From 740f35790033dbf038040555c3884013db8290e6 Mon Sep 17 00:00:00 2001
From: upstream <upstream@localhost>
Date: Sat, 10 Oct 2026 12:28:07 +0200
Subject: [PATCH] Upstream twpayne/chezmoi state of the touched files before
 41a618c046

---
 internal/cmd/shellquote.go      | 67 +++++++++++++++++++++++++++++++++
 internal/cmd/shellquote_test.go | 60 +++++++++++++++++++++++++++++
 2 files changed, 127 insertions(+)
 create mode 100644 internal/cmd/shellquote.go
 create mode 100644 internal/cmd/shellquote_test.go

diff --git a/internal/cmd/shellquote.go b/internal/cmd/shellquote.go
new file mode 100644
index 0000000..95e3fd4
--- /dev/null
+++ b/internal/cmd/shellquote.go
@@ -0,0 +1,67 @@
+package cmd
+
+import (
+	"regexp"
+	"strings"
+)
+
+// nonShellLiteralRx is a regular expression that matches anything that is not a
+// shell literal.
+var nonShellLiteralRx = regexp.MustCompile(`[^+\-./0-9=A-Z_a-z]`)
+
+// shellQuote returns s quoted as a shell argument, if necessary.
+func shellQuote(s string) string {
+	const (
+		backslash   = '\\'
+		singleQuote = '\''
+	)
+
+	switch {
+	case s == "":
+		return "''"
+	case nonShellLiteralRx.MatchString(s):
+		result := make([]byte, 0, 2+len(s))
+		inSingleQuotes := false
+		for _, b := range []byte(s) {
+			switch b {
+			case backslash:
+				if !inSingleQuotes {
+					result = append(result, singleQuote)
+					inSingleQuotes = true
+				}
+				result = append(result, backslash, backslash)
+			case singleQuote:
+				if inSingleQuotes {
+					result = append(result, singleQuote)
+					inSingleQuotes = false
+				}
+				result = append(result, '\\', singleQuote)
+			default:
+				if !inSingleQuotes {
+					result = append(result, singleQuote)
+					inSingleQuotes = true
+				}
+				result = append(result, b)
+			}
+		}
+		if inSingleQuotes {
+			result = append(result, singleQuote)
+		}
+		return string(result)
+	default:
+		return s
+	}
+}
+
+// shellQuoteCommand returns a string containing command and args shell quoted.
+func shellQuoteCommand(command string, args []string) string {
+	if len(args) == 0 {
+		return shellQuote(command)
+	}
+	elems := make([]string, 1+len(args))
+	elems[0] = shellQuote(command)
+	for i, arg := range args {
+		elems[i+1] = shellQuote(arg)
+	}
+	return strings.Join(elems, " ")
+}
diff --git a/internal/cmd/shellquote_test.go b/internal/cmd/shellquote_test.go
new file mode 100644
index 0000000..8586209
--- /dev/null
+++ b/internal/cmd/shellquote_test.go
@@ -0,0 +1,60 @@
+package cmd
+
+import (
+	"maps"
+	"slices"
+	"testing"
+
+	"github.com/alecthomas/assert/v2"
+)
+
+func TestShellQuote(t *testing.T) {
+	tcs := map[string]string{
+		``:            `''`,
+		`'`:           `\'`,
+		`''`:          `\'\'`,
+		`'a'`:         `\''a'\'`,
+		`\`:           `'\\'`,
+		`\a`:          `'\\a'`,
+		`$a`:          `'$a'`,
+		`a`:           `a`,
+		`a/b`:         `a/b`,
+		`a b`:         `'a b'`,
+		`--arg`:       `--arg`,
+		`--arg=value`: `--arg=value`,
+		`it's`:        `'it'\''s'`,
+		`$(echo foo)`: `'$(echo foo)'`,
+	}
+	for _, s := range slices.Sorted(maps.Keys(tcs)) {
+		assert.Equal(t, tcs[s], shellQuote(s), "quoting %q", s)
+	}
+}
+
+func TestShellQuoteCommand(t *testing.T) {
+	for _, tc := range []struct {
+		command  string
+		args     []string
+		expected string
+	}{
+		{
+			command:  "command",
+			expected: "command",
+		},
+		{
+			command:  "command with spaces",
+			expected: "'command with spaces'",
+		},
+		{
+			command:  "command",
+			args:     []string{"arg1"},
+			expected: "command arg1",
+		},
+		{
+			command:  "command",
+			args:     []string{"arg1", "arg 2 with spaces"},
+			expected: "command arg1 'arg 2 with spaces'",
+		},
+	} {
+		assert.Equal(t, tc.expected, shellQuoteCommand(tc.command, tc.args))
+	}
+}