Prepare CLI for move into mainline

packages/cli/src/cargo.rs

@@ -0,0 +1,94 @@
+//! Utilities for working with cargo and rust files
+use crate::error::{Error, Result};
+use std::{
+    env, fs,
+    path::{Path, PathBuf},
+    process::Command,
+    str,
+};
+
+/// How many parent folders are searched for a `Cargo.toml`
+const MAX_ANCESTORS: u32 = 10;
+
+/// Some fields parsed from `cargo metadata` command
+pub struct Metadata {
+    pub workspace_root: PathBuf,
+    pub target_directory: PathBuf,
+}
+
+/// Returns the root of the crate that the command is run from
+///
+/// If the command is run from the workspace root, this will return the top-level Cargo.toml
+pub fn crate_root() -> Result<PathBuf> {
+    // From the current directory we work our way up, looking for `Cargo.toml`
+    env::current_dir()
+        .ok()
+        .and_then(|mut wd| {
+            for _ in 0..MAX_ANCESTORS {
+                if contains_manifest(&wd) {
+                    return Some(wd);
+                }
+                if !wd.pop() {
+                    break;
+                }
+            }
+            None
+        })
+        .ok_or_else(|| {
+            Error::CargoError("Failed to find directory containing Cargo.toml".to_string())
+        })
+}
+
+/// Checks if the directory contains `Cargo.toml`
+fn contains_manifest(path: &Path) -> bool {
+    fs::read_dir(path)
+        .map(|entries| {
+            entries
+                .filter_map(Result::ok)
+                .any(|ent| &ent.file_name() == "Cargo.toml")
+        })
+        .unwrap_or(false)
+}
+
+impl Metadata {
+    /// Returns the struct filled from `cargo metadata` output
+    /// TODO @Jon, find a different way that doesn't rely on the cargo metadata command (it's slow)
+    pub fn get() -> Result<Self> {
+        let output = Command::new("cargo")
+            .args(&["metadata"])
+            .output()
+            .map_err(|_| Error::CargoError("Manifset".to_string()))?;
+
+        if !output.status.success() {
+            let mut msg = str::from_utf8(&output.stderr).unwrap().trim();
+            if msg.starts_with("error: ") {
+                msg = &msg[7..];
+            }
+
+            return Err(Error::CargoError(msg.to_string()));
+        }
+
+        let stdout = str::from_utf8(&output.stdout).unwrap();
+        if let Some(line) = stdout.lines().next() {
+            let meta: serde_json::Value = serde_json::from_str(line)
+                .map_err(|_| Error::CargoError("InvalidOutput".to_string()))?;
+
+            let workspace_root = meta["workspace_root"]
+                .as_str()
+                .ok_or_else(|| Error::CargoError("InvalidOutput".to_string()))?
+                .into();
+
+            let target_directory = meta["target_directory"]
+                .as_str()
+                .ok_or_else(|| Error::CargoError("InvalidOutput".to_string()))?
+                .into();
+
+            return Ok(Self {
+                workspace_root,
+                target_directory,
+            });
+        }
+
+        Err(Error::CargoError("InvalidOutput".to_string()))
+    }
+}