[v2] devtools: check %l format specifier
Checks
Commit Message
From: Ferruh Yigit <ferruh.yigit@intel.com>
%lx or %llx tend to be wrong for 32-bit platform
if used for fixed size variable like uint64_t.
A checkpatch warning will avoid this common mistake.
Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
---
v2: proposal to reword the message and comment
---
devtools/checkpatches.sh | 8 ++++++++
1 file changed, 8 insertions(+)
Comments
On 5/19/2021 8:24 PM, Thomas Monjalon wrote:
> From: Ferruh Yigit <ferruh.yigit@intel.com>
>
> %lx or %llx tend to be wrong for 32-bit platform
> if used for fixed size variable like uint64_t.
> A checkpatch warning will avoid this common mistake.
>
> Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> ---
> v2: proposal to reword the message and comment
> ---
> devtools/checkpatches.sh | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/devtools/checkpatches.sh b/devtools/checkpatches.sh
> index db4c7d8301..0e09b2cab8 100755
> --- a/devtools/checkpatches.sh
> +++ b/devtools/checkpatches.sh
> @@ -69,6 +69,14 @@ check_forbidden_additions() { # <patch>
> -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
> "$1" || res=1
>
> + # check %l or %ll format specifier
> + awk -v FOLDERS='lib drivers app examples' \
> + -v EXPRESSIONS='%ll*[xud]' \
> + -v RET_ON_FAIL=1 \
> + -v MESSAGE='Using %l format, should it be %PRI*64?' \
> + -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
> + "$1" || res=1
> +
> # forbid variable declaration inside "for" loop
> awk -v FOLDERS='.' \
> -v EXPRESSIONS='for[[:space:]]*\\((char|u?int|unsigned|s?size_t)' \
>
Using the %l or %ll format specifier is correct when the variable type is "long
int" or "long long int", it is only wrong if the variable type is fixed size
like 'unit64_t'.
My concern is above warning log may cause people change the correct usage.
That was why I tried to make wording less strict, more like a reminder to double
check the usage.
If we can check that format specifier is used for 'unit64_t' variable, that will
be the best solution but that is very hard to do.
Should we add a little more information to the message to prevent false hit on
the correct usage?
21/05/2021 14:01, Ferruh Yigit:
> On 5/19/2021 8:24 PM, Thomas Monjalon wrote:
> > From: Ferruh Yigit <ferruh.yigit@intel.com>
> >
> > %lx or %llx tend to be wrong for 32-bit platform
> > if used for fixed size variable like uint64_t.
> > A checkpatch warning will avoid this common mistake.
> >
> > Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> > Signed-off-by: Thomas Monjalon <thomas@monjalon.net>
> > ---
> > v2: proposal to reword the message and comment
> > ---
> > + # check %l or %ll format specifier
> > + awk -v FOLDERS='lib drivers app examples' \
> > + -v EXPRESSIONS='%ll*[xud]' \
> > + -v RET_ON_FAIL=1 \
> > + -v MESSAGE='Using %l format, should it be %PRI*64?' \
> > + -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
> > + "$1" || res=1
>
> Using the %l or %ll format specifier is correct when the variable type is "long
> int" or "long long int", it is only wrong if the variable type is fixed size
> like 'unit64_t'.
>
> My concern is above warning log may cause people change the correct usage.
>
> That was why I tried to make wording less strict, more like a reminder to double
> check the usage.
This is a question now: "should it be", why do you think it is strict?
> If we can check that format specifier is used for 'unit64_t' variable, that will
> be the best solution but that is very hard to do.
> Should we add a little more information to the message to prevent false hit on
> the correct usage?
Your message was:
"Please check %llx usage which tends to be wrong most of the times"
Mine:
"Using %l format, should it be %PRI*64?"
Trying to give more info about what can be wrong while keeping short:
"Using %l format, is it a long variable or should it be %PRI*64?
@@ -69,6 +69,14 @@ check_forbidden_additions() { # <patch>
-f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
"$1" || res=1
+ # check %l or %ll format specifier
+ awk -v FOLDERS='lib drivers app examples' \
+ -v EXPRESSIONS='%ll*[xud]' \
+ -v RET_ON_FAIL=1 \
+ -v MESSAGE='Using %l format, should it be %PRI*64?' \
+ -f $(dirname $(readlink -f $0))/check-forbidden-tokens.awk \
+ "$1" || res=1
+
# forbid variable declaration inside "for" loop
awk -v FOLDERS='.' \
-v EXPRESSIONS='for[[:space:]]*\\((char|u?int|unsigned|s?size_t)' \