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//! Zero-boilerplate configuration management
//!
//! ## Why?
//!
//! There are a lot of different requirements when
//! selecting, loading and writing a config,
//! depending on the operating system and other
//! environment factors.
//!
//! In many applications this burden is left to you,
//! the developer of an application, to figure out
//! where to place the configuration files.
//!
//! This is where `confy` comes in.
//!
//! ## Idea
//!
//! `confy` takes care of figuring out operating system
//! specific and environment paths before reading and
//! writing a configuration.
//!
//! It gives you easy access to a configuration file
//! which is mirrored into a Rust `struct` via [serde].
//! This way you only need to worry about the layout of
//! your configuration, not where and how to store it.
//!
//! [serde]: https://docs.rs/serde
//!
//! `confy` uses the [`Default`] trait in Rust to automatically
//! create a new configuration, if none is available to read
//! from yet.
//! This means that you can simply assume your application
//! to have a configuration, which will be created with
//! default values of your choosing, without requiring
//! any special logic to handle creation.
//!
//! [`Default`]: https://doc.rust-lang.org/std/default/trait.Default.html
//!
//! ```rust,no_run
//! use serde_derive::{Serialize, Deserialize};
//!
//! #[derive(Serialize, Deserialize)]
//! struct MyConfig {
//! version: u8,
//! api_key: String,
//! }
//!
//! /// `MyConfig` implements `Default`
//! impl ::std::default::Default for MyConfig {
//! fn default() -> Self { Self { version: 0, api_key: "".into() } }
//! }
//!
//! fn main() -> Result<(), confy::ConfyError> {
//! let cfg = confy::load("my-app-name", None)?;
//! Ok(())
//! }
//! ```
//!
//! Serde is a required dependency, and can be added with either the `serde_derive` crate or `serde` crate with feature derive as shown below
//!```toml,no_run
//![dependencies]
//!serde = { version = "1.0.152", features = ["derive"] } # <- Only one serde version needed (serde or serde_derive)
//!serde_derive = "1.0.152" # <- Only one serde version needed (serde or serde_derive)
//!confy = "^0.5"
//!```
//! Updating the configuration is then done via the [`store`] function.
//!
//! [`store`]: fn.store.html
//!
mod utils;
use utils::*;
use directories::ProjectDirs;
use serde::{de::DeserializeOwned, Serialize};
use std::fs::{self, File, OpenOptions, Permissions};
use std::io::{ErrorKind::NotFound, Write};
use std::path::{Path, PathBuf};
use thiserror::Error;
#[cfg(not(any(feature = "toml_conf", feature = "yaml_conf", feature = "ron_conf")))]
compile_error!(
"Exactly one config language feature must be enabled to use \
confy. Please enable one of either the `toml_conf`, `yaml_conf`, \
or `ron_conf` features."
);
#[cfg(any(
all(feature = "toml_conf", feature = "yaml_conf"),
all(feature = "toml_conf", feature = "ron_conf"),
all(feature = "ron_conf", feature = "yaml_conf"),
))]
compile_error!(
"Exactly one config language feature must be enabled to compile \
confy. Please disable one of either the `toml_conf`, `yaml_conf`, or `ron_conf` features. \
NOTE: `toml_conf` is a default feature, so disabling it might mean switching off \
default features for confy in your Cargo.toml"
);
#[cfg(feature = "toml_conf")]
const EXTENSION: &str = "toml";
#[cfg(feature = "yaml_conf")]
const EXTENSION: &str = "yml";
#[cfg(feature = "ron_conf")]
const EXTENSION: &str = "ron";
/// The errors the confy crate can encounter.
