OvmfPkg: Add C runtime apis referenced by Boringssl

[leenasoman]

Description

As part of the effort to get Boringssl to work with EDK2, there are many C runtime apis that get referenced and are currently not implemented in EDK2. This change adds those apis to edk2. In particular, this change adds the following :

Stubs for file functions. These have been implemented to return -1 rather than 0 since there is no file system support. This will ensure that any calls into these apis will return failure.

Implementations of the following api which are referenced and used by Boringssl code :
strdup : string duplication function
bsearch : binary search
getentropy : return entropy of requested length

• Breaking change?
  • Breaking change - Does this PR cause a break in build or boot behavior?
  • Examples: Does it add a new library class or move a module to a different repo.
• Impacts security?
  • Security - Does this PR have a direct security impact?
  • Examples: Crypto algorithm change or buffer overflow fix.
• Includes tests?
  • Tests - Does this PR include any explicit test code?
  • Examples: Unit tests or integration tests.

How This Was Tested

Integration Instructions

NA

[ardbiesheuvel]

Please provide some context about what BoringSSL is, why it exists and why it is important for us [Google] to support it in EDK2.

The changes themselves look reasonable to me, but it would be better to create a separate C file for them - that way, even non-LTO builds will only pull bsearch() or strdup() into the build if they are being used.

[leenasoman]

Thank you @ardbiesheuvel . I have addressed these comments, except that I kept strdup in CrtWrapper.c with other string functions.

Please provide some context about what BoringSSL is, why it exists and why it is important for us [Google] to support it in EDK2.

The changes themselves look reasonable to me, but it would be better to create a separate C file for them - that way, even non-LTO builds will only pull bsearch() or strdup() into the build if they are being used.

[ardbiesheuvel]

Thank you @ardbiesheuvel . I have addressed these comments, except that I kept strdup in CrtWrapper.c with other string functions.

OK

But please combine these changes into a single patch.

[liyi77]

Is this part of the work to bring in BoringSSL? I don't see the benefit of this change at the moment when BoringSSL is not supported in CryptoPkg yet.
I prefer to review it after your entire patch series is ready.

[leenasoman]

Is this part of the work to bring in BoringSSL? I don't see the benefit of this change at the moment when BoringSSL is not supported in CryptoPkg yet. I prefer to review it after your entire patch series is ready.
Thanks for the review. Yes it is part of the work. There will be more patches, but I think this patch adds stubs and generic utility functions, hence trying to upstream it.

[leenasoman]

Hi @liyi77 ,
Will it be possible to review and upstream this in parts? As stated earlier, this patch adds stubs and generic utility functions which might be useful for other consumers of CrtWrapper as well.