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, 30 insertions, 6 deletions

diff --git a/go/internal/command/fallback/fallback.go b/go/internal/command/fallback/fallback.go
index 81baaf5..781eda1 100644
--- a/go/internal/command/fallback/fallback.go
+++ b/go/internal/command/fallback/fallback.go
@@ -1,33 +1,57 @@
 package fallback
 
 import (
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
 	"syscall"
 
 	"gitlab.com/gitlab-org/gitlab-shell/go/internal/command/commandargs"
+	"gitlab.com/gitlab-org/gitlab-shell/go/internal/executable"
 )
 
 type Command struct {
-	RootDir string
-	Args    commandargs.CommandArgs
+	Executable *executable.Executable
+	RootDir    string
+	Args       commandargs.CommandArgs
 }
 
 var (
 	// execFunc is overridden in tests
-	execFunc = syscall.Exec
+	execFunc  = syscall.Exec
+	whitelist = []string{
+		executable.GitlabShell,
+		executable.AuthorizedKeysCheck,
+		executable.AuthorizedPrincipalsCheck,
+	}
 )
 
 func (c *Command) Execute() error {
-	rubyCmd := filepath.Join(c.RootDir, "bin", c.fallbackProgram())
+	if !c.isWhitelisted() {
+		return errors.New("Failed to execute unknown executable")
+	}
+
+	rubyCmd := c.fallbackProgram()
 
 	// Ensure rubyArgs[0] is the full path to gitlab-shell-ruby
-	rubyArgs := append([]string{rubyCmd}, c.Args.Arguments()...)
+	rubyArgs := append([]string{rubyCmd}, c.Args.GetArguments()...)
 
 	return execFunc(rubyCmd, rubyArgs, os.Environ())
 }
 
+func (c *Command) isWhitelisted() bool {
+	for _, item := range whitelist {
+		if c.Executable.Name == item {
+			return true
+		}
+	}
+
+	return false
+}
+
 func (c *Command) fallbackProgram() string {
-	return fmt.Sprintf("%s-ruby", c.Args.Executable())
+	fileName := fmt.Sprintf("%s-ruby", c.Executable.Name)
+
+	return filepath.Join(c.RootDir, "bin", fileName)
 }