Re: [Patch v2 1/3] MdePkg/Include/IndustryStandard: Add Operator and Xor field names

["Michael D Kinney" <michael.d.kinney@intel.com>]

Hi Pedro,

It appears other projects have run into this same issue with the
TPM specifications and have changed the field names by appending '_'.

https://github.com/MIPS/external-tpm2/blob/d704926273cf17498c95ff0dc50b4b17e523c109/generator/structure_generator.py#L1183

Mike

> -----Original Message-----
> From: Kinney, Michael D <michael.d.kinney@intel.com>
> Sent: Wednesday, May 31, 2023 11:42 AM
> To: Pedro Falcato <pedro.falcato@gmail.com>
> Cc: devel@edk2.groups.io; Gao, Liming <gaoliming@byosoft.com.cn>; Liu,
> Zhiguang <zhiguang.liu@intel.com>; Oliver Smith-Denny
> <osde@linux.microsoft.com>; Pop, Aaron <aaronpop@microsoft.com>; Kinney,
> Michael D <michael.d.kinney@intel.com>
> Subject: RE: [Patch v2 1/3] MdePkg/Include/IndustryStandard: Add Operator
> and Xor field names
> 
> 
> 
> > -----Original Message-----
> > From: Pedro Falcato <pedro.falcato@gmail.com>
> > Sent: Wednesday, May 31, 2023 11:17 AM
> > To: Kinney, Michael D <michael.d.kinney@intel.com>
> > Cc: devel@edk2.groups.io; Gao, Liming <gaoliming@byosoft.com.cn>; Liu,
> > Zhiguang <zhiguang.liu@intel.com>; Oliver Smith-Denny
> > <osde@linux.microsoft.com>; Pop, Aaron <aaronpop@microsoft.com>
> > Subject: Re: [Patch v2 1/3] MdePkg/Include/IndustryStandard: Add Operator
> > and Xor field names
> >
> > On Tue, May 30, 2023 at 7:53 PM Michael D Kinney
> > <michael.d.kinney@intel.com> wrote:
> > >
> > > Update Tpm12.h and Tpm20.h and not use c++ reserved keywords
> > > operator and xor in C structures to support use of these
> > > include files when building with a C++ compiler.
> > >
> > > This patch temporarily introduces an anonymous union to add
> > > Operator and Xor fields to support migration from the current
> > > field names to the new field names.
> > >
> > > Warning 4201 is disabled for VS20xx tool chains is a temporary
> > > change to allow the use of anonymous unions.
> > >
> > > Cc: Liming Gao <gaoliming@byosoft.com.cn>
> > > Cc: Zhiguang Liu <zhiguang.liu@intel.com>
> > > Cc: Oliver Smith-Denny <osde@linux.microsoft.com>
> > > Cc: Pedro Falcato <pedro.falcato@gmail.com>
> > > Cc: Aaron Pop <aaronpop@microsoft.com>
> > > Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
> > > ---
> > >  MdePkg/Include/IndustryStandard/Tpm12.h | 22 ++++++++++++++++++++--
> > >  MdePkg/Include/IndustryStandard/Tpm20.h | 25 +++++++++++++++++++++++--
> > >  2 files changed, 43 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/MdePkg/Include/IndustryStandard/Tpm12.h
> > b/MdePkg/Include/IndustryStandard/Tpm12.h
> > > index 155dcc9f5f99..56e89d9d0835 100644
> > > --- a/MdePkg/Include/IndustryStandard/Tpm12.h
> > > +++ b/MdePkg/Include/IndustryStandard/Tpm12.h
> > > @@ -9,6 +9,14 @@
> > >  #ifndef _TPM12_H_
> > >  #define _TPM12_H_
> > >
> > > +///
> > > +/// Temporary disable 4201 to support anonymous unions
> > > +///
> > > +#if defined (_MSC_EXTENSIONS)
> > > +#pragma warning( push )
> > > +#pragma warning ( disable : 4201 )
> > > +#endif
> > > +
> > >  ///
> > >  /// The start of TPM return codes
> > >  ///
> > > @@ -744,8 +752,11 @@ typedef struct tdTPM_PERMANENT_FLAGS {
> > >    BOOLEAN              TPMpost;
> > >    BOOLEAN              TPMpostLock;
> > >    BOOLEAN              FIPS;
> > > -  BOOLEAN                           operator;
> > > -  BOOLEAN                           enableRevokeEK;
> > > +  union {
> > > +    BOOLEAN            operator;
