| Message ID | 20241028114831.27487-1-roger.pau@citrix.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | tools/libxl: remove usage of VLA arrays | expand |
On Mon, Oct 28, 2024 at 11:48 AM Roger Pau Monne <roger.pau@citrix.com> wrote: > > Clang 19 complains with the following error when building libxl: > > libxl_utils.c:48:15: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant] > 48 | char path[strlen("/local/domain") + 12]; > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Replace the usage of strlen() with ARRAY_SIZE(), which allows the literal > string length to be known at build time. Note ARRAY_SIZE() accounts for the > NUL terminator while strlen() didn't, hence subtract 1 from the total size > calculation. > > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > --- > tools/libs/light/libxl_utils.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c > index 10398a6c8611..b3f5e751cc3f 100644 > --- a/tools/libs/light/libxl_utils.c > +++ b/tools/libs/light/libxl_utils.c > @@ -45,7 +45,7 @@ unsigned long libxl_get_required_shadow_memory(unsigned long maxmem_kb, unsigned > char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid) > { > unsigned int len; > - char path[strlen("/local/domain") + 12]; > + char path[ARRAY_SIZE("/local/domain") + 11]; > char *s; > > snprintf(path, sizeof(path), "/local/domain/%d/name", domid); > @@ -141,7 +141,7 @@ int libxl_cpupool_qualifier_to_cpupoolid(libxl_ctx *ctx, const char *p, > char *libxl_cpupoolid_to_name(libxl_ctx *ctx, uint32_t poolid) > { > unsigned int len; > - char path[strlen("/local/pool") + 12]; > + char path[ARRAY_SIZE("/local/pool") + 11]; > char *s; > > snprintf(path, sizeof(path), "/local/pool/%d/name", poolid); Minor: why not sizeof instead of ARRAY_SIZE ? Not a regression, but looking at final strings and size added, it looks like the numbers should be more uint16_t than uint32_t. Maybe we want something like char path[sizeof("/local/pool//name") + 12]; BTW, Reviewed-by: Frediano Ziglio <frediano.ziglio@cloud.com> Frediano
On 28/10/2024 11:48 am, Roger Pau Monne wrote: > Clang 19 complains with the following error when building libxl: > > libxl_utils.c:48:15: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant] > 48 | char path[strlen("/local/domain") + 12]; > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Replace the usage of strlen() with ARRAY_SIZE(), which allows the literal > string length to be known at build time. Note ARRAY_SIZE() accounts for the > NUL terminator while strlen() didn't, hence subtract 1 from the total size > calculation. > > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > --- > tools/libs/light/libxl_utils.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c > index 10398a6c8611..b3f5e751cc3f 100644 > --- a/tools/libs/light/libxl_utils.c > +++ b/tools/libs/light/libxl_utils.c > @@ -45,7 +45,7 @@ unsigned long libxl_get_required_shadow_memory(unsigned long maxmem_kb, unsigned > char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid) > { > unsigned int len; > - char path[strlen("/local/domain") + 12]; > + char path[ARRAY_SIZE("/local/domain") + 11]; > char *s; > > snprintf(path, sizeof(path), "/local/domain/%d/name", domid); > @@ -141,7 +141,7 @@ int libxl_cpupool_qualifier_to_cpupoolid(libxl_ctx *ctx, const char *p, > char *libxl_cpupoolid_to_name(libxl_ctx *ctx, uint32_t poolid) > { > unsigned int len; > - char path[strlen("/local/pool") + 12]; > + char path[ARRAY_SIZE("/local/pool") + 11]; > char *s; > > snprintf(path, sizeof(path), "/local/pool/%d/name", poolid); Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> Although I have a minor preference for sizeof() as suggested by Frediano. Can fix on commit, if you're happy? ~Andrew
