> > > > > are correct; an "r+m" file is read() not mmaped.
> > > >
> > > > Have you written a test program that verifies (presumably via
> > > > monitoring via 'strace') how 'm' changes the behaviour of stdio
> > > > with respect to the use of mmap()?
> > > Erm, yes, thats what I'm talking about (and is strace exactly what I
> > > did). But I'm not sure if I understand you .. I verified that all 3
> > > routines mmap() a file if "m" is given (and it is read-only), and do
> > > not mmap() it if "m" is not given (or if it is not read-only).
> > >
> > > I include now the test program :)
> >
> > Yes, but did you verify:
> >
> > -- which file is being mmap()ed? (There might be many other
> > unrelated mmap() calls going on.)
> Yes; note that it only happens after you fread() for the first time.
>
> > -- whether the behaviour changes if 'm' is removed from the fopen()?
> > (the strace output shd be different).
> Yes:
> > > routines mmap() a file if "m" is given (and it is read-only), and do
> > > not mmap() it if "m" is not given (or if it is not read-only).
Hmmm -- I'm not seeing this. Can you post for each of the two
test cases:
-- the fopen() call that is used.
-- the command line that is used to run the program.
-- the results of grep the strace output using:
egrep '(mmap|open|read)'
Thanks,
Michael
--
Michael Kerrisk
maintainer of Linux man pages Sections 2, 3, 4, 5, and 7
Want to help with man page maintenance?
Grab the latest tarball at
ftp://ftp.win.tue.nl/pub/linux-local/manpages/,
read the HOWTOHELP file and grep the source
files for 'FIXME'.
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