func_test.go

// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: 2023 The Ebitengine Authors

package purego_test

import (
	"bytes"
	"errors"
	"fmt"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"
	"sync"
	"testing"
	"unsafe"

	"github.com/ebitengine/purego"
	"github.com/ebitengine/purego/internal/load"
)

func getSystemLibrary() (string, error) {
	switch runtime.GOOS {
	case "darwin":
		return "/usr/lib/libSystem.B.dylib", nil
	case "freebsd":
		return "libc.so.7", nil
	case "linux":
		return "libc.so.6", nil
	case "netbsd":
		return "libc.so", nil
	case "windows":
		return "ucrtbase.dll", nil
	default:
		return "", fmt.Errorf("GOOS=%s is not supported", runtime.GOOS)
	}
}

func TestRegisterFunc_ConcurrentPointerReturn(t *testing.T) {
	library, err := getSystemLibrary()
	if err != nil {
		t.Fatalf("couldn't get system library: %s", err)
	}
	libc, err := load.OpenLibrary(library)
	if err != nil {
		t.Fatalf("failed to dlopen: %s", err)
	}

	var alloc func(uint64) *byte
	var free func(*byte)
	purego.RegisterLibFunc(&alloc, libc, "malloc")
	purego.RegisterLibFunc(&free, libc, "free")

	var wg sync.WaitGroup

	for i := 0; i < runtime.NumCPU(); i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			for j := 0; j < 400_000; j++ {
				ptr := alloc(5)
				if ptr == nil {
					continue
				}
				free(ptr)
			}
		}(i)
	}

	wg.Wait()
}

func TestRegisterFunc(t *testing.T) {
	library, err := getSystemLibrary()
	if err != nil {
		t.Fatalf("couldn't get system library: %s", err)
	}
	libc, err := load.OpenLibrary(library)
	if err != nil {
		t.Fatalf("failed to dlopen: %s", err)
	}
	var puts func(string)
	purego.RegisterLibFunc(&puts, libc, "puts")
	puts("Calling C from from Go without Cgo!")
}

func Test_qsort(t *testing.T) {
	if runtime.GOARCH != "arm" && runtime.GOARCH != "arm64" && runtime.GOARCH != "386" && runtime.GOARCH != "amd64" && runtime.GOARCH != "loong64" && runtime.GOARCH != "ppc64le" && runtime.GOARCH != "riscv64" && runtime.GOARCH != "s390x" {
		t.Skip("Platform doesn't support Floats")
		return
	}
	library, err := getSystemLibrary()
	if err != nil {
		t.Fatalf("couldn't get system library: %s", err)
	}
	libc, err := load.OpenLibrary(library)
	if err != nil {
		t.Fatalf("failed to dlopen: %s", err)
	}

	data := []int{88, 56, 100, 2, 25}
	sorted := []int{2, 25, 56, 88, 100}
	compare := func(_ purego.CDecl, a, b *int) int {
		return *a - *b
	}
	var qsort func(data []int, nitms uintptr, size uintptr, compar func(_ purego.CDecl, a, b *int) int)
	purego.RegisterLibFunc(&qsort, libc, "qsort")
	qsort(data, uintptr(len(data)), unsafe.Sizeof(int(0)), compare)
	for i := range data {
		if data[i] != sorted[i] {
			t.Errorf("got %d wanted %d at %d", data[i], sorted[i], i)
		}
	}
}

