Add a function for setting permission on directories

Author: cbandy

internal/shell/paths.go

@@ -0,0 +1,57 @@
+// Copyright 2024 - 2025 Crunchy Data Solutions, Inc.
+//
+// SPDX-License-Identifier: Apache-2.0
+
+// We want the [filepath] package to behave correctly for Linux containers.
+//go:build unix
+
+package shell
+
+import (
+	"fmt"
+	"io/fs"
+	"path/filepath"
+	"strings"
+)
+
+// MakeDirectories returns a list of POSIX shell commands that ensure each path
+// exists. It creates every directory leading to path from (but not including)
+// base and sets their permissions to exactly perms, regardless of umask.
+//
+// See:
+//   - https://pubs.opengroup.org/onlinepubs/9799919799/utilities/chmod.html
+//   - https://pubs.opengroup.org/onlinepubs/9799919799/utilities/mkdir.html
+//   - https://pubs.opengroup.org/onlinepubs/9799919799/utilities/test.html
+//   - https://pubs.opengroup.org/onlinepubs/9799919799/utilities/umask.html
+func MakeDirectories(perms fs.FileMode, base string, paths ...string) string {
+	// Without any paths, return a command that succeeds when the base path
+	// exists.
+	if len(paths) == 0 {
+		return `test -d ` + QuoteWord(base)
+	}
+
+	allPaths := append([]string(nil), paths...)
+	for _, p := range paths {
+		if r, err := filepath.Rel(base, p); err == nil && filepath.IsLocal(r) {
+			// The result of [filepath.Rel] is a shorter representation
+			// of the full path; skip it.
+			r = filepath.Dir(r)
+
+			for r != "." {
+				allPaths = append(allPaths, filepath.Join(base, r))
+				r = filepath.Dir(r)
+			}
+		}
+	}
+
+	return `` +
+		// Create all the paths and any missing parents.
+		`mkdir -p ` + strings.Join(QuoteWords(paths...), " ") +
+
+		// Set the permissions of every path and each parent.
+		// NOTE: FileMode bits other than file permissions are ignored.
+		fmt.Sprintf(` && chmod %#o %s`,
+			perms&fs.ModePerm,
+			strings.Join(QuoteWords(allPaths...), " "),
+		)
+}

internal/shell/paths_test.go

@@ -0,0 +1,66 @@
+// Copyright 2024 - 2025 Crunchy Data Solutions, Inc.
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package shell
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"gotest.tools/v3/assert"
+	"sigs.k8s.io/yaml"
+
+	"github.com/crunchydata/postgres-operator/internal/testing/require"
+)
+
+func TestMakeDirectories(t *testing.T) {
+	t.Parallel()
+
+	t.Run("NoPaths", func(t *testing.T) {
+		assert.Equal(t,
+			MakeDirectories(0o755, "/asdf/jklm"),
+			`test -d '/asdf/jklm'`)
+	})
+
+	t.Run("Children", func(t *testing.T) {
+		assert.DeepEqual(t,
+			MakeDirectories(0o775, "/asdf", "/asdf/jklm", "/asdf/qwerty"),
+			`mkdir -p '/asdf/jklm' '/asdf/qwerty' && chmod 0775 '/asdf/jklm' '/asdf/qwerty'`)
+	})
+
+	t.Run("Grandchild", func(t *testing.T) {
+		script := MakeDirectories(0o775, "/asdf", "/asdf/qwerty/boots")
+		assert.DeepEqual(t, script,
+			`mkdir -p '/asdf/qwerty/boots' && chmod 0775 '/asdf/qwerty/boots' '/asdf/qwerty'`)
+
+		t.Run("ShellCheckPOSIX", func(t *testing.T) {
+			shellcheck := require.ShellCheck(t)
+
+			dir := t.TempDir()
+			file := filepath.Join(dir, "script.sh")
+			assert.NilError(t, os.WriteFile(file, []byte(script), 0o600))
+
+			// Expect ShellCheck for "sh" to be happy.
+			// - https://www.shellcheck.net/wiki/SC2148
+			cmd := exec.Command(shellcheck, "--enable=all", "--shell=sh", file)
+			output, err := cmd.CombinedOutput()
+			assert.NilError(t, err, "%q\n%s", cmd.Args, output)
+		})
+	})
+
+	t.Run("Long", func(t *testing.T) {
+		script := MakeDirectories(0o700, "/", strings.Repeat("/asdf", 20))
+
+		t.Run("PrettyYAML", func(t *testing.T) {
+			b, err := yaml.Marshal(script)
+			s := string(b)
+			assert.NilError(t, err)
+			assert.Assert(t, !strings.HasPrefix(s, `"`) && !strings.HasPrefix(s, `'`),
+				"expected plain unquoted scalar, got:\n%s", b)
+		})
+	})
+}