pkg/environment: Migrate fs functions to fsx

pkg/fsx/unmasked.go

@@ -0,0 +1,101 @@
+package fsx
+
+import (
+	"io/fs"
+	"os"
+	"sync"
+	"syscall"
+	"time"
+)
+
+// mask is the global mask lock
+var m mask
+
+// mask allows disabling and re-enabling the global umask.
+// it is used by allow functions of this package.
+type mask struct {
+	l     sync.Mutex // locked?
+	umask int        // previous mask
+}
+
+// Lock blocks until no other function is using this umask
+// and then sets it to 0.
+func (mask *mask) Lock() {
+	mask.l.Lock()
+	mask.umask = syscall.Umask(0)
+}
+
+func (mask *mask) Unlock() {
+	mask.umask = syscall.Umask(mask.umask)
+	mask.l.Unlock()
+}
+
+// WriteFile is like [os.WriteFile], but ignores the umask.
+func WriteFile(path string, data []byte, mode fs.FileMode) error {
+	handle, err := Create(path, mode)
+	if err != nil {
+		return err
+	}
+	defer handle.Close()
+
+	if _, err := handle.Write(data); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// Create creates a new file with the given mode.
+// This function ignores the umask.
+func Create(path string, mode fs.FileMode) (*os.File, error) {
+	m.Lock()
+	defer m.Unlock()
+
+	return os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode)
+}
+
+// Mkdir creates a new directory with the given mode.
+// This function ignores the umask.
+func Mkdir(path string, mode fs.FileMode) error {
+	m.Lock()
+	defer m.Unlock()
+
+	return os.Mkdir(path, fs.ModeDir|mode)
+}
+
+// MkdirAll creates a new directory and all potentially missing parent directories.
+// This function ignores the umask.
+func MkdirAll(path string, mode fs.FileMode) error {
+	m.Lock()
+	defer m.Unlock()
+
+	return os.MkdirAll(path, fs.ModeDir|mode)
+}
+
+// Touch touches a file.
+// It is similar to the unix 'touch' command.
+//
+// If the file does not exist exists, it is created using [Create].
+// If the file does exist, it's access and modification times are updated to the current time.
+//
+// This function ignores the umask.
+func Touch(path string, perm fs.FileMode) error {
+	if perm == 0 {
+		perm = DefaultFilePerm
+	}
+	_, err := os.Stat(path)
+	switch {
+	case os.IsNotExist(err):
+		f, err := Create(path, perm)
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		return nil
+	case err != nil:
+		return err
+	default:
+		now := time.Now().Local()
+		return os.Chtimes(path, now, now)
+	}
+}