* [PATCH] migration: Silence compiler warning in global_state_store_running()
@ 2020-09-16 17:19 Thomas Huth
2020-09-16 17:42 ` Eric Blake
2020-09-17 6:30 ` Thomas Huth
0 siblings, 2 replies; 5+ messages in thread
From: Thomas Huth @ 2020-09-16 17:19 UTC (permalink / raw)
To: Juan Quintela, Dr. David Alan Gilbert, qemu-devel
Cc: qemu-trivial, Marc-André Lureau, Richard Henderson,
Paolo Bonzini
GCC 9.3.0 on Ubuntu complains:
In file included from /usr/include/string.h:495,
from /home/travis/build/huth/qemu/include/qemu/osdep.h:87,
from ../migration/global_state.c:13:
In function ‘strncpy’,
inlined from ‘global_state_store_running’ at ../migration/global_state.c:47:5:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound 100 equals destination size [-Werror=stringop-truncation]
106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
... but we apparently really want to do the strncpy here. Silence the
warning with QEMU_NONSTRING.
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
migration/global_state.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/migration/global_state.c b/migration/global_state.c
index 25311479a4..f1355d7d97 100644
--- a/migration/global_state.c
+++ b/migration/global_state.c
@@ -43,9 +43,9 @@ int global_state_store(void)
void global_state_store_running(void)
{
const char *state = RunState_str(RUN_STATE_RUNNING);
+ QEMU_NONSTRING char *dest = (char *)global_state.runstate;
assert(strlen(state) < sizeof(global_state.runstate));
- strncpy((char *)global_state.runstate,
- state, sizeof(global_state.runstate));
+ strncpy(dest, state, sizeof(global_state.runstate));
}
bool global_state_received(void)
--
2.18.2
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH] migration: Silence compiler warning in global_state_store_running()
2020-09-16 17:19 [PATCH] migration: Silence compiler warning in global_state_store_running() Thomas Huth
@ 2020-09-16 17:42 ` Eric Blake
2020-09-17 6:30 ` Thomas Huth
1 sibling, 0 replies; 5+ messages in thread
From: Eric Blake @ 2020-09-16 17:42 UTC (permalink / raw)
To: Thomas Huth, Juan Quintela, Dr. David Alan Gilbert, qemu-devel
Cc: qemu-trivial, Marc-André Lureau, Richard Henderson,
Paolo Bonzini
On 9/16/20 12:19 PM, Thomas Huth wrote:
> GCC 9.3.0 on Ubuntu complains:
>
> In file included from /usr/include/string.h:495,
> from /home/travis/build/huth/qemu/include/qemu/osdep.h:87,
> from ../migration/global_state.c:13:
> In function ‘strncpy’,
> inlined from ‘global_state_store_running’ at ../migration/global_state.c:47:5:
> /usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound 100 equals destination size [-Werror=stringop-truncation]
> 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> ... but we apparently really want to do the strncpy here. Silence the
> warning with QEMU_NONSTRING.
>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
> migration/global_state.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/migration/global_state.c b/migration/global_state.c
> index 25311479a4..f1355d7d97 100644
> --- a/migration/global_state.c
> +++ b/migration/global_state.c
> @@ -43,9 +43,9 @@ int global_state_store(void)
> void global_state_store_running(void)
> {
> const char *state = RunState_str(RUN_STATE_RUNNING);
> + QEMU_NONSTRING char *dest = (char *)global_state.runstate;
Do we still need the cast to char*?
> assert(strlen(state) < sizeof(global_state.runstate));
> - strncpy((char *)global_state.runstate,
> - state, sizeof(global_state.runstate));
> + strncpy(dest, state, sizeof(global_state.runstate));
> }
>
Otherwise,
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] migration: Silence compiler warning in global_state_store_running()
2020-09-16 17:19 [PATCH] migration: Silence compiler warning in global_state_store_running() Thomas Huth
2020-09-16 17:42 ` Eric Blake
@ 2020-09-17 6:30 ` Thomas Huth
2020-09-17 7:18 ` Paolo Bonzini
1 sibling, 1 reply; 5+ messages in thread
From: Thomas Huth @ 2020-09-17 6:30 UTC (permalink / raw)
To: Juan Quintela, Dr. David Alan Gilbert, qemu-devel
Cc: qemu-trivial, Marc-André Lureau, Richard Henderson,
Paolo Bonzini
On 16/09/2020 19.19, Thomas Huth wrote:
> GCC 9.3.0 on Ubuntu complains:
>
> In file included from /usr/include/string.h:495,
> from /home/travis/build/huth/qemu/include/qemu/osdep.h:87,
> from ../migration/global_state.c:13:
> In function ‘strncpy’,
> inlined from ‘global_state_store_running’ at ../migration/global_state.c:47:5:
> /usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound 100 equals destination size [-Werror=stringop-truncation]
> 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> ... but we apparently really want to do the strncpy here. Silence the
> warning with QEMU_NONSTRING.
>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
> migration/global_state.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/migration/global_state.c b/migration/global_state.c
> index 25311479a4..f1355d7d97 100644
> --- a/migration/global_state.c
> +++ b/migration/global_state.c
> @@ -43,9 +43,9 @@ int global_state_store(void)
> void global_state_store_running(void)
> {
> const char *state = RunState_str(RUN_STATE_RUNNING);
> + QEMU_NONSTRING char *dest = (char *)global_state.runstate;
> assert(strlen(state) < sizeof(global_state.runstate));
> - strncpy((char *)global_state.runstate,
> - state, sizeof(global_state.runstate));
> + strncpy(dest, state, sizeof(global_state.runstate));
> }
Darn, I was sending too fast here, sorry, but seems like this does *not*
fix the issue with GCC 9.3:
https://travis-ci.com/github/huth/qemu/jobs/385871010#L2930
... so maybe we should simply switch to strpadcpy() instead?
