Jeff Johnston jjohnstn@redhat.com
Tue Jan 22 00:25:00 GMT 2008

Neal H. Walfield wrote:
> At Mon, 21 Jan 2008 12:12:23 -0500,
> Jeff Johnston wrote:
>> The code that uses HAVE_DD_LOCK in libc/posix was taken from an existing 
>> code base (IIRC FreeBSD).
>> The code in libc/posix is offered optionally to platforms.  The dir 
>> family routines code there can be ignored if the platform already 
>> supplies these functions (via the flag HAVE_OPENDIR).  If not 
>> short-circuited via HAVE_OPENDIR, a port must implement sys/dirent.h or 
>> else the code will not build to begin with as you are probably already 
>> well-aware.  A platform can also build these and also override them in 
>> either the libc/machine/xxx or libc/sys/xxxx directories.
>> So, if you choose to build the functions in libc/posix for your platform 
>> and you do not short-circuit them with HAVE_OPENDIR and do not override 
>> them yourself in your libc/sys directory and you support 
>> multi-threading, then you had either better implement the dd_lock field 
>> and set HAVE_DD_LOCK or else document that those functions are not 
>> thread-safe.
> Does that mean you agree that !__SINGLE_THREAD__ implies HAVE_DD_LOCK?
> (A simple fix would be s/HAVE_DD_LOCK/!__SINGLE_THREAD__/g.)

It doesn't have to, but it is unlikely any platform would override and 
not specify HAVE_OPENDIR.  So, sure.

-- Jeff J.

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