Re: [Qemu-devel] [PATCH] replace O_SYNC with O_FSYNC

[Christoph Hellwig <hch@lst.de>]

On Fri, Jun 19, 2009 at 10:22:07PM -0400, m a wrote:
> This patch replaces O_SYNC with O_FSYNC. These two flags do the same 
> thing, but only O_FSYNC is available in Mac OS 10.3 and under. It only 
> replaces O_SYNC if it doesn't exist. This patch allows the file 
> block-raw-posix.c to compile on Mac OS 10.3. This is my first time 
> submitting a patch, so there might have been a few mistakes made.

But O_SYNC is a standard posix flag, while O_FSYNC appears to be
a BSD extension.  Also the actual code uses O_DSYNC anyway, which
also is in Posix but not actually natively supported by some OSes,
e.g. Linux (but still provided in libc there).


> --- block-raw-posix.c	Wed May 20 16:46:58 2009
> +++ block-raw-posix (updated).c	Fri Jun 19 22:01:07 2009
> @@ -73,6 +73,12 @@
> 
> +// O_SYNC isn't available on Mac OS 10.3 and under
> +// O_SYNC and O_FSYNC do the same thing
> +#ifndef O_SYNC
> +#define O_SYNC O_FSYNC
> +#endif
> +
>  /* OS X does not have O_DSYNC */
>  #ifndef O_DSYNC
>  #define O_DSYNC O_SYNC

So if the code here is correct and Darwin is the only supported OS where
O_DSYNC is missing we could just replace the O_SYNC in the last line
with O_FSYNC.