I meant
the behavior by the spec was unpredictable.
"Passing in a VariableName parameter that is neither a Null-terminated
string nor a value that was returned on the previous call to
GetNextVariableName() may also produce *unpredictable* results."
The behavior by the code was to return EFI_NOT_FOUND, it was our code's
implementation choice.
Do you mean which piece of comments to be put in code? :)
Thanks,
Star
-----Original Message-----
From: Ni, Ruiyu
Sent: Monday, June 26, 2017 2:18 PM
To: Zeng, Star <star.z...@intel.com>; edk2-devel@lists.01.org
Cc: Gao, Liming <liming....@intel.com>
Subject: RE: [PATCH V2 3/3] DuetPkg FsVariable: Update GetNextVariableName to
follow UEFI 2.7
Thanks! Could you please put the comments in code?
But why do you say it's unpredictable? The behavior is to return EFI_NOT_FOUND.
Thanks/Ray
> -----Original Message-----
> From: Zeng, Star
> Sent: Monday, June 26, 2017 1:52 PM
> To: Ni, Ruiyu <ruiyu...@intel.com>; edk2-devel@lists.01.org
> Cc: Gao, Liming <liming....@intel.com>; Zeng, Star
> <star.z...@intel.com>
> Subject: RE: [PATCH V2 3/3] DuetPkg FsVariable: Update
> GetNextVariableName to follow UEFI 2.7
>
> Before UEFI 2.6a and 2.7, the behavior is unpredictable, our *CODE*
> chose to return EFI_NOT_FOUND.
>
> "Passing in a VariableName parameter that is neither a Null-terminated
> string nor a value that was returned on the previous call to
> GetNextVariableName() may also produce unpredictable results."
>
>
>
> Thanks,
> Star
> -----Original Message-----
> From: Ni, Ruiyu
> Sent: Monday, June 26, 2017 1:47 PM
> To: Zeng, Star <star.z...@intel.com>; edk2-devel@lists.01.org
> Cc: Gao, Liming <liming....@intel.com>
> Subject: RE: [PATCH V2 3/3] DuetPkg FsVariable: Update
> GetNextVariableName to follow UEFI 2.7
>
> Can you add more comments here to describe the purpose is to change
> the return status from Not Found to Invalid Parameter, and the reason
> of choosing Invalid Parameter?
>
> Thanks/Ray
>
> > -----Original Message-----
> > From: Zeng, Star
> > Sent: Monday, June 26, 2017 1:41 PM
> > To: Ni, Ruiyu <ruiyu...@intel.com>; edk2-devel@lists.01.org
> > Cc: Gao, Liming <liming....@intel.com>; Zeng, Star
> > <star.z...@intel.com>
> > Subject: RE: [PATCH V2 3/3] DuetPkg FsVariable: Update
> > GetNextVariableName to follow UEFI 2.7
> >
> > It is to return EFI_INVALID_PARAMETER when the input VariableName
> > and VendorGuid are not a valid variable to search next variable.
> > It is added from UEFI 2.7 spec.
> > Before the spec change, the code is to return EFI_NOT_FOUND at that case.
> > After the spec change, EFI_NOT_FOUND seemingly is reserved to
> > indicate the ending of searching.
> >
> >
> > Thanks,
> > Star
> > -----Original Message-----
> > From: Ni, Ruiyu
> > Sent: Monday, June 26, 2017 1:37 PM
> > To: Zeng, Star <star.z...@intel.com>; edk2-devel@lists.01.org
> > Cc: Gao, Liming <liming....@intel.com>
> > Subject: RE: [PATCH V2 3/3] DuetPkg FsVariable: Update
> > GetNextVariableName to follow UEFI 2.7
> >
> > I understand your point.
> > But I do think it hurts readability.
> >
> > BTW, what does the below change does?
> > if (Variable.CurrPtr == NULL || EFI_ERROR (Status)) {
> > + if (VariableName[0] != 0) {
> > + //
> > + // The input values of VariableName and VendorGuid are not a
> > + name
> > and GUID of an existing variable.
