Re: [PATCH] tools: iio: avoid returning error when channel does not have an offset

[Jonathan Cameron <jic23@kernel.org>]

On 30/10/15 13:11, Ioana Ciornei wrote:
> This patch avoids getting an error and aborting when a channel does not have a
> specific parameter like 'offset' and the file associated with it is not present.
> When none of the files from the device folder does not matches the desired channel's
> param function iioutils_get_param_float should return 0.
> 
> This change is safe previous to calling the function the parameters are set to
> their defaults, 0 in case of 'offset'
> 
> Signed-off-by: Ioana Ciornei <ciorneiioana@gmail.com>
This is rather fixing it in the wrong place.  This function is specifically getting
the parameter. If it is not there, then the function should return that fact.
It's the caller that should know whether the parameter is optional.

For example, build_channel_array explicitly catches the -ENOENT error and allows
for that case.

Perhaps we need to improve the documentation to make it clear that this is
the expected behaviour?

> ---
> not tested
> 
>  tools/iio/iio_utils.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/iio/iio_utils.c b/tools/iio/iio_utils.c
> index 5eb6793..cbaf696 100644
> --- a/tools/iio/iio_utils.c
> +++ b/tools/iio/iio_utils.c
> @@ -241,7 +241,7 @@ int iioutils_get_param_float(float *output, const char *param_name,
>  		goto error_free_builtname_generic;
>  	}
>  
> -	ret = -ENOENT;
> +	ret = 0;
>  	while (ent = readdir(dp), ent)
>  		if ((strcmp(builtname, ent->d_name) == 0) ||
>  		    (strcmp(builtname_generic, ent->d_name) == 0)) {
>