feature(metadata): get correct target dir when in workspace

Cargo.toml

@@ -17,6 +17,7 @@ gumdrop = "0.8"
 hmac-sha256 = "1.1"
 serde = { version = "1.0", features = ["derive"] }
 toml = "0.8"
+cargo_metadata = "0.19"
 
 [profile.release]
 lto = true

src/error.rs

@@ -10,6 +10,7 @@ pub(crate) enum Error {
     MissingMuslTarget,
     MissingLicense,
     TargetNotAbsolute(PathBuf),
+    Metadata(cargo_metadata::Error),
 }
 
 impl Display for Error {
@@ -29,6 +30,9 @@ impl Display for Error {
             Error::TargetNotAbsolute(p) => {
                 write!(f, "Target filepath is not absolute: {}", p.display())
             }
+            Error::Metadata(m) => {
+                write!(f, "Failed to gather metadata: {}", m)
+            }
         }
     }
 }
@@ -39,6 +43,12 @@ impl From<std::str::Utf8Error> for Error {
     }
 }
 
+impl From<cargo_metadata::Error> for Error {
+    fn from(v: cargo_metadata::Error) -> Self {
+        Self::Metadata(v)
+    }
+}
+
 impl From<toml::de::Error> for Error {
     fn from(v: toml::de::Error) -> Self {
         Self::Toml(v)

src/main.rs

@@ -2,6 +2,7 @@ mod error;
 
 use crate::error::Error;
 use cargo_aur::{GitHost, Package};
+use cargo_metadata::MetadataCommand;
 use colored::*;
 use gumdrop::{Options, ParsingStyle};
 use hmac_sha256::Hash;
@@ -99,12 +100,15 @@ fn work(args: Args) -> Result<(), Error> {
     // Where cargo expects to read and write to. By default we want to read the
     // built binary from `target/release` and we want to write our results to
     // `target/cargo-aur`, but these are configurable by the user.
-    let cargo_target: PathBuf = match std::env::var_os("CARGO_TARGET_DIR") {
-        Some(p) => PathBuf::from(p),
-        None => PathBuf::from("target"),
-    };
+    let metadata = MetadataCommand::new().exec()?;
+    let cargo_target: PathBuf = metadata.target_directory.canonicalize()?;
 
-    let output = args.output.unwrap_or(cargo_target.join("cargo-aur"));
+    let output = if let Some(pkgname) = metadata.root_package() {
+        args.output
+            .unwrap_or(cargo_target.join("cargo-aur").join(&pkgname.name))
+    } else {
+        args.output.unwrap_or(cargo_target.join("cargo-aur"))
+    };
 
     // Ensure the target can actually be written to. Otherwise the `tar`
     // operation later on will fail.