Re: First cut at git port to Cygwin

From: H. Peter Anvin <hpa@zytor.com>
Date: Oct 10, 2005, 19:26 UTC
Message-ID: <434AC058.60803@zytor.com>
In-Reply-To: <Pine.LNX.4.63.0510102100010.7688@wbgn013.biozentrum.uni-wuerzburg.de>

Johannes Schindelin wrote:

Show 13 quoted lines

> 
>>Junio C Hamano wrote:
>>
>>>PROT_WRITE is true, but we do MAP_PRIVATE, and if I recall
>>>correctly we do not write file via mmap -- at least we do not
>>>intend to.
>>>
>>
>>Then PROT_READ probably makes more sense?
> 
> Not necessarily. Sometimes you need to annotate the data from the index, 
> and this does not need to be written back to the index file.
>

In the above sentence, emphasis on "at least we do not intend to." If writes are done legitimately then that's fine, but we shouldn't have "accidental writes" -- those would be program bugs!

Show 8 quoted lines

> 
>>>Yes.  It might have been overkill that you supported writing
>>>changes back, though.
>>
>>Not just overkill; if we do MAP_PRIVATE it's actively WRONG.
> 
> See above.
>

Eh? If we MAP_PRIVATE, *and* we (intentionally) write to it, we *BETTER* not write anything back.

	-hpa