#[derive(Debug, Error)]
pub enum ConfyError {
#[cfg(feature = "toml_conf")]
#[error("Bad TOML data")]
BadTomlData(#[source] toml::de::Error),
#[cfg(feature = "yaml_conf")]
#[error("Bad YAML data")]
BadYamlData(#[source] serde_yaml::Error),
#[cfg(feature = "ron_conf")]
#[error("Bad RON data")]
BadRonData(#[source] ron::error::SpannedError),
#[error("Failed to create directory")]
DirectoryCreationFailed(#[source] std::io::Error),
#[error("Failed to load configuration file")]
GeneralLoadError(#[source] std::io::Error),
#[error("Bad configuration directory: {0}")]
BadConfigDirectory(String),
#[cfg(feature = "toml_conf")]
#[error("Failed to serialize configuration data into TOML")]
SerializeTomlError(#[source] toml::ser::Error),
#[cfg(feature = "yaml_conf")]
#[error("Failed to serialize configuration data into YAML")]
SerializeYamlError(#[source] serde_yaml::Error),
#[cfg(feature = "ron_conf")]
#[error("Failed to serialize configuration data into RON")]
SerializeRonError(#[source] ron::error::Error),
#[error("Failed to write configuration file")]
WriteConfigurationFileError(#[source] std::io::Error),
#[error("Failed to read configuration file")]
ReadConfigurationFileError(#[source] std::io::Error),
#[error("Failed to open configuration file")]
OpenConfigurationFileError(#[source] std::io::Error),
#[error("Failed to set configuration file permissions")]
SetPermissionsFileError(#[source] std::io::Error),
}
/// Load an application configuration from disk
///
/// A new configuration file is created with default values if none
/// exists.
///
/// Errors that are returned from this function are I/O related,
/// for example if the writing of the new configuration fails
/// or `confy` encounters an operating system or environment
/// that it does not support.
///
/// **Note:** The type of configuration needs to be declared in some way
/// that is inferable by the compiler. Also note that your
/// configuration needs to implement `Default`.
///
/// ```rust,no_run
/// # use confy::ConfyError;
/// # use serde_derive::{Serialize, Deserialize};
/// # fn main() -> Result<(), ConfyError> {
/// #[derive(Default, Serialize, Deserialize)]
/// struct MyConfig {}
///
/// let cfg: MyConfig = confy::load("my-app-name", None)?;
/// # Ok(())
/// # }
/// ```
pub fn load<'a, T: Serialize + DeserializeOwned + Default>(
app_name: &str,
config_name: impl Into<Option<&'a str>>,
) -> Result<T, ConfyError> {
get_configuration_file_path(app_name, config_name).and_then(load_path)
}
/// Load an application configuration from a specified path.
///
/// A new configuration file is created with default values if none
/// exists.
///
/// This is an alternate version of [`load`] that allows the specification of
/// an arbitrary path instead of a system one. For more information on errors
/// and behavior, see [`load`]'s documentation.
///
/// [`load`]: fn.load.html
pub fn load_path<T: Serialize + DeserializeOwned + Default>(
path: impl AsRef<Path>,
) -> Result<T, ConfyError> {
match File::open(&path) {
Ok(mut cfg) => {
let cfg_string = cfg
.get_string()
.map_err(ConfyError::ReadConfigurationFileError)?;
#[cfg(feature = "toml_conf")]
{
let cfg_data = toml::from_str(&cfg_string);
cfg_data.map_err(ConfyError::BadTomlData)
}
#[cfg(feature = "yaml_conf")]
{
let cfg_data = serde_yaml::from_str(&cfg_string);
cfg_data.map_err(ConfyError::BadYamlData)
}
#[cfg(feature = "ron_conf")]
{
let cfg_data = ron::from_str(&cfg_string);
cfg_data.map_err(ConfyError::BadRonData)
}
}
Err(ref e) if e.kind() == NotFound => {
if let Some(parent) = path.as_ref().parent() {
fs::create_dir_all(parent).map_err(ConfyError::DirectoryCreationFailed)?;
}
let cfg = T::default();
store_path(path, &cfg)?;
Ok(cfg)
}
Err(e) => Err(ConfyError::GeneralLoadError(e)),
}
}
/// Save changes made to a configuration object
///
/// This function will update a configuration,
/// with the provided values, and create a new one,
/// if none exists.
///
/// You can also use this function to create a new configuration
/// with different initial values than which are provided
/// by your `Default` trait implementation, or if your
/// configuration structure _can't_ implement `Default`.
///
/// ```rust,no_run
/// # use serde_derive::{Serialize, Deserialize};
/// # use confy::ConfyError;
/// # fn main() -> Result<(), ConfyError> {
/// #[derive(Serialize, Deserialize)]
/// struct MyConf {}
///
/// let my_cfg = MyConf {};
/// confy::store("my-app-name", None, my_cfg)?;
/// # Ok(())
/// # }
/// ```
///
/// Errors returned are I/O errors related to not being
/// able to write the configuration file or if `confy`
/// encounters an operating system or environment it does
/// not support.
pub fn store<'a, T: Serialize>(
app_name: &str,
config_name: impl Into<Option<&'a str>>,
cfg: T,
) -> Result<(), ConfyError> {
let path = get_configuration_file_path(app_name, config_name)?;
store_path(path, cfg)
}
/// Save changes made to a configuration object at a specified path
///
/// This is an alternate version of [`store`] that allows the specification of
/// file permissions that must be set. For more information on errors and
/// behavior, see [`store`]'s documentation.
