Signing a fat binary may result in different binary identifier in csreq about apple-platform-rs

[roblabla]

I think the problem comes from as_nested_macho_settings. Essentially, in import_settings_from_macho, we set the binary_identifier for each sub-binary using the SettingsScope::MultiArchIndex scope. The problem is, this happens before the Info.plist is parsed and sets the binary_identifier at the Main scope level (as evidenced by the logs:

WARN apple_codesign::bundle_signing: signing main executable Contents/MacOS/test
    at /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/apple-codesign-0.17.0/src/bundle_signing.rs:574
INFO apple_codesign::signing_settings: inferring default signing settings from Mach-O binary
    at /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/apple-codesign-0.17.0/src/signing_settings.rs:754
INFO apple_codesign::signing_settings: preserving existing binary identifier in Mach-O
    at /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/apple-codesign-0.17.0/src/signing_settings.rs:809
INFO apple_codesign::signing_settings: using team ID from settings
    at /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/apple-codesign-0.17.0/src/signing_settings.rs:817
INFO apple_codesign::signing_settings: using code signature flags from settings
    at /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/apple-codesign-0.17.0/src/signing_settings.rs:828
INFO apple_codesign::bundle_signing: setting main executable binary identifier to quick.test (derived from CFBundleIdentifier in Info.plist)
    at /usr/local/cargo/registry/src/github.com-1ecc6299db9ec823/apple-codesign-0.17.0/src/bundle_signing.rs:589

So we now have a SigningSettings that contains both a binary_identifier on scope Main, and binary_identifiers with scope SettingsScope::MultiArchIndex. At this point, as_nested_macho_settings, through clone_with_filter_map, will bring the binary_identifiers with the correct MultiArchIndex scope into the Main scope, potentially colliding with the one set by the Info.plist. And at that point, hell ensues.

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I think the proper solution is to either parse the Info.plist first, or make it so that when we set a binary identifier with the main scope in the SigningSettings, it automatically drops those in the Multi* subscopes.

[roblabla]

FWIW: I found out about this because TCC had the weirdest behavior with my binaries. My app needs "Full Disk Access" permission, and when I'd tick the box to give it in the "Security & Privacy" preference pannel, it'd untick the next time I'd start. After a lot of debugging, I figured that those different bundle identifiers were the cause! The AArch64 binary didn't match the Info.plist, so macos was very confused about it!

[indygreg]

Thanks for filing this.

The binary identifier logic is a bit convoluted and I'm honestly not sure what the correct logic should be! I feel like someone will have to test what codesign does and then emulate that behavior in our code.