func TestRegisterFunc_Floats(t *testing.T) {
	if runtime.GOARCH != "arm" && runtime.GOARCH != "arm64" && runtime.GOARCH != "386" && runtime.GOARCH != "amd64" && runtime.GOARCH != "loong64" && runtime.GOARCH != "ppc64le" && runtime.GOARCH != "riscv64" && runtime.GOARCH != "s390x" {
		t.Skip("Platform doesn't support Floats")
		return
	}
	if runtime.GOOS == "windows" && runtime.GOARCH == "386" {
		t.Skip("need a 32bit gcc to run this test") // TODO: find 32bit gcc for test
	}
	library, err := getSystemLibrary()
	if err != nil {
		t.Fatalf("couldn't get system library: %s", err)
	}
	libc, err := load.OpenLibrary(library)
	if err != nil {
		t.Fatalf("failed to dlopen: %s", err)
	}
	{
		var strtof func(arg string) float32
		purego.RegisterLibFunc(&strtof, libc, "strtof")
		const (
			arg = "2"
		)
		got := strtof(arg)
		expected := float32(2)
		if got != expected {
			t.Errorf("strtof failed. got %f but wanted %f", got, expected)
		}
	}
	{
		var strtod func(arg string, ptr **byte) float64
		purego.RegisterLibFunc(&strtod, libc, "strtod")
		const (
			arg = "1"
		)
		got := strtod(arg, nil)
		expected := float64(1)
		if got != expected {
			t.Errorf("strtod failed. got %f but wanted %f", got, expected)
		}
	}
}

func TestRegisterLibFunc_Bool(t *testing.T) {
	if runtime.GOARCH != "arm" && runtime.GOARCH != "arm64" && runtime.GOARCH != "386" && runtime.GOARCH != "amd64" && runtime.GOARCH != "loong64" && runtime.GOARCH != "ppc64le" && runtime.GOARCH != "riscv64" && runtime.GOARCH != "s390x" {
		t.Skip("Platform doesn't support callbacks")
		return
	}
	// this callback recreates the state where the return register
	// contains other information but the least significant byte is false
	cbFalse := purego.NewCallback(func() uintptr {
		x := uint64(0x7F5948AE9A00)
		return uintptr(x)
	})
	var runFalse func() bool
	purego.RegisterFunc(&runFalse, cbFalse)
	expected := false
	if got := runFalse(); got != expected {
		t.Errorf("runFalse failed. got %t but wanted %t", got, expected)
	}
}

func TestABI(t *testing.T) {
	if runtime.GOOS == "windows" && runtime.GOARCH == "386" {
		t.Skip("need a 32bit gcc to run this test") // TODO: find 32bit gcc for test
	}
	libFileName := filepath.Join(t.TempDir(), "abitest.so")
	t.Logf("Build %v", libFileName)

	if err := buildSharedLib("CC", libFileName, filepath.Join("testdata", "abitest", "abi_test.c")); err != nil {
		t.Fatal(err)
	}

	lib, err := load.OpenLibrary(libFileName)
	if err != nil {
		t.Fatalf("Dlopen(%q) failed: %v", libFileName, err)
	}
	defer func() {
		if err := load.CloseLibrary(lib); err != nil {
			t.Fatalf("failed to close library: %s", err)
		}
	}()
	{
		const cName = "stack_uint8_t"
		const expect = 2047
		var fn func(a, b, c, d, e, f, g, h uint32, i, j uint8, k uint32) uint32
		purego.RegisterLibFunc(&fn, lib, cName)
		res := fn(256, 512, 4, 8, 16, 32, 64, 128, 1, 2, 1024)
		if res != expect {
			t.Fatalf("%s: got %d, want %d", cName, res, expect)
		}
	}
	{
		const cName = "reg_uint8_t"
		const expect = 1027
		var fn func(a, b uint8, c uint32) uint32
		purego.RegisterLibFunc(&fn, lib, cName)
		res := fn(1, 2, 1024)
		if res != expect {
			t.Fatalf("%s: got %d, want %d", cName, res, expect)
		}
	}
	{
		const cName = "stack_string"
		const expect = 255
		var fn func(a, b, c, d, e, f, g, h uint32, i string) uint32
		purego.RegisterLibFunc(&fn, lib, cName)
		res := fn(1, 2, 4, 8, 16, 32, 64, 128, "test")
		if res != expect {
			t.Fatalf("%s: got %d, want %d", cName, res, expect)
		}
	}
	{
		const cName = "stack_8i32_3strings"
		var fn func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, string, string, string)
		purego.RegisterLibFunc(&fn, lib, cName)
		buf := make([]byte, 256)
		fn(&buf[0], uintptr(len(buf)), 1, 2, 3, 4, 5, 6, 7, 8, "foo", "bar", "baz")
		res := string(buf[:bytes.IndexByte(buf, 0)])
		const want = "1:2:3:4:5:6:7:8:foo:bar:baz"
		if res != want {
			t.Fatalf("%s: got %q, want %q", cName, res, want)
		}
	}
}