///
/// [`store`]: fn.store.html
pub fn store_perms<'a, T: Serialize>(
app_name: &str,
config_name: impl Into<Option<&'a str>>,
cfg: T,
perms: Permissions,
) -> Result<(), ConfyError> {
let path = get_configuration_file_path(app_name, config_name)?;
store_path_perms(path, cfg, perms)
}
/// Save changes made to a configuration object at a specified path
///
/// This is an alternate version of [`store`] that allows the specification of
/// an arbitrary path instead of a system one. For more information on errors
/// and behavior, see [`store`]'s documentation.
///
/// [`store`]: fn.store.html
pub fn store_path<T: Serialize>(path: impl AsRef<Path>, cfg: T) -> Result<(), ConfyError> {
do_store(path.as_ref(), cfg, None)
}
/// Save changes made to a configuration object at a specified path
///
/// This is an alternate version of [`store_path`] that allows the
/// specification of file permissions that must be set. For more information on
/// errors and behavior, see [`store`]'s documentation.
///
/// [`store_path`]: fn.store_path.html
pub fn store_path_perms<T: Serialize>(
path: impl AsRef<Path>,
cfg: T,
perms: Permissions,
) -> Result<(), ConfyError> {
do_store(path.as_ref(), cfg, Some(perms))
}
fn do_store<T: Serialize>(
path: &Path,
cfg: T,
perms: Option<Permissions>,
) -> Result<(), ConfyError> {
let config_dir = path
.parent()
.ok_or_else(|| ConfyError::BadConfigDirectory(format!("{path:?} is a root or prefix")))?;
fs::create_dir_all(config_dir).map_err(ConfyError::DirectoryCreationFailed)?;
let s;
#[cfg(feature = "toml_conf")]
{
s = toml::to_string_pretty(&cfg).map_err(ConfyError::SerializeTomlError)?;
}
#[cfg(feature = "yaml_conf")]
{
s = serde_yaml::to_string(&cfg).map_err(ConfyError::SerializeYamlError)?;
}
#[cfg(feature = "ron_conf")]
{
let pretty_cfg = ron::ser::PrettyConfig::default();
s = ron::ser::to_string_pretty(&cfg, pretty_cfg).map_err(ConfyError::SerializeRonError)?;
}
let mut f = OpenOptions::new()
.write(true)
.create(true)
.truncate(true)
.open(path)
.map_err(ConfyError::OpenConfigurationFileError)?;
if let Some(p) = perms {
f.set_permissions(p)
.map_err(ConfyError::SetPermissionsFileError)?;
}
f.write_all(s.as_bytes())
.map_err(ConfyError::WriteConfigurationFileError)?;
Ok(())
}
/// Get the configuration file path used by [`load`] and [`store`]
///
/// This is useful if you want to show where the configuration file is to your user.
///
/// [`load`]: fn.load.html
/// [`store`]: fn.store.html
pub fn get_configuration_file_path<'a>(
app_name: &str,
config_name: impl Into<Option<&'a str>>,
) -> Result<PathBuf, ConfyError> {
let config_name = config_name.into().unwrap_or("default-config");
let project = ProjectDirs::from("rs", "", app_name).ok_or_else(|| {
ConfyError::BadConfigDirectory("could not determine home directory path".to_string())
})?;
let config_dir_str = get_configuration_directory_str(&project)?;
let path = [config_dir_str, &format!("{config_name}.{EXTENSION}")]
.iter()
.collect();
Ok(path)
}
fn get_configuration_directory_str(project: &ProjectDirs) -> Result<&str, ConfyError> {
let path = project.config_dir();
path.to_str()
.ok_or_else(|| ConfyError::BadConfigDirectory(format!("{path:?} is not valid Unicode")))
}
#[cfg(test)]
mod tests {
use super::*;
use serde::Serializer;
use serde_derive::{Deserialize, Serialize};
#[cfg(unix)]
use std::os::unix::fs::PermissionsExt;
#[derive(PartialEq, Default, Debug, Serialize, Deserialize)]
struct ExampleConfig {
name: String,
count: usize,
}
/// Run a test function with a temporary config path as fixture.
fn with_config_path(test_fn: fn(&Path)) {
let config_dir = tempfile::tempdir().expect("creating test fixture failed");
// config_path should roughly correspond to the result of `get_configuration_file_path("example-app", "example-config")`
let config_path = config_dir
.path()
.join("example-app")
.join("example-config")
.with_extension(EXTENSION);
test_fn(&config_path);
config_dir.close().expect("removing test fixture failed");
}
/// [`load_path`] loads [`ExampleConfig`].