> > + //
> > + Status = EFI_INVALID_PARAMETER;
> > + }
> > return Status;
> > }
> >
> >
> > Thanks/Ray
> >
> > > -----Original Message-----
> > > From: Zeng, Star
> > > Sent: Monday, June 26, 2017 11:05 AM
> > > To: Ni, Ruiyu <ruiyu...@intel.com>; edk2-devel@lists.01.org
> > > Cc: Gao, Liming <liming....@intel.com>; Zeng, Star
> > > <star.z...@intel.com>
> > > Subject: RE: [PATCH V2 3/3] DuetPkg FsVariable: Update
> > > GetNextVariableName to follow UEFI 2.7
> > >
> > > Ray,
> > >
> > > The code is like low hanging fruit from my practice for me, and I
> > > don't think it hurts readability although it may not bring
> > > performance improvement, it depends on how many variables in
> > > variable region, how many times of calling GetNextVariableName,
> > > and how fast of
> > GetNextVariableName.
> > >
> > > The code practice I did is on NT32 and my real platforms. Is there
> > > anyone can make sure he/she tested all the systems in the world
> > > for their
> > code?
> > >
> > >
> > > Anyway, I can update the patch if you insist.
> > >
> > >
> > > Thanks,
> > > Star
> > > -----Original Message-----
> > > From: Ni, Ruiyu
> > > Sent: Saturday, June 24, 2017 10:08 AM
> > > To: Zeng, Star <star.z...@intel.com>; edk2-devel@lists.01.org
> > > Cc: Gao, Liming <liming....@intel.com>
> > > Subject: RE: [PATCH V2 3/3] DuetPkg FsVariable: Update
> > > GetNextVariableName to follow UEFI 2.7
> > >
> > > Star,
> > > I don't recommend to add the additional check for performance
> > > consideration.
> > > Because we have no idea what the input VariableName buffer is like.
> > > If the VariableName is like ['\0', '?', '?', '?'] with MaxLen
> > > equals to 4, "VariableName[MaxLen-1] != 0" check is redundant.
> > > The NT32 case you met cannot represent the all possible cases.
> > > You could use the possibility theory to decide what the most
> > > efficient way
> > is.
> > >
> > > Additionally I think code readability is more important than efficiency.
> > > In this case, we need the data about the performance improvement
> > > to decide whether this check is necessary.
> > >
> > >
> > > Regards,
> > > Ray
> > >
> > > >-----Original Message-----
> > > >From: Zeng, Star
> > > >Sent: Friday, June 23, 2017 5:33 PM
> > > >To: Ni, Ruiyu <ruiyu...@intel.com>; edk2-devel@lists.01.org
> > > >Cc: Gao, Liming <liming....@intel.com>; Zeng, Star
> > > ><star.z...@intel.com>
> > > >Subject: RE: [PATCH V2 3/3] DuetPkg FsVariable: Update
> > > >GetNextVariableName to follow UEFI 2.7
> > > >
> > > >Ray,
> > > >
> > > >It is to pass the check quickly and avoid scanning all the chars
> > > >in VariableName by StrnLenS for normal boot without invalid cases.
> > > >I did experiments in the code of GetNextVariableName with below
> > > >debug code for normal boot on NT32 and my real platforms, all the
> > > >cases will go
> > > into the branch "xxx 2".
> > > > if (((VariableName[MaxLen - 1] != 0))) {
> > > > DEBUG ((DEBUG_INFO, "xxx 1\n")); } else {
> > > > DEBUG ((DEBUG_INFO, "xxx 2\n")); }
> > > >
> > > >
> > > >Thanks,
> > > >Star
> > > >-----Original Message-----
> > > >From: Ni, Ruiyu
> > > >Sent: Friday, June 23, 2017 4:20 PM
> > > >To: Zeng, Star <star.z...@intel.com>; edk2-devel@lists.01.org
> > > >Cc: Gao, Liming <liming....@intel.com>
> > > >Subject: RE: [PATCH V2 3/3] DuetPkg FsVariable: Update
> > > >GetNextVariableName to follow UEFI 2.7
> > > >
> > > >Star,
> > > >What's the benefit of this check "VariableName[MaxLen - 1] != 0"?
> > > >I think this check "StrnLenS (VariableName, MaxLen) == MaxLen"
> > > >should be
> > > enough.
> > > >
> > > >Thanks/Ray
> > > >
> > > >> -----Original Message-----
> > > >> From: Zeng, Star
> > > >> Sent: Friday, June 23, 2017 4:08 PM
> > > >> To: edk2-devel@lists.01.org
> > > >> Cc: Zeng, Star <star.z...@intel.com>; Gao, Liming
> > > >> <liming....@intel.com>; Ni, Ruiyu <ruiyu...@intel.com>
> > > >> Subject: [PATCH V2 3/3] DuetPkg FsVariable: Update
> > > >> GetNextVariableName to follow UEFI 2.7
> > > >>
> > > >> "The size must be large enough to fit input string supplied in
> > > >> VariableName buffer" is added in the description for
> VariableNameSize.
