tools/lib/config_client/src/lib.rs

// Copyright 2021 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

//! Library for generating structured configuration accessors. Each generated
//! language-specific library depends on the output of [`create_fidl_source`].

pub mod cpp;
pub mod fidl;
pub mod rust;

use syn::Error as SynError;
use thiserror::Error;

// TODO(http://fxbug.dev/91666): This list should be kept in sync with fidlgen_rust.
const RESERVED_SUFFIXES: [&str; 7] =
    ["Impl", "Marker", "Proxy", "ProxyProtocol", "ControlHandle", "Responder", "Server"];

// TODO(http://fxbug.dev/91666): This list should be kept in sync with fidlgen_rust.
const RESERVED_WORDS: [&str; 73] = [
    "as",
    "box",
    "break",
    "const",
    "continue",
    "crate",
    "else",
    "enum",
    "extern",
    "false",
    "fn",
    "for",
    "if",
    "impl",
    "in",
    "let",
    "loop",
    "match",
    "mod",
    "move",
    "mut",
    "pub",
    "ref",
    "return",
    "self",
    "Self",
    "static",
    "struct",
    "super",
    "trait",
    "true",
    "type",
    "unsafe",
    "use",
    "where",
    "while",
    // Keywords reserved for future use (future-proofing...)
    "abstract",
    "alignof",
    "await",
    "become",
    "do",
    "final",
    "macro",
    "offsetof",
    "override",
    "priv",
    "proc",
    "pure",
    "sizeof",
    "typeof",
    "unsized",
    "virtual",
    "yield",
    // Weak keywords (special meaning in specific contexts)
    // These are ok in all contexts of fidl names.
    //"default",
    //"union",

    // Things that are not keywords, but for which collisions would be very unpleasant
    "Result",
    "Ok",
    "Err",
    "Vec",
    "Option",
    "Some",
    "None",
    "Box",
    "Future",
    "Stream",
    "Never",
    "Send",
    "fidl",
    "futures",
    "zx",
    "async",
    "on_open",
    "OnOpen",
    // TODO(fxbug.dev/66767): Remove "WaitForEvent".
    "wait_for_event",
    "WaitForEvent",
];

/// Error from generating a source file
#[derive(Debug, Error)]
pub enum SourceGenError {
    #[error("The given string `{input}` is not a valid Rust identifier")]
    InvalidIdentifier { input: String, source: SynError },
}

// TODO(http://fxbug.dev/91666): This logic should be kept in sync with fidlgen_rust.
fn normalize_field_key(key: &str) -> String {
    let mut identifier = String::new();
    let mut saw_lowercase_or_digit = false;
    for c in key.chars() {
        if c.is_ascii_uppercase() {
            if saw_lowercase_or_digit {
                // A lowercase letter or digit preceded this uppercase letter.
                // Break this into two words.
                identifier.push('_');
                saw_lowercase_or_digit = false;
            }
            identifier.push(c.to_ascii_lowercase());
        } else if c == '_' {
            identifier.push('_');
            saw_lowercase_or_digit = false;
        } else {
            identifier.push(c);
            saw_lowercase_or_digit = true;
        }
    }

    if RESERVED_WORDS.contains(&key) || RESERVED_SUFFIXES.iter().any(|s| key.starts_with(s)) {
        identifier.push('_')
    }

    identifier
}

#[cfg(test)]
mod tests {
    use super::*;
    use cm_rust::ConfigChecksum;
    use fidl_fuchsia_component_config_ext::config_decl;
    use quote::quote;

    fn test_checksum() -> ConfigChecksum {
        // sha256("Back to the Fuchsia")
        ConfigChecksum::Sha256([
            0xb5, 0xf9, 0x33, 0xe8, 0x94, 0x56, 0x3a, 0xf9, 0x61, 0x39, 0xe5, 0x05, 0x79, 0x4b,
            0x88, 0xa5, 0x3e, 0xd4, 0xd1, 0x5c, 0x32, 0xe2, 0xb4, 0x49, 0x9e, 0x42, 0xeb, 0xa3,
            0x32, 0xb1, 0xf5, 0xbb,
        ])
    }

