feat(android): add Rust cross-compilation setup for Android environment (#2650)

cibuildwheel/resources/_rust_shim.py

@@ -0,0 +1,57 @@
+#!/usr/bin/env python3
+
+import os
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+
+def main() -> None:
+    # CIBW_HOST_TRIPLET is set in the android_env to the Android target triplet.
+    target = os.environ.get("CIBW_HOST_TRIPLET")
+
+    cmd_name = Path(sys.argv[0]).name
+
+    # Find the real command in PATH, excluding the current script's directory
+    path_env = os.environ.get("PATH", "")
+    script_dir = Path(__file__).resolve().parent
+
+    paths = path_env.split(os.pathsep)
+    # Filter out the script directory to avoid recursion
+    filtered_paths = [p for p in paths if Path(p).resolve() != script_dir]
+    filtered_path_env = os.pathsep.join(filtered_paths)
+
+    real_cmd = shutil.which(cmd_name, path=filtered_path_env)
+
+    if not real_cmd:
+        sys.stderr.write(f"cibuildwheel: Error: Could not find system {cmd_name}\n")
+        sys.exit(1)
+
+    # If we have a target (i.e. we are in the android_env), try to install it.
+    if target:
+        # Check if rustup is available to install the target
+        rustup_path = shutil.which("rustup", path=filtered_path_env)
+
+        if rustup_path:
+            try:
+                # We call rustup to ensure the target is installed.
+                subprocess.run(
+                    [rustup_path, "target", "add", target],
+                    check=True,
+                    stdout=subprocess.DEVNULL,
+                    stderr=subprocess.PIPE,
+                    text=True,
+                )
+            except subprocess.CalledProcessError as e:
+                sys.stderr.write(
+                    f"cibuildwheel: Error: Failed to install Rust target {target}: {e.stderr}\n"
+                )
+                sys.exit(1)
+
+    # Execute the real command
+    os.execv(real_cmd, [real_cmd, *sys.argv[1:]])
+
+
+if __name__ == "__main__":
+    main()