On Thu, Feb 12, 2009 at 12:10:58PM +0900, Tetsuo Handa wrote:
> > static inline int open_to_namei_flags(int flag)
> > {
> > if ((flag+1) & O_ACCMODE)
> > flag++;
> > return flag;
> > }
>
> I noticed that open_to_namei_flags() can't yield
> "00 - no permissions needed" output for "11 - special" input.
> To yield "00 - no permissions needed" output for "11 - special" input,
> I think
>
> static inline int open_to_namei_flags(int flag)
> {
> return (flag + 1) & O_ACCMODE;
> }
>
> is needed.
No. Comments are rather misleading; the code is correct.
> sys_open(path, 0) is open for reading.
> sys_open(path, 1) is open for writing.
> sys_open(path, 2) is open for reading and writing.
> What is sys_open(path, 3) for?
open for ioctls only; checks for rw permissions, doesn't allow read or
write calls. Note that the latter is controlled by ->f_mode, which does
*not* come from open_to_namei_flags() (and is calculated as you suggested).
Results of open_to_namei_flags() are used for permission checks, where
3 -> read|write is correct.
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