Initial structure

internal/config/paths.go

@@ -0,0 +1,140 @@
+// Package config owns the on-disk layout of a node's state.
+//
+// Two YAML files live under the data directory:
+//
+//	node.yaml     — local identity, never replicated (id, addresses, key paths)
+//	cluster.yaml  — replicated state (peers, checks, alerts, version)
+//	trust.yaml    — local fingerprint trust store
+//	keys/         — RSA private + public keys + self-signed cert
+//	state.json    — runtime cache (last check results, current master)
+//
+// A unix socket for the local CLI lives alongside (defaults to
+// /var/run/quptime/quptime.sock when running as root, otherwise
+// $XDG_RUNTIME_DIR/quptime/quptime.sock).
+package config
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+)
+
+// Default file names. Callers should always go through DataDir() so an
+// override via QUPTIME_DIR is respected.
+const (
+	NodeFile    = "node.yaml"
+	ClusterFile = "cluster.yaml"
+	TrustFile   = "trust.yaml"
+	StateFile   = "state.json"
+	KeysDir     = "keys"
+	PrivateKey  = "private.pem"
+	PublicKey   = "public.pem"
+	CertFile    = "cert.pem"
+	SocketName  = "quptime.sock"
+
+	envDataDir = "QUPTIME_DIR"
+)
+
+// DataDir returns the configured data directory. Order of resolution:
+//  1. $QUPTIME_DIR if set
+//  2. /etc/quptime when running as root
+//  3. $XDG_CONFIG_HOME/quptime (or ~/.config/quptime) otherwise
+func DataDir() string {
+	if v := os.Getenv(envDataDir); v != "" {
+		return v
+	}
+	if os.Geteuid() == 0 {
+		return "/etc/quptime"
+	}
+	if v := os.Getenv("XDG_CONFIG_HOME"); v != "" {
+		return filepath.Join(v, "quptime")
+	}
+	home, err := os.UserHomeDir()
+	if err != nil || home == "" {
+		return "./quptime"
+	}
+	return filepath.Join(home, ".config", "quptime")
+}
+
+// SocketPath returns the unix socket used for local CLI ↔ daemon control.
+func SocketPath() string {
+	if v := os.Getenv("QUPTIME_SOCKET"); v != "" {
+		return v
+	}
+	if os.Geteuid() == 0 {
+		return "/var/run/quptime/" + SocketName
+	}
+	if v := os.Getenv("XDG_RUNTIME_DIR"); v != "" {
+		return filepath.Join(v, "quptime", SocketName)
+	}
+	return filepath.Join(os.TempDir(), "quptime-"+envUserSuffix(), SocketName)
+}
+
+func envUserSuffix() string {
+	if u := os.Getenv("USER"); u != "" {
+		return u
+	}
+	return "default"
+}
+
+// NodeFilePath returns the absolute path to node.yaml.
+func NodeFilePath() string { return filepath.Join(DataDir(), NodeFile) }
+
+// ClusterFilePath returns the absolute path to cluster.yaml.
+func ClusterFilePath() string { return filepath.Join(DataDir(), ClusterFile) }
+
+// TrustFilePath returns the absolute path to trust.yaml.
+func TrustFilePath() string { return filepath.Join(DataDir(), TrustFile) }
+
+// StateFilePath returns the absolute path to state.json.
+func StateFilePath() string { return filepath.Join(DataDir(), StateFile) }
+
+// PrivateKeyPath returns the absolute path to the RSA private key.
+func PrivateKeyPath() string { return filepath.Join(DataDir(), KeysDir, PrivateKey) }
+
+// PublicKeyPath returns the absolute path to the RSA public key.
+func PublicKeyPath() string { return filepath.Join(DataDir(), KeysDir, PublicKey) }
+
+// CertFilePath returns the absolute path to the self-signed cert (PEM).
+func CertFilePath() string { return filepath.Join(DataDir(), KeysDir, CertFile) }
+
+// EnsureDataDir creates the data directory tree if absent.
+func EnsureDataDir() error {
+	dir := DataDir()
+	if err := os.MkdirAll(filepath.Join(dir, KeysDir), 0o700); err != nil {
+		return err
+	}
+	return os.MkdirAll(filepath.Dir(SocketPath()), 0o700)
+}
+
+// AtomicWrite writes data to path through a temp file + rename. The temp
+// file is created in the same directory so the rename is atomic on POSIX.
+func AtomicWrite(path string, data []byte, perm os.FileMode) error {
+	if path == "" {
+		return errors.New("empty path")
+	}
+	dir := filepath.Dir(path)
+	if err := os.MkdirAll(dir, 0o700); err != nil {
+		return err
+	}
+	tmp, err := os.CreateTemp(dir, filepath.Base(path)+".tmp-*")
+	if err != nil {
+		return err
+	}
+	tmpName := tmp.Name()
+	if _, err := tmp.Write(data); err != nil {
+		tmp.Close()
+		os.Remove(tmpName)
+		return err
+	}
+	if err := tmp.Chmod(perm); err != nil {
+		tmp.Close()
+		os.Remove(tmpName)
+		return err
+	}
+	if err := tmp.Close(); err != nil {
+		os.Remove(tmpName)
+		return err
+	}
+	return os.Rename(tmpName, path)
+}