Loop on EINTR on Linux (#50)

Co-authored-by: greatroar <@>

xattr_linux.go

@@ -3,6 +3,7 @@
 package xattr
 
 import (
+	"errors"
 	"os"
 	"syscall"
 
@@ -22,52 +23,109 @@ const (
 	ENOATTR = syscall.ENODATA
 )
 
+// On Linux, FUSE and CIFS filesystems can return EINTR for interrupted system
+// calls. This function works around this by retrying system calls until they
+// stop returning EINTR.
+//
+// See https://github.com/golang/go/commit/6b420169d798c7ebe733487b56ea5c3fa4aab5ce.
+func ignoringEINTR(fn func() error) (err error) {
+	for {
+		err = fn()
+		if !errors.Is(err, unix.EINTR) {
+			break
+		}
+	}
+	return err
+}
+
 func getxattr(path string, name string, data []byte) (int, error) {
-	return unix.Getxattr(path, name, data)
+	var r int
+	err := ignoringEINTR(func() (err error) {
+		r, err = unix.Getxattr(path, name, data)
+		return err
+	})
+	return r, err
 }
 
 func lgetxattr(path string, name string, data []byte) (int, error) {
-	return unix.Lgetxattr(path, name, data)
+	var r int
+	err := ignoringEINTR(func() (err error) {
+		r, err = unix.Lgetxattr(path, name, data)
+		return err
+	})
+	return r, err
 }
 
 func fgetxattr(f *os.File, name string, data []byte) (int, error) {
-	return unix.Fgetxattr(int(f.Fd()), name, data)
+	var r int
+	err := ignoringEINTR(func() (err error) {
+		r, err = unix.Fgetxattr(int(f.Fd()), name, data)
+		return err
+	})
+	return r, err
 }
 
 func setxattr(path string, name string, data []byte, flags int) error {
-	return unix.Setxattr(path, name, data, flags)
+	return ignoringEINTR(func() (err error) {
+		return unix.Setxattr(path, name, data, flags)
+	})
 }
 
 func lsetxattr(path string, name string, data []byte, flags int) error {
-	return unix.Lsetxattr(path, name, data, flags)
+	return ignoringEINTR(func() (err error) {
+		return unix.Lsetxattr(path, name, data, flags)
+	})
 }
 
 func fsetxattr(f *os.File, name string, data []byte, flags int) error {
-	return unix.Fsetxattr(int(f.Fd()), name, data, flags)
+	return ignoringEINTR(func() (err error) {
+		return unix.Fsetxattr(int(f.Fd()), name, data, flags)
+	})
 }
 
 func removexattr(path string, name string) error {
-	return unix.Removexattr(path, name)
+	return ignoringEINTR(func() (err error) {
+		return unix.Removexattr(path, name)
+	})
 }
 
 func lremovexattr(path string, name string) error {
-	return unix.Lremovexattr(path, name)
+	return ignoringEINTR(func() (err error) {
+		return unix.Lremovexattr(path, name)
+	})
 }
 
 func fremovexattr(f *os.File, name string) error {
-	return unix.Fremovexattr(int(f.Fd()), name)
+	return ignoringEINTR(func() (err error) {
+		return unix.Fremovexattr(int(f.Fd()), name)
+	})
 }
 
 func listxattr(path string, data []byte) (int, error) {
-	return unix.Listxattr(path, data)
+	var r int
+	err := ignoringEINTR(func() (err error) {
+		r, err = unix.Listxattr(path, data)
+		return err
+	})
+	return r, err
 }
 
 func llistxattr(path string, data []byte) (int, error) {
-	return unix.Llistxattr(path, data)
+	var r int
+	err := ignoringEINTR(func() (err error) {
+		r, err = unix.Llistxattr(path, data)
+		return err
+	})
+	return r, err
 }
 
 func flistxattr(f *os.File, data []byte) (int, error) {
-	return unix.Flistxattr(int(f.Fd()), data)
+	var r int
+	err := ignoringEINTR(func() (err error) {
+		r, err = unix.Flistxattr(int(f.Fd()), data)
+		return err
+	})
+	return r, err
 }
 
 // stringsFromByteSlice converts a sequence of attributes to a []string.

xattr_linux_test.go

@@ -0,0 +1,21 @@
+package xattr
+
+import (
+	"syscall"
+	"testing"
+)
+
+func TestIgnoringEINTR(t *testing.T) {
+	eintrs := 100
+	err := ignoringEINTR(func() error {
+		if eintrs == 0 {
+			return nil
+		}
+		eintrs--
+		return syscall.EINTR
+	})
+
+	if err != nil {
+		t.Fatal(err)
+	}
+}