syscallcompat: move asUser to its own file

2 files changed, 49 insertions, 41 deletions

diff --git a/internal/syscallcompat/asuser_linux.go b/internal/syscallcompat/asuser_linux.go
new file mode 100644
index 0000000..dac94f4
--- /dev/null
+++ b/internal/syscallcompat/asuser_linux.go
@@ -0,0 +1,49 @@
+package syscallcompat
+
+import (
+	"runtime"
+
+	"golang.org/x/sys/unix"
+
+	"github.com/hanwen/go-fuse/v2/fuse"
+)
+
+// asUser runs `f()` under the effective uid, gid, groups specified
+// in `context`.
+//
+// If `context` is nil, `f()` is executed directly without switching user id.
+func asUser(f func() (int, error), context *fuse.Context) (int, error) {
+	if context == nil {
+		return f()
+	}
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	// Since go1.16beta1 (commit d1b1145cace8b968307f9311ff611e4bb810710c ,
+	// https://go-review.googlesource.com/c/go/+/210639 )
+	// syscall.{Setgroups,Setregid,Setreuid} affects all threads, which
+	// is exactly what we not want.
+	//
+	// We now use unix.{Setgroups,Setregid,Setreuid} instead.
+
+	err := unix.Setgroups(getSupplementaryGroups(context.Pid))
+	if err != nil {
+		return -1, err
+	}
+	defer unix.Setgroups(nil)
+
+	err = unix.Setregid(-1, int(context.Owner.Gid))
+	if err != nil {
+		return -1, err
+	}
+	defer unix.Setregid(-1, 0)
+
+	err = unix.Setreuid(-1, int(context.Owner.Uid))
+	if err != nil {
+		return -1, err
+	}
+	defer unix.Setreuid(-1, 0)
+
+	return f()
+}
diff --git a/internal/syscallcompat/sys_linux.go b/internal/syscallcompat/sys_linux.go
index a64b27e..d769f96 100644
--- a/internal/syscallcompat/sys_linux.go
+++ b/internal/syscallcompat/sys_linux.go
@@ -4,7 +4,6 @@ package syscallcompat
 import (
 	"fmt"
 	"io/ioutil"
-	"runtime"
 	"strconv"
 	"strings"
 	"sync"
@@ -93,46 +92,6 @@ func getSupplementaryGroups(pid uint32) (gids []int) {
 	return nil
 }
 
-// asUser runs `f()` under the effective uid, gid, groups specified
-// in `context`.
-//
-// If `context` is nil, `f()` is executed directly without switching user id.
-func asUser(f func() (int, error), context *fuse.Context) (int, error) {
-	if context == nil {
-		return f()
-	}
-
-	runtime.LockOSThread()
-	defer runtime.UnlockOSThread()
-
-	// Since go1.16beta1 (commit d1b1145cace8b968307f9311ff611e4bb810710c ,
-	// https://go-review.googlesource.com/c/go/+/210639 )
-	// syscall.{Setgroups,Setregid,Setreuid} affects all threads, which
-	// is exactly what we not want.
-	//
-	// We now use unix.{Setgroups,Setregid,Setreuid} instead.
-
-	err := unix.Setgroups(getSupplementaryGroups(context.Pid))
-	if err != nil {
-		return -1, err
-	}
-	defer unix.Setgroups(nil)
-
-	err = unix.Setregid(-1, int(context.Owner.Gid))
-	if err != nil {
-		return -1, err
-	}
-	defer unix.Setregid(-1, 0)
-
-	err = unix.Setreuid(-1, int(context.Owner.Uid))
-	if err != nil {
-		return -1, err
-	}
-	defer unix.Setreuid(-1, 0)
-
-	return f()
-}
-
 // OpenatUser runs the Openat syscall in the context of a different user.
 //
 // It switches the current thread to the new user, performs the syscall,