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    SubjectRe: Bug in open() function (?)
    	While I'm sure I don't have a grasp of "the big picture", I would have 
    imagines these would have acted like a mask against the file system
    attributes. In effect setting O_RDONLY would clear the write permission bits
    read by stat(), and O_WRONLY would clear the read permission bits. O_RDONLY
    + O_WRONLY (O_RDWR) would leave the permissions alone. These would be
    applied somewhere around the may_open() call in fs/open_namei.c

    A poor mans umaks(), I guess.


    On Saturday 12 July 2003 01:11 am, wrote:
    > On Fri, 11 Jul 2003 20:38:09 PDT, Andrew Morton said:
    > > "J.C. Wren" <> wrote:
    > > > I was playing around today and found that if an existing file is opened
    > > > wit
    > h
    > > > O_TRUNC | O_RDONLY, the existing file is truncated.
    > >
    > > Well that's fairly idiotic, isn't it?
    > Not idiotic at all, and even if it was, it's still contrary to specific
    > language in the manpage.
    > I could *easily* see some program having a line of code:
    > if (do_ro_testing) openflags |= O_RDONLY;
    > I'd not be surprised if J.C. was playing around because a file unexpectedly
    > shrank to zero size because of code like this. There's a LOT of programs
    > that implement some sort of "don't really do it" option, from "/bin/bash
    > -n" to "cdrecord -dummy". So you do something like the above to make your
    > file R/O - and O_TRUNC *STILL* zaps the file, in *direct violation* of the
    > language in the manpage.
    > Whoops. Ouch. Where's the backup tapes?
    > > The Open Group go on to say "The result of using O_TRUNC with O_RDONLY is
    > > undefined" which is also rather silly.
    > >
    > > I'd be inclined to leave it as-is, really.
    > I hate to think how many programmers are relying on the *documented*
    > behavior to prevent data loss during debugging/test runs....
    > /Valdis

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