src/common/file.cpp

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        file.cpp
   3 // Purpose:     wxFile - encapsulates low-level "file descriptor"
   4 //              wxTempFile
   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 // ----------------------------------------------------------------------------
  14 // headers
  15 // ----------------------------------------------------------------------------
  16
  17 #ifdef __GNUG__
  18 #pragma implementation "file.h"
  19 #endif
  20
  21 // For compilers that support precompilation, includes "wx.h".
  22 #include "wx/wxprec.h"
  23 #include "wx/defs.h"
  24
  25 #ifdef __BORLANDC__
  26 #pragma hdrstop
  27 #endif
  28
  29 // standard
  30 #if     defined(__WXMSW__) && !defined(__GNUWIN32__)
  31   #include  <io.h>
  32 #elif (defined(__UNIX__) || defined(__GNUWIN32__))
  33   #include  <unistd.h>
  34 #else
  35         #error  "Please specify the header with file functions declarations."
  36 #endif  //Win/UNIX
  37
  38 #include  <stdio.h>       // SEEK_xxx constants
  39 #include  <fcntl.h>       // O_RDONLY &c
  40 #include  <sys/types.h>   // needed for stat
  41 #include  <sys/stat.h>    // stat
  42
  43 // Microsoft compiler loves underscores, feed them to it
  44 #ifdef    _MSC_VER
  45   // functions
  46   #define   open        _open
  47   #define   close       _close
  48   #define   read        _read
  49   #define   write       _write
  50   #define   lseek       _lseek
  51   #define   fsync       _commit
  52   #define   access      _access
  53   #define   eof         _eof
  54
  55   // types
  56   #define   stat        _stat
  57
  58   // constants
  59   #define   O_RDONLY    _O_RDONLY
  60   #define   O_WRONLY    _O_WRONLY
  61   #define   O_RDWR      _O_RDWR
  62   #define   O_EXCL      _O_EXCL
  63   #define   O_CREAT     _O_CREAT
  64   #define   O_BINARY    _O_BINARY
  65
  66   #define   S_IFDIR     _S_IFDIR
  67   #define   S_IFREG     _S_IFREG
  68
  69   #define   S_IREAD     _S_IREAD
  70   #define   S_IWRITE    _S_IWRITE
  71 #else
  72   #define   tell(fd)    lseek(fd, 0, SEEK_CUR)
  73 #endif  //_MSC_VER
  74
  75 // there is no distinction between text and binary files under Unix
  76 #ifdef          __UNIX__
  77         #define         O_BINARY                (0)
  78 #endif  //__UNIX__
  79
  80 // wxWindows
  81 #include  <wx/string.h>
  82 #include  <wx/intl.h>
  83 #include  <wx/file.h>
  84 #include  <wx/log.h>
  85
  86
  87 // ============================================================================
  88 // implementation of wxFile
  89 // ============================================================================
  90
  91 // ----------------------------------------------------------------------------
  92 // static functions
  93 // ----------------------------------------------------------------------------
  94 bool wxFile::Exists(const char *sz)
  95 {
  96   struct stat st;
  97   return !access(sz, 0) && !stat(sz, &st) && (st.st_mode & S_IFREG);
  98 }
  99
 100 // ----------------------------------------------------------------------------
 101 // opening/closing
 102 // ----------------------------------------------------------------------------
 103
 104 // ctors
 105 wxFile::wxFile(const char *szFileName, OpenMode mode)
 106 {
 107   m_fd = fd_invalid;
 108
 109   Open(szFileName, mode);
 110 }
 111
 112 // dtor
 113 wxFile::~wxFile()
 114 {
 115   Close();
 116 }
 117
 118 // create the file, fail if it already exists and bOverwrite
 119 bool wxFile::Create(const char *szFileName, bool bOverwrite)
 120 {
 121   // if bOverwrite we create a new file or truncate the existing one,
 122   // otherwise we only create the new file and fail if it already exists
 123   int fd = open(szFileName, O_CREAT | (bOverwrite ? O_TRUNC : O_EXCL));
 124
 125   if ( fd == -1 ) {
 126     wxLogSysError("can't create file '%s'", szFileName);
 127     return FALSE;
 128   }
 129   else {
 130     Attach(fd);
 131     return TRUE;
 132   }
 133 }
 134
 135 // open the file
 136 bool wxFile::Open(const char *szFileName, OpenMode mode)
 137 {
 138   int flags = O_BINARY;
 139
 140   switch ( mode ) {
 141     case read:
