On Fri, Mar 15, 2013 at 1:52 PM, Michael Roth <mdr...@linux.vnet.ibm.com> wrote:
> On Thu, Mar 14, 2013 at 10:31 PM, Peter Crosthwaite
> <peter.crosthwa...@xilinx.com> wrote:
>> Hi Michael, Anthony,
>>
>> On Tue, Mar 12, 2013 at 10:53 AM, Michael Roth
>> <mdr...@linux.vnet.ibm.com> wrote:
>>> Hosts hold on to handles provided by guest-file-open for periods that can
>>> span beyond the life of the qemu-ga process that issued them. Since these
>>> are issued starting from 0 on every restart, we run the risk of issuing
>>> duplicate handles after restarts/reboots.
>>>
>>> As a result, users with a stale copy of these handles may end up
>>> reading/writing corrupted data due to their existing handles effectively
>>> being re-assigned to an unexpected file or offset.
>>>
>>> We unfortunately do not issue handles as strings, but as integers, so a
>>> solution such as using UUIDs can't be implemented without introducing a
>>> new interface.
>>>
>>> As a workaround, we fix this by implementing a persistent key-value store
>>> that will be used to track the value of the last handle that was issued
>>> across restarts/reboots to avoid issuing duplicates.
>>>
>>> The store is automatically written to the same directory we currently
>>> set via --statedir to track fsfreeze state, and so should be applicable
>>> for stable releases where this flag is supported.
>>>
>>> A follow-up can use this same store for handling fsfreeze state, but
>>> that change is cosmetic and left out for now.
>>>
>>> Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com>
>>> Cc: qemu-sta...@nongnu.org
>>>
>>> * fixed guest_file_handle_add() return value from uint64_t to int64_t
>>> ---
>>> qga/commands-posix.c | 25 +++++--
>>> qga/guest-agent-core.h | 1 +
>>> qga/main.c | 184
>>> ++++++++++++++++++++++++++++++++++++++++++++++++
>>> 3 files changed, 204 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
>>> index 7a0202e..1c2aff3 100644
>>> --- a/qga/commands-posix.c
>>> +++ b/qga/commands-posix.c
>> [snip]
>>> + g_assert(pstate);
>>> + g_assert(keyfile);
>>> + /* if any fields are missing, either because the file was tampered with
>>> + * by agents of chaos, or because the field wasn't present at the time
>>> the
>>> + * file was created, the best we can ever do is start over with the
>>> default
>>> + * values. so load them now, and ignore any errors in accessing
>>> key-value
>>> + * pairs
>>> + */
>>> + set_persistent_state_defaults(pstate);
>>> +
>>> + if (g_key_file_has_key(keyfile, "global", "fd_counter", NULL)) {
>>> + pstate->fd_counter =
>>> + g_key_file_get_int64(keyfile, "global", "fd_counter", NULL);
>>
>> This function (and friends) doesn't exist in glib pre v2.26, breaking
>> the build for a few distros (RHEL 5.6 and Ubuntu 10.04 are two that I
>> am building with). Are we mandating glib > 2.26 as of this series (and
>> should configure be updated) or do we need an alternate implementation
>> of this code?
>
> Sigh...that certainly wasn't the intention, and something I specifically tried
> to avoid doing. GKeyFile was added in 2.6 according to the documentation:
>
> https://developer.gnome.org/glib/2.31/glib-Key-value-file-parser.html
>
> It seems that it may specifically be g_key_file_get_int64() which is
> causing the 2.26 dependency.
>
> Would you mind testing with get_int64/set_int64 swapped out for
> get_integer/set_integer? If that does the trick I can send an updated
> patch tomorrow.
>
That did the trick,
Patch up on list if you want to sign it off or suggested-by it.
Regards,
Peter
>>
>> Regards,
>> peter
>>
>
