Re: [PATCH] manual: Clarify File Access Modes section and add O_PATH

[Florian Weimer via Libc-alpha <libc-alpha@sourceware.org>]

* Michael Kerrisk:

>> +mode.  Usually, The mode will be @code{O_RDONLY}, @code{O_WRONLY}, or
>> +@code{O_RDWR}.
>> +@end deftypevr
>> +
>> +If the mode is zero, it means that a non-standard access mode has been
>> +used.
>
> Either I misunderstand the previous sentence, or I think it is
> wrong. O_RDONLY has the value 0; that's a standard access mode.

Meh, I had forgotten about that.  That makes the interaction of
O_ACCMODE and non-POSIX access modes certainly more complicated.

I'll have to think about it.

>>  @code{O_WRONLY} are independent bits that can be bitwise-ORed together,
>>  and it is valid for either bit to be set or clear.  This means that
>> @@ -3591,40 +3626,21 @@ mode of zero is permissible; it allows no operations that do input or
>>  output to the file, but does allow other operations such as
>>  @code{fchmod}.  On @gnuhurdsystems{}, since ``read-only'' or ``write-only''
>>  is a misnomer, @file{fcntl.h} defines additional names for the file
>> -access modes.  These names are preferred when writing GNU-specific code.
>> -But most programs will want to be portable to other POSIX.1 systems and
>> -should use the POSIX.1 names above instead.
>> +access modes.
>
> I do think removing this advice about POSIX is a bad move.
> Why do you want to advise people to use GNU-specific names?
> (I suspect I must be missing something...)

“GNU-specific code” is ambiguous.  We sometimes talk about the
platform-independent GNU API, meaning the API that glibc provides on all
ports.  But here, “GNU-specific” really means “Hurd-specific”.

Thanks,
Florian