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 #include  "wx/string.h"
  21 #include  "wx/filefn.h"
  22
  23 // ----------------------------------------------------------------------------
  24 // constants
  25 // ----------------------------------------------------------------------------
  26
  27 // error return value for Seek() functions
  28 const off_t ofsInvalid = (off_t)-1;
  29
  30 // we redefine these constants here because S_IREAD &c are _not_ standard
  31 // however, we do assume that the values correspond to the Unix umask bits
  32 #define wxS_IRUSR 00400
  33 #define wxS_IWUSR 00200
  34 #define wxS_IXUSR 00100
  35
  36 #define wxS_IRGRP 00040
  37 #define wxS_IWGRP 00020
  38 #define wxS_IXGRP 00010
  39
  40 #define wxS_IROTH 00004
  41 #define wxS_IWOTH 00002
  42 #define wxS_IXOTH 00001
  43
  44 // default mode for the new files: corresponds to umask 022
  45 #define wxS_DEFAULT   (wxS_IRUSR | wxS_IWUSR | wxS_IRGRP | wxS_IWGRP |\
  46                        wxS_IROTH | wxS_IWOTH)
  47
  48 // ----------------------------------------------------------------------------
  49 // class wxFile: raw file IO
  50 //
  51 // NB: for space efficiency this class has no virtual functions, including
  52 //     dtor which is _not_ virtual, so it shouldn't be used as a base class.
  53 // ----------------------------------------------------------------------------
  54 class WXDLLEXPORT wxFile
  55 {
  56 public:
  57   // more file constants
  58   // -------------------
  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   static bool Exists(const char *sz);  // also checks it's a regular file
  68
  69   // ctors
  70   // -----
  71     // def ctor
  72   wxFile() { m_fd = fd_invalid; }
  73     // open specified file (may fail, use IsOpened())
  74   wxFile(const char *szFileName, OpenMode mode = read);
  75     // attach to (already opened) file
  76   wxFile(int fd) { m_fd = fd; }
  77
  78   // open/close
  79     // create a new file (with the default value of bOverwrite, it will fail if
  80     // the file already exists, otherwise it will overwrite it and succeed)
  81   bool Create(const char *szFileName, bool bOverwrite = FALSE,
  82               int access = wxS_DEFAULT);
  83   bool Open(const char *szFileName, OpenMode mode = read,
  84             int access = wxS_DEFAULT);
  85   bool Close();  // Close is a NOP if not opened
  86
  87   // assign an existing file descriptor and get it back from wxFile object
  88   void Attach(int fd) { Close(); m_fd = fd; }
  89   void Detach()       { m_fd = fd_invalid;  }
  90   int  fd() const { return m_fd; }
  91
  92   // read/write (unbuffered)
  93     // returns number of bytes read or ofsInvalid on error
  94   off_t Read(void *pBuf, off_t nCount);
  95     // returns true on success
  96   uint Write(const void *pBuf, uint nCount);
  97     // returns true on success
  98   bool Write(const wxString& s) { return Write(s.c_str(), s.Len()) != 0; }
  99     // flush data not yet written
 100   bool Flush();
 101
 102   // file pointer operations (return ofsInvalid on failure)
 103     // move ptr ofs bytes related to start/current off_t/end of file
 104   off_t Seek(off_t ofs, wxSeekMode mode = wxFromStart);
 105     // move ptr to ofs bytes before the end
 106   off_t SeekEnd(off_t ofs = 0) { return Seek(ofs, wxFromEnd); }
 107     // get current off_t
 108   off_t Tell() const;
 109     // get current file length
 110   off_t Length() const;
 111
 112   // simple accessors
 113     // is file opened?
 114   bool IsOpened() const { return m_fd != fd_invalid; }
 115     // is end of file reached?
 116   bool Eof() const;
 117     // is an error occured?
 118   bool Error() const { return m_error; }
 119
 120   // dtor closes the file if opened
 121  ~wxFile();
 122
 123 private:
 124   // copy ctor and assignment operator are private because
 125   // it doesn't make sense to copy files this way:
 126   // attempt to do it will provoke a compile-time error.
 127   wxFile(const wxFile&);
 128   wxFile& operator=(const wxFile&);
 129
 130   int m_fd; // file descriptor or INVALID_FD if not opened
 131   bool m_error; // error memory
 132 };
 133
 134 // ----------------------------------------------------------------------------
 135 // class wxTempFile: if you want to replace another file, create an instance
 136 // of wxTempFile passing the name of the file to be replaced to the ctor. Then
 137 // you can write to wxTempFile and call Commit() function to replace the old
 138 // file (and close this one) or call Discard() to cancel the modification. If
 139 // you call neither of them, dtor will call Discard().
 140 // ----------------------------------------------------------------------------
 141 class WXDLLEXPORT wxTempFile
 142 {
 143 public:
 144   // ctors
 145     // default
 146   wxTempFile() { }
 147     // associates the temp file with the file to be replaced and opens it
 148   wxTempFile(const wxString& strName);
 149
 150   // open the temp file (strName is the name of file to be replaced)
 151   bool Open(const wxString& strName);
 152
 153   // is the file opened?
 154   bool IsOpened() const { return m_file.IsOpened(); }
 155
 156   // I/O (both functions return true on success, false on failure)
 157   bool Write(const void *p, uint n) { return m_file.Write(p, n) != 0; }
 158   bool Write(const wxString& str)   { return m_file.Write(str); }
 159
 160   // different ways to close the file
 161     // validate changes and delete the old file of name m_strName
 162   bool Commit();
 163     // discard changes
 164   void Discard();
 165
 166   // dtor calls Discard() if file is still opened
 167  ~wxTempFile();
 168
 169 private:
 170   wxString  m_strName,  // name of the file to replace in Commit()
 171             m_strTemp;  // temporary file name
 172   wxFile    m_file;     // the temporary file
 173 };
 174
 175 #endif
 176         // __FILEH__