 142       flags |= O_RDONLY;
 143       break;
 144
 145     case write:
 146       flags |= O_WRONLY | O_CREAT | O_TRUNC;
 147       break;
 148
 149     case write_append:
 150       flags |= O_WRONLY | O_APPEND;
 151       break;
 152
 153     case read_write:
 154       flags |= O_RDWR;
 155       break;
 156   }
 157
 158   int fd = open(szFileName, flags, S_IREAD | S_IWRITE);
 159
 160   if ( fd == -1 ) {
 161     wxLogSysError("can't open file '%s'", szFileName);
 162     return FALSE;
 163   }
 164   else {
 165     Attach(fd);
 166     return TRUE;
 167   }
 168 }
 169
 170 // close
 171 bool wxFile::Close()
 172 {
 173   if ( IsOpened() ) {
 174     if ( close(m_fd) == -1 ) {
 175       wxLogSysError("can't close file descriptor %d", m_fd);
 176       m_fd = fd_invalid;
 177       return FALSE;
 178     }
 179     else
 180       m_fd = fd_invalid;
 181   }
 182
 183   return TRUE;
 184 }
 185
 186 // ----------------------------------------------------------------------------
 187 // read/write
 188 // ----------------------------------------------------------------------------
 189
 190 // read
 191 off_t wxFile::Read(void *pBuf, off_t nCount)
 192 {
 193   wxCHECK( (pBuf != NULL) && IsOpened(), 0 );
 194
 195   int iRc = ::read(m_fd, pBuf, nCount);
 196   if ( iRc == -1 ) {
 197     wxLogSysError("can't read from file descriptor %d", m_fd);
 198     return ofsInvalid;
 199   }
 200   else
 201     return (uint)iRc;
 202 }
 203
 204 // write
 205 bool wxFile::Write(const void *pBuf, uint nCount)
 206 {
 207   wxCHECK( (pBuf != NULL) && IsOpened(), 0 );
 208
 209   int iRc = ::write(m_fd, pBuf, nCount);
 210   if ( iRc == -1 ) {
 211     wxLogSysError("can't write to file descriptor %d", m_fd);
 212     return FALSE;
 213   }
 214   else
 215     return TRUE;
 216 }
 217
 218 // flush
 219 bool wxFile::Flush()
 220 {
 221   if ( IsOpened() ) {
 222                 // @@@ fsync() is not ANSI (BSDish)
 223 //    if ( fsync(m_fd) == -1 ) { // TODO
 224       if (TRUE) {
 225       wxLogSysError("can't flush file descriptor %d", m_fd);
 226       return FALSE;
 227     }
 228   }
 229
 230   return TRUE;
 231 }
 232
 233 // ----------------------------------------------------------------------------
 234 // seek
 235 // ----------------------------------------------------------------------------
 236
 237 // seek
 238 off_t wxFile::Seek(off_t ofs, SeekMode mode)
 239 {
 240   wxASSERT( IsOpened() );
 241
 242   int flag = -1;
 243   switch ( mode ) {
 244     case FromStart:
 245       flag = SEEK_SET;
 246       break;
 247
 248     case FromCurrent:
 249       flag = SEEK_CUR;
 250       break;
 251
 252     case FromEnd:
 253       flag = SEEK_END;
 254       break;
 255
 256     default:
 257       wxFAIL_MSG("unknown seek origin");
 258   }
 259
 260   int iRc = lseek(m_fd, ofs, flag);
 261   if ( iRc == -1 ) {
 262     wxLogSysError("can't seek on file descriptor %d", m_fd);
 263     return ofsInvalid;
 264   }
 265   else
 266     return (off_t)iRc;
 267 }
 268
 269 // get current off_t
 270 off_t wxFile::Tell() const
 271 {
 272   wxASSERT( IsOpened() );
 273
 274   int iRc = tell(m_fd);
 275   if ( iRc == -1 ) {
 276     wxLogSysError("can't get seek position on file descriptor %d", m_fd);
 277     return ofsInvalid;
 278   }
 279   else
 280     return (off_t)iRc;
 281 }
 282
 283 // get current file length
 284 off_t wxFile::Length() const
 285 {
 286   wxASSERT( IsOpened() );
 287
 288   #ifdef  _MSC_VER
 289     int iRc = _filelength(m_fd);
 290   #else
 291     int iRc = tell(m_fd);
 292     if ( iRc != -1 ) {
 293                         // @ have to use const_cast :-(
 294       int iLen = ((wxFile *)this)->SeekEnd();
 295       if ( iLen != -1 ) {
 296         // restore old position
 297         if ( ((wxFile *)this)->Seek(iRc) == -1 ) {
 298           // error
 299           iLen = -1;
 300         }
 301       }
 302
 303       iRc = iLen;
 304     }
 305
 306   #endif  //_MSC_VER
 307
 308   if ( iRc == -1 ) {
 309     wxLogSysError("can't find length of file on file descriptor %d", m_fd);
 310     return ofsInvalid;
 311   }
 312   else
 313     return (off_t)iRc;
 314 }
 315
 316 // is end of file reached?