> > > >> And two cases of EFI_INVALID_PARAMETER are added.
> > > >> 1. The input values of VariableName and VendorGuid are not a
> > > >> name
> > and
> > > >> GUID of an existing variable.
> > > >> 2. Null-terminator is not found in the first VariableNameSize bytes of
> > > >> the input VariableName buffer.
> > > >>
> > > >> This patch is to update code to follow them.
> > > >>
> > > >> Cc: Liming Gao <liming....@intel.com>
> > > >> Cc: Ruiyu Ni <ruiyu...@intel.com>
> > > >> Contributed-under: TianoCore Contribution Agreement 1.0
> > > >> Signed-off-by: Star Zeng <star.z...@intel.com>
> > > >> ---
> > > >> DuetPkg/FSVariable/FSVariable.c | 21 ++++++++++++++++++++-
> > > >> 1 file changed, 20 insertions(+), 1 deletion(-)
> > > >>
> > > >> diff --git a/DuetPkg/FSVariable/FSVariable.c
> > > >> b/DuetPkg/FSVariable/FSVariable.c index
> > > >> 34b79305c871..6069cfa8fb98
> > > >> 100644
> > > >> --- a/DuetPkg/FSVariable/FSVariable.c
> > > >> +++ b/DuetPkg/FSVariable/FSVariable.c
> > > >> @@ -6,7 +6,7 @@ disk. They can be changed by user. BIOS is not
> > > >> able to protoect those.
> > > >> Duet trusts all meta data from disk. If variable code,
> > > >> variable metadata and variable data is modified in inproper
> > > >> way, the behavior is undefined.
> > > >>
> > > >> -Copyright (c) 2006 - 2016, Intel Corporation. All rights
> > > >> reserved.<BR>
> > > >> +Copyright (c) 2006 - 2017, Intel Corporation. All rights
> > > >> +reserved.<BR>
> > > >> This program and the accompanying materials are licensed and
> > > >> made available under the terms and conditions of the BSD
> > > >> License which accompanies this distribution. The full text of
> > > >> the license may be found at @@ -1400,14 +1400,33 @@ Returns:
> > > >> VARIABLE_POINTER_TRACK Variable;
> > > >> UINTN VarNameSize;
> > > >> EFI_STATUS Status;
> > > >> + UINTN MaxLen;
> > > >>
> > > >> if (VariableNameSize == NULL || VariableName == NULL ||
> > > >> VendorGuid ==
> > > >> NULL) {
> > > >> return EFI_INVALID_PARAMETER;
> > > >> }
> > > >>
> > > >> + //
> > > >> + // Calculate the possible maximum length of name string,
> > > >> + including the Null
> > > >> terminator.
> > > >> + //
> > > >> + MaxLen = *VariableNameSize / sizeof (CHAR16); if ((MaxLen
> > > >> + ==
> > > >> + 0)
> > > >> + ||
> > > >> + ((VariableName[MaxLen - 1] != 0) && (StrnLenS
> > > >> + (VariableName,
> > > >> + MaxLen)
> > > >> == MaxLen))) {
> > > >> + //
> > > >> + // Null-terminator is not found in the first
> > > >> + VariableNameSize bytes of the
> > > >> input VariableName buffer.
> > > >> + //
> > > >> + return EFI_INVALID_PARAMETER; }
> > > >> +
> > > >> Status = FindVariable (VariableName, VendorGuid, &Variable);
> > > >>
> > > >> if (Variable.CurrPtr == NULL || EFI_ERROR (Status)) {
> > > >> + if (VariableName[0] != 0) {
> > > >> + //
> > > >> + // The input values of VariableName and VendorGuid are
> > > >> + not a name
> > > >> and GUID of an existing variable.
> > > >> + //
> > > >> + Status = EFI_INVALID_PARAMETER;
> > > >> + }
> > > >> return Status;
> > > >> }
> > > >>
> > > >> --
> > > >> 2.7.0.windows.1
_______________________________________________
edk2-devel mailing list
edk2-devel@lists.01.org
https://lists.01.org/mailman/listinfo/edk2-devel
