cmd: build local package graphs

lib/os/os.ww

@@ -855,6 +855,27 @@ export fn stat(out: *filestat, path: str) (void | oserror) = {
 	fillfilestat(out, &k);
 };
 
+// samefile reports whether two existing paths resolve to the same kernel
+// object. It follows terminal symlinks, like stat(2), and compares both the
+// device and inode kept in the native stat record. Package loading uses this
+// narrow primitive to intern directories by identity without exposing a
+// platform-specific canonical pathname policy.
+export fn samefile(a: str, b: str) bool = {
+	let ap: *u8 = kpath(a);
+	if (ap == nil: *u8) { return false; };
+	let ak: kstat;
+	let ar: i64 = syscall4(nr.NEWFSTATAT,
+	    AT_FDCWD: i64, ap: i64, (&ak): i64, 0i64);
+	if (ar < 0) { return false; };
+	let bp: *u8 = kpath(b);
+	if (bp == nil: *u8) { return false; };
+	let bk: kstat;
+	let br: i64 = syscall4(nr.NEWFSTATAT,
+	    AT_FDCWD: i64, bp: i64, (&bk): i64, 0i64);
+	if (br < 0) { return false; };
+	return ak.dev == bk.dev && ak.ino == bk.ino;
+};
+
 // lstat — like [[stat]] but does NOT follow a terminal symlink.
 // Mirrors Hare's sys::lstat (ref/hare/sys/+linux/stat.ha:57).
 export fn lstat(out: *filestat, path: str) (void | oserror) = {