#[test]
fn load_path_works() {
with_config_path(|path| {
let config: ExampleConfig = load_path(path).expect("load_path failed");
assert_eq!(config, ExampleConfig::default());
})
}
/// [`store_path`] stores [`ExampleConfig`].
#[test]
fn test_store_path() {
with_config_path(|path| {
let config: ExampleConfig = ExampleConfig {
name: "Test".to_string(),
count: 42,
};
store_path(path, &config).expect("store_path failed");
let loaded = load_path(path).expect("load_path failed");
assert_eq!(config, loaded);
})
}
/// [`store_path_perms`] stores [`ExampleConfig`], with only read permission for owner (UNIX).
#[test]
#[cfg(unix)]
fn test_store_path_perms() {
with_config_path(|path| {
let config: ExampleConfig = ExampleConfig {
name: "Secret".to_string(),
count: 16549,
};
store_path_perms(path, &config, Permissions::from_mode(0o600))
.expect("store_path_perms failed");
let loaded = load_path(path).expect("load_path failed");
assert_eq!(config, loaded);
})
}
/// [`store_path_perms`] stores [`ExampleConfig`], as read-only.
#[test]
fn test_store_path_perms_readonly() {
with_config_path(|path| {
let config: ExampleConfig = ExampleConfig {
name: "Soon read-only".to_string(),
count: 27115,
};
store_path(path, &config).expect("store_path failed");
let metadata = fs::metadata(path).expect("reading metadata failed");
let mut permissions = metadata.permissions();
permissions.set_readonly(true);
store_path_perms(path, &config, permissions).expect("store_path_perms failed");
assert!(fs::metadata(path)
.expect("reading metadata failed")
.permissions()
.readonly());
})
}
/// [`store_path`] fails when given a root path.
#[test]
fn test_store_path_root_error() {
let err = store_path(PathBuf::from("/"), &ExampleConfig::default())
.expect_err("store_path should fail");
assert_eq!(
err.to_string(),
r#"Bad configuration directory: "/" is a root or prefix"#,
)
}
struct CannotSerialize;
impl Serialize for CannotSerialize {
fn serialize<S>(&self, _serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
use serde::ser::Error;
Err(S::Error::custom("cannot serialize CannotSerialize"))
}
}
/// Verify that if you call store_path() with an object that fails to serialize,
/// the file on disk will not be overwritten or truncated.
#[test]
fn test_store_path_atomic() -> Result<(), ConfyError> {
let tmp = tempfile::NamedTempFile::new().expect("Failed to create NamedTempFile");
let path = tmp.path();
let message = "Hello world!";
// Write to file.
{
let mut f = OpenOptions::new()
.write(true)
.create(true)
.truncate(true)
.open(path)
.map_err(ConfyError::OpenConfigurationFileError)?;
f.write_all(message.as_bytes())
.map_err(ConfyError::WriteConfigurationFileError)?;
f.flush().map_err(ConfyError::WriteConfigurationFileError)?;
}
// Call store_path() to overwrite file with an object that fails to serialize.
let store_result = store_path(path, CannotSerialize);
assert!(matches!(store_result, Err(_)));
// Ensure file was not overwritten.
let buf = {
let mut f = OpenOptions::new()
.read(true)
.open(path)
.map_err(ConfyError::OpenConfigurationFileError)?;
let mut buf = String::new();
use std::io::Read;
f.read_to_string(&mut buf)
.map_err(ConfyError::ReadConfigurationFileError)?;
buf
};
assert_eq!(buf, message);
Ok(())
}
// Verify that [`load_path`] can deserialize into structs with differing names
// as long as they have the same fields
#[test]
fn test_change_struct_name() -> Result<(), ConfyError> {
with_config_path(|path| {
#[derive(PartialEq, Default, Debug, Serialize, Deserialize)]
struct AnotherExampleConfig {
name: String,
count: usize,
}
store_path(path, &ExampleConfig::default()).expect("store_path failed");
let _: AnotherExampleConfig = load_path(path).expect("load_path failed");
});
Ok(())
}
}