feat: Parse Cargo's --manifest-path option to determine mounted docker

root

This commits adds support for parsing the `--manifest-path` option to cross. So
far, the `Cargo.toml` manifest of the crate (or its Cargo workspace) to compile
has been assumed to be in the current working directory. This means, that
relative crate dependencies were not supported, because those paths were not
mapped into the docker container.

Take the following example structure, where `my-bin` depends on `my-lib`:
.
├── my-bin
│   ├── Cargo.toml
│   └── src
│       └── main.rs
└── my-lib
    ├── Cargo.toml
    └── src
        └── lib.rs

This commits enables such scenarios, by running cross from `.` like so:
`cross build --manifest-path=my-lib/Cargo.toml --target x86_64-pc-windows-gnu`,
as `.` is mapped as the container's root, and the options passed through to
Cargo.

Related #388 #139 #277 #78

Co-authored-by: Kviring Alexey <alex@kviring.com>

CHANGELOG.md

@@ -45,6 +45,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Re-enabled `sparc64-unknown-linux-gnu` image
 - #582 - Added `libprocstat.so` to FreeBSD images
 - #665 - when not using [env.volumes](https://github.com/cross-rs/cross#mounting-volumes-into-the-build-environment), mount project in /project
+- #494 - Parse Cargo's --manifest-path option to determine mounted docker root
 
 
 ### Removed

README.md

@@ -367,6 +367,9 @@ $ QEMU_STRACE=1 cross run --target aarch64-unknown-linux-gnu
 - path dependencies (in Cargo.toml) that point outside the Cargo project won't
   work because `cross` use docker containers only mounts the Cargo project so
   the container doesn't have access to the rest of the filesystem.
+  However, you may use Cargo's `--manifest-path` option to reference your
+  target crate, executed from a common root directory from which all your
+  dependencies are available.
 
 ## Minimum Supported Rust Version (MSRV)
 

src/cargo.rs

@@ -1,9 +1,12 @@
 use serde::Deserialize;
+use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::process::{Command, ExitStatus};
 
+use crate::cli::Args;
+use crate::config::Config;
 use crate::errors::*;
-use crate::extensions::CommandExt;
+use crate::extensions::{CommandExt, OutputExt};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum Subcommand {
@@ -52,42 +55,63 @@ impl<'a> From<&'a str> for Subcommand {
     }
 }
 
-#[derive(Debug)]
-pub struct Root {
-    pub path: PathBuf,
+#[derive(Debug, Deserialize)]
+pub struct CargoMetadata {
+    pub workspace_root: PathBuf,
 }
 
-impl Root {
-    pub fn path(&self) -> &Path {
-        &self.path
+impl CargoMetadata {
+    pub fn workspace_root(&self) -> &Path {
+        &self.workspace_root
     }
 }
 
-/// Cargo project root
-pub fn root(cd: Option<&Path>) -> Result<Option<Root>> {
-    #[derive(Deserialize)]
-    struct Manifest {
-        workspace_root: PathBuf,
-    }
+/// Cargo metadata with specific invocation
+pub fn cargo_metadata_with_args(
+    cd: Option<&Path>,
+    args: Option<&Args>,
+) -> Result<Option<CargoMetadata>> {
     let mut command = std::process::Command::new(
         std::env::var("CARGO")
             .ok()
             .unwrap_or_else(|| "cargo".to_string()),
     );
-    command
-        .arg("metadata")
-        .arg("--format-version=1")
-        .arg("--no-deps");
+    command.arg("metadata").arg("--format-version=1");
+    if let Some(cd) = cd {
+        command.current_dir(cd);
+    }
+    if let Some(config) = args {
+        if let Some(ref manifest_path) = config.manifest_path {
+            command.args(["--manifest-path".as_ref(), manifest_path.as_os_str()]);
+        }
+    } else {
+        command.arg("--no-deps");
+    }
+    #[derive(Deserialize)]
+    struct Manifest {
+        workspace_root: PathBuf,
+    }
     if let Some(cd) = cd {
         command.current_dir(cd);
     }
-    let output = command.output()?;
+    let output = command.run_and_get_output(false)?;
+    if !output.status.success() {
+        let mut stderr = std::io::stderr();
+        stderr.write_all(&output.stderr)?;
+        stderr.flush()?;
+        std::process::exit(output.status.code().unwrap_or(1));
+    }
     let manifest: Option<Manifest> = serde_json::from_slice(&output.stdout)?;
-    Ok(manifest.map(|m| Root {
-        path: m.workspace_root,
+    Ok(manifest.map(|m| CargoMetadata {
+        workspace_root: m.workspace_root,
     }))
 }
 
