On 02/06/2013 11:32 AM, John Ferlan wrote:
+ + ignore_value(sscanf(entry->d_name, "host%d",&host));
Why ignore_value()? If == -1, then host is undefined - could be something that results in the following being successful..
I don't think it's possible to return -1, as all the entries under SYSFS_FC_HOST_PATH should be "hostN". Entry "." and ".." are already skipped.
sscanf can return -1 for other errors (ENOMEM included) - I would think it's safer to check and fail than assume anything.
sscanf should NEVER be used to parse raw "%d". POSIX says that the result is undefined on integer overflow (sscanf is not required to fail in that case, yet you are not guaranteed if you got MAX_INT, wraparound modulo 2**32, or some other weird behavior). Something like sscanf("%5d") for parsing at most five digits is slightly more tolerable because it prevents you from getting to the overflow situation, although I still think that using sscanf to parse integers is dangerous. And even in the cases where using sscanf is safe (fixed-length parsing not subject to integer overflow), you should NEVER ignore failure, and you should always end with a %n to ensure that you parsed as much as you were expecting to parse. sscanf() is so difficult to correctly use directly that I recommend that we avoid adding any new uses of it into libvirt (I'd like to turn on the 'make syntax-check' rule that forbids *scanf entirely, but we'd have to first convert our existing uses into alternative code). I'd much rather see virStrToLong_i() used here. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org