Re: [Qemu-block] ping [PATCH v14] block/raw-posix.c: Make physical devices usable in QEMU under Mac OS X host

[Kevin Wolf]

Am 02.03.2016 um 17:39 hat Programmingkid geschrieben:
> 
> On Mar 2, 2016, at 4:02 AM, Kevin Wolf wrote:
> 
> > Am 02.03.2016 um 04:32 hat Programmingkid geschrieben:
> >> 
> >> On Mar 1, 2016, at 10:16 AM, Kevin Wolf wrote:
> >> 
> >>> Am 29.02.2016 um 16:17 hat Programmingkid geschrieben:
> >>>> I do think this patch is ready to be added to QEMU. I have listened to 
> >>>> what you said and implemented your changes. 
> >>>> 
> >>>> https://patchwork.ozlabs.org/patch/579325/
> >>>> 
> >>>> Mac OS X can be picky when it comes to allowing the user
> >>>> to use physical devices in QEMU. Most mounted volumes
> >>>> appear to be off limits to QEMU. If an issue is detected,
> >>>> a message is displayed showing the user how to unmount a
> >>>> volume. Now QEMU uses both CD and DVD media.
> >>>> 
> >>>> Signed-off-by: John Arbuckle <address@hidden>
> >>>> 
> >>>> ---
> >>>> Changed filename variable to const char * type.
> >>>> Removed snprintf call for filename variable.
> >>>> filename is set to bsd_path if using a physical device that isn't a DVD 
> >>>> or CD.
> >>> 
> >>>> @@ -2112,33 +2166,57 @@ static int hdev_open(BlockDriverState *bs, QDict 
> >>>> *options, int flags,
> >>>> 
> >>>> #if defined(__APPLE__) && defined(__MACH__)
> >>>>    const char *filename = qdict_get_str(options, "filename");
> >>>> +    char bsd_path[MAXPATHLEN] = "";
> >>>> +    bool error_occurred = false;
> >>>> +    
> >>> 
> >>> This line adds trailing whitespace.
> >>> 
> >>>> @@ -2147,7 +2225,16 @@ static int hdev_open(BlockDriverState *bs, QDict 
> >>>> *options, int flags,
> >>>>        if (local_err) {
> >>>>            error_propagate(errp, local_err);
> >>>>        }
> >>>> -        return ret;
> >>>> +#if defined(__APPLE__) && defined(__MACH__)
> >>>> +        if (*bsd_path) {
> >>>> +            filename = bsd_path;
> >>>> +        }
> >>>> +        /* if a physical device experienced an error while being opened 
> >>>> */
> >>>> +        if (strncmp(filename, "/dev/", 5) == 0) {
> >>>> +            print_unmounting_directions(filename);
> >>>> +            return -1;
> >>> 
> >>> Please use a negative errno number instead of -1.
> >> 
> >> Is this ok:
> >>    return -EPERM;
> >> 
> >> According to http://man7.org/linux/man-pages/man3/errno.3.html, it means 
> >> "operation not permitted".
> > 
> > Well, to be honest I don't understand why there is a different error
> > code here to begin with. Maybe when you add the "return ret" back after
> > the #endif you can just leave out this line and return the real error
> > code this way.
> 
> I like this idea more.
> 
> > 
> > If for some reason (that I fail to understand) ret doesn't contain an
> > appropriate error code in this case, though, you can return a constant.
> > If it's related to permissions, -EPERM is okay, otherwise it's probably
> > not. I don't see a connection between paths starting with /dev/ and
> > there being a permission problem.
> 
> I have placed "return ret;" right after the #endif and removed the "return 
> -1" in the if condition because it is now redundant. Does this look right:
> 
>     if (ret < 0) {
>         if (local_err) {
>             error_propagate(errp, local_err);
>         }
> #if defined(__APPLE__) && defined(__MACH__)
>         if (*bsd_path) {
>             filename = bsd_path;
>         }
>         /* if a physical device experienced an error while being opened */
>         if (strncmp(filename, "/dev/", 5) == 0) {
>             print_unmounting_directions(filename);
>         }
> #endif /* defined(__APPLE__) && defined(__MACH__) */
>         return ret;
>     }

Looks right to me.

Kevin