Thomas
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] migration: Silence compiler warning in global_state_store_running()
2020-09-17 6:30 ` Thomas Huth
@ 2020-09-17 7:18 ` Paolo Bonzini
2020-09-17 7:29 ` Thomas Huth
0 siblings, 1 reply; 5+ messages in thread
From: Paolo Bonzini @ 2020-09-17 7:18 UTC (permalink / raw)
To: Thomas Huth, Juan Quintela, Dr. David Alan Gilbert, qemu-devel
Cc: qemu-trivial, Marc-André Lureau, Richard Henderson
On 17/09/20 08:30, Thomas Huth wrote:
> On 16/09/2020 19.19, Thomas Huth wrote:
>> GCC 9.3.0 on Ubuntu complains:
>>
>> In file included from /usr/include/string.h:495,
>> from /home/travis/build/huth/qemu/include/qemu/osdep.h:87,
>> from ../migration/global_state.c:13:
>> In function ‘strncpy’,
>> inlined from ‘global_state_store_running’ at ../migration/global_state.c:47:5:
>> /usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound 100 equals destination size [-Werror=stringop-truncation]
>> 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> ... but we apparently really want to do the strncpy here. Silence the
>> warning with QEMU_NONSTRING.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>> migration/global_state.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/migration/global_state.c b/migration/global_state.c
>> index 25311479a4..f1355d7d97 100644
>> --- a/migration/global_state.c
>> +++ b/migration/global_state.c
>> @@ -43,9 +43,9 @@ int global_state_store(void)
>> void global_state_store_running(void)
>> {
>> const char *state = RunState_str(RUN_STATE_RUNNING);
>> + QEMU_NONSTRING char *dest = (char *)global_state.runstate;
>> assert(strlen(state) < sizeof(global_state.runstate));
>> - strncpy((char *)global_state.runstate,
>> - state, sizeof(global_state.runstate));
>> + strncpy(dest, state, sizeof(global_state.runstate));
>> }
>
> Darn, I was sending too fast here, sorry, but seems like this does *not*
> fix the issue with GCC 9.3:
>
> https://travis-ci.com/github/huth/qemu/jobs/385871010#L2930
>
> ... so maybe we should simply switch to strpadcpy() instead?
Yes, and probably do so everywhere that strncpy is used.
Paolo
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] migration: Silence compiler warning in global_state_store_running()
2020-09-17 7:18 ` Paolo Bonzini
@ 2020-09-17 7:29 ` Thomas Huth
0 siblings, 0 replies; 5+ messages in thread
From: Thomas Huth @ 2020-09-17 7:29 UTC (permalink / raw)
To: Paolo Bonzini, Juan Quintela, Dr. David Alan Gilbert, qemu-devel
Cc: qemu-trivial, Marc-André Lureau, Richard Henderson
On 17/09/2020 09.18, Paolo Bonzini wrote:
> On 17/09/20 08:30, Thomas Huth wrote:
>> On 16/09/2020 19.19, Thomas Huth wrote:
>>> GCC 9.3.0 on Ubuntu complains:
>>>
>>> In file included from /usr/include/string.h:495,
>>> from /home/travis/build/huth/qemu/include/qemu/osdep.h:87,
>>> from ../migration/global_state.c:13:
>>> In function ‘strncpy’,
>>> inlined from ‘global_state_store_running’ at ../migration/global_state.c:47:5:
>>> /usr/include/x86_64-linux-gnu/bits/string_fortified.h:106:10: error: ‘__builtin_strncpy’ specified bound 100 equals destination size [-Werror=stringop-truncation]
>>> 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
>>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>> ... but we apparently really want to do the strncpy here. Silence the
>>> warning with QEMU_NONSTRING.
>>>
>>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>>> ---
>>> migration/global_state.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/migration/global_state.c b/migration/global_state.c
>>> index 25311479a4..f1355d7d97 100644
>>> --- a/migration/global_state.c
>>> +++ b/migration/global_state.c
>>> @@ -43,9 +43,9 @@ int global_state_store(void)
>>> void global_state_store_running(void)
>>> {
>>> const char *state = RunState_str(RUN_STATE_RUNNING);
>>> + QEMU_NONSTRING char *dest = (char *)global_state.runstate;
>>> assert(strlen(state) < sizeof(global_state.runstate));
>>> - strncpy((char *)global_state.runstate,
>>> - state, sizeof(global_state.runstate));
>>> + strncpy(dest, state, sizeof(global_state.runstate));
>>> }
>>
>> Darn, I was sending too fast here, sorry, but seems like this does *not*
>> fix the issue with GCC 9.3:
>>
>> https://travis-ci.com/github/huth/qemu/jobs/385871010#L2930
>>
>> ... so maybe we should simply switch to strpadcpy() instead?
>
> Yes, and probably do so everywhere that strncpy is used.
I think the trick with QEMU_NONSTRING should work fine in all cases
where we have a real array, see e.g. buf[] in find_vdi_name() in
block/sheepdog.c. It just does not seem to work in case you have a char*
pointer instead of an array...
Thomas
^ permalink raw reply [flat|nested] 5+ messages in thread
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2020-09-16 17:19 [PATCH] migration: Silence compiler warning in global_state_store_running() Thomas Huth
2020-09-16 17:42 ` Eric Blake
2020-09-17 6:30 ` Thomas Huth
2020-09-17 7:18 ` Paolo Bonzini
2020-09-17 7:29 ` Thomas Huth
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