[Qemu-devel] [PATCH 0/3] qemu-io/img: Fix -U/force-share conflict testing

[Qemu-devel] [PATCH 0/3] qemu-io/img: Fix -U/force-share conflict testing

[Max Reitz]

qemu-img and qemu-io try to detect when you use both -U and force-share
manually, but a conflict is not rejected with an error message but with
a segmentation fault.  I guess that works, but it's probably not the way
it was meant to be.


Max Reitz (3):
  qemu-io: Use purely string blockdev options
  qemu-img: Use only string options in img_open_opts
  iotests: Add test for -U/force-share conflicts

 qemu-img.c                 |  4 ++--
 qemu-io.c                  |  4 ++--
 tests/qemu-iotests/153     | 17 +++++++++++++++++
 tests/qemu-iotests/153.out | 16 ++++++++++++++++
 4 files changed, 37 insertions(+), 4 deletions(-)

-- 
2.14.3

[Qemu-devel] [PATCH 1/3] qemu-io: Use purely string blockdev options

[Max Reitz]

Currently, qemu-io only uses string-valued blockdev options (as all are
converted directly from QemuOpts) -- with one exception: -U adds the
force-share option as a boolean.  This in itself is already a bit
questionable, but a real issue is that it also assumes the value already
existing in the options QDict would be a boolean, which is wrong.

That has the following effect:

$ ./qemu-io -r -U --image-opts \
    driver=file,filename=/dev/null,force-share=off
[1]    15200 segmentation fault (core dumped)  ./qemu-io -r -U
--image-opts driver=file,filename=/dev/null,force-share=off

Since @opts is converted from QemuOpts, the value must be a string, and
we have to compare it as such.  Consequently, it makes sense to also set
it as a string instead of a boolean.

Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 qemu-io.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/qemu-io.c b/qemu-io.c
index e692c555e0..0755a30447 100644
--- a/qemu-io.c
+++ b/qemu-io.c
@@ -95,12 +95,12 @@ static int openfile(char *name, int flags, bool writethrough, bool force_share,
             opts = qdict_new();
         }
         if (qdict_haskey(opts, BDRV_OPT_FORCE_SHARE)
-            && !qdict_get_bool(opts, BDRV_OPT_FORCE_SHARE)) {
+            && strcmp(qdict_get_str(opts, BDRV_OPT_FORCE_SHARE), "on")) {
             error_report("-U conflicts with image options");
             QDECREF(opts);
             return 1;
         }
-        qdict_put_bool(opts, BDRV_OPT_FORCE_SHARE, true);
+        qdict_put_str(opts, BDRV_OPT_FORCE_SHARE, "on");
     }
     qemuio_blk = blk_new_open(name, NULL, opts, flags, &local_err);
     if (!qemuio_blk) {
-- 
2.14.3

[Qemu-devel] [PATCH 2/3] qemu-img: Use only string options in img_open_opts

[Max Reitz]

img_open_opts() takes a QemuOpts and converts them to a QDict, so all
values therein are strings.  Then it may try to call qdict_get_bool(),
however, which will fail with a segmentation fault every time:

$ ./qemu-img info -U --image-opts \
    driver=file,filename=/dev/null,force-share=off
[1]    27869 segmentation fault (core dumped)  ./qemu-img info -U
--image-opts driver=file,filename=/dev/null,force-share=off

Fix this by using qdict_get_str() and comparing the value as a string.
Also, when adding a force-share value to the QDict, add it as a string
so it fits the rest of the dict.

Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 qemu-img.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/qemu-img.c b/qemu-img.c
index 855fa52514..42b60917b0 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -277,12 +277,12 @@ static BlockBackend *img_open_opts(const char *optstr,
     options = qemu_opts_to_qdict(opts, NULL);
     if (force_share) {
         if (qdict_haskey(options, BDRV_OPT_FORCE_SHARE)
-            && !qdict_get_bool(options, BDRV_OPT_FORCE_SHARE)) {
+            && strcmp(qdict_get_str(options, BDRV_OPT_FORCE_SHARE), "on")) {
             error_report("--force-share/-U conflicts with image options");
             QDECREF(options);
             return NULL;
         }
-        qdict_put_bool(options, BDRV_OPT_FORCE_SHARE, true);
+        qdict_put_str(options, BDRV_OPT_FORCE_SHARE, "on");
     }
     blk = blk_new_open(NULL, NULL, options, flags, &local_err);
     if (!blk) {
-- 
2.14.3

[Qemu-devel] [PATCH 3/3] iotests: Add test for -U/force-share conflicts

[Max Reitz]

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 tests/qemu-iotests/153     | 17 +++++++++++++++++
 tests/qemu-iotests/153.out | 16 ++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/tests/qemu-iotests/153 b/tests/qemu-iotests/153
index a0fd815483..ec508c758f 100755
--- a/tests/qemu-iotests/153
+++ b/tests/qemu-iotests/153
@@ -242,6 +242,23 @@ _run_cmd $QEMU_IO "${TEST_IMG}" -c 'write 0 512'
 
 _cleanup_qemu
 
+echo
+echo "== Detecting -U and force-share conflicts =="
+
+echo
+echo 'No conflict:'
+$QEMU_IMG info -U --image-opts driver=null-co,force-share=on
+echo
+echo 'Conflict:'
+$QEMU_IMG info -U --image-opts driver=null-co,force-share=off
+
+echo
+echo 'No conflict:'
+$QEMU_IO -c 'open -r -U -o driver=null-co,force-share=on'
+echo
+echo 'Conflict:'
+$QEMU_IO -c 'open -r -U -o driver=null-co,force-share=off'
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/153.out b/tests/qemu-iotests/153.out
index bb721cb747..2510762ba1 100644
--- a/tests/qemu-iotests/153.out
+++ b/tests/qemu-iotests/153.out
@@ -399,4 +399,20 @@ Is another process using the image?
 Closing the other
 
