Hi,
 if you open file for read-only and want to flush() it, it fails on freebsd5.2.
 It works okay on linux. If file is openned for r/w it works on freebsd.

     
f=file("/etc/passwd","r")
f.read(10)
f.flush()
f.close()

result:
(hsn@ttyv2):~% python snakeoil.py
Traceback (most recent call last):
  File "snakeoil.py", line 3, in ?
      f.flush()
      IOError: [Errno 9] Bad file descriptor

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In C, flushing a file that was opened for read only causes
undefined behaviour. So it is not surprising that systems
behave differently in this respect.

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I have wrote a simple program which calls fsync() on file opened for readonly. Test programs works okay (no error) on both platforms (FreeBSD and Linux). So error is not in FreeBSD5 kernel.

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Can you please also try a program that uses fflush, like the
Python program does:
fopen("/etc/passwd","r");
fread(buf, 10, 1, f);
fflush(f); /* check errno here */
fclose(f);

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fflush() on readonly file fails in freebsd5, because libc checks this case.

This is bug in freebsd libc.  I have submited bug report with patch to freebsd
team.

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As I explained earlier, according to C99, invoking fflush on
a stream opened for read only causes undefined behaviour. So
FreeBSD is conforming to the spec by reporting an error, and
Python follows its documentation and its spirit by passing
that error report to the user.

So closing the report as invalid.