func TestABI_ArgumentPassing(t *testing.T) {
	if runtime.GOOS == "windows" && runtime.GOARCH == "386" {
		t.Skip("need a 32bit gcc to run this test") // TODO: find 32bit gcc for test
	}
	libFileName := filepath.Join(t.TempDir(), "abitest.so")
	if err := buildSharedLib("CC", libFileName, filepath.Join("testdata", "abitest", "abi_test.c")); err != nil {
		t.Fatal(err)
	}
	lib, err := load.OpenLibrary(libFileName)
	if err != nil {
		t.Fatalf("Failed to open library %q: %v", libFileName, err)
	}
	t.Cleanup(func() {
		if err := load.CloseLibrary(lib); err != nil {
			t.Errorf("Failed to close library: %v", err)
		}
	})

	tests := []struct {
		name string
		fn   any
		cFn  string
		call func(any) string
		want string
	}{
		{
			name: "10_int32_baseline",
			fn:   new(func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32)),
			cFn:  "stack_10_int32",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32)))(&buf[0], 256, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1:2:3:4:5:6:7:8:9:10",
		},
		{
			name: "11_int32",
			fn:   new(func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32)),
			cFn:  "stack_11_int32",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32)))(&buf[0], 256, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1:2:3:4:5:6:7:8:9:10:11",
		},
		{
			name: "10_float32",
			fn:   new(func(*byte, uintptr, float32, float32, float32, float32, float32, float32, float32, float32, float32, float32)),
			cFn:  "stack_10_float32",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, float32, float32, float32, float32, float32, float32, float32, float32, float32, float32)))(&buf[0], 256, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0)
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1.0:2.0:3.0:4.0:5.0:6.0:7.0:8.0:9.0:10.0",
		},
		{
			name: "mixed_stack_strings",
			fn:   new(func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, string, bool, int32, string)),
			cFn:  "stack_mixed_stack_4args",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, string, bool, int32, string)))(&buf[0], 256, 1, 2, 3, 4, 5, 6, 7, 8, "foo", false, 99, "bar")
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1:2:3:4:5:6:7:8:foo:0:99:bar",
		},
		{
			name: "20_int32",
			fn:   new(func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32)),
			cFn:  "stack_20_int32",
			call: func(f any) string {
				buf := make([]byte, 512)
				(*f.(*func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32, int32)))(&buf[0], 512, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1:2:3:4:5:6:7:8:9:10:11:12:13:14:15:16:17:18:19:20",
		},
		{
			name: "8int_hfa2_stack",
			fn:   new(func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, struct{ x, y float32 })),
			cFn:  "stack_8int_hfa2_stack",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, struct{ x, y float32 })))(&buf[0], 256, 1, 2, 3, 4, 5, 6, 7, 8, struct{ x, y float32 }{10.0, 20.0})
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1:2:3:4:5:6:7:8:10.0:20.0",
		},
		{
			name: "8int_2structs_stack",
			fn:   new(func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, struct{ x, y int32 }, struct{ x, y int32 })),
			cFn:  "stack_8int_2structs_stack",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, struct{ x, y int32 }, struct{ x, y int32 })))(&buf[0], 256, 1, 2, 3, 4, 5, 6, 7, 8, struct{ x, y int32 }{9, 10}, struct{ x, y int32 }{11, 12})
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1:2:3:4:5:6:7:8:9:10:11:12",
