[PATCH v2] fs: align write return codes with POSIX

[Sascha Hauer]

On Thu, Feb 02, 2023 at 02:27:34PM +0100, Ahmad Fatoum wrote:
> Writing past end of a file results in a cryptic error code:
> 
>   barebox at board:/ cp /dev/zero /dev/mmc0.part
>   write: Operation not permitted
>   cp: Operation not permitted
> 
> Because the cdev's truncate is not implemented and as such partition
> can't be increased in size. POSIX specifies EPERM as the correct return
> code for truncate(2) in such a situation, but for write(2) it is ENOSPC.
> Thus most truncate callbacks in barebox instead return ENOSPC, when
> according to POSIX, EPERM would have been the correct error code to
> propagate.
> 
> Switching all truncate drivers is a bit more involved, so for now let's
> treat EPERM and ENOSPC instead when truncate fails to enlarge a file.
> 
> Reported-by: Marco Felsch <m.felsch at pengutronix.de>
> Reviewed-by: Marco Felsch <m.felsch at pengutronix.de>
> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
> ---
> v1 -> v2:
>   - fix commit message title (s/truncate/write/)
>   - added Marco's Reviewed-by
> ---
>  fs/fs.c | 2 ++
>  1 file changed, 2 insertions(+)

Updated to this version of the patch.

Sascha

> 
> diff --git a/fs/fs.c b/fs/fs.c
> index 752688b574a0..c463466e1be0 100644
> --- a/fs/fs.c
> +++ b/fs/fs.c
> @@ -441,6 +441,8 @@ static ssize_t __write(FILE *f, const void *buf, size_t count)
>  	if (f->size != FILE_SIZE_STREAM && f->pos + count > f->size) {
>  		ret = fsdev_truncate(&f->fsdev->dev, f, f->pos + count);
>  		if (ret) {
> +			if (ret == -EPERM)
> +				ret = -ENOSPC;
>  			if (ret != -ENOSPC)
>  				goto out;
>  			count = f->size - f->pos;
> -- 
> 2.30.2
> 
> 
> 

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