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