Add Executable struct181-migrate-gitlab-shell-checks-fallback

This struct is responsible for determining the name and
root dir of the executable.

The `RootDir` property will be used to find the config.

The `Name` property will be used to determine what `Command`
and `CommandArgs` to be built.

1 files changed, 58 insertions, 0 deletions

diff --git a/go/internal/executable/executable.go b/go/internal/executable/executable.go
new file mode 100644
index 0000000..63f4c90
--- /dev/null
+++ b/go/internal/executable/executable.go
@@ -0,0 +1,58 @@
+package executable
+
+import (
+	"os"
+	"path/filepath"
+)
+
+const (
+	GitlabShell               = "gitlab-shell"
+	AuthorizedKeysCheck       = "gitlab-shell-authorized-keys-check"
+	AuthorizedPrincipalsCheck = "gitlab-shell-authorized-principals-check"
+)
+
+type Executable struct {
+	Name    string
+	RootDir string
+}
+
+var (
+	// osExecutable is overridden in tests
+	osExecutable = os.Executable
+)
+
+func New() (*Executable, error) {
+	path, err := osExecutable()
+	if err != nil {
+		return nil, err
+	}
+
+	rootDir, err := findRootDir(path)
+	if err != nil {
+		return nil, err
+	}
+
+	executable := &Executable{
+		Name:    filepath.Base(path),
+		RootDir: rootDir,
+	}
+
+	return executable, nil
+}
+
+func findRootDir(path string) (string, error) {
+	// Start: /opt/.../gitlab-shell/bin/gitlab-shell
+	// Ends:  /opt/.../gitlab-shell
+	rootDir := filepath.Dir(filepath.Dir(path))
+	pathFromEnv := os.Getenv("GITLAB_SHELL_DIR")
+
+	if pathFromEnv != "" {
+		if _, err := os.Stat(pathFromEnv); os.IsNotExist(err) {
+			return "", err
+		}
+
+		rootDir = pathFromEnv
+	}
+
+	return rootDir, nil
+}