// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test that SIGSETXID runs on signal stack, since it's likely to
// overflow if it runs on the Go stack.

package cgotest

/*
#include <sys/types.h>
#include <unistd.h>
*/
import "C"

import (
	"runtime"
	"runtime/debug"
	"sync/atomic"
	"testing"

// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Stress test setgid and thread creation. A thread
// can get a SIGSETXID signal early on at thread
// initialization, causing crash. See issue 53374.

package cgotest

/*
#include <sys/types.h>
#include <unistd.h>
*/
import "C"

import (
	"runtime"
	"testing"
)

generally be honored. However, some signals are explicitly unblocked:
the synchronous signals, SIGILL, SIGTRAP, SIGSTKFLT, SIGCHLD, SIGPROF,
and, on Linux, signals 32 (SIGCANCEL) and 33 (SIGSETXID)
(SIGCANCEL and SIGSETXID are used internally by glibc). Subprocesses
started by [os.Exec], or by [os/exec], will inherit the
modified signal mask.

# Changing the behavior of signals in Go programs

	/*  31 */ {_SigNotify, "SIGXFSZ: file size limit exceeded"},
	/*  32 */ {_SigSetStack + _SigUnblock, "signal 32"}, /* SIGCANCEL; see issue 6997 */
	/*  33 */ {_SigSetStack + _SigUnblock, "signal 33"}, /* SIGSETXID; see issues 3871, 9400, 12498 */
	/*  34 */ {_SigSetStack + _SigUnblock, "signal 34"}, /* musl SIGSYNCCALL; see issue 39343 */
	/*  35 */ {_SigNotify, "signal 35"},
	/*  36 */ {_SigNotify, "signal 36"},

	/* 31 */ {_SigThrow, "SIGSYS: bad system call"},
	/* 32 */ {_SigSetStack + _SigUnblock, "signal 32"}, /* SIGCANCEL; see issue 6997 */
	/* 33 */ {_SigSetStack + _SigUnblock, "signal 33"}, /* SIGSETXID; see issues 3871, 9400, 12498 */
	/* 34 */ {_SigSetStack + _SigUnblock, "signal 34"}, /* musl SIGSYNCCALL; see issue 39343 */
	/* 35 */ {_SigNotify, "signal 35"},
	/* 36 */ {_SigNotify, "signal 36"},

				q.To.Reg = REGSP
				q.Spadj = +autosize

				q = c.ctxt.EndUnsafePoint(q, c.newprog, -1)

				// On Linux, in a cgo binary we may get a SIGSETXID signal early on
				// before the signal stack is set, as glibc doesn't allow us to block
				// SIGSETXID. So a signal may land on the current stack and clobber
				// the content below the SP. We store the LR again after the SP is
				// decremented.

package runtime

import (
	"internal/abi"
	"internal/goarch"
	"internal/runtime/atomic"
	"internal/runtime/syscall"
	"unsafe"
)

// sigPerThreadSyscall is the same signal (SIGSETXID) used by glibc for
// per-thread syscalls on Linux. We use it for the same purpose in non-cgo
// binaries.
const sigPerThreadSyscall = _SIGRTMIN + 1

type mOS struct {

				q.To.Reg = REGSP
				q.Spadj = autosize

				q = c.ctxt.EndUnsafePoint(q, c.newprog, -1)

				// On Linux, in a cgo binary we may get a SIGSETXID signal early on
				// before the signal stack is set, as glibc doesn't allow us to block
				// SIGSETXID. So a signal may land on the current stack and clobber
				// the content below the SP. We store the LR again after the SP is
				// decremented.

				// the traceback code will not see a half-updated stack frame.
				// Also, on Linux, in a cgo binary we may get a SIGSETXID signal
				// early on before the signal stack is set, as glibc doesn't allow
				// us to block SIGSETXID. So it is important that we don't write below
				// the SP until the signal stack is set.
				// Luckily, all the functions from thread entry to setting the signal

				q.To.Reg = REGSP
				q.Spadj = +autosize

				q = c.ctxt.EndUnsafePoint(q, c.newprog, -1)

				// On Linux, in a cgo binary we may get a SIGSETXID signal early on
				// before the signal stack is set, as glibc doesn't allow us to block
				// SIGSETXID. So a signal may land on the current stack and clobber
				// the content below the SP. We store the LR again after the SP is
				// decremented.