On 06/05/2017 04:38 PM, Eric Blake wrote: > Most callback commands in qemu-io return 0 to keep the interpreter > loop running, or 1 to quit immediately. However, open_f() just > passed through the return value of openfile(), which has different > semantics of returning 0 if a file was opened, or 1 on any failure. > > As a result of mixing the return semantics, we are forcing the > qemu-io interpreter to exit early on any failures, which is rather > annoying when some of the failures are obviously trying to give > the user a hint of how to proceed (if we didn't then kill qemu-io > out from under the user's feet): > > $ qemu-io > qemu-io> open foo > qemu-io> open foo > file open already, try 'help close' > $ echo $? > 0 > > In general, we WANT openfile() to report failures, since it is the > function used in the form 'qemu-io -c "$something" no_such_file' > for performing one or more -c options on a single file, and it is > not worth attempting $something if the file itself cannot be opened. > So the solution is to fix open_f() to always return 0 (when we are > in interactive mode, even failure to open should not end the > session), and save the return value of openfile() for command line > use in main(). > > Note, however, that we do have some qemu-iotests that do 'qemu-io > -c "open file" -c "$something"'; such tests will now proceed to > attempt $something whether or not the open succeeded, the same way > as if the two commands had been attempted in interactive mode. As > such, the expected output for those tests has to be modified. But it > also means that it is now possible to use -c close and have a single > qemu-io command line operate on more than one file even without > using interactive mode. Although the '-c open' action is a subtle > change in behavior, remember that qemu-io is for debugging purposes, > so as long as it serves the needs of qemu-iotests while still being > reasonable for interactive use, it should not be a problem that we > are changing tests to the new behavior. > > This has been awkward since at least as far back as commit > e3aff4f, in 2009. > > Signed-off-by: Eric Blake <ebl...@redhat.com> > Reviewed-by: Fam Zheng <f...@redhat.com>
Reviewed-by: John Snow <js...@redhat.com>
