Re: [Qemu-block] [PATCH] qemu-img convert: Deprecate using -n and -o together

[Nir Soffer]

On Fri, Aug 9, 2019 at 12:11 PM Kevin Wolf <address@hidden> wrote:

bdrv_create options specified with -o have no effect when skipping image
creation with -n, so this doesn't make sense. Warn against the misuse
and deprecate the combination so we can make it a hard error later.

Signed-off-by: Kevin Wolf <address@hidden>
---
 qemu-img.c           | 5 +++++
 qemu-deprecated.texi | 7 +++++++
 2 files changed, 12 insertions(+)

diff --git a/qemu-img.c b/qemu-img.c
index 79983772de..d9321f6418 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -2231,6 +2231,11 @@ static int img_convert(int argc, char **argv)
         goto fail_getopt;
     }

+    if (skip_create && options) {
+        warn_report("-o has no effect when skipping image creation");
+        warn_report("This will become an error in future QEMU versions.");
+    }
+
     s.src_num = argc - optind - 1;
     out_filename = s.src_num >= 1 ? argv[argc - 1] : NULL;

diff --git a/qemu-deprecated.texi b/qemu-deprecated.texi
index fff07bb2a3..7673d079c5 100644
--- a/qemu-deprecated.texi
+++ b/qemu-deprecated.texi
@@ -305,6 +305,13 @@ to just export the entire image and then mount only /dev/nbd0p1 than
 it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
 subset of the image.

+@subsection qemu-img convert -n -o (since 4.2.0)
+
+All options specified in @option{-o} are image creation options, so they
+have no effect when used with @option{-n} to skip image creation. This
+combination never made sense and shows that the user misunderstood the
+effect of the options, so this will be made an error in future versions.

The user misunderstood by not reading qemu code? 

Both the online help and the manual page do not mention anything about that, so I think

they should be fixed to explain the behavior, and this text should mention that the behavior

was never documented.

Nir

 

+
 @section Build system

 @subsection Python 2 support (since 4.1.0)
--
2.20.1