+/// Cargo metadata
+pub fn cargo_metadata(cd: Option<&Path>) -> Result<Option<CargoMetadata>> {
+    cargo_metadata_with_args(cd, None)
+}
+
 /// Pass-through mode
 pub fn run(args: &[String], verbose: bool) -> Result<ExitStatus> {
     Command::new("cargo").args(args).run_and_get_status(verbose)

src/cli.rs

@@ -15,6 +15,7 @@ pub struct Args {
     pub target_dir: Option<PathBuf>,
     pub docker_in_docker: bool,
     pub enable_doctests: bool,
+    pub manifest_path: Option<PathBuf>,
 }
 
 // Fix for issue #581. target_dir must be absolute.
@@ -72,6 +73,7 @@ pub fn fmt_subcommands(stdout: &str) {
 pub fn parse(target_list: &TargetList) -> Result<Args> {
     let mut channel = None;
     let mut target = None;
+    let mut manifest_path: Option<PathBuf> = None;
     let mut target_dir = None;
     let mut sc = None;
     let mut all: Vec<String> = Vec::new();
@@ -82,7 +84,21 @@ pub fn parse(target_list: &TargetList) -> Result<Args> {
             if arg.is_empty() {
                 continue;
             }
-            if let ("+", ch) = arg.split_at(1) {
+            if arg == "--manifest-path" {
+                all.push(arg);
+                if let Some(m) = args.next() {
+                    let p = PathBuf::from(&m);
+                    all.push(m);
+                    manifest_path = env::current_dir().ok().map(|cwd| cwd.join(p));
+                }
+            } else if arg.starts_with("--manifest-path=") {
+                manifest_path = arg
+                    .split_once('=')
+                    .map(|x| x.1)
+                    .map(PathBuf::from)
+                    .and_then(|p| env::current_dir().ok().map(|cwd| cwd.join(p)));
+                all.push(arg);
+            } else if let ("+", ch) = arg.split_at(1) {
                 channel = Some(ch.to_string());
             } else if arg == "--target" {
                 all.push(arg);
@@ -131,5 +147,6 @@ pub fn parse(target_list: &TargetList) -> Result<Args> {
         target_dir,
         docker_in_docker,
         enable_doctests,
+        manifest_path,
     })
 }

src/docker.rs

@@ -2,7 +2,7 @@ use std::path::{Path, PathBuf};
 use std::process::{Command, ExitStatus};
 use std::{env, fs};
 
-use crate::cargo::Root;
+use crate::cargo::CargoMetadata;
 use crate::errors::*;
 use crate::extensions::{CommandExt, SafeCommand};
 use crate::id;
@@ -70,27 +70,29 @@ pub fn run(
     target: &Target,
     args: &[String],
     target_dir: &Option<PathBuf>,
-    root: &Root,
+    metadata: &CargoMetadata,
     config: &Config,
     uses_xargo: bool,
     sysroot: &Path,
     verbose: bool,
     docker_in_docker: bool,
+    cwd: &Path,
 ) -> Result<ExitStatus> {
     let mount_finder = if docker_in_docker {
         MountFinder::new(docker_read_mount_paths()?)
     } else {
         MountFinder::default()
     };
 
-    let root = root.path();
     let home_dir = home::home_dir().ok_or_else(|| eyre::eyre!("could not find home directory"))?;
     let cargo_dir = home::cargo_home()?;
     let xargo_dir = env::var_os("XARGO_HOME")
         .map(PathBuf::from)
         .unwrap_or_else(|| home_dir.join(".xargo"));
     let nix_store_dir = env::var_os("NIX_STORE").map(PathBuf::from);
-    let target_dir = target_dir.clone().unwrap_or_else(|| root.join("target"));
+    let target_dir = target_dir
+        .clone()
+        .unwrap_or_else(|| metadata.workspace_root().join("target"));
 
     // create the directories we are going to mount before we mount them,
     // otherwise `docker` will create them but they will be owned by `root`
@@ -102,7 +104,12 @@ pub fn run(
     let cargo_dir = mount_finder.find_mount_path(cargo_dir);
     let xargo_dir = mount_finder.find_mount_path(xargo_dir);
     let target_dir = mount_finder.find_mount_path(target_dir);
-    let host_root = mount_finder.find_mount_path(root);
+    // root is either workspace_root, or, if we're outside the workspace root, the current directory
+    let host_root = mount_finder.find_mount_path(if metadata.workspace_root().starts_with(cwd) {
+        cwd
+    } else {
+        metadata.workspace_root()
+    });
     let mount_root: PathBuf;
     #[cfg(target_os = "windows")]
     {
@@ -117,11 +124,11 @@ pub fn run(
     #[cfg(target_os = "windows")]
     {
         // On Windows, we can not mount the directory name directly. Instead, we use wslpath to convert the path to a linux compatible path.
-        mount_cwd = wslpath(&std::env::current_dir()?, verbose)?;
+        mount_cwd = wslpath(&cwd, verbose)?;
     }
     #[cfg(not(target_os = "windows"))]
     {
-        mount_cwd = mount_finder.find_mount_path(std::env::current_dir()?);
+        mount_cwd = mount_finder.find_mount_path(cwd);
     }
     let sysroot = mount_finder.find_mount_path(sysroot);
 
