lgl/fseeko.c

   1 /* An fseek() function that, together with fflush(), is POSIX compliant.
   2    Copyright (C) 2007 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 #undef fseeko
  27 #if !HAVE_FSEEKO
  28 # define fseeko fseek
  29 #endif
  30
  31 int
  32 rpl_fseeko (FILE *fp, off_t offset, int whence)
  33 {
  34   /* These tests are based on fpurge.c.  */
  35 #if defined _IO_ferror_unlocked     /* GNU libc, BeOS */
  36   if (fp->_IO_read_end == fp->_IO_read_ptr
  37       && fp->_IO_write_ptr == fp->_IO_write_base
  38       && fp->_IO_save_base == NULL)
  39 #elif defined __sferror             /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
  40 # if defined __NetBSD__ || defined __OpenBSD__ /* NetBSD, OpenBSD */
  41    /* See <http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup>
  42       and <http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup> */
  43 #  define fp_ub ((struct { struct __sbuf _ub; } *) fp->_ext._base)->_ub
  44 # else                                         /* FreeBSD, MacOS X, Cygwin */
  45 #  define fp_ub fp->_ub
  46 # endif
  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 _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, mingw */
  67 # if defined __sun && defined __sparc && defined _LP64 /* Solaris/SPARC 64-bit */
  68 #  define fp_ ((struct { unsigned char *_ptr; \
  69                          unsigned char *_base; \
  70                          unsigned char *_end; \
  71                          long _cnt; \
  72                        } *) fp)
  73   if (fp_->_ptr == fp_->_base
  74       && (fp_->_ptr == NULL || fp_->_cnt == 0))
  75 # else
  76   if (fp->_ptr == fp->_base
  77       && (fp->_ptr == NULL || fp->_cnt == 0))
  78 # endif
  79 #else
  80   #error "Please port gnulib fseeko.c to your platform! Look at the code in fpurge.c, then report this to bug-gnulib."
  81 #endif
  82     {
  83       off_t pos = lseek (fileno (fp), offset, whence);
  84       if (pos == -1)
  85         {
  86 #if defined __sferror               /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
  87           fp->_flags &= ~__SOFF;
  88 #endif
  89           return -1;
  90         }
  91       else
  92         {
  93 #if defined __sferror               /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
  94           fp->_offset = pos;
  95           fp->_flags |= __SOFF;
  96 #endif
  97           return 0;
  98         }
  99     }
 100   else
 101     return fseeko (fp, offset, whence);
 102 }