lgl/fseeko.c

   1 /* An fseeko() function that, together with fflush(), is POSIX compliant.
   2    Copyright (C) 2007-2008 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as published by
   6    the Free Software Foundation; either version 2.1, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License along
  15    with this program; if not, write to the Free Software Foundation,
  16    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include <stdio.h>
  22
  23 /* Get off_t and lseek.  */
  24 #include <unistd.h>
  25
  26 #include "stdio-impl.h"
  27
  28 #undef fseeko
  29 #if !HAVE_FSEEKO
  30 # undef fseek
  31 # define fseeko fseek
  32 #endif
  33
  34 int
  35 rpl_fseeko (FILE *fp, off_t offset, int whence)
  36 {
  37 #if LSEEK_PIPE_BROKEN
  38   /* mingw gives bogus answers rather than failure on non-seekable files.  */
  39   if (lseek (fileno (fp), 0, SEEK_CUR) == -1)
  40     return EOF;
  41 #endif
  42
  43   /* These tests are based on fpurge.c.  */
  44 #if defined _IO_ferror_unlocked || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Linux libc5 */
  45   if (fp->_IO_read_end == fp->_IO_read_ptr
  46       && fp->_IO_write_ptr == fp->_IO_write_base
  47       && fp->_IO_save_base == NULL)
  48 #elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
  49 # if defined __SL64 && defined __SCLE /* Cygwin */
  50   if ((fp->_flags & __SL64) == 0)
  51     {
  52       /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
  53          mode; but has an fseeko that requires 64-bit mode.  */
  54       FILE *tmp = fopen ("/dev/null", "r");
  55       if (!tmp)
  56         return -1;
  57       fp->_flags |= __SL64;
  58       fp->_seek64 = tmp->_seek64;
  59       fclose (tmp);
  60     }
  61 # endif
  62   if (fp_->_p == fp_->_bf._base
  63       && fp_->_r == 0
  64       && fp_->_w == ((fp_->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
  65                      ? fp_->_bf._size
  66                      : 0)
  67       && fp_ub._base == NULL)
  68 #elif defined __EMX__               /* emx+gcc */
  69   if (fp->_ptr == fp->_buffer
  70       && fp->_rcount == 0
  71       && fp->_wcount == 0
  72       && fp->_ungetc_count == 0)
  73 #elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */
  74   if (fp_->_ptr == fp_->_base
  75       && (fp_->_ptr == NULL || fp_->_cnt == 0))
  76 #elif defined __UCLIBC__            /* uClibc */
  77   if (((fp->__modeflags & __FLAG_WRITING) == 0
  78        || fp->__bufpos == fp->__bufstart)
  79       && ((fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) == 0
  80           || fp->__bufpos == fp->__bufread))
  81 #elif defined __QNX__               /* QNX */
  82   if ((fp->_Mode & _MWRITE ? fp->_Next == fp->_Buf : fp->_Next == fp->_Rend)
  83       && fp->_Rback == fp->_Back + sizeof (fp->_Back)
  84       && fp->_Rsave == NULL)
  85 #else
  86   #error "Please port gnulib fseeko.c to your platform! Look at the code in fpurge.c, then report this to bug-gnulib."
  87 #endif
  88     {
  89       off_t pos = lseek (fileno (fp), offset, whence);
  90       if (pos == -1)
  91         {
  92 #if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
  93           fp_->_flags &= ~__SOFF;
  94 #endif
  95           return -1;
  96         }
  97       else
  98         {
  99 #if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
 100           fp_->_offset = pos;
 101           fp_->_flags |= __SOFF;
 102           fp_->_flags &= ~__SEOF;
 103 #elif defined __EMX__               /* emx+gcc */
 104           fp->_flags &= ~_IOEOF;
 105 #elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */
 106           fp->_flag &= ~_IOEOF;
 107 #endif
 108           return 0;
 109         }
 110     }
 111   else
 112     return fseeko (fp, offset, whence);
 113 }