Support user-defined generic password options/attributes.

[tmpfs]

This is a quick sketch to discuss support for custom attributes/options when creating generic passwords.

The desire is to be able to support more complex use cases such as specifying kSecAccessControl, kSecAccessGroup etc. for a generic password.

Currently I've added this as an additional set_generic_password_options() function so as not to introduce any breaking changes but ultimately I think a builder style API for PasswordOptions would be more ergonomic. Perhaps:

let options = PasswordOptions::builder()
  .service("com.example")
  .account("user-id")
  .password("mock-password")
  .access_control(AccessControlOptions::USER_PRESENCE)
  .access_group("com.example.shared-keychain-group")
  .build()
  .unwrap();  // Panic here as kSecAccessControl and kSecAccessGroup are mutually exclusive?

Then we could make the breaking change that set_generic_password() just accepts PasswordOptions and the password and wouldn't need the additional function if that is acceptable for the next major release.

I notice in #186 there are other people that would also like to be able to use kSecAccessControl with SecItemAdd so I think it makes sense that we support the other attributes too.

Your thoughts and feedback would be appreciated 🙏

Closes #219

[crashdump]

Just for info, in the key management side of things, the pattern is to use a GenerateOptions struct which contains all your parameters, such as access control, etc.

rust-security-framework/security-framework/src/key.rs

Line 149 in b2189b2

pub fn new(options: &GenerateKeyOptions) -> Result<Self, CFError> {

pub struct GenerateKeyOptions {
    /// kSecAttrKeyType
    pub key_type: Option<KeyType>,
    /// kSecAttrKeySizeInBits
    pub size_in_bits: Option<u32>,
    /// kSecAttrLabel
    pub label: Option<String>,
    /// kSecAttrTokenID
    pub token: Option<Token>,
    /// Which keychain to store the key in, if any.
    pub location: Option<Location>,
    /// Access control
    pub access_control: Option<SecAccessControl>,
}

Validation parameters is implemented in the GenerateKeyOptions::to_dictionary() method.

[kornelski]

Thanks