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, wxMBConv& conv = wxConvLibc)
 103   {
 104       const wxWX2MBbuf buf = s.mb_str(conv);
 105       size_t size = strlen(buf);
 106       return Write((const char *) buf, size) == size;
 107   }
 108     // flush data not yet written
 109   bool Flush();
 110
 111   // file pointer operations (return ofsInvalid on failure)
 112     // move ptr ofs bytes related to start/current off_t/end of file
 113   off_t Seek(off_t ofs, wxSeekMode mode = wxFromStart);
 114     // move ptr to ofs bytes before the end
 115   off_t SeekEnd(off_t ofs = 0) { return Seek(ofs, wxFromEnd); }
 116     // get current off_t
 117   off_t Tell() const;
 118     // get current file length
 119   off_t Length() const;
 120
 121   // simple accessors
 122     // is file opened?
 123   bool IsOpened() const { return m_fd != fd_invalid; }
 124     // is end of file reached?
 125   bool Eof() const;
 126     // has an error occured?
 127   bool Error() const { return m_error; }
 128
 129   // dtor closes the file if opened
 130   ~wxFile() { Close(); }
 131
 132 private:
 133   // copy ctor and assignment operator are private because
 134   // it doesn't make sense to copy files this way:
 135   // attempt to do it will provoke a compile-time error.
 136   wxFile(const wxFile&);
 137   wxFile& operator=(const wxFile&);
 138
 139   int m_fd; // file descriptor or INVALID_FD if not opened
 140   bool m_error; // error memory
 141 };
 142
 143 // ----------------------------------------------------------------------------
 144 // class wxTempFile: if you want to replace another file, create an instance
 145 // of wxTempFile passing the name of the file to be replaced to the ctor. Then
 146 // you can write to wxTempFile and call Commit() function to replace the old
 147 // file (and close this one) or call Discard() to cancel the modification. If
 148 // you call neither of them, dtor will call Discard().
 149 // ----------------------------------------------------------------------------
 150 class WXDLLEXPORT wxTempFile
 151 {
 152 public:
 153   // ctors
 154     // default
 155   wxTempFile() { }
 156     // associates the temp file with the file to be replaced and opens it
 157   wxTempFile(const wxString& strName);
 158
 159   // open the temp file (strName is the name of file to be replaced)
 160   bool Open(const wxString& strName);
 161
 162   // is the file opened?
 163   bool IsOpened() const { return m_file.IsOpened(); }
 164
 165   // I/O (both functions return true on success, false on failure)
 166   bool Write(const void *p, size_t n) { return m_file.Write(p, n) != 0; }
 167   bool Write(const wxString& str)   { return m_file.Write(str); }
 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__