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Date: Fri, 22 Jun 2007 14:50:51 -0500
From: Brian Ford <Brian DOT Ford AT FlightSafety DOT com>
To: newlib AT sources DOT redhat DOT com
cc: cygwin AT cygwin DOT com
Subject: fseek064 calling fflush on Cygwin
Message-ID: <Pine.CYG.4.58.0706221436300.4312@PC1163-8460-XP.flightsafety.com>
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I have an application that is having a 64-bit file I/O problem with Cygwin
1.7.0 CVS that it did not have with Cygwin 1.5.18.  I have tracked it
down to the following series of calls in newlib:

#0  fflush (fp=0x7b5a764)
    at ../../../../../cygwin/newlib/libc/stdio/fflush.c:124
#1  0x611049ff in _fseeko64_r (ptr=0x16cbd008, fp=0x7b5a764,
    offset=27368291304, whence=0)
    at ../../../../../cygwin/newlib/libc/stdio64/fseeko64.c:326
#2  0x61104edf in fseeko64 (fp=0x7b5a764, offset=27368291304, whence=0)
    at ../../../../../cygwin/newlib/libc/stdio64/fseeko64.c:350

(gdb) l 110
105              to make the change simpler, more contained, and less
likely
106              to miss a code scenario.  */
107           if ((fp->_r > 0 || fp->_ur > 0) && (seekfn = fp->_seek) !=
NULL)
108             {
109               _fpos_t curoff;
110
111               /* Get the physical position we are at in the file.  */
112               if (fp->_flags & __SOFF)
113                 curoff = fp->_offset;
114               else
115                 {
116                   /* We don't know current physical offset, so ask for
it.  */
117                   curoff = (*seekfn) (fp->_cookie, (_fpos_t) 0, SEEK_CUR);
118                   if (curoff == -1L)
119                     {
120                       _funlockfile (fp);
121                       return 0;
122                     }
123                 }
124               if (fp->_flags & __SRD)

(gdb) p/x fp->_offset
$12 = 0x65f468000
(gdb) ptype fp->_offset
type = long long int

(gdb) p/x curoff
$13 = 0x5f468000
(gdb) ptype curoff
type = long int

So, it would seem that fflush is not 64 bit safe and fseeko64 should not
be calling it, but I'm not sure how to fix it.

Any suggestions?

-- 
Brian Ford
Lead Realtime Software Engineer
VITAL - Visual Simulation Systems
FlightSafety International
the best safety device in any aircraft is a well-trained crew...

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