feat: enforce formatter name format

Signed-off-by: Brian McGee <brian@bmcgee.ie>

Author: brianmcgee

cmd/root_test.go

@@ -332,6 +332,44 @@ func TestSpecifyingFormatters(t *testing.T) {
 			}),
 		)
 	})
+
+	t.Run("bad names", func(t *testing.T) {
+		for _, name := range []string{"foo$", "/bar", "baz%"} {
+			treefmt(t,
+				withArgs("--formatters", name),
+				withError(func(as *require.Assertions, err error) {
+					as.ErrorContains(err, fmt.Sprintf("formatter name %q is invalid", name))
+				}),
+			)
+
+			t.Setenv("TREEFMT_FORMATTERS", name)
+
+			treefmt(t,
+				withError(func(as *require.Assertions, err error) {
+					as.ErrorContains(err, fmt.Sprintf("formatter name %q is invalid", name))
+				}),
+			)
+
+			t.Setenv("TREEFMT_FORMATTERS", "")
+
+			cfg.FormatterConfigs[name] = &config.Formatter{
+				Command:  "echo",
+				Includes: []string{"*"},
+			}
+
+			test.WriteConfig(t, configPath, cfg)
+
+			treefmt(t,
+				withError(func(as *require.Assertions, err error) {
+					as.ErrorContains(err, fmt.Sprintf("formatter name %q is invalid", name))
+				}),
+			)
+
+			delete(cfg.FormatterConfigs, name)
+
+			test.WriteConfig(t, configPath, cfg)
+		}
+	})
 }
 
 func TestIncludesAndExcludes(t *testing.T) {
@@ -1633,7 +1671,7 @@ func TestStdin(t *testing.T) {
 	treefmt(t,
 		withArgs("--stdin", "../test.nix"),
 		withError(func(as *require.Assertions, err error) {
-			as.ErrorContains(err, fmt.Sprintf("path ../test.nix not inside the tree root %s", tempDir))
+			as.ErrorContains(err, "path ../test.nix not inside the tree root "+tempDir)
 		}),
 		withStderr(func(out []byte) {
 			as.Contains(string(out), "Error: path ../test.nix not inside the tree root")

config/config.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 
 	"github.com/numtide/treefmt/v2/walk"
@@ -210,12 +211,32 @@ func FromViper(v *viper.Viper) (*Config, error) {
 		cfg.Excludes = cfg.Global.Excludes
 	}
 
+	// validate formatter names do not contain invalid characters
+
+	nameRegex := regexp.MustCompile("^[a-zA-Z0-9_-]+$")
+
+	for name := range cfg.FormatterConfigs {
+		if !nameRegex.MatchString(name) {
+			return nil, fmt.Errorf(
+				"formatter name %q is invalid, must be of the form %s",
+				name, nameRegex.String(),
+			)
+		}
+	}
+
 	// filter formatters based on provided names
 	if len(cfg.Formatters) > 0 {
 		filtered := make(map[string]*Formatter)
 
 		// check if the provided names exist in the config
 		for _, name := range cfg.Formatters {
+			if !nameRegex.MatchString(name) {
+				return nil, fmt.Errorf(
+					"formatter name %q is invalid, must be of the form %s",
+					name, nameRegex.String(),
+				)
+			}
+
 			formatterCfg, ok := cfg.FormatterConfigs[name]
 			if !ok {
 				return nil, fmt.Errorf("formatter %v not found in config", name)