From d0a251916f5749a6411978ddd02f9fe856cf2c8c Mon Sep 17 00:00:00 2001
From: Ayman Bagabas <ayman.bagabas@gmail.com>
Date: Mon, 24 Apr 2023 13:44:35 -0400
Subject: [PATCH] fix: expand file path

Recognize tile `~` symbol and environment variables in path.

Fixes: 472a463d0e8d ("ref: change api to expose ssh.PublicKey and authorizd_key")

Signed-off-by: Ayman Bagabas <ayman.bagabas@gmail.com>
---
 keygen.go      | 16 +++++++++++++++-
 keygen_test.go | 21 +++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/keygen.go b/keygen.go
index d406380..37b5ce3 100644
--- a/keygen.go
+++ b/keygen.go
@@ -154,7 +154,7 @@ func WithEllipticCurve(curve elliptic.Curve) Option {
 func New(path string, opts ...Option) (*SSHKeyPair, error) {
 	var err error
 	s := &SSHKeyPair{
-		path:       path,
+		path:       expandPath(path),
 		rsaBitSize: rsaDefaultBits,
 		ec:         elliptic.P384(),
 		keyType:    Ed25519,
@@ -501,6 +501,20 @@ func fileExists(path string) bool {
 	return true
 }
 
+// expandPath resolves the tilde `~` and any environment variables in path.
+func expandPath(path string) string {
+	if len(path) > 0 && path[0] == '~' {
+		userdir, err := os.UserHomeDir()
+		if err != nil {
+			return path
+		}
+
+		path = filepath.Join(userdir, path[1:])
+	}
+
+	return os.ExpandEnv(path)
+}
+
 // attaches a user@host suffix to a serialized public key. returns the original
 // pubkey if we can't get the username or host.
 func pubKeyMemo() string {
diff --git a/keygen_test.go b/keygen_test.go
index 2ae8367..8188a95 100644
--- a/keygen_test.go
+++ b/keygen_test.go
@@ -336,3 +336,24 @@ func TestKeynameSuffix(t *testing.T) {
 		})
 	}
 }
+
+func TestExpandPath(t *testing.T) {
+	tmpdir := t.TempDir()
+	os.Setenv("TEMP", tmpdir)
+	defer os.Unsetenv("TEMP")
+
+	// Test environment variable expansion
+	if fp := expandPath(filepath.Join("$TEMP", "testkey")); fp != filepath.Join(tmpdir, "testkey") {
+		t.Errorf("error expanding path: %s", fp)
+	}
+
+	// Test tilde expansion
+	homedir, err := os.UserHomeDir()
+	if err != nil {
+		t.Fatalf("error getting user home directory: %v", err)
+	}
+
+	if fp := expandPath(filepath.Join("~", "testkey")); fp != filepath.Join(homedir, "testkey") {
+		t.Errorf("error expanding path: %s", fp)
+	}
+}