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_IROTH)
  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
  59     // opening mode
  60   enum OpenMode { read, write, read_write, write_append };
  61     // standard values for file descriptor
  62   enum { fd_invalid = -1, fd_stdin, fd_stdout, fd_stderr };
  63
  64   // static functions
  65   // ----------------
  66   static bool Exists(const char *sz);  // also checks it's a regular file
  67
  68   // ctors
  69   // -----
  70     // def ctor
  71   wxFile() { m_fd = fd_invalid; }
  72     // open specified file (may fail, use IsOpened())
  73   wxFile(const char *szFileName, OpenMode mode = read);
  74     // attach to (already opened) file
  75   wxFile(int fd) { m_fd = fd; }
  76
  77   // open/close
  78     // create a new file (with the default value of bOverwrite, it will fail if
  79     // the file already exists, otherwise it will overwrite it and succeed)
  80   bool Create(const char *szFileName, bool bOverwrite = FALSE,
  81               int access = wxS_DEFAULT);
  82   bool Open(const char *szFileName, OpenMode mode = read,
  83             int access = wxS_DEFAULT);
  84   bool Close();  // Close is a NOP if not opened
  85
  86   // assign an existing file descriptor and get it back from wxFile object
  87   void Attach(int fd) { Close(); m_fd = fd; }
  88   void Detach()       { m_fd = fd_invalid;  }
  89   int  fd() const { return m_fd; }
  90
  91   // read/write (unbuffered)
  92     // returns number of bytes read or ofsInvalid on error
  93   off_t Read(void *pBuf, off_t nCount);
  94     // returns true on success
  95   uint Write(const void *pBuf, uint nCount);
  96     // returns true on success
  97   bool Write(const wxString& s) { return Write(s.c_str(), s.Len()) != 0; }
  98     // flush data not yet written
  99   bool Flush();
 100
 101   // file pointer operations (return ofsInvalid on failure)
 102     // move ptr ofs bytes related to start/current off_t/end of file
 103   off_t Seek(off_t ofs, wxSeekMode mode = wxFromStart);
 104     // move ptr to ofs bytes before the end
 105   off_t SeekEnd(off_t ofs = 0) { return Seek(ofs, wxFromEnd); }
 106     // get current off_t
 107   off_t Tell() const;
 108     // get current file length
 109   off_t Length() const;
 110
 111   // simple accessors
 112     // is file opened?
 113   bool IsOpened() const { return m_fd != fd_invalid; }
 114     // is end of file reached?
 115   bool Eof() const;
 116     // is an error occured?
 117   bool Error() const { return m_error; }
 118
 119   // dtor closes the file if opened
 120  ~wxFile();
 121
 122 private:
 123   // copy ctor and assignment operator are private because
 124   // it doesn't make sense to copy files this way:
 125   // attempt to do it will provoke a compile-time error.
 126   wxFile(const wxFile&);
 127   wxFile& operator=(const wxFile&);
 128
 129   int m_fd; // file descriptor or INVALID_FD if not opened
 130   bool m_error; // error memory
 131 };
 132
 133 // ----------------------------------------------------------------------------
 134 // class wxTempFile: if you want to replace another file, create an instance
 135 // of wxTempFile passing the name of the file to be replaced to the ctor. Then
 136 // you can write to wxTempFile and call Commit() function to replace the old
 137 // file (and close this one) or call Discard() to cancel the modification. If
 138 // you call neither of them, dtor will call Discard().
 139 // ----------------------------------------------------------------------------
 140 class WXDLLEXPORT wxTempFile
 141 {
 142 public:
 143   // ctors
 144     // default
 145   wxTempFile() { }
 146     // associates the temp file with the file to be replaced and opens it
 147   wxTempFile(const wxString& strName);
 148
 149   // open the temp file (strName is the name of file to be replaced)
 150   bool Open(const wxString& strName);
 151
 152   // is the file opened?
 153   bool IsOpened() const { return m_file.IsOpened(); }
 154
 155   // I/O (both functions return true on success, false on failure)
 156   bool Write(const void *p, uint n) { return m_file.Write(p, n) != 0; }
 157   bool Write(const wxString& str)   { return m_file.Write(str); }
 158
 159   // different ways to close the file
 160     // validate changes and delete the old file of name m_strName
 161   bool Commit();
 162     // discard changes
 163   void Discard();
 164
 165   // dtor calls Discard() if file is still opened
 166  ~wxTempFile();
 167
 168 private:
 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
 175         // __FILEH__