gl/fseeko.c

   1 /* An fseeko() function that, together with fflush(), is POSIX compliant.
   2    Copyright (C) 2007-2010 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 General Public License as published by
   6    the Free Software Foundation; either version 3, 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 General Public License for more details.
  13
  14    You should have received a copy of the GNU 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_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, 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 & 0x2000 /* _MWRITE */ ? fp->_Next == fp->_Buf : fp->_Next == fp->_Rend)
  83       && fp->_Rback == fp->_Back + sizeof (fp->_Back)
  84       && fp->_Rsave == NULL)
  85 #elif defined __MINT__              /* Atari FreeMiNT */
  86   if (fp->__bufp == fp->__buffer
  87       && fp->__get_limit == fp->__bufp
  88       && fp->__put_limit == fp->__bufp
  89       && !fp->__pushed_back)
  90 #else
  91   #error "Please port gnulib fseeko.c to your platform! Look at the code in fpurge.c, then report this to bug-gnulib."
  92 #endif
  93     {
  94       /* We get here when an fflush() call immediately preceded this one.  We
  95          know there are no buffers.
  96          POSIX requires us to modify the file descriptor's position.
  97          But we cannot position beyond end of file here.  */
  98       off_t pos =
  99         lseek (fileno (fp),
 100                whence == SEEK_END && offset > 0 ? 0 : offset,
 101                whence);
 102       if (pos == -1)
 103         {
 104 #if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
 105           fp_->_flags &= ~__SOFF;
 106 #endif
 107           return -1;
 108         }
 109
 110 #if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
 111       fp->_flags &= ~_IO_EOF_SEEN;
 112 #elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
 113 # if defined __CYGWIN__
 114       /* fp_->_offset is typed as an integer.  */
 115       fp_->_offset = pos;
 116 # else
 117       /* fp_->_offset is an fpos_t.  */
 118       {
 119         /* Use a union, since on NetBSD, the compilation flags
 120            determine whether fpos_t is typedef'd to off_t or a struct
 121            containing a single off_t member.  */
 122         union
 123           {
 124             fpos_t f;
 125             off_t o;
 126           } u;
 127         u.o = pos;
 128         fp_->_offset = u.f;
 129       }
 130 # endif
 131       fp_->_flags |= __SOFF;
 132       fp_->_flags &= ~__SEOF;
 133 #elif defined __EMX__               /* emx+gcc */
 134       fp->_flags &= ~_IOEOF;
 135 #elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */
 136       fp->_flag &= ~_IOEOF;
 137 #elif defined __MINT__              /* Atari FreeMiNT */
 138       fp->__offset = pos;
 139       fp->__eof = 0;
 140 #endif
 141       /* If we were not requested to position beyond end of file, we're
 142          done.  */
 143       if (!(whence == SEEK_END && offset > 0))
 144         return 0;
 145     }
 146   return fseeko (fp, offset, whence);
 147 }