		},
		{
			name: "8float_hfa2_stack",
			fn:   new(func(*byte, uintptr, float32, float32, float32, float32, float32, float32, float32, float32, struct{ x, y float32 })),
			cFn:  "stack_8float_hfa2_stack",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, float32, float32, float32, float32, float32, float32, float32, float32, struct{ x, y float32 })))(&buf[0], 256, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, struct{ x, y float32 }{9.0, 10.0})
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1.0:2.0:3.0:4.0:5.0:6.0:7.0:8.0:9.0:10.0",
		},
		{
			name: "8int_hfa2_floatregs",
			fn:   new(func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, struct{ x, y float32 })),
			cFn:  "stack_8int_hfa2_floatregs",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, struct{ x, y float32 })))(&buf[0], 256, 1, 2, 3, 4, 5, 6, 7, 8, struct{ x, y float32 }{10.0, 20.0})
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1:2:3:4:5:6:7:8:10.0:20.0",
		},
		{
			name: "8int_int_struct_int",
			fn:   new(func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, int32, struct{ x, y int32 }, int32)),
			cFn:  "stack_8int_int_struct_int",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, int32, struct{ x, y int32 }, int32)))(&buf[0], 256, 1, 2, 3, 4, 5, 6, 7, 8, 9, struct{ x, y int32 }{10, 11}, 12)
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1:2:3:4:5:6:7:8:9:10:11:12",
		},
		{
			name: "8int_hfa4_stack",
			fn:   new(func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, struct{ x, y, z, w float32 })),
			cFn:  "stack_8int_hfa4_stack",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, struct{ x, y, z, w float32 })))(&buf[0], 256, 1, 2, 3, 4, 5, 6, 7, 8, struct{ x, y, z, w float32 }{10.0, 20.0, 30.0, 40.0})
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1:2:3:4:5:6:7:8:10.0:20.0:30.0:40.0",
		},
		{
			name: "8int_mixed_struct",
			fn: new(func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, struct {
				a int32
				b float32
			})),
			cFn: "stack_8int_mixed_struct",
			call: func(f any) string {
				buf := make([]byte, 256)
				(*f.(*func(*byte, uintptr, int32, int32, int32, int32, int32, int32, int32, int32, struct {
					a int32
					b float32
				})))(&buf[0], 256, 1, 2, 3, 4, 5, 6, 7, 8, struct {
					a int32
					b float32
				}{9, 10.0})
				return string(buf[:bytes.IndexByte(buf, 0)])
			},
			want: "1:2:3:4:5:6:7:8:9:10.0",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if tt.name == "20_int32" && runtime.GOARCH == "ppc64le" {
				t.Skip("ppc64le retains the 15-argument limit")
			}
			if tt.name == "10_float32" && (runtime.GOARCH == "loong64" || runtime.GOARCH == "ppc64le" || runtime.GOARCH == "riscv64" || runtime.GOARCH == "s390x") {
				t.Skip("float32 stack arguments not yet supported on this platform")
			}
			// Struct tests require Darwin ARM64 or AMD64
			if strings.HasPrefix(tt.name, "8int_") && (runtime.GOOS != "darwin" || (runtime.GOARCH != "arm64" && runtime.GOARCH != "amd64")) {
				t.Skip("struct argument tests only supported on Darwin ARM64/AMD64")
			}
			if strings.HasPrefix(tt.name, "8float_") && (runtime.GOOS != "darwin" || (runtime.GOARCH != "arm64" && runtime.GOARCH != "amd64")) {
				t.Skip("struct argument tests only supported on Darwin ARM64/AMD64")
			}

			purego.RegisterLibFunc(tt.fn, lib, tt.cFn)
			got := tt.call(tt.fn)
			if got != tt.want {
				t.Errorf("%s\n  got:  %q\n  want: %q", tt.cFn, got, tt.want)
			}
		})
	}