@@ -145,6 +152,12 @@ pub fn run(
         docker.args(&["-e", var]);
     }
     let mut env_volumes = false;
+    // FIXME(emilgardis 2022-04-07): This is a fallback so that if it's hard for use to do mounting logic, make it simple(r)
+    // Preferably we would not have to do this.
+    if cwd.strip_prefix(metadata.workspace_root()).is_err() {
+        env_volumes = true;
+    }
+
     for ref var in config.env_volumes(target)? {
         let (var, value) = validate_env_var(var)?;
         let value = match value {
@@ -247,12 +260,12 @@ pub fn run(
 
     if env_volumes {
         docker.args(&["-w".as_ref(), mount_cwd.as_os_str()]);
-    } else if mount_cwd == root {
+    } else if mount_cwd == metadata.workspace_root() {
         docker.args(&["-w", "/project"]);
     } else {
         // We do this to avoid clashes with path separators. Windows uses `\` as a path separator on Path::join
-        let cwd = &std::env::current_dir()?;
-        let working_dir = Path::new("project").join(cwd.strip_prefix(root)?);
+        let cwd = &cwd;
+        let working_dir = Path::new("project").join(cwd.strip_prefix(metadata.workspace_root())?);
         // No [T].join for OsStr
         let mut mount_wd = std::ffi::OsString::new();
         for part in working_dir.iter() {

src/main.rs

@@ -25,7 +25,7 @@ use config::Config;
 use rustc_version::Channel;
 use serde::Deserialize;
 
-use self::cargo::{Root, Subcommand};
+use self::cargo::{CargoMetadata, Subcommand};
 use self::cross_toml::CrossToml;
 use self::errors::*;
 use self::extensions::OutputExt;
@@ -282,9 +282,10 @@ fn run() -> Result<ExitStatus> {
 
     let host_version_meta =
         rustc_version::version_meta().wrap_err("couldn't fetch the `rustc` version")?;
-    if let Some(root) = cargo::root(None)? {
+    let cwd = std::env::current_dir()?;
+    if let Some(metadata) = cargo::cargo_metadata_with_args(Some(&cwd), Some(&args))? {
         let host = host_version_meta.host();
-        let toml = toml(&root)?;
+        let toml = toml(&metadata)?;
         let config = Config::new(toml);
         let target = args
             .target
@@ -407,16 +408,18 @@ fn run() -> Result<ExitStatus> {
                     docker::register(&target, verbose)?
                 }
 
+                let docker_root = env::current_dir()?;
                 return docker::run(
                     &target,
                     &filtered_args,
                     &args.target_dir,
-                    &root,
+                    &metadata,
                     &config,
                     uses_xargo,
                     &sysroot,
                     verbose,
                     args.docker_in_docker,
+                    &cwd,
                 );
             }
         }
@@ -489,10 +492,10 @@ pub(crate) fn warn_host_version_mismatch(
 
 /// Parses the `Cross.toml` at the root of the Cargo project or from the
 /// `CROSS_CONFIG` environment variable (if any exist in either location).
-fn toml(root: &Root) -> Result<Option<CrossToml>> {
+fn toml(root: &CargoMetadata) -> Result<Option<CrossToml>> {
     let path = match env::var("CROSS_CONFIG") {
         Ok(var) => PathBuf::from(var),
-        Err(_) => root.path().join("Cross.toml"),
+        Err(_) => root.workspace_root().join("Cross.toml"),
     };
 
     if path.exists() {
@@ -505,7 +508,7 @@ fn toml(root: &Root) -> Result<Option<CrossToml>> {
         Ok(Some(config))
     } else {
         // Checks if there is a lowercase version of this file
-        if root.path().join("cross.toml").exists() {
+        if root.workspace_root().join("cross.toml").exists() {
             eprintln!("There's a file named cross.toml, instead of Cross.toml. You may want to rename it, or it won't be considered.");
         }
         Ok(None)

src/tests.rs

@@ -7,18 +7,17 @@ use std::{
 
 use once_cell::sync::OnceCell;
 use rustc_version::VersionMeta;
-use serde::Deserialize;
 
 static WORKSPACE: OnceCell<PathBuf> = OnceCell::new();
 
 /// Returns the cargo workspace for the manifest
 pub fn get_cargo_workspace() -> &'static Path {
     let manifest_dir = env!("CARGO_MANIFEST_DIR");
     WORKSPACE.get_or_init(|| {
-        crate::cargo::root(Some(manifest_dir.as_ref()))
+        crate::cargo::cargo_metadata(Some(manifest_dir.as_ref()))
             .unwrap()
             .unwrap()
-            .path
+            .workspace_root
     })
 }