Re: [libvirt] [PATCH 00/21] tests: qemuxml2argv: support optional arguments

On 3/14/19 9:43 AM, Cole Robinson wrote: > Right now in qemuxml2argv we have a proliferation of DO_*TEST* macros. > They essentially fill in data in the testInfo struct and invoke the > test function. > > There's several bits of data that we want to specify for a small > subset of tests: flags, parseFlags, migrateFrom/migrateFd, gic. The > base macros need to handle these in their argument lists, and we > provide many convenience macros that fill in default values for the > less common parameters. Any time we want to add a new bit of data > though, the base macros are extended, and every caller of those > needs to be adjusted, and we are faced with the question of whether > to extend the combinatorial explosion of convenience macros which > have only a subset of options exposed. > > This series adds a testInfoSetArgs which uses va_args to make these > mandatory parameters optional. The general format is: > > DO_TEST_FULL(... > ARG_FOO, foovalue, > ARG_BAR, barvalue, ...) > > Specifically, one of the migrate tests went from: > > DO_TEST_FULL("restore-v2", "exec:cat", 7, 0, 0, GIC_NONE, NONE); > > to: > > DO_TEST_FULL("restore-v2", > ARG_MIGRATE_FROM, "exec:cat", > ARG_MIGRATE_FD, 7, > ARG_QEMU_CAPS, NONE); Umm, what's your sentinel value here? It is undefined behavior to call va_arg more times than there are arguments present, but without some sort of sentinel, you don't know when to stop calling va_arg. The overall idea is nice, but I think you need an ARG_END sentinel.