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//! Configuration file support.
use std::{
env, fmt,
fs::{create_dir_all, File},
io::{self, Read},
path::{Path, PathBuf},
};
use toml_edit::{Array, Document, Item, Value};
use crate::common::*;
/// Return `dirs::config_dir()`.
#[cfg(not(target_os = "macos"))]
fn system_config_dir() -> Option<PathBuf> {
dirs::config_dir()
}
/// (Mac only.) Return `dirs::preference_dir()` if contains a `dbcrossbar`
/// directory, or `dirs::config_dir()` otherwise.
///
/// See https://github.com/dirs-dev/directories-rs/issues/62 for an explanation
/// of why this changed.
///
/// TODO: We should really use xdg directories on all platforms.
#[cfg(target_os = "macos")]
fn system_config_dir() -> Option<PathBuf> {
if let Some(preference_dir) = dirs::preference_dir() {
let old_config_dir = preference_dir.join("dbcrossbar");
if old_config_dir.is_dir() {
// Warn the user only once per run.
use std::sync::Once;
static ONCE: Once = Once::new();
ONCE.call_once(|| {
// Deprecate the old location.
if let Some(system_config_dir) = dirs::config_dir() {
let new_config_dir = system_config_dir.join("dbcrossbar");
eprintln!(
"DEPRECATION WARNING: Please move `{}` to `{}`",
old_config_dir.display(),
new_config_dir.display(),
);
}
});
return Some(preference_dir);
}
}
dirs::config_dir()
}
/// Find the path to our configuration directory.
pub(crate) fn config_dir() -> Result<PathBuf> {
// Use `var_os` instead of `var`, because if it returns a non-Unicode path,
// we can hand it off directly to `PathBuf`.
match env::var_os("DBCROSSBAR_CONFIG_DIR") {
// The user specified a config directory, so use that.
Some(dir) => Ok(PathBuf::from(dir)),
// Use `dbcrossbar/` in the system configuration directory.
None => Ok(system_config_dir()
// AFAIK, this only fails under weird conditions, such as no home
// directory.
.ok_or_else(|| format_err!("could not find user config dir"))?
.join("dbcrossbar")),
}
}
/// Find the path to our configuration file.
pub(crate) fn config_file() -> Result<PathBuf> {
Ok(config_dir()?.join("dbcrossbar.toml"))
}
/// A configuration file key.
///
/// This is opaque to allow for driver-specific and host-specific keys in the
/// future.
#[derive(Debug)]
pub struct Key<'a> {
/// The key in the TOML file.
key: &'a str,
}
impl Key<'_> {
/// A key for accessing `temporary`
pub fn temporary() -> Key<'static> {
Self::global("temporary")
}
/// A top-level configuration key.
pub(crate) fn global(key: &str) -> Key<'_> {
Key { key }
}
}
impl<'a> fmt::Display for Key<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.key.fmt(f)
}
}
/// Our `dbcrossbar.toml` configuration file.
#[derive(Debug)]
pub struct Configuration {
/// The path from which we read this file.
path: PathBuf,
/// Our raw configuration data.
doc: Document,
}
// A lot of the implementation of `Configuration` is fairly verbose, because
// we're using `toml_edit`. The upside of `toml_edit` is that it allows us to
// load, edit and configuration file without losing whitespace or comments that
// the user had in the file. The downside is that it's not nearly as nice as
// `serde`, and we have to manipulate a lot of dynamic, untyped data in Rust.
// This tends to be more verbose than either using `serde` or writing similar
// code in Ruby. But on the other hand: We can edit files with comments in them!
impl Configuration {
/// Load our default configuration.
pub fn try_default() -> Result<Self> {
Self::from_path(&config_file()?)
