1 files changed, 59 insertions, 0 deletions
diff --git a/internal/environ.go b/internal/environ.go
new file mode 100644
index 00000000..25f44964
--- /dev/null
+++ b/internal/environ.go
@@ -0,0 +1,59 @@
+package internal
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"strconv"
+	"sync"
+
+	"git.ophivana.moe/cat/fortify/internal/verbose"
+)
+
+// state that remain constant for the lifetime of the process
+// fetched and cached here
+
+const (
+	xdgRuntimeDir = "XDG_RUNTIME_DIR"
+)
+
+// SystemConstants contains state from the operating system
+type SystemConstants struct {
+	// path to shared directory e.g. /tmp/fortify.%d
+	SharePath string `json:"share_path"`
+	// XDG_RUNTIME_DIR value e.g. /run/user/%d
+	RuntimePath string `json:"runtime_path"`
+	// application runtime directory e.g. /run/user/%d/fortify
+	RunDirPath string `json:"run_dir_path"`
+}
+
+var (
+	scVal  SystemConstants
+	scOnce sync.Once
+)
+
+func copySC() {
+	sc := SystemConstants{
+		SharePath: path.Join(os.TempDir(), "fortify."+strconv.Itoa(os.Geteuid())),
+	}
+
+	verbose.Println("process share directory at", sc.SharePath)
+
+	// runtimePath, runDirPath
+	if r, ok := os.LookupEnv(xdgRuntimeDir); !ok {
+		fmt.Println("Env variable", xdgRuntimeDir, "unset")
+		os.Exit(1)
+	} else {
+		sc.RuntimePath = r
+		sc.RunDirPath = path.Join(sc.RuntimePath, "fortify")
+		verbose.Println("XDG runtime directory at", sc.RunDirPath)
+	}
+
+	scVal = sc
+}
+
+// GetSC returns a populated SystemConstants value
+func GetSC() SystemConstants {
+	scOnce.Do(copySC)
+	return scVal
+}