include/wx/file.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        file.cpp
   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   __FILEH__
  14 #define   __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 // ----------------------------------------------------------------------------
  26 // constants
  27 // ----------------------------------------------------------------------------
  28
  29 // we redefine these constants here because S_IREAD &c are _not_ standard
  30 // however, we do assume that the values correspond to the Unix umask bits
  31 #define wxS_IRUSR 00400
  32 #define wxS_IWUSR 00200
  33 #define wxS_IXUSR 00100
  34
  35 #define wxS_IRGRP 00040
  36 #define wxS_IWGRP 00020
  37 #define wxS_IXGRP 00010
  38
  39 #define wxS_IROTH 00004
  40 #define wxS_IWOTH 00002
  41 #define wxS_IXOTH 00001
  42
  43 // default mode for the new files: corresponds to umask 022
  44 #define wxS_DEFAULT   (wxS_IRUSR | wxS_IWUSR | wxS_IRGRP | wxS_IWGRP |\
  45                        wxS_IROTH | wxS_IWOTH)
  46
  47 // ----------------------------------------------------------------------------
  48 // class wxFile: raw file IO
  49 //
  50 // NB: for space efficiency this class has no virtual functions, including
  51 //     dtor which is _not_ virtual, so it shouldn't be used as a base class.
  52 // ----------------------------------------------------------------------------
  53 class WXDLLEXPORT wxFile
  54 {
  55 public:
  56   // more file constants
  57   // -------------------
  58     // opening mode
  59   enum OpenMode { read, write, read_write, write_append };
  60     // standard values for file descriptor
  61   enum { fd_invalid = -1, fd_stdin, fd_stdout, fd_stderr };
  62
  63   // static functions
  64   // ----------------
  65     // check whether a regular file by this name exists
  66   static bool Exists(const char *name);
  67     // check whetther we can access the given file in given mode
  68     // (only read and write make sense here)
  69   static bool Access(const char *name, OpenMode mode);
  70
  71   // ctors
  72   // -----
  73     // def ctor
  74   wxFile() { m_fd = fd_invalid; }
  75     // open specified file (may fail, use IsOpened())
  76   wxFile(const char *szFileName, OpenMode mode = read);
  77     // attach to (already opened) file
  78   wxFile(int fd) { m_fd = fd; }
  79
  80   // open/close
  81     // create a new file (with the default value of bOverwrite, it will fail if
  82     // the file already exists, otherwise it will overwrite it and succeed)
  83   bool Create(const char *szFileName, bool bOverwrite = FALSE,
  84               int access = wxS_DEFAULT);
  85   bool Open(const char *szFileName, OpenMode mode = read,
  86             int access = wxS_DEFAULT);
  87   bool Close();  // Close is a NOP if not opened
  88
  89   // assign an existing file descriptor and get it back from wxFile object
  90   void Attach(int fd) { Close(); m_fd = fd; }
  91   void Detach()       { m_fd = fd_invalid;  }
  92   int  fd() const { return m_fd; }
  93
  94   // read/write (unbuffered)
  95     // returns number of bytes read or ofsInvalid on error
  96   off_t Read(void *pBuf, off_t nCount);
  97     // returns true on success
  98   size_t Write(const void *pBuf, size_t nCount);
  99     // returns true on success
 100   bool Write(const wxString& s) { return Write(s.c_str(), s.Len()) != 0; }
 101     // flush data not yet written
 102   bool Flush();
 103
 104   // file pointer operations (return ofsInvalid on failure)
 105     // move ptr ofs bytes related to start/current off_t/end of file
 106   off_t Seek(off_t ofs, wxSeekMode mode = wxFromStart);
 107     // move ptr to ofs bytes before the end
 108   off_t SeekEnd(off_t ofs = 0) { return Seek(ofs, wxFromEnd); }
 109     // get current off_t
 110   off_t Tell() const;
 111     // get current file length
 112   off_t Length() const;
 113
 114   // simple accessors
 115     // is file opened?
 116   bool IsOpened() const { return m_fd != fd_invalid; }
 117     // is end of file reached?
 118   bool Eof() const;
 119     // is an error occured?
 120   bool Error() const { return m_error; }
 121
 122   // dtor closes the file if opened
 123   ~wxFile();
 124
 125 private:
 126   // copy ctor and assignment operator are private because
 127   // it doesn't make sense to copy files this way:
 128   // attempt to do it will provoke a compile-time error.
 129   wxFile(const wxFile&);
 130   wxFile& operator=(const wxFile&);
 131
 132   int m_fd; // file descriptor or INVALID_FD if not opened
 133   bool m_error; // error memory
 134 };
 135
 136 // ----------------------------------------------------------------------------
 137 // class wxTempFile: if you want to replace another file, create an instance
 138 // of wxTempFile passing the name of the file to be replaced to the ctor. Then
 139 // you can write to wxTempFile and call Commit() function to replace the old
 140 // file (and close this one) or call Discard() to cancel the modification. If
 141 // you call neither of them, dtor will call Discard().
 142 // ----------------------------------------------------------------------------
 143 class WXDLLEXPORT wxTempFile
 144 {
 145 public:
 146   // ctors
 147     // default
 148   wxTempFile() { }
 149     // associates the temp file with the file to be replaced and opens it
 150   wxTempFile(const wxString& strName);
 151
 152   // open the temp file (strName is the name of file to be replaced)
 153   bool Open(const wxString& strName);
 154
 155   // is the file opened?
 156   bool IsOpened() const { return m_file.IsOpened(); }
 157
 158   // I/O (both functions return true on success, false on failure)
 159   bool Write(const void *p, size_t n) { return m_file.Write(p, n) != 0; }
 160   bool Write(const wxString& str)   { return m_file.Write(str); }
 161
 162   // different ways to close the file
 163     // validate changes and delete the old file of name m_strName
 164   bool Commit();
 165     // discard changes
 166   void Discard();
 167
 168   // dtor calls Discard() if file is still opened
 169  ~wxTempFile();
 170
 171 private:
 172   wxString  m_strName,  // name of the file to replace in Commit()
 173             m_strTemp;  // temporary file name
 174   wxFile    m_file;     // the temporary file
 175 };
 176
 177 #endif
 178         // _WX_FILEH__