 _qemu_io_wrapper TEST_DIR/t.qcow2 -c write 0 512
+
+== Detecting -U and force-share conflicts ==
+
+No conflict:
+image: null-co://
+file format: null-co
+virtual size: 1.0G (1073741824 bytes)
+disk size: unavailable
+
+Conflict:
+qemu-img: --force-share/-U conflicts with image options
+
+No conflict:
+
+Conflict:
+-U conflicts with image options
 *** done
-- 
2.14.3

Re: [Qemu-devel] [PATCH 1/3] qemu-io: Use purely string blockdev options

[Eric Blake]

On 05/02/2018 03:20 PM, Max Reitz wrote:
> Currently, qemu-io only uses string-valued blockdev options (as all are
> converted directly from QemuOpts) -- with one exception: -U adds the
> force-share option as a boolean.  This in itself is already a bit
> questionable, but a real issue is that it also assumes the value already
> existing in the options QDict would be a boolean, which is wrong.
> 
> That has the following effect:
> 
> $ ./qemu-io -r -U --image-opts \
>      driver=file,filename=/dev/null,force-share=off
> [1]    15200 segmentation fault (core dumped)  ./qemu-io -r -U
> --image-opts driver=file,filename=/dev/null,force-share=off
> 
> Since @opts is converted from QemuOpts, the value must be a string, and
> we have to compare it as such.  Consequently, it makes sense to also set
> it as a string instead of a boolean.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   qemu-io.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 

The curse of poor typing in QemuOpts keeps on giving ;)
Adding Markus, so he's aware of yet another wart that his command-line 
cleanups may need to visit.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Re: [Qemu-devel] [PATCH 2/3] qemu-img: Use only string options in img_open_opts

[Eric Blake]

On 05/02/2018 03:20 PM, Max Reitz wrote:
> img_open_opts() takes a QemuOpts and converts them to a QDict, so all
> values therein are strings.  Then it may try to call qdict_get_bool(),
> however, which will fail with a segmentation fault every time:

I have no idea if it's worth fixing qdict_get_bool() to at least not 
segfault when called on a non-bool Dict member (but what should it 
return, true or false? or should it abort() for at least a cleaner 
failure than a segfault?)

But in the meantime, your fix is correct.

> 
> $ ./qemu-img info -U --image-opts \
>      driver=file,filename=/dev/null,force-share=off
> [1]    27869 segmentation fault (core dumped)  ./qemu-img info -U
> --image-opts driver=file,filename=/dev/null,force-share=off
> 
> Fix this by using qdict_get_str() and comparing the value as a string.
> Also, when adding a force-share value to the QDict, add it as a string
> so it fits the rest of the dict.
> 
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   qemu-img.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Re: [Qemu-devel] [PATCH 3/3] iotests: Add test for -U/force-share conflicts

[Eric Blake]

On 05/02/2018 03:20 PM, Max Reitz wrote:
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>   tests/qemu-iotests/153     | 17 +++++++++++++++++
>   tests/qemu-iotests/153.out | 16 ++++++++++++++++
>   2 files changed, 33 insertions(+)
> 

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

Re: [Qemu-devel] [PATCH 2/3] qemu-img: Use only string options in img_open_opts

[Max Reitz]

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On 2018-05-03 00:00, Eric Blake wrote:
> On 05/02/2018 03:20 PM, Max Reitz wrote:
>> img_open_opts() takes a QemuOpts and converts them to a QDict, so all
>> values therein are strings.  Then it may try to call qdict_get_bool(),
>> however, which will fail with a segmentation fault every time:
> 
> I have no idea if it's worth fixing qdict_get_bool() to at least not
> segfault when called on a non-bool Dict member (but what should it
> return, true or false? or should it abort() for at least a cleaner
> failure than a segfault?)

There's qdict_get_try_bool() which returns a default.  For testing
whether the member is a bool I suppose you can use
qdict_to(QBool, qdict_get(qdict, member)).

Max

> But in the meantime, your fix is correct.
> 
>>
>> $ ./qemu-img info -U --image-opts \
>>      driver=file,filename=/dev/null,force-share=off
>> [1]    27869 segmentation fault (core dumped)  ./qemu-img info -U
>> --image-opts driver=file,filename=/dev/null,force-share=off
>>
>> Fix this by using qdict_get_str() and comparing the value as a string.
>> Also, when adding a force-share value to the QDict, add it as a string
>> so it fits the rest of the dict.
>>
>> Cc: qemu-stable@nongnu.org
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>   qemu-img.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
> 
> Reviewed-by: Eric Blake <eblake@redhat.com>
> 



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Re: [Qemu-devel] [PATCH 0/3] qemu-io/img: Fix -U/force-share conflict testing

[Max Reitz]

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On 2018-05-02 22:20, Max Reitz wrote:
> qemu-img and qemu-io try to detect when you use both -U and force-share
> manually, but a conflict is not rejected with an error message but with
> a segmentation fault.  I guess that works, but it's probably not the way
> it was meant to be.
> 
> 
> Max Reitz (3):
>   qemu-io: Use purely string blockdev options
>   qemu-img: Use only string options in img_open_opts
>   iotests: Add test for -U/force-share conflicts
> 
>  qemu-img.c                 |  4 ++--
>  qemu-io.c                  |  4 ++--
>  tests/qemu-iotests/153     | 17 +++++++++++++++++
>  tests/qemu-iotests/153.out | 16 ++++++++++++++++
>  4 files changed, 37 insertions(+), 4 deletions(-)

Thanks for the review, applied to my block branch.

Max


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