Use install.root in $CARGO_HOME/config.toml (#884)

Fixed #859

* Impl `cargo_config`
* Use `install.root` in `$CARGO_HOME/.cargo/config.toml`
   before fallback to `cargo_home`.
* Improve logging in `get_cargo_roots_path`

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

crates/bin/src/install_path.rs

@@ -4,23 +4,33 @@ use std::{
 };
 
 use binstalk::home::cargo_home;
+use binstalk_manifests::cargo_config::Config;
 use tracing::debug;
 
 pub fn get_cargo_roots_path(cargo_roots: Option<PathBuf>) -> Option<PathBuf> {
     if let Some(p) = cargo_roots {
-        return Some(p);
-    }
-
-    // Environmental variables
-    if let Some(p) = var_os("CARGO_INSTALL_ROOT") {
+        Some(p)
+    } else if let Some(p) = var_os("CARGO_INSTALL_ROOT") {
+        // Environmental variables
         let p = PathBuf::from(p);
         debug!("using CARGO_INSTALL_ROOT ({})", p.display());
-        return Some(p);
-    }
-
-    if let Ok(p) = cargo_home() {
-        debug!("using ({}) as cargo home", p.display());
         Some(p)
+    } else if let Ok(cargo_home) = cargo_home() {
+        let config_path = cargo_home.join("config.toml");
+        if let Some(root) = Config::load_from_path(&config_path)
+            .ok()
+            .and_then(|config| config.install.root)
+        {
+            debug!(
+                "using `install.root` {} from config {}",
+                root.display(),
+                config_path.display()
+            );
+            Some(root)
+        } else {
+            debug!("using ({}) as cargo home", cargo_home.display());
+            Some(cargo_home)
+        }
     } else {
         None
     }

crates/binstalk-manifests/src/cargo_config.rs

@@ -0,0 +1,161 @@
+//! Cargo's `.cargo/config.toml`
+//!
+//! This manifest is used by Cargo to load configurations stored by users.
+//!
+//! Binstall reads from them to be compatible with `cargo-install`'s behavior.
+
+use std::{
+    fs::File,
+    io,
+    path::{Path, PathBuf},
+};
+
+use compact_str::CompactString;
+use fs_lock::FileLock;
+use home::cargo_home;
+use miette::Diagnostic;
+use serde::Deserialize;
+use thiserror::Error;
+
+#[derive(Debug, Default, Deserialize)]
+pub struct Install {
+    /// `cargo install` destination directory
+    pub root: Option<PathBuf>,
+}
+
+#[derive(Debug, Default, Deserialize)]
+pub struct Http {
+    /// HTTP proxy in libcurl format: "host:port"
+    pub proxy: Option<CompactString>,
+    /// timeout for each HTTP request, in seconds
+    pub timeout: Option<u64>,
+    /// path to Certificate Authority (CA) bundle
+    pub cainfo: Option<PathBuf>,
+    // TODO:
+    // Support field ssl-version, ssl-version.max, ssl-version.min,
+    // which needs `toml_edit::Item`.
+}
+
+#[derive(Debug, Default, Deserialize)]
+pub struct Config {
+    pub install: Install,
+    pub http: Http,
+    // TODO:
+    // Add support for section patch, source and registry for alternative
+    // crates.io registry.
+
+    // TODO:
+    // Add field env for specifying env vars
+    // which needs `toml_edit::Item`.
+}
+
+fn join_if_relative(path: &mut Option<PathBuf>, dir: &Path) {
+    match path {
+        Some(path) if path.is_relative() => *path = dir.join(&path),
+        _ => (),
+    }
+}
+
+impl Config {
+    pub fn default_path() -> Result<PathBuf, ConfigLoadError> {
+        Ok(cargo_home()?.join("config.toml"))
+    }
+
+    pub fn load() -> Result<Self, ConfigLoadError> {
+        Self::load_from_path(Self::default_path()?)
+    }
+
+    /// * `dir` - path to the dir where the config.toml is located.
+    ///           For relative path in the config, `Config::load_from_reader`
+    ///           will join the `dir` and the relative path to form the final
+    ///           path.
+    pub fn load_from_reader<R: io::Read>(
+        mut reader: R,
+        dir: &Path,
+    ) -> Result<Self, ConfigLoadError> {
+        fn inner(reader: &mut dyn io::Read, dir: &Path) -> Result<Config, ConfigLoadError> {
+            let mut vec = Vec::new();
+            reader.read_to_end(&mut vec)?;
+
+            if vec.is_empty() {
+                Ok(Default::default())
+            } else {
+                let mut config: Config = toml_edit::de::from_slice(&vec)?;
+                join_if_relative(&mut config.install.root, dir);
+                join_if_relative(&mut config.http.cainfo, dir);
+                Ok(config)
+            }
+        }
+
+        inner(&mut reader, dir)
+    }
+
+    pub fn load_from_path(path: impl AsRef<Path>) -> Result<Self, ConfigLoadError> {
+        let path = path.as_ref();
+        let file = FileLock::new_shared(File::open(path)?)?;
+        // Any regular file must have a parent dir
+        Self::load_from_reader(file, path.parent().unwrap())
+    }
+}
+
+#[derive(Debug, Diagnostic, Error)]
+#[non_exhaustive]
+pub enum ConfigLoadError {
+    #[error("I/O Error: {0}")]
+    Io(#[from] io::Error),
+
+    #[error("Failed to deserialize toml: {0}")]
+    TomlParse(Box<toml_edit::de::Error>),
+}
+
+impl From<toml_edit::de::Error> for ConfigLoadError {
+    fn from(e: toml_edit::de::Error) -> Self {
+        ConfigLoadError::TomlParse(Box::new(e))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use std::io::Cursor;
+
+    const CONFIG: &str = r#"
+[env]
+# Set ENV_VAR_NAME=value for any process run by Cargo
+ENV_VAR_NAME = "value"
+# Set even if already present in environment
+ENV_VAR_NAME_2 = { value = "value", force = true }
+# Value is relative to .cargo directory containing `config.toml`, make absolute
+ENV_VAR_NAME_3 = { value = "relative/path", relative = true }
+
+[http]
+debug = false               # HTTP debugging
+proxy = "host:port"         # HTTP proxy in libcurl format
+timeout = 30                # timeout for each HTTP request, in seconds
+cainfo = "cert.pem"         # path to Certificate Authority (CA) bundle
+
+[install]
+root = "/some/path"         # `cargo install` destination directory
+    "#;
+
+    #[test]
+    fn test_loading() {
+        let config = Config::load_from_reader(Cursor::new(&CONFIG), Path::new("/root")).unwrap();
+
+        assert_eq!(
+            config.install.root.as_deref().unwrap(),
+            Path::new("/some/path")
+        );
+        assert_eq!(
+            config.http.proxy,
+            Some(CompactString::new_inline("host:port"))
+        );
+
+        assert_eq!(config.http.timeout, Some(30));
+        assert_eq!(
+            config.http.cainfo.as_deref().unwrap(),
+            Path::new("/root/cert.pem")
+        );
+    }
+}

crates/binstalk-manifests/src/lib.rs

@@ -11,6 +11,7 @@
 mod helpers;
 
 pub mod binstall_crates_v1;
+pub mod cargo_config;
 pub mod cargo_crates_v1;
 
 pub use binstalk_types::{cargo_toml_binstall, crate_info};