stash: add multicall support for stash-copy and stash-paste

We can finally tell the users that they can uninstall `wl-copy` and
`wl-paste` on their systems. Stash now somewhat supports being invoked
under the names `stash-copy` and `stash-paste` to fully reimplement the
functionality of `wl-copy` and `wl-paste` respectively.

A build wrapper has been added generate symlinks for `stash-copy`, `stash-paste`,
`wl-copy`, and `wl-paste`. `wl-copy` and `wl-paste` links are provided
only for backwards compatibility, but they will not go away anytime
soon.

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I6a6a6964463b35427cb720fbab68b252944cc90c

build.rs

@@ -0,0 +1,56 @@
+use std::{env, fs, path::Path};
+
+/// List of multicall symlinks to create (name, target)
+const MULTICALL_LINKS: &[&str] =
+  &["stash-copy", "stash-paste", "wl-copy", "wl-paste"];
+
+fn main() {
+  // Only run on Unix-like systems
+  #[cfg(not(unix))]
+  {
+    println!(
+      "cargo:warning=Multicall symlinks are only supported on Unix-like \
+       systems."
+    );
+    return;
+  }
+
+  // OUT_DIR is something like .../target/debug/build/<pkg>/out
+  // We want .../target/debug or .../target/release
+  let out_dir = env::var("OUT_DIR").expect("OUT_DIR not set");
+  let bin_dir = Path::new(&out_dir)
+    .ancestors()
+    .nth(3)
+    .expect("Failed to find binary dir");
+
+  // Path to the main stash binary
+  let stash_bin = bin_dir.join("stash");
+
+  // Create symlinks for each multicall binary
+  for link in MULTICALL_LINKS {
+    let link_path = bin_dir.join(link);
+    // Remove existing symlink or file if present
+    let _ = fs::remove_file(&link_path);
+    #[cfg(unix)]
+    {
+      use std::os::unix::fs::symlink;
+      match symlink(&stash_bin, &link_path) {
+        Ok(()) => {
+          println!(
+            "cargo:warning=Created symlink: {} -> {}",
+            link_path.display(),
+            stash_bin.display()
+          );
+        },
+        Err(e) => {
+          println!(
+            "cargo:warning=Failed to create symlink {} -> {}: {}",
+            link_path.display(),
+            stash_bin.display(),
+            e
+          );
+        },
+      }
+    }
+  }
+}