 317 bool wxFile::Eof() const
 318 {
 319   wxASSERT( IsOpened() );
 320
 321   int iRc;
 322
 323   #if defined(__UNIX__) || defined(__GNUWIN32__)
 324     // @@ this doesn't work, of course, on unseekable file descriptors
 325     off_t ofsCur = Tell(),
 326           ofsMax = Length();
 327     if ( ofsCur == ofsInvalid || ofsMax == ofsInvalid )
 328       iRc = -1;
 329     else
 330      iRc = ofsCur == ofsMax;
 331   #else  // Windows and "native" compiler
 332     iRc = eof(m_fd);
 333   #endif // Windows/Unix
 334
 335   switch ( iRc ) {
 336     case 1:
 337       break;
 338
 339     case 0:
 340       return FALSE;
 341
 342     case -1:
 343       wxLogSysError("can't determine if the end of file is reached on "
 344                     "descriptor %d", m_fd);
 345       break;
 346
 347     default:
 348       wxFAIL_MSG("invalid eof() return value.");
 349   }
 350
 351   return TRUE;
 352 }
 353
 354 // ============================================================================
 355 // implementation of wxTempFile
 356 // ============================================================================
 357
 358 // ----------------------------------------------------------------------------
 359 // construction
 360 // ----------------------------------------------------------------------------
 361 wxTempFile::wxTempFile(const wxString& strName)
 362 {
 363   Open(strName);
 364 }
 365
 366 bool wxTempFile::Open(const wxString& strName)
 367 {
 368   m_strName = strName;
 369
 370   // we want to create the file in the same directory as strName because
 371   // otherwise rename() in Commit() might not work (if the files are on
 372   // different partitions for example). Unfortunately, the only standard
 373   // (POSIX) temp file creation function tmpnam() can't do it.
 374   #ifdef  __UNIX__
 375     static const char *szMktempSuffix = "XXXXXX";
 376     m_strTemp << strName << szMktempSuffix;
 377     mktemp((char *)m_strTemp.c_str()); // @@@ even if the length doesn't change
 378     //m_strTemp.UngetWriteBuf();
 379   #else // Windows
 380     m_strTemp = tmpnam(NULL);
 381   #endif  // Windows/Unix
 382
 383   return m_file.Open(m_strTemp, wxFile::write);
 384 }
 385
 386 // ----------------------------------------------------------------------------
 387 // destruction
 388 // ----------------------------------------------------------------------------
 389
 390 wxTempFile::~wxTempFile()
 391 {
 392   if ( IsOpened() )
 393     Discard();
 394 }
 395
 396 bool wxTempFile::Commit()
 397 {
 398   m_file.Close();
 399
 400   if ( wxFile::Exists(m_strName) && remove(m_strName) != 0 ) {
 401     wxLogSysError("can't remove file '%s'", m_strName.c_str());
 402     return FALSE;
 403   }
 404
 405   if ( rename(m_strTemp, m_strName) != 0 ) {
 406     wxLogSysError("can't commit changes to file '%s'", m_strName.c_str());
 407     return FALSE;
 408   }
 409
 410   return TRUE;
 411 }
 412
 413 void wxTempFile::Discard()
 414 {
 415   m_file.Close();
 416   if ( remove(m_strTemp) != 0 )
 417     wxLogSysError("can't remove temporary file '%s'", m_strTemp.c_str());
 418 }