On 5 January 2016 at 16:20, Eric Auger <eric.au...@linaro.org> wrote: > Hi Peter, > On 12/18/2015 03:36 PM, Peter Maydell wrote: >> On 17 December 2015 at 12:29, Eric Auger <eric.au...@linaro.org> wrote: >>> Current qemu_fdt_getprop exits if the property is not found. It is >>> sometimes needed to read an optional property, in which case we do >>> not wish to exit but simply returns a null value. >>> >>> This patch converts qemu_fdt_getprop to accept an Error **, and existing >>> users are converted to pass &error_fatal. This preserves the existing >>> behaviour. Then to use the API with your optional semantic a null >>> parameter can be conveyed. >>> >>> Signed-off-by: Eric Auger <eric.au...@linaro.org> >>> >>> --- >>> >>> RFC -> v1: >>> - get rid of qemu_fdt_getprop_optional and implement Peter's suggestion >>> that consists in using the error API >> >> This doesn't seem to me like a great way for qemu_fdt_getprop to >> report "property not found", because there's no way for the caller >> to distinguish "property not found" from "function went wrong >> some other way" (since Errors just report human readable strings, >> and in any case you're not distinguishing -FDT_ERR_NOTFOUND >> from any of the other FDT errors). > Not sure I get what you mean here. In case fdt_getprop fails, as long as > the caller provided a lenp != NULL, *lenp contains the error code so > qemu_fdt_getprop's caller can discriminate a -FDT_ERR_NOTFOUND from any > other errors. Do I miss something?
There's no documentation of this behaviour of qemu_fdt_getprop in either this commit message or in a doc comment in the header, so I didn't realise that was your intention. thanks -- PMM