}
/// Load the configuration file at `path`.
pub(crate) fn from_path(path: &Path) -> Result<Self> {
match File::open(path) {
Ok(rdr) => Ok(Self::from_reader(path.to_owned(), rdr)
.with_context(|| format!("could not read file {}", path.display()))?),
Err(err) if err.kind() == io::ErrorKind::NotFound => Ok(Self {
path: path.to_owned(),
doc: Document::default(),
}),
Err(err) => {
Err(err).context(format!("could not open file {}", path.display()))
}
}
}
/// Load a configuration file from the specified reader.
fn from_reader<R>(path: PathBuf, mut rdr: R) -> Result<Self>
where
R: Read + 'static,
{
let mut buf = String::new();
rdr.read_to_string(&mut buf)?;
let doc = buf.parse::<Document>()?;
Ok(Self { path, doc })
}
/// Write the configuration file to disk.
pub fn write(&self) -> Result<()> {
let parent = self.path.parent().ok_or_else(|| {
format_err!("cannot find parent directory of {}", self.path.display())
})?;
create_dir_all(parent)
.with_context(|| format!("cannot create {}", parent.display()))?;
let data = self.doc.to_string();
let mut f = File::create(&self.path)
.with_context(|| format!("cannot create {}", self.path.display()))?;
f.write_all(data.as_bytes())
.with_context(|| format!("error writing to {}", self.path.display()))?;
f.flush()
.with_context(|| format!("error writing to {}", self.path.display()))?;
Ok(())
}
/// Return a list of places to store temporary data.
pub fn temporaries(&self) -> Result<Vec<String>> {
self.string_array(&Key::global("temporary"))
}
/// Get an array of strings from our config file.
fn string_array(&self, key: &Key<'_>) -> Result<Vec<String>> {
let mut temps = vec![];
if let Some(raw_value) = self.doc.as_table().get(key.key) {
if let Some(raw_array) = raw_value.as_array() {
for raw_item in raw_array.iter() {
if let Some(temp) = raw_item.as_str() {
temps.push(temp.to_owned());
} else {
return Err(format_err!(
"expected string, found {:?} in {}",
raw_item,
self.path.display(),
));
}
}
} else {
return Err(format_err!(
"expected array, found {:?} in {}",
raw_value,
self.path.display(),
));
}
}
Ok(temps)
}
/// Get our an array of strings in mutable form.
fn raw_string_array_mut<'a>(&'a mut self, key: &Key<'_>) -> Result<&'a mut Array> {
let array_value = self
.doc
.as_table_mut()
.entry(key.key)
.or_insert(Item::Value(Value::Array(Array::default())));
match array_value.as_array_mut() {
Some(array) => Ok(array),
None => Err(format_err!(
"expected array for {} in {}",
key,
self.path.display(),
)),
}
}
/// Add a new value to an array of strings, if it's not already there.
pub fn add_to_string_array(&mut self, key: &Key<'_>, value: &str) -> Result<()> {
let raw_array = self.raw_string_array_mut(key)?;
for raw_item in raw_array.iter() {
if raw_item.as_str() == Some(value) {
// Already present, so don't add it again.
return Ok(());
}
}
raw_array.push(value);
raw_array.fmt();
Ok(())
}
/// Remove a value from an array of strings, if present. If more
/// than one copy is present it will remove all.
pub fn remove_from_string_array(
&mut self,
key: &Key<'_>,
value: &str,
) -> Result<()> {
let raw_array = self.raw_string_array_mut(key)?;
// Find matches.
let mut indices = vec![];
for (idx, raw_item) in raw_array.iter().enumerate() {
if raw_item.as_str() == Some(value) {
indices.push(idx);
}
}
// Remove in reverse order to avoid invalidating indices.
for idx in indices.iter().rev().cloned() {
raw_array.remove(idx);
}
raw_array.fmt();
Ok(())
}
}
#[test]
fn temporaries_can_be_added_and_removed() {
let temp = tempfile::Builder::new()
.prefix("dbcrossbar")
.suffix(".toml")
.tempfile()
.unwrap();
let path = temp.path();
let mut config = Configuration::from_path(path).unwrap();
let key = Key::global("temporary");
assert_eq!(config.temporaries().unwrap(), Vec::<String>::new());
config.add_to_string_array(&key, "s3://example/").unwrap();
assert_eq!(config.temporaries().unwrap(), &["s3://example/".to_owned()]);
config.write().unwrap();
config = Configuration::from_path(path).unwrap();
assert_eq!(config.temporaries().unwrap(), &["s3://example/".to_owned()]);
config
.remove_from_string_array(&key, "s3://example/")
.unwrap();
assert_eq!(config.temporaries().unwrap(), Vec::<String>::new());
}