	t.Run("20_uintptr", func(t *testing.T) {
		if runtime.GOARCH == "ppc64le" {
			t.Skip("ppc64le retains the 15-argument limit")
		}
		var fn func(uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr) uintptr
		purego.RegisterLibFunc(&fn, lib, "stack_20_uintptr")
		got := fn(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
		const want = uintptr(210)
		if got != want {
			t.Fatalf("stack_20_uintptr: got %d, want %d", got, want)
		}
	})

	t.Run("32_uintptr", func(t *testing.T) {
		if runtime.GOARCH == "ppc64le" {
			t.Skip("ppc64le retains the 15-argument limit")
		}
		var fn func(
			uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr,
			uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr,
			uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr,
			uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr,
		) uintptr
		purego.RegisterLibFunc(&fn, lib, "stack_32_uintptr")
		got := fn(
			1, 2, 3, 4, 5, 6, 7, 8,
			9, 10, 11, 12, 13, 14, 15, 16,
			17, 18, 19, 20, 21, 22, 23, 24,
			25, 26, 27, 28, 29, 30, 31, 32,
		)
		const want = uintptr(528)
		if got != want {
			t.Fatalf("stack_32_uintptr: got %d, want %d", got, want)
		}
	})

	t.Run("syscalln_20_uintptr", func(t *testing.T) {
		if runtime.GOARCH == "ppc64le" {
			t.Skip("ppc64le retains the 15-argument limit")
		}
		fn, err := load.OpenSymbol(lib, "stack_20_uintptr")
		if err != nil {
			t.Fatalf("OpenSymbol(stack_20_uintptr) failed: %v", err)
		}
		got, _, _ := purego.SyscallN(fn,
			1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
			11, 12, 13, 14, 15, 16, 17, 18, 19, 20,
		)
		const want = uintptr(210)
		if got != want {
			t.Fatalf("stack_20_uintptr SyscallN: got %d, want %d", got, want)
		}
	})

	t.Run("syscalln_32_uintptr", func(t *testing.T) {
		if runtime.GOARCH == "ppc64le" {
			t.Skip("ppc64le retains the 15-argument limit")
		}
		fn, err := load.OpenSymbol(lib, "stack_32_uintptr")
		if err != nil {
			t.Fatalf("OpenSymbol(stack_32_uintptr) failed: %v", err)
		}
		got, _, _ := purego.SyscallN(fn,
			1, 2, 3, 4, 5, 6, 7, 8,
			9, 10, 11, 12, 13, 14, 15, 16,
			17, 18, 19, 20, 21, 22, 23, 24,
			25, 26, 27, 28, 29, 30, 31, 32,
		)
		const want = uintptr(528)
		if got != want {
			t.Fatalf("stack_32_uintptr SyscallN: got %d, want %d", got, want)
		}
	})

	t.Run("32_mixed_int_float", func(t *testing.T) {
		if unsafe.Sizeof(uintptr(0)) == 4 {
			t.Skip("requires 64-bit uintptr slots")
		}
		if runtime.GOARCH == "ppc64le" {
			t.Skip("mixed int/float stack arguments are not yet supported on ppc64le")
		}

		var fn func(
			uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr,
			uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr, uintptr,
			float64, float64, float64, float64, float64, float64, float64, float64,
			float64, float64, float64, float64, float64, float64, float64, float64,
		) float64
		purego.RegisterLibFunc(&fn, lib, "stack_32_mixed_int_float")
		got := fn(
			1, 2, 3, 4, 5, 6, 7, 8,
			9, 10, 11, 12, 13, 14, 15, 16,
			1, 2, 3, 4, 5, 6, 7, 8,
			9, 10, 11, 12, 13, 14, 15, 16,
		)
		const want = 5168.0
		if got != want {
			t.Fatalf("stack_32_mixed_int_float: got %f, want %f", got, want)
		}
	})
}

func TestABI_TooManyArguments(t *testing.T) {
	mustPanic := func(t *testing.T, want string, f func()) {
		t.Helper()
		defer func() {
			r := recover()
			if r == nil {
				t.Fatalf("expected panic %q, got none", want)
			}
			got := fmt.Sprint(r)
			if got != want {
				t.Fatalf("panic mismatch:\n  got:  %q\n  want: %q", got, want)
			}
		}()
		f()
	}

