Sergey: Now, VS and GCC don't report such issue. How do you find them? And, this change modifies the function API, does it impact the consumer code?
Thanks Liming > -----Original Message----- > From: Sergei Temerkhanov [mailto:[email protected]] > Sent: Tuesday, May 16, 2017 8:11 PM > To: Gao, Liming <[email protected]> > Cc: [email protected] > Subject: Re: [edk2] [PATCH] MdePkg: Fix undefined behavior on variadic > parameters > > On Tue, May 16, 2017 at 8:10 AM, Gao, Liming <[email protected]> wrote: > > Sergey: > > Could you give more detail on the undefined behavior on variadic > > parameters? > > > > I see https://bugzilla.tianocore.org/show_bug.cgi?id=410 describe this > > issues found in the latest CLANG tool chain. Do you find > other tool chain reports it? > > Yes, this is exactly the bug this patch fixes. > > As per the C99 standard: > "The parameter parmN is the identifier of the rightmost parameter in > the variable parameter list in the function definition (the one just > before the , ...). If the parameter parmN is declared with the > register storage class, with a function or array type, or with a type > that is not compatible with the type that results after application of > the default argument promotions, the behavior is undefined." > > That's exactly the case here since BOOLEAN is a typedef for unsigned > char. It undergoes a promotion to an unsigned int which is not a > compatible type for unsigned char. Correct me if I'm wrong. > > Regards, > Sergey > > > > > Thanks > > Liming > >> -----Original Message----- > >> From: edk2-devel [mailto:[email protected]] On Behalf Of > >> Sergey Temerkhanov > >> Sent: Tuesday, May 16, 2017 10:57 AM > >> To: [email protected] > >> Subject: [edk2] [PATCH] MdePkg: Fix undefined behavior on variadic > >> parameters > >> > >> Fix undefined behavior by avoiding parameter type promotion > >> > >> Signed-off-by: Sergey Temerkhanov <[email protected]> > >> --- > >> MdePkg/Include/Library/UefiLib.h | 2 +- > >> MdePkg/Library/UefiLib/UefiLib.c | 2 +- > >> 2 files changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/MdePkg/Include/Library/UefiLib.h > >> b/MdePkg/Include/Library/UefiLib.h > >> index 0b14792..4e4697c 100644 > >> --- a/MdePkg/Include/Library/UefiLib.h > >> +++ b/MdePkg/Include/Library/UefiLib.h > >> @@ -818,7 +818,7 @@ CHAR8 * > >> EFIAPI > >> GetBestLanguage ( > >> IN CONST CHAR8 *SupportedLanguages, > >> - IN BOOLEAN Iso639Language, > >> + IN UINTN Iso639Language, > >> ... > >> ); > >> > >> diff --git a/MdePkg/Library/UefiLib/UefiLib.c > >> b/MdePkg/Library/UefiLib/UefiLib.c > >> index a7eee01..74528ec 100644 > >> --- a/MdePkg/Library/UefiLib/UefiLib.c > >> +++ b/MdePkg/Library/UefiLib/UefiLib.c > >> @@ -1514,7 +1514,7 @@ CHAR8 * > >> EFIAPI > >> GetBestLanguage ( > >> IN CONST CHAR8 *SupportedLanguages, > >> - IN BOOLEAN Iso639Language, > >> + IN UINTN Iso639Language, > >> ... > >> ) > >> { > >> -- > >> 2.7.4 > >> > >> _______________________________________________ > >> edk2-devel mailing list > >> [email protected] > >> https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
