Re: [PATCH] Fix checkout of large files to network shares under Windows XP

From: Albert Dvornik <dvornik+git@gmail.com>
Date: Apr 19, 2010, 22:46 UTC
Message-ID: <z2l9f74dc2c1004191546n5562759an54342e3efdaa9539@mail.gmail.com>
In-Reply-To: <4BCCC05E.4030206@lsrfire.ath.cx>

On Mon, Apr 19, 2010 at 4:43 PM, René Scharfe
<rene.scharfe@lsrfire.ath.cx> wrote:
  [...]

Show 8 quoted lines

>> +                     if (total + size > count)
>> +                             size = count - total;
>> +             }
>> +     }
>
> Shouldn't the loop be left in the successful case, too?  write(2) is
> allowed to write less than requested, so the caller already needs to
> deal with that case anyway.

That's what I thought initially, since the code would be cleaner, but I don't like the fact that you could actually end up making a lot more failed write() calls that way, since you restart the size search on each call to mingw_write().

For example, suppose you were calling mingw_write() with a count that was exactly 11.5 times bigger than whatever maximum size write() was willing to accept. If you only did one write() per mingw_write(), letting the caller restart, this will result in 47 failed writes and 16 successes. Letting mingw_write() do the restart (as in the existing code) will end up with 4 failed writes and 16 successes. Now, I assume (wait, this is Windows-- I'd *like to hope*) that a failed write() is a lot cheaper than a successful one, but this still rubs me the wrong way.

Of course, if we know (or can guess) the maximum size write() will take, that would be best.

--bert