    #[test]
    fn bad_field_names() {
        let decl = config_decl! {
            ck@ test_checksum(),
            snake_case_string: { bool },
            lowerCamelCaseString: { bool },
            UpperCamelCaseString: { bool },
            CONST_CASE: { bool },
            stringThatHas02Digits: { bool },
            mixedLowerCamel_snakeCaseString: { bool },
            MixedUpperCamel_SnakeCaseString: { bool },
            multiple__underscores: { bool },
            unsafe: { bool },
            ServerMode: { bool },
        };

        let observed_fidl_src = fidl::create_fidl_source(&decl, "cf.sc.internal".to_string());
        let expected_fidl_src = "
library cf.sc.internal;

type Config = struct {
  snake_case_string bool;
  lower_camel_case_string bool;
  upper_camel_case_string bool;
  const_case bool;
  string_that_has02_digits bool;
  mixed_lower_camel_snake_case_string bool;
  mixed_upper_camel_snake_case_string bool;
  multiple__underscores bool;
  unsafe_ bool;
  server_mode_ bool;
};
";
        assert_eq!(observed_fidl_src, expected_fidl_src);

        let actual_rust_src =
            rust::create_rust_wrapper(&decl, "cf.sc.internal".to_string()).unwrap();

        let expected_rust_src = quote! {
            use fidl_cf_sc_internal::Config as FidlConfig;
            use fidl::encoding::decode_persistent;
            use fuchsia_inspect::{Node};
            use fuchsia_runtime::{take_startup_handle, HandleInfo, HandleType};
            use fuchsia_zircon as zx;

            pub struct Config {
                pub snake_case_string: bool,
                pub lower_camel_case_string: bool,
                pub upper_camel_case_string: bool,
                pub const_case: bool,
                pub string_that_has02_digits: bool,
                pub mixed_lower_camel_snake_case_string: bool,
                pub mixed_upper_camel_snake_case_string: bool,
                pub multiple__underscores: bool,
                pub unsafe_: bool,
                pub server_mode_: bool
            }

            impl Config {
                pub fn take_from_startup_handle() -> Self {
                    let config_vmo: zx::Vmo = take_startup_handle(HandleInfo::new(HandleType::ConfigVmo, 0))
                        .expect("must have been provided with a config vmo")
                        .into();
                    let config_size = config_vmo.get_content_size().expect("must be able to read config vmo content size");
                    assert_ne!(config_size, 0, "config vmo must be non-empty");

                    let mut config_bytes = Vec::new();
                    config_bytes.resize(config_size as usize, 0);
                    config_vmo.read(&mut config_bytes, 0).expect("must be able to read config vmo");

                    let checksum_length = u16::from_le_bytes([config_bytes[0], config_bytes[1]]) as usize;
                    let fidl_start = 2 + checksum_length;
                    let observed_checksum = &config_bytes[2..fidl_start];
                    let expected_checksum = vec![
                        0xb5, 0xf9, 0x33, 0xe8, 0x94, 0x56, 0x3a, 0xf9, 0x61, 0x39, 0xe5, 0x05, 0x79,
                        0x4b, 0x88, 0xa5, 0x3e, 0xd4, 0xd1, 0x5c, 0x32, 0xe2, 0xb4, 0x49, 0x9e, 0x42,
                        0xeb, 0xa3, 0x32, 0xb1, 0xf5, 0xbb
                    ];

                    assert_eq!(observed_checksum, expected_checksum, "checksum from config VMO does not match expected checksum");

                    let fidl_config: FidlConfig = decode_persistent(&config_bytes[fidl_start..]).expect("must be able to parse bytes as config FIDL");

                    Self {
                        snake_case_string: fidl_config.snake_case_string,
                        lower_camel_case_string: fidl_config.lower_camel_case_string,
                        upper_camel_case_string: fidl_config.upper_camel_case_string,
                        const_case: fidl_config.const_case,
                        string_that_has02_digits: fidl_config.string_that_has02_digits,
                        mixed_lower_camel_snake_case_string: fidl_config.mixed_lower_camel_snake_case_string,
                        mixed_upper_camel_snake_case_string: fidl_config.mixed_upper_camel_snake_case_string,
                        multiple__underscores: fidl_config.multiple__underscores,
                        unsafe_: fidl_config.unsafe_,
                        server_mode_: fidl_config.server_mode_
                    }
                }
                pub fn record_inspect(&self, inspector_node : & Node) {
                    inspector_node.record_bool("snake_case_string", self.snake_case_string);
                    inspector_node.record_bool("lowerCamelCaseString", self.lower_camel_case_string);
                    inspector_node.record_bool("UpperCamelCaseString", self.upper_camel_case_string);
                    inspector_node.record_bool("CONST_CASE", self.const_case);
                    inspector_node.record_bool("stringThatHas02Digits", self.string_that_has02_digits);
                    inspector_node.record_bool("mixedLowerCamel_snakeCaseString", self.mixed_lower_camel_snake_case_string);
                    inspector_node.record_bool("MixedUpperCamel_SnakeCaseString", self.mixed_upper_camel_snake_case_string);
                    inspector_node.record_bool("multiple__underscores", self.multiple__underscores);
                    inspector_node.record_bool("unsafe", self.unsafe_);
                    inspector_node.record_bool("ServerMode", self.server_mode_);
                }
            }
        }.to_string();

        assert_eq!(actual_rust_src, expected_rust_src);
    }
}