> > > +    BOOLEAN            Operator;
> > > +  };
> >
> > Do you know if this works cleanly for the other toolchains? i.e
> > supported GCCs and CLANGs?
> > I don't *think* there's a warning for anonymous unions beyond passing
> > -pedantic + -std=c<something>, but it'd be good to know.
> > If so, we may need a pragma for this.
> 
> I did not see any issues with my local testing or with EDK II CI.
> 
> >
> > > +  BOOLEAN              enableRevokeEK;
> > >    BOOLEAN              nvLocked;
> > >    BOOLEAN              readSRKPub;
> > >    BOOLEAN              tpmEstablished;
> > > @@ -2162,4 +2173,11 @@ typedef struct tdTPM_RSP_COMMAND_HDR {
> > >
> > >  #pragma pack ()
> > >
> > > +///
> > > +/// Temporary disable 4201 to support anonymous unions
> > > +///
> > > +#if defined (_MSC_EXTENSIONS)
> > > +#pragma warning( pop )
> > > +#endif
> > > +
> > >  #endif
> > > diff --git a/MdePkg/Include/IndustryStandard/Tpm20.h
> > b/MdePkg/Include/IndustryStandard/Tpm20.h
> > > index 4440f3769f26..a602c0d9c289 100644
> > > --- a/MdePkg/Include/IndustryStandard/Tpm20.h
> > > +++ b/MdePkg/Include/IndustryStandard/Tpm20.h
> > > @@ -15,6 +15,14 @@ SPDX-License-Identifier: BSD-2-Clause-Patent
> > >
> > >  #include <IndustryStandard/Tpm12.h>
> > >
> > > +///
> > > +/// Temporary disable 4201 to support anonymous unions
> > > +///
> > > +#if defined (_MSC_EXTENSIONS)
> > > +#pragma warning( push )
> > > +#pragma warning ( disable : 4201 )
> > > +#endif
> > > +
> > >  #pragma pack (1)
> > >
> > >  // Annex A Algorithm Constants
> > > @@ -1247,7 +1255,10 @@ typedef union {
> > >    TPMI_AES_KEY_BITS    aes;
> > >    TPMI_SM4_KEY_BITS    SM4;
> > >    TPM_KEY_BITS         sym;
> > > -  TPMI_ALG_HASH     xor;
> > > +  union {
> > > +    TPMI_ALG_HASH      xor;
> > > +    TPMI_ALG_HASH      Xor;
> > > +  };
> > >  } TPMU_SYM_KEY_BITS;
> > >
> > >  // Table 123 - TPMU_SYM_MODE Union
> > > @@ -1320,7 +1331,10 @@ typedef struct {
> > >  // Table 136 - TPMU_SCHEME_KEYEDHASH Union
> > >  typedef union {
> > >    TPMS_SCHEME_HMAC    hmac;
> > > -  TPMS_SCHEME_XOR  xor;
> > > +  union {
> > > +    TPMS_SCHEME_XOR   xor;
> > > +    TPMS_SCHEME_XOR   Xor;
> > > +  };
> > >  } TPMU_SCHEME_KEYEDHASH;
> > >
> > >  // Table 137 - TPMT_KEYEDHASH_SCHEME Structure
> > > @@ -1809,4 +1823,11 @@ typedef struct {
> > >  #define HASH_ALG_SHA512   0x00000008
> > >  #define HASH_ALG_SM3_256  0x00000010
> > >
> > > +///
> > > +/// Temporary disable 4201 to support anonymous unions
> > > +///
> > > +#if defined (_MSC_EXTENSIONS)
> > > +#pragma warning( pop )
> > > +#endif
> > > +
> > >  #endif
> > > --
> > > 2.40.1.windows.1
> > >
> >
> > All in all, this looks ok to me. Although I have to say, I'm not a
> > huge fan of the naming style inconsistency introduced here (i.e Xor vs
> > hmac).
> > What if we made all the struct members MixedCase? Or what if we did
> > something like calling them xor_ and operator_?
> 
> The more we change, the greater the potential impact to downstream use of
> these structures.  I prefer to do the smallest possible change to address
> the c++ reserved keyword name collisions in this patch series.
> 
> I do not have strong opinion between 'xor_' vs 'Xor'.  These files are
> based on the TCG TPM Specifications that typically start field names with
> lower case and camel case after that for multi-word field names.
> 
> https://trustedcomputinggroup.org/resource/tpm-library-specification/
> https://trustedcomputinggroup.org/wp-
> content/uploads/TCG_TPM2_r1p59_Part2_Structures_pub.pdf
> 
> >
> > --
> > Pedro