syscallcompat: add thread_credentials.go & friends

Private copies of per-thread Setreuid/Setegid/Setgroups.

https://github.com/rfjakob/gocryptfs/issues/893
https://github.com/rfjakob/gocryptfs/issues/892

1 files changed, 35 insertions, 0 deletions

diff --git a/internal/syscallcompat/thread_credentials_368_arm.go b/internal/syscallcompat/thread_credentials_368_arm.go
new file mode 100644
index 0000000..1244160
--- /dev/null
+++ b/internal/syscallcompat/thread_credentials_368_arm.go
@@ -0,0 +1,35 @@
+//go:build (linux && 386) || (linux && arm)
+
+package syscallcompat
+
+import (
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+// See thread_credentials.go for docs
+
+func Setreuid(ruid int, euid int) (err error) {
+	_, _, e1 := unix.RawSyscall(unix.SYS_SETREUID32, uintptr(ruid), uintptr(euid), 0)
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}
+
+func Setregid(rgid int, egid int) (err error) {
+	_, _, e1 := unix.RawSyscall(unix.SYS_SETREGID32, uintptr(rgid), uintptr(egid), 0)
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}
+
+func setgroups(n int, list *uint32) (err error) {
+	_, _, e1 := unix.RawSyscall(unix.SYS_SETGROUPS32, uintptr(n), uintptr(unsafe.Pointer(list)), 0)
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}