The only users of print_block_option_help() are qemu-img create and qemu-img convert for the output image, so this function is always used for image creation (it used to be used for amendment also, but that is no longer the case).
So if image creation is not supported by either the format or the protocol, there is no need to print any option description, because the user cannot create an image like this anyway. This also fixes an assertion failure: $ qemu-img create -f bochs -o help Supported options: qemu-img: util/qemu-option.c:219: qemu_opts_print_help: Assertion `list' failed. [1] 24831 abort (core dumped) qemu-img create -f bochs -o help Signed-off-by: Max Reitz <mre...@redhat.com> Reviewed-by: John Snow <js...@redhat.com> Reviewed-by: Eric Blake <ebl...@redhat.com> --- qemu-img.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/qemu-img.c b/qemu-img.c index a1ae718a52..81ad1e040c 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -250,6 +250,11 @@ static int print_block_option_help(const char *filename, const char *fmt) return 1; } + if (!drv->create_opts) { + error_report("Format driver '%s' does not support image creation", fmt); + return 1; + } + create_opts = qemu_opts_append(create_opts, drv->create_opts); if (filename) { proto_drv = bdrv_find_protocol(filename, true, &local_err); @@ -258,6 +263,11 @@ static int print_block_option_help(const char *filename, const char *fmt) qemu_opts_free(create_opts); return 1; } + if (!proto_drv->create_opts) { + error_report("Protocal driver '%s' does not support image creation", + proto_drv->format_name); + return 1; + } create_opts = qemu_opts_append(create_opts, proto_drv->create_opts); } -- 2.14.3