unix: add Getresuid, Getresgid for linux

Fixes golang/go#60483

Change-Id: Id4c1bf8367066485a16bedeea337c384a3555942
GitHub-Last-Rev: 61f0fe6f6a5be1cd34ddf99e72a75cfd32355793
GitHub-Pull-Request: golang/sys#159
Reviewed-on: https://go-review.googlesource.com/c/sys/+/499055
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

unix/syscall_linux.go

@@ -2420,6 +2420,21 @@ func PthreadSigmask(how int, set, oldset *Sigset_t) error {
 	return rtSigprocmask(how, set, oldset, _C__NSIG/8)
 }
 
+//sysnb	getresuid(ruid *_C_int, euid *_C_int, suid *_C_int)
+//sysnb	getresgid(rgid *_C_int, egid *_C_int, sgid *_C_int)
+
+func Getresuid() (ruid, euid, suid int) {
+	var r, e, s _C_int
+	getresuid(&r, &e, &s)
+	return int(r), int(e), int(s)
+}
+
+func Getresgid() (rgid, egid, sgid int) {
+	var r, e, s _C_int
+	getresgid(&r, &e, &s)
+	return int(r), int(e), int(s)
+}
+
 /*
  * Unimplemented
  */

unix/zsyscall_linux.go

@@ -2172,3 +2172,17 @@ func rtSigprocmask(how int, set *Sigset_t, oldset *Sigset_t, sigsetsize uintptr)
 	}
 	return
 }
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func getresuid(ruid *_C_int, euid *_C_int, suid *_C_int) {
+	RawSyscallNoError(SYS_GETRESUID, uintptr(unsafe.Pointer(ruid)), uintptr(unsafe.Pointer(euid)), uintptr(unsafe.Pointer(suid)))
+	return
+}
+
+// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT
+
+func getresgid(rgid *_C_int, egid *_C_int, sgid *_C_int) {
+	RawSyscallNoError(SYS_GETRESGID, uintptr(unsafe.Pointer(rgid)), uintptr(unsafe.Pointer(egid)), uintptr(unsafe.Pointer(sgid)))
+	return
+}