On 28.10.2024 13:03, Andrew Cooper wrote: > On 28/10/2024 11:48 am, Roger Pau Monne wrote: >> Clang 19 complains with the following error when building libxl: >> >> libxl_utils.c:48:15: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant] >> 48 | char path[strlen("/local/domain") + 12]; >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> >> Replace the usage of strlen() with ARRAY_SIZE(), which allows the literal >> string length to be known at build time. Note ARRAY_SIZE() accounts for the >> NUL terminator while strlen() didn't, hence subtract 1 from the total size >> calculation. >> >> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> >> --- >> tools/libs/light/libxl_utils.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c >> index 10398a6c8611..b3f5e751cc3f 100644 >> --- a/tools/libs/light/libxl_utils.c >> +++ b/tools/libs/light/libxl_utils.c >> @@ -45,7 +45,7 @@ unsigned long libxl_get_required_shadow_memory(unsigned long maxmem_kb, unsigned >> char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid) >> { >> unsigned int len; >> - char path[strlen("/local/domain") + 12]; >> + char path[ARRAY_SIZE("/local/domain") + 11]; >> char *s; >> >> snprintf(path, sizeof(path), "/local/domain/%d/name", domid); >> @@ -141,7 +141,7 @@ int libxl_cpupool_qualifier_to_cpupoolid(libxl_ctx *ctx, const char *p, >> char *libxl_cpupoolid_to_name(libxl_ctx *ctx, uint32_t poolid) >> { >> unsigned int len; >> - char path[strlen("/local/pool") + 12]; >> + char path[ARRAY_SIZE("/local/pool") + 11]; >> char *s; >> >> snprintf(path, sizeof(path), "/local/pool/%d/name", poolid); > > Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> > > Although I have a minor preference for sizeof() as suggested by Frediano. > > Can fix on commit, if you're happy? Please can we stick to ARRAY_SIZE() when it comes to strings? It's the same as sizeof() when the base type is char, but the difference becomes relevant if the base type was e.g. wchar_t. Jan
On Mon, Oct 28, 2024 at 12:48 PM Jan Beulich <jbeulich@suse.com> wrote: > > On 28.10.2024 13:03, Andrew Cooper wrote: > > On 28/10/2024 11:48 am, Roger Pau Monne wrote: > >> Clang 19 complains with the following error when building libxl: > >> > >> libxl_utils.c:48:15: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant] > >> 48 | char path[strlen("/local/domain") + 12]; > >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > >> > >> Replace the usage of strlen() with ARRAY_SIZE(), which allows the literal > >> string length to be known at build time. Note ARRAY_SIZE() accounts for the > >> NUL terminator while strlen() didn't, hence subtract 1 from the total size > >> calculation. > >> > >> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > >> --- > >> tools/libs/light/libxl_utils.c | 4 ++-- > >> 1 file changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c > >> index 10398a6c8611..b3f5e751cc3f 100644 > >> --- a/tools/libs/light/libxl_utils.c > >> +++ b/tools/libs/light/libxl_utils.c > >> @@ -45,7 +45,7 @@ unsigned long libxl_get_required_shadow_memory(unsigned long maxmem_kb, unsigned > >> char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid) > >> { > >> unsigned int len; > >> - char path[strlen("/local/domain") + 12]; > >> + char path[ARRAY_SIZE("/local/domain") + 11]; > >> char *s; > >> > >> snprintf(path, sizeof(path), "/local/domain/%d/name", domid); > >> @@ -141,7 +141,7 @@ int libxl_cpupool_qualifier_to_cpupoolid(libxl_ctx *ctx, const char *p, > >> char *libxl_cpupoolid_to_name(libxl_ctx *ctx, uint32_t poolid) > >> { > >> unsigned int len; > >> - char path[strlen("/local/pool") + 12]; > >> + char path[ARRAY_SIZE("/local/pool") + 11]; > >> char *s; > >> > >> snprintf(path, sizeof(path), "/local/pool/%d/name", poolid); > > > > Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> > > > > Although I have a minor preference for sizeof() as suggested by Frediano. > > > > Can fix on commit, if you're happy? > > Please can we stick to ARRAY_SIZE() when it comes to strings? It's the > same as sizeof() when the base type is char, but the difference becomes > relevant if the base type was e.g. wchar_t. > > Jan > But "literal" is not a wide string, and the type is "char" which is not wide too. BTW, both me and Andrew are not strong about. Frediano
