gl/fseeko.c

   1 /* An fseeko() 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 General Public License as published by
   6    the Free Software Foundation; either version 2, 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 #undef fseeko
  27 #if !HAVE_FSEEKO
  28 # undef fseek
  29 # define fseeko fseek
  30 #endif
  31
  32 int
  33 rpl_fseeko (FILE *fp, off_t offset, int whence)
  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_ferror_unlocked     /* GNU libc, BeOS */
  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             /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
  47 # if defined __NetBSD__ || defined __OpenBSD__ /* NetBSD, OpenBSD */
  48    /* See <http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup>
  49       and <http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup> */
  50 #  define fp_ub ((struct { struct __sbuf _ub; } *) fp->_ext._base)->_ub
  51 # else                                         /* FreeBSD, MacOS X, Cygwin */
  52 #  define fp_ub fp->_ub
  53 # endif
  54 # if defined __SL64 && defined __SCLE /* Cygwin */
  55   if ((fp->_flags & __SL64) == 0)
  56     {
  57       /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
  58          mode; but has an fseeko that requires 64-bit mode.  */
  59       FILE *tmp = fopen ("/dev/null", "r");
  60       if (!tmp)
  61         return -1;
  62       fp->_flags |= __SL64;
  63       fp->_seek64 = tmp->_seek64;
  64       fclose (tmp);
  65     }
  66 # endif
  67   if (fp->_p == fp->_bf._base
  68       && fp->_r == 0
  69       && fp->_w == ((fp->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
  70                     ? fp->_bf._size
  71                     : 0)
  72       && fp_ub._base == NULL)
  73 #elif defined _IOERR                /* AIX, HP-UX, IRIX, OSF/1, Solaris, mingw */
  74 # if defined __sun && defined _LP64 /* Solaris/{SPARC,AMD64} 64-bit */
  75 #  define fp_ ((struct { unsigned char *_ptr; \
  76                          unsigned char *_base; \
  77                          unsigned char *_end; \
  78                          long _cnt; \
  79                          int _file; \
  80                          unsigned int _flag; \
  81                        } *) fp)
  82   if (fp_->_ptr == fp_->_base
  83       && (fp_->_ptr == NULL || fp_->_cnt == 0))
  84 # else
  85   if (fp->_ptr == fp->_base
  86       && (fp->_ptr == NULL || fp->_cnt == 0))
  87 # endif
  88 #elif defined __UCLIBC__            /* uClibc */
  89   if (((fp->__modeflags & __FLAG_WRITING) == 0
  90        || fp->__bufpos == fp->__bufstart)
  91       && ((fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) == 0
  92           || fp->__bufpos == fp->__bufread))
  93 #else
  94   #error "Please port gnulib fseeko.c to your platform! Look at the code in fpurge.c, then report this to bug-gnulib."
  95 #endif
  96     {
  97       off_t pos = lseek (fileno (fp), offset, whence);
  98       if (pos == -1)
  99         {
 100 #if defined __sferror               /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
 101           fp->_flags &= ~__SOFF;
 102 #endif
 103           return -1;
 104         }
 105       else
 106         {
 107 #if defined __sferror               /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
 108           fp->_offset = pos;
 109           fp->_flags |= __SOFF;
 110 #endif
 111           return 0;
 112         }
 113     }
 114   else
 115     return fseeko (fp, offset, whence);
 116 }