Remove generate-bindings feature from tss-esapi

[sarroutbi]

The generate-bindings feature causes tss-esapi-sys to regenerate FFI bindings from the system's tpm2-tss C headers at build time. On systems with tpm2-tss 4.x (e.g. Fedora 44), many TPM2 structs (TPML_DIGEST, TPMT_TK_HASHCHECK, TPM2B_ECC_POINT, etc.) are now opaque, which makes the regenerated bindings incompatible with tss-esapi 7.6.0 code that directly accesses struct fields.

Without this feature, tss-esapi-sys uses its pre-bundled bindings generated against tpm2-tss 3.x, which contain the correct non-opaque struct definitions expected by the Rust wrapper code.

[sarroutbi]

Example of a CI job where Fedora 44 compilation fails without this patch:
https://artifacts.dev.testing-farm.io/73a58516-f26b-450f-bf45-88c5bfd6260f/

[ansasaki]

If it uses the bindings generated for the tpm2-tss version 3.x, will it work with the version 4.x? I mean, apparently the ABI was broken from 3.x to 4.x (otherwise the bindings would work just fine). I'm trying to remember when we introduced the use of generate-bindings feature exactly to make it more flexible with these sudden breaking changes coming from the tpm stack.

[sarroutbi]

If it uses the bindings generated for the tpm2-tss version 3.x, will it work with the version 4.x? I mean, apparently the ABI was broken from 3.x to 4.x (otherwise the bindings would work just fine). I'm trying to remember when we introduced the use of generate-bindings feature exactly to make it more flexible with these sudden breaking changes coming from the tpm stack.

You're right that it was introduced for flexibility. Removing it is a workaround, not a proper fix. The correct long-term solution is to upgrade to tss-esapi 8.x, which properly supports the 4.x opaque API by using accessor functions instead of direct field access. But tss-esapi 8.0.0 is still in alpha, and, obviously, not available in Fedora.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.54%. Comparing base (28ee5b2) to head (058c826).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

Flag	Coverage Δ
e2e-testsuite	39.05% <ø> (-0.03%)	⬇️
upstream-unit-tests	66.13% <ø> (+0.01%)	⬆️

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[sarroutbi]

Fedora 44 compilation is fixed if this change is applied:
https://github.com/keylime/keylime/pull/1863/checks?check_run_id=66515389433

[ansasaki]

LGTM! Since the tests are now passing on Fedora 44, let's merge this (and hope breaking changes are not introduced again)