On Tue, Mar 06, 2018 at 11:47:51AM -0500, John Ferlan wrote:
On 03/05/2018 09:43 AM, Erik Skultety wrote:
When commit 3545cbef moved the sysfs attribute reading logic from _udev.c module to virmdev.c, it had to replace our udev read wrappers with the ones available from virfile.c. The problem is that the original logic worked correctly with udev read wrappers which don't return an error code for a missing attribute, virfile.c readers however - not so much. Therefore add another parameter to the macro, so we can again accept the fact that optional attributes may be missing.
Signed-off-by: Erik Skultety <eskultet@redhat.com> --- src/util/virmdev.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-)
The virFileReadValue* API's return -2 for non existing file, so instead of messing with errno, you should be able to
rc = cb(); if (rc == -2 && optional) rc = 0; if (rc < 0) goto cleanup;
As it seems to be the more common way to use the functions.
Honestly, that was my first approach, but then I told myself that rather than comparing against a "magic" value which in order to understand the caller has to go and read the function being called, so I went for the errno and I liked it more, it's standardized (you don't care what the function does and under what circumstances it returns, you just want the errno), there was less lines of code involved, I can change it if you insist, but I wanted to express my intentions first. Erik