t n) { return m_file.Write(p, n) != 0; }
 166   bool Write(const wxString& str)   { return m_file.Write(str); }
 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__