On Mon, Oct 28, 2024 at 12:57:30PM +0000, Frediano Ziglio wrote: > On Mon, Oct 28, 2024 at 12:48 PM Jan Beulich <jbeulich@suse.com> wrote: > > > > On 28.10.2024 13:03, Andrew Cooper wrote: > > > On 28/10/2024 11:48 am, Roger Pau Monne wrote: > > >> Clang 19 complains with the following error when building libxl: > > >> > > >> libxl_utils.c:48:15: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant] > > >> 48 | char path[strlen("/local/domain") + 12]; > > >> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > >> > > >> Replace the usage of strlen() with ARRAY_SIZE(), which allows the literal > > >> string length to be known at build time. Note ARRAY_SIZE() accounts for the > > >> NUL terminator while strlen() didn't, hence subtract 1 from the total size > > >> calculation. > > >> > > >> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > > >> --- > > >> tools/libs/light/libxl_utils.c | 4 ++-- > > >> 1 file changed, 2 insertions(+), 2 deletions(-) > > >> > > >> diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c > > >> index 10398a6c8611..b3f5e751cc3f 100644 > > >> --- a/tools/libs/light/libxl_utils.c > > >> +++ b/tools/libs/light/libxl_utils.c > > >> @@ -45,7 +45,7 @@ unsigned long libxl_get_required_shadow_memory(unsigned long maxmem_kb, unsigned > > >> char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid) > > >> { > > >> unsigned int len; > > >> - char path[strlen("/local/domain") + 12]; > > >> + char path[ARRAY_SIZE("/local/domain") + 11]; > > >> char *s; > > >> > > >> snprintf(path, sizeof(path), "/local/domain/%d/name", domid); > > >> @@ -141,7 +141,7 @@ int libxl_cpupool_qualifier_to_cpupoolid(libxl_ctx *ctx, const char *p, > > >> char *libxl_cpupoolid_to_name(libxl_ctx *ctx, uint32_t poolid) > > >> { > > >> unsigned int len; > > >> - char path[strlen("/local/pool") + 12]; > > >> + char path[ARRAY_SIZE("/local/pool") + 11]; > > >> char *s; > > >> > > >> snprintf(path, sizeof(path), "/local/pool/%d/name", poolid); > > > > > > Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> > > > > > > Although I have a minor preference for sizeof() as suggested by Frediano. > > > > > > Can fix on commit, if you're happy? > > > > Please can we stick to ARRAY_SIZE() when it comes to strings? It's the > > same as sizeof() when the base type is char, but the difference becomes > > relevant if the base type was e.g. wchar_t. > > > > Jan > > > > But "literal" is not a wide string, and the type is "char" which is > not wide too. > > BTW, both me and Andrew are not strong about. No strong opinion either, I've assumed it was clearer to not make implicit assumptions about the size of the string literal array elements. I would rather like to get this committed, and Jan seems to prefer to use ARRAY_SIZE(), so I suggest we get the patch committed as-is. Thanks, Roger.
On 28.10.2024 18:26, Roger Pau Monné wrote: > On Mon, Oct 28, 2024 at 12:57:30PM +0000, Frediano Ziglio wrote: >> On Mon, Oct 28, 2024 at 12:48 PM Jan Beulich <jbeulich@suse.com> wrote: >>> >>> On 28.10.2024 13:03, Andrew Cooper wrote: >>>> On 28/10/2024 11:48 am, Roger Pau Monne wrote: >>>>> Clang 19 complains with the following error when building libxl: >>>>> >>>>> libxl_utils.c:48:15: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant] >>>>> 48 | char path[strlen("/local/domain") + 12]; >>>>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ >>>>> >>>>> Replace the usage of strlen() with ARRAY_SIZE(), which allows the literal >>>>> string length to be known at build time. Note ARRAY_SIZE() accounts for the >>>>> NUL terminator while strlen() didn't, hence subtract 1 from the total size >>>>> calculation. >>>>> >>>>> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> >>>>> --- >>>>> tools/libs/light/libxl_utils.c | 4 ++-- >>>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c >>>>> index 10398a6c8611..b3f5e751cc3f 100644 >>>>> --- a/tools/libs/light/libxl_utils.c >>>>> +++ b/tools/libs/light/libxl_utils.c >>>>> @@ -45,7 +45,7 @@ unsigned long libxl_get_required_shadow_memory(unsigned long maxmem_kb, unsigned >>>>> char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid) >>>>> { >>>>> unsigned int len; >>>>> - char path[strlen("/local/domain") + 12]; >>>>> + char path[ARRAY_SIZE("/local/domain") + 11]; >>>>> char *s; >>>>> >>>>> snprintf(path, sizeof(path), "/local/domain/%d/name", domid); >>>>> @@ -141,7 +141,7 @@ int libxl_cpupool_qualifier_to_cpupoolid(libxl_ctx *ctx, const char *p, >>>>> char *libxl_cpupoolid_to_name(libxl_ctx *ctx, uint32_t poolid) >>>>> { >>>>> unsigned int len; >>>>> - char path[strlen("/local/pool") + 12]; >>>>> + char path[ARRAY_SIZE("/local/pool") + 11]; >>>>> char *s; >>>>> >>>>> snprintf(path, sizeof(path), "/local/pool/%d/name", poolid); >>>> >>>> Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> >>>> >>>> Although I have a minor preference for sizeof() as suggested by Frediano. >>>> >>>> Can fix on commit, if you're happy? >>> >>> Please can we stick to ARRAY_SIZE() when it comes to strings? It's the >>> same as sizeof() when the base type is char, but the difference becomes >>> relevant if the base type was e.g. wchar_t. >>> >>> Jan >>> >> >> But "literal" is not a wide string, and the type is "char" which is >> not wide too. >> >> BTW, both me and Andrew are not strong about. > > No strong opinion either, I've assumed it was clearer to not make > implicit assumptions about the size of the string literal array > elements. I would rather like to get this committed, and Jan seems to > prefer to use ARRAY_SIZE(), so I suggest we get the patch committed > as-is. Well, ultimately it's Anthony's call, for still being the sole maintainer. Jan
On Mon, Oct 28, 2024 at 12:03:59PM +0000, Andrew Cooper wrote: > On 28/10/2024 11:48 am, Roger Pau Monne wrote: > > Clang 19 complains with the following error when building libxl: > > > > libxl_utils.c:48:15: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant] > > 48 | char path[strlen("/local/domain") + 12]; > > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > Replace the usage of strlen() with ARRAY_SIZE(), which allows the literal > > string length to be known at build time. Note ARRAY_SIZE() accounts for the > > NUL terminator while strlen() didn't, hence subtract 1 from the total size > > calculation. > > > > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> > > --- > > tools/libs/light/libxl_utils.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c > > index 10398a6c8611..b3f5e751cc3f 100644 > > --- a/tools/libs/light/libxl_utils.c > > +++ b/tools/libs/light/libxl_utils.c > > @@ -45,7 +45,7 @@ unsigned long libxl_get_required_shadow_memory(unsigned long maxmem_kb, unsigned > > char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid) > > { > > unsigned int len; > > - char path[strlen("/local/domain") + 12]; > > + char path[ARRAY_SIZE("/local/domain") + 11]; > > char *s; > > > > snprintf(path, sizeof(path), "/local/domain/%d/name", domid); > > @@ -141,7 +141,7 @@ int libxl_cpupool_qualifier_to_cpupoolid(libxl_ctx *ctx, const char *p, > > char *libxl_cpupoolid_to_name(libxl_ctx *ctx, uint32_t poolid) > > { > > unsigned int len; > > - char path[strlen("/local/pool") + 12]; > > + char path[ARRAY_SIZE("/local/pool") + 11]; > > char *s; > > > > snprintf(path, sizeof(path), "/local/pool/%d/name", poolid); > > Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> > > Although I have a minor preference for sizeof() as suggested by Frediano. I have a preference for sizeof() too, we even used it this way (more or less) in libxl before, for `eom` here: https://elixir.bootlin.com/xen/v4.19.0/source/tools/libs/light/libxl_qmp.c#L1608 I was a bit supprised by the use of ARRAY_SIZE on a string literal but it's just an array of char :-). For the patch, with sizeof() or ARRAY_SIZE(): Acked-by: Anthony PERARD <anthony.perard@vates.tech> Thanks,
