fix(unix): handle Statfs field types for disk space check (#646)

* fix(unix): handle Statfs field types for disk space check

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

* fix(freebsd): build disk space check without type mismatch

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

---------

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

cmd/bd/daemon_health_freebsd.go

@@ -0,0 +1,25 @@
+//go:build freebsd && !wasm
+
+package main
+
+import (
+	"golang.org/x/sys/unix"
+)
+
+// checkDiskSpace returns the available disk space in MB for the given path.
+// Returns (availableMB, true) on success, (0, false) on failure.
+func checkDiskSpace(path string) (uint64, bool) {
+	var stat unix.Statfs_t
+	if err := unix.Statfs(path, &stat); err != nil {
+		return 0, false
+	}
+
+	if stat.Bavail < 0 {
+		return 0, true
+	}
+
+	availableBytes := uint64(stat.Bavail) * stat.Bsize //nolint:gosec
+	availableMB := availableBytes / (1024 * 1024)
+
+	return availableMB, true
+}

cmd/bd/daemon_health_unix.go

@@ -1,4 +1,4 @@
-//go:build !windows && !wasm
+//go:build !windows && !wasm && !freebsd
 
 package main
 
@@ -14,8 +14,8 @@ func checkDiskSpace(path string) (uint64, bool) {
 		return 0, false
 	}
 
-	// Calculate available space in bytes, then convert to MB
-	// Bavail is uint64, Bsize is int64; overflow is intentional/safe in this context
+	// Calculate available space in bytes, then convert to MB.
+	// On most unix platforms, Bavail is unsigned but Bsize is signed.
 	availableBytes := stat.Bavail * uint64(stat.Bsize) //nolint:gosec
 	availableMB := availableBytes / (1024 * 1024)