gl/fseeko.c

   1 /* An fseeko() function that, together with fflush(), is POSIX compliant.
   2    Copyright (C) 2007-2012 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, see <http://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 /* Specification.  */
  20 #include <stdio.h>
  21
  22 /* Get off_t and lseek.  */
  23 #include <unistd.h>
  24
  25 #include "stdio-impl.h"
  26
  27 int
  28 fseeko (FILE *fp, off_t offset, int whence)
  29 #undef fseeko
  30 #if !HAVE_FSEEKO
  31 # undef fseek
  32 # define fseeko fseek
  33 #endif
  34 #if _GL_WINDOWS_64_BIT_OFF_T
  35 # undef fseeko
  36 # if HAVE__FSEEKI64 /* msvc, mingw64 */
  37 #  define fseeko _fseeki64
  38 # else /* mingw */
  39 #  define fseeko fseeko64
  40 # endif
  41 #endif
  42 {
  43 #if LSEEK_PIPE_BROKEN
  44   /* mingw gives bogus answers rather than failure on non-seekable files.  */
  45   if (lseek (fileno (fp), 0, SEEK_CUR) == -1)
  46     return EOF;
  47 #endif
  48
  49   /* These tests are based on fpurge.c.  */
  50 #if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
  51   if (fp->_IO_read_end == fp->_IO_read_ptr
  52       && fp->_IO_write_ptr == fp->_IO_write_base
  53       && fp->_IO_save_base == NULL)
  54 #elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
  55 # if defined __SL64 && defined __SCLE /* Cygwin */
  56   if ((fp->_flags & __SL64) == 0)
  57     {
  58       /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
  59          mode; but has an fseeko that requires 64-bit mode.  */
  60       FILE *tmp = fopen ("/dev/null", "r");
  61       if (!tmp)
  62         return -1;
  63       fp->_flags |= __SL64;
  64       fp->_seek64 = tmp->_seek64;
  65       fclose (tmp);
  66     }
  67 # endif
  68   if (fp_->_p == fp_->_bf._base
  69       && fp_->_r == 0
  70       && fp_->_w == ((fp_->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
  71                      ? fp_->_bf._size
  72                      : 0)
  73       && fp_ub._base == NULL)
  74 #elif defined __EMX__               /* emx+gcc */
  75   if (fp->_ptr == fp->_buffer
  76       && fp->_rcount == 0
  77       && fp->_wcount == 0
  78       && fp->_ungetc_count == 0)
  79 #elif defined __minix               /* Minix */
  80   if (fp_->_ptr == fp_->_buf
  81       && (fp_->_ptr == NULL || fp_->_count == 0))
  82 #elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw, NonStop Kernel */
  83   if (fp_->_ptr == fp_->_base
  84       && (fp_->_ptr == NULL || fp_->_cnt == 0))
  85 #elif defined __UCLIBC__            /* uClibc */
  86   if (((fp->__modeflags & __FLAG_WRITING) == 0
  87        || fp->__bufpos == fp->__bufstart)
  88       && ((fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) == 0
  89           || fp->__bufpos == fp->__bufread))
  90 #elif defined __QNX__               /* QNX */
  91   if ((fp->_Mode & 0x2000 /* _MWRITE */ ? fp->_Next == fp->_Buf : fp->_Next == fp->_Rend)
  92       && fp->_Rback == fp->_Back + sizeof (fp->_Back)
  93       && fp->_Rsave == NULL)
  94 #elif defined __MINT__              /* Atari FreeMiNT */
  95   if (fp->__bufp == fp->__buffer
  96       && fp->__get_limit == fp->__bufp
  97       && fp->__put_limit == fp->__bufp
  98       && !fp->__pushed_back)
  99 #elif defined EPLAN9                /* Plan9 */
 100   if (fp->rp == fp->buf
 101       && fp->wp == fp->buf)
 102 #else
 103   #error "Please port gnulib fseeko.c to your platform! Look at the code in fpurge.c, then report this to bug-gnulib."
 104 #endif
 105     {
 106       /* We get here when an fflush() call immediately preceded this one (or
 107          if ftell() has created buffers but no I/O has occurred on a
 108          newly-opened stream).  We know there are no buffers.  */
 109       off_t pos = lseek (fileno (fp), offset, whence);
 110       if (pos == -1)
 111         {
 112 #if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
 113           fp_->_flags &= ~__SOFF;
 114 #endif
 115           return -1;
 116         }
 117
 118 #if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */
 119       fp->_flags &= ~_IO_EOF_SEEN;
 120       fp->_offset = pos;
 121 #elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
 122 # if defined __CYGWIN__
 123       /* fp_->_offset is typed as an integer.  */
 124       fp_->_offset = pos;
 125 # else
 126       /* fp_->_offset is an fpos_t.  */
 127       {
 128         /* Use a union, since on NetBSD, the compilation flags
 129            determine whether fpos_t is typedef'd to off_t or a struct
 130            containing a single off_t member.  */
 131         union
 132           {
 133             fpos_t f;
 134             off_t o;
 135           } u;
 136         u.o = pos;
 137         fp_->_offset = u.f;
 138       }
 139 # endif
 140       fp_->_flags |= __SOFF;
 141       fp_->_flags &= ~__SEOF;
 142 #elif defined __EMX__               /* emx+gcc */
 143       fp->_flags &= ~_IOEOF;
 144 #elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw, NonStop Kernel */
 145       fp->_flag &= ~_IOEOF;
 146 #elif defined __MINT__              /* Atari FreeMiNT */
 147       fp->__offset = pos;
 148       fp->__eof = 0;
 149 #endif
 150       return 0;
 151     }
 152   return fseeko (fp, offset, whence);
 153 }