On 05/11/2024 3:05 pm, Anthony PERARD wrote: > On Mon, Oct 28, 2024 at 12:03:59PM +0000, Andrew Cooper wrote: >> On 28/10/2024 11:48 am, Roger Pau Monne wrote: >>> Clang 19 complains with the following error when building libxl: >>> >>> libxl_utils.c:48:15: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant] >>> 48 | char path[strlen("/local/domain") + 12]; >>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ >>> >>> Replace the usage of strlen() with ARRAY_SIZE(), which allows the literal >>> string length to be known at build time. Note ARRAY_SIZE() accounts for the >>> NUL terminator while strlen() didn't, hence subtract 1 from the total size >>> calculation. >>> >>> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> >>> --- >>> tools/libs/light/libxl_utils.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c >>> index 10398a6c8611..b3f5e751cc3f 100644 >>> --- a/tools/libs/light/libxl_utils.c >>> +++ b/tools/libs/light/libxl_utils.c >>> @@ -45,7 +45,7 @@ unsigned long libxl_get_required_shadow_memory(unsigned long maxmem_kb, unsigned >>> char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid) >>> { >>> unsigned int len; >>> - char path[strlen("/local/domain") + 12]; >>> + char path[ARRAY_SIZE("/local/domain") + 11]; >>> char *s; >>> >>> snprintf(path, sizeof(path), "/local/domain/%d/name", domid); >>> @@ -141,7 +141,7 @@ int libxl_cpupool_qualifier_to_cpupoolid(libxl_ctx *ctx, const char *p, >>> char *libxl_cpupoolid_to_name(libxl_ctx *ctx, uint32_t poolid) >>> { >>> unsigned int len; >>> - char path[strlen("/local/pool") + 12]; >>> + char path[ARRAY_SIZE("/local/pool") + 11]; >>> char *s; >>> >>> snprintf(path, sizeof(path), "/local/pool/%d/name", poolid); >> Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> >> >> Although I have a minor preference for sizeof() as suggested by Frediano. > I have a preference for sizeof() too, we even used it this way (more or > less) in libxl before, for `eom` here: > https://elixir.bootlin.com/xen/v4.19.0/source/tools/libs/light/libxl_qmp.c#L1608 > > I was a bit supprised by the use of ARRAY_SIZE on a string literal but > it's just an array of char :-). > > For the patch, with sizeof() or ARRAY_SIZE(): > Acked-by: Anthony PERARD <anthony.perard@vates.tech> That's 3 for sizeof(), one ambivalent, and one for ARRAY_SIZE(), with the maintainer (who gets the majority say) already in the largest group already. I've adjusted and committed. ~Andrew
diff --git a/tools/libs/light/libxl_utils.c b/tools/libs/light/libxl_utils.c index 10398a6c8611..b3f5e751cc3f 100644 --- a/tools/libs/light/libxl_utils.c +++ b/tools/libs/light/libxl_utils.c @@ -45,7 +45,7 @@ unsigned long libxl_get_required_shadow_memory(unsigned long maxmem_kb, unsigned char *libxl_domid_to_name(libxl_ctx *ctx, uint32_t domid) { unsigned int len; - char path[strlen("/local/domain") + 12]; + char path[ARRAY_SIZE("/local/domain") + 11]; char *s; snprintf(path, sizeof(path), "/local/domain/%d/name", domid); @@ -141,7 +141,7 @@ int libxl_cpupool_qualifier_to_cpupoolid(libxl_ctx *ctx, const char *p, char *libxl_cpupoolid_to_name(libxl_ctx *ctx, uint32_t poolid) { unsigned int len; - char path[strlen("/local/pool") + 12]; + char path[ARRAY_SIZE("/local/pool") + 11]; char *s; snprintf(path, sizeof(path), "/local/pool/%d/name", poolid);
Clang 19 complains with the following error when building libxl: libxl_utils.c:48:15: error: variable length array folded to constant array as an extension [-Werror,-Wgnu-folding-constant] 48 | char path[strlen("/local/domain") + 12]; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ Replace the usage of strlen() with ARRAY_SIZE(), which allows the literal string length to be known at build time. Note ARRAY_SIZE() accounts for the NUL terminator while strlen() didn't, hence subtract 1 from the total size calculation. Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> --- tools/libs/light/libxl_utils.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)