	// 33 int64 parameters exceeds maxArgs=32.
	t.Run("registerfunc_33_int64_exceeds_limit", func(t *testing.T) {
		mustPanic(t, "purego: too many stack arguments", func() {
			var fn func(
				int64, int64, int64, int64, int64, int64, int64, int64,
				int64, int64, int64, int64, int64, int64, int64, int64,
				int64, int64, int64, int64, int64, int64, int64, int64,
				int64, int64, int64, int64, int64, int64, int64, int64,
				int64,
			)
			purego.RegisterFunc(&fn, 1)
		})
	})

	t.Run("registerfunc_16_int64_exceeds_ppc64le_limit", func(t *testing.T) {
		if runtime.GOARCH != "ppc64le" {
			t.Skip("ppc64le retains the 15-argument limit")
		}
		mustPanic(t, "purego: too many stack arguments", func() {
			var fn func(
				int64, int64, int64, int64, int64, int64, int64, int64,
				int64, int64, int64, int64, int64, int64, int64, int64,
			)
			purego.RegisterFunc(&fn, 1)
		})
	})

	t.Run("syscalln_33_uintptr_exceeds_limit", func(t *testing.T) {
		mustPanic(t, "purego: too many arguments to SyscallN", func() {
			purego.SyscallN(1,
				1, 2, 3, 4, 5, 6, 7, 8,
				9, 10, 11, 12, 13, 14, 15, 16,
				17, 18, 19, 20, 21, 22, 23, 24,
				25, 26, 27, 28, 29, 30, 31, 32,
				33,
			)
		})
	})

	t.Run("syscalln_16_uintptr_exceeds_ppc64le_limit", func(t *testing.T) {
		if runtime.GOARCH != "ppc64le" {
			t.Skip("ppc64le retains the 15-argument limit")
		}
		mustPanic(t, "purego: too many arguments to SyscallN", func() {
			purego.SyscallN(1,
				1, 2, 3, 4, 5, 6, 7, 8,
				9, 10, 11, 12, 13, 14, 15, 16,
			)
		})
	})
}

func buildSharedLib(compilerEnv, libFile string, sources ...string) error {
	out, err := exec.Command("go", "env", compilerEnv).Output()
	if err != nil {
		return fmt.Errorf("go env %s error: %w", compilerEnv, err)
	}

	compiler := strings.TrimSpace(string(out))
	if compiler == "" {
		return errors.New("compiler not found")
	}

	args := []string{"-shared", "-Wall", "-Werror", "-fPIC", "-o", libFile}
	if runtime.GOARCH == "386" {
		args = append(args, "-m32")
	}
	// macOS arm64 can run amd64 tests through Rossetta.
	// Build the shared library based on the GOARCH and not
	// the default behavior of the compiler.
	if runtime.GOOS == "darwin" {
		var arch string
		switch runtime.GOARCH {
		case "arm64":
			arch = "arm64"
		case "amd64":
			arch = "x86_64"
		default:
			return fmt.Errorf("unknown macOS architecture %s", runtime.GOARCH)
		}
		args = append(args, "-arch", arch)
	}
	cmd := exec.Command(compiler, append(args, sources...)...)
	if out, err := cmd.CombinedOutput(); err != nil {
		return fmt.Errorf("compile lib: %w\n%q\n%s", err, cmd, string(out))
	}

	return nil
}