Peter Xu <pet...@redhat.com> writes: > There're a lot of cases where we only have an errno set in last_error but > without a detailed error description. When this happens, try to generate > an error contains the errno as a descriptive error. > > This will be helpful in cases where one relies on the Error*. E.g., > migration state only caches Error* in MigrationState.error. With this, > we'll display correct error messages in e.g. query-migrate when the error > was only set by qemu_file_set_error(). > > Signed-off-by: Peter Xu <pet...@redhat.com> > --- > migration/qemu-file.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/migration/qemu-file.c b/migration/qemu-file.c > index acc282654a..419b4092e7 100644 > --- a/migration/qemu-file.c > +++ b/migration/qemu-file.c > @@ -156,15 +156,24 @@ void qemu_file_set_hooks(QEMUFile *f, const > QEMUFileHooks *hooks) > * > * Return negative error value if there has been an error on previous > * operations, return 0 if no error happened. > - * Optional, it returns Error* in errp, but it may be NULL even if return > value > - * is not 0. > * > + * If errp is specified, a verbose error message will be copied over. > */ > int qemu_file_get_error_obj(QEMUFile *f, Error **errp) > { > + if (!f->last_error) { > + return 0; > + } > + > + /* There is an error */ > if (errp) { > - *errp = f->last_error_obj ? error_copy(f->last_error_obj) : NULL; > + if (f->last_error_obj) { > + *errp = error_copy(f->last_error_obj); > + } else { > + error_setg_errno(errp, -f->last_error, "Channel error");
There are a couple of places that do: ret = vmstate_save(f, se, ms->vmdesc); if (ret) { qemu_file_set_error(f, ret); break; } and vmstate_save() can return > 0 on error. This would make this message say "Unknown error". This is minor. But take a look at qemu_fclose(). It can return f->last_error while the function documentation says it should return negative on error. Should we make qemu_file_set_error() check 'ret' and always set a negative value for f->last_error?