Add various support for cargo configuration.

Also adds support for parsing and reading configuration options/environment variables from cargo, and allows users to ignore config files in the package.

This adds the `[build.env.cargo-config]` option, which can be set to `complete`, `ignore`, or `default`. If set to `complete`, cross will have access to every to every cargo config file on the host (if using remote cross, a config file is written to a temporary file which is mounted on the data volume at `/.cargo/config.toml`). If set to ignore, any `.cargo/config.toml` files outside of `CARGO_HOME` are ignored, by mounting anonymous data volumes to hide config files in any `.cargo` directories. The default behavior uses the backwards-compatible behavior, allowing cross to access any config files in the package and `CARGO_HOME` directories. If the build is called outside the workspace root or at the workspace root, then we only mount an anonymous volume at `$PWD/.cargo`.

The alias support includes recursive subcommand detection, and errors before it invokes cargo. A sample error message is `[cross] error: alias y has unresolvable recursive definition: x -> y -> z -> a -> y`, and therefore can handle non-trivial recursive subcommands.

.changes/931.json

@@ -1,4 +1,12 @@
-{
-    "description": "deny installation of debian packages that conflict with our cross-compiler toolchains.",
-    "type": "fixed"
-}
+[
+    {
+        "description": "add support for cargo aliases.",
+        "type": "added",
+        "issues": [562]
+    },
+    {
+        "description": "allow users to ignore config files in the package.",
+        "type": "added",
+        "issues": [621]
+    }
+]

.changes/933.json

@@ -0,0 +1,4 @@
+{
+    "description": "deny installation of debian packages that conflict with our cross-compiler toolchains.",
+    "type": "fixed"
+}

docs/cross_toml.md

@@ -21,6 +21,7 @@ For example:
 
 ```toml
 [build.env]
+cargo-config = "complete"
 volumes = ["VOL1_ARG", "VOL2_ARG"]
 passthrough = ["IMPORTANT_ENV_VARIABLES"]
 ```
@@ -74,6 +75,7 @@ This is similar to `build.env`, but allows you to be more specific per target.
 
 ```toml
 [target.x86_64-unknown-linux-gnu.env]
+cargo-config = "ignore"
 volumes = ["VOL1_ARG", "VOL2_ARG"]
 passthrough = ["IMPORTANT_ENV_VARIABLES"]
 ```

src/bin/commands/containers.rs

@@ -392,7 +392,7 @@ pub fn create_persistent_volume(
     channel: Option<&Toolchain>,
     msg_info: &mut MessageInfo,
 ) -> cross::Result<()> {
-    let config = cross::config::Config::new(None);
+    let config = cross::CrossConfig::new(None);
     let toolchain_host: cross::Target = toolchain.into();
     let mut toolchain = QualifiedToolchain::default(&config, msg_info)?;
     toolchain.replace_host(&ImagePlatform::from_target(
@@ -483,7 +483,7 @@ pub fn remove_persistent_volume(
     channel: Option<&Toolchain>,
     msg_info: &mut MessageInfo,
 ) -> cross::Result<()> {
-    let config = cross::config::Config::new(None);
+    let config = cross::CrossConfig::new(None);
     let target_host: cross::Target = toolchain.into();
     let mut toolchain = QualifiedToolchain::default(&config, msg_info)?;
     toolchain.replace_host(&ImagePlatform::from_target(target_host.target().clone())?);

src/bin/cross.rs

@@ -8,18 +8,20 @@ use std::{
 use cross::{
     cargo, cli, rustc,
     shell::{self, Verbosity},
-    OutputExt, Subcommand,
+    CargoConfig, CargoToml, OutputExt, Subcommand,
 };
 
 pub fn main() -> cross::Result<()> {
     cross::install_panic_hook()?;
     cross::install_termination_hook()?;
 
     let target_list = rustc::target_list(&mut Verbosity::Quiet.into())?;
-    let args = cli::parse(&target_list)?;
+    let cargo_toml = CargoToml::read()?;
+    let cargo_config = CargoConfig::new(cargo_toml);
+    let args = cli::parse(&target_list, &cargo_config)?;
     let subcommand = args.subcommand;
     let mut msg_info = shell::MessageInfo::create(args.verbose, args.quiet, args.color.as_deref())?;
-    let status = match cross::run(args, target_list, &mut msg_info)? {
+    let status = match cross::run(args, target_list, cargo_config, &mut msg_info)? {
         Some(status) => status,
         None => {
             // if we fallback to the host cargo, use the same invocation that was made to cross

src/cargo_config.rs

@@ -0,0 +1,64 @@
+use std::collections::HashMap;
+
+use crate::cargo_toml::CargoToml;
+use crate::config::{split_to_cloned_by_ws, Environment};
+use crate::errors::*;
+
+pub const CARGO_NO_PREFIX_ENVVARS: &[&str] = &[
+    "http_proxy",
+    "TERM",
+    "RUSTDOCFLAGS",
+    "RUSTFLAGS",
+    "BROWSER",
+    "HTTPS_PROXY",
+    "HTTP_TIMEOUT",
+    "https_proxy",
+];
+
+#[derive(Debug)]
+struct CargoEnvironment(Environment);
+
+impl CargoEnvironment {
+    fn new(map: Option<HashMap<&'static str, &'static str>>) -> Self {
+        CargoEnvironment(Environment::new("CARGO", map))
+    }
+
+    pub fn alias(&self, name: &str) -> Option<Vec<String>> {
+        let key = format!("ALIAS_{name}");
+        self.0
+            .get_var(&self.0.var_name(&key))
+            .map(|x| split_to_cloned_by_ws(&x))
+    }
+}
+
+#[derive(Debug)]
+pub struct CargoConfig {
+    toml: Option<CargoToml>,
+    env: CargoEnvironment,
+}
+
+impl CargoConfig {
+    pub fn new(toml: Option<CargoToml>) -> Self {
+        CargoConfig {
+            toml,
+            env: CargoEnvironment::new(None),
+        }
+    }
+
+    pub fn alias(&self, name: &str) -> Result<Option<Vec<String>>> {
+        match self.env.alias(name) {
+            Some(alias) => Ok(Some(alias)),
+            None => match self.toml.as_ref() {
+                Some(t) => t.alias(name),
+                None => Ok(None),
+            },
+        }
+    }
+
+    pub fn to_toml(&self) -> Result<Option<String>> {
+        match self.toml.as_ref() {
+            Some(t) => Ok(Some(t.to_toml()?)),
+            None => Ok(None),
+        }
+    }
+}