src/crypto/x509/root_linux_test.go - go - Git at Google

 // Copyright 2025 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.

 //go:build linux

 package x509

 import (
 	"encoding/pem"
 	"fmt"
 	"internal/testenv"
 	"os"
 	"syscall"
 	"testing"
 )

 func TestSetFallbackRoots(t *testing.T) {
 	if testing.Short() {
 		t.Skip("skipping test in short mode")
 	}

 	test := func(t *testing.T, name string, f func(t *testing.T)) {
 		t.Run(name, func(t *testing.T) {
 			if os.Getenv("CRYPTO_X509_SETFALLBACKROOTS_TEST") != "1" {
 				// Execute test in a separate process with CRYPTO_X509_SETFALBACKROOTS_TEST env.
 				cmd := testenv.Command(t, testenv.Executable(t), fmt.Sprintf("-test.run=^%v$", t.Name()), "-test.v")
 				cmd.Env = append(os.Environ(), "CRYPTO_X509_SETFALLBACKROOTS_TEST=1")
 				cmd.SysProcAttr = &syscall.SysProcAttr{
 					Cloneflags:  syscall.CLONE_NEWNS | syscall.CLONE_NEWUSER,
 					UidMappings: []syscall.SysProcIDMap{{ContainerID: 0, HostID: os.Getuid(), Size: 1}},
 					GidMappings: []syscall.SysProcIDMap{{ContainerID: 0, HostID: os.Getgid(), Size: 1}},
 				}
 				out, err := cmd.CombinedOutput()
 				if testenv.SyscallIsNotSupported(err) {
 					t.Skipf("skipping: could not start process with CLONE_NEWNS and CLONE_NEWUSER: %v", err)
 				}
 				t.Logf("running with CRYPTO_X509_SETFALLBACKROOTS_TEST=1:\n%s", out)
 				if err != nil {
 					t.Errorf("CRYPTO_X509_SETFALLBACKROOTS_TEST=1 subprocess failed: %v", err)
 				}
 				return
 			}

 			// This test is executed in a separate user and mount namespace, thus
 			// we can mount a separate "/etc" empty bind mount, without the need for root access.
 			// On linux all certs reside in /etc, so as we bind an empty dir, we
 			// get a full control over the system CAs, required for this test.
 			if err := syscall.Mount(t.TempDir(), "/etc", "", syscall.MS_BIND, ""); err != nil {
 				if testenv.SyscallIsNotSupported(err) {
 					t.Skipf("Failed to mount /etc: %v", err)
 				}
 				t.Fatalf("Failed to mount /etc: %v", err)
 			}

 			t.Cleanup(func() {
 				if err := syscall.Unmount("/etc", 0); err != nil {
 					t.Errorf("failed to unmount /etc: %v", err)
 				}
 			})

 			f(t)
 		})
 	}

 	newFallbackCertPool := func(t *testing.T) *CertPool {
 		t.Helper()

 		const fallbackCert = `-----BEGIN CERTIFICATE-----
 MIICGzCCAaGgAwIBAgIQQdKd0XLq7qeAwSxs6S+HUjAKBggqhkjOPQQDAzBPMQsw
 CQYDVQQGEwJVUzEpMCcGA1UEChMgSW50ZXJuZXQgU2VjdXJpdHkgUmVzZWFyY2gg
 R3JvdXAxFTATBgNVBAMTDElTUkcgUm9vdCBYMjAeFw0yMDA5MDQwMDAwMDBaFw00
 MDA5MTcxNjAwMDBaME8xCzAJBgNVBAYTAlVTMSkwJwYDVQQKEyBJbnRlcm5ldCBT
 ZWN1cml0eSBSZXNlYXJjaCBHcm91cDEVMBMGA1UEAxMMSVNSRyBSb290IFgyMHYw
 EAYHKoZIzj0CAQYFK4EEACIDYgAEzZvVn4CDCuwJSvMWSj5cz3es3mcFDR0HttwW
 +1qLFNvicWDEukWVEYmO6gbf9yoWHKS5xcUy4APgHoIYOIvXRdgKam7mAHf7AlF9
 ItgKbppbd9/w+kHsOdx1ymgHDB/qo0IwQDAOBgNVHQ8BAf8EBAMCAQYwDwYDVR0T
 AQH/BAUwAwEB/zAdBgNVHQ4EFgQUfEKWrt5LSDv6kviejM9ti6lyN5UwCgYIKoZI
 zj0EAwMDaAAwZQIwe3lORlCEwkSHRhtFcP9Ymd70/aTSVaYgLXTWNLxBo1BfASdW
 tL4ndQavEi51mI38AjEAi/V3bNTIZargCyzuFJ0nN6T5U6VR5CmD1/iQMVtCnwr1
 /q4AaOeMSQ+2b1tbFfLn
 -----END CERTIFICATE-----
 `
 		b, _ := pem.Decode([]byte(fallbackCert))
 		cert, err := ParseCertificate(b.Bytes)
 		if err != nil {
 			t.Fatal(err)
 		}
 		p := NewCertPool()
 		p.AddCert(cert)
 		return p
 	}

 	installSystemRootCAs := func(t *testing.T) {
 		t.Helper()

 		const systemCAs = `-----BEGIN CERTIFICATE-----
 MIIFazCCA1OgAwIBAgIRAIIQz7DSQONZRGPgu2OCiwAwDQYJKoZIhvcNAQELBQAw
 TzELMAkGA1UEBhMCVVMxKTAnBgNVBAoTIEludGVybmV0IFNlY3VyaXR5IFJlc2Vh
 cmNoIEdyb3VwMRUwEwYDVQQDEwxJU1JHIFJvb3QgWDEwHhcNMTUwNjA0MTEwNDM4
 WhcNMzUwNjA0MTEwNDM4WjBPMQswCQYDVQQGEwJVUzEpMCcGA1UEChMgSW50ZXJu
 ZXQgU2VjdXJpdHkgUmVzZWFyY2ggR3JvdXAxFTATBgNVBAMTDElTUkcgUm9vdCBY
 MTCCAiIwDQYJKoZIhvcNAQEBBQADggIPADCCAgoCggIBAK3oJHP0FDfzm54rVygc
 h77ct984kIxuPOZXoHj3dcKi/vVqbvYATyjb3miGbESTtrFj/RQSa78f0uoxmyF+
 0TM8ukj13Xnfs7j/EvEhmkvBioZxaUpmZmyPfjxwv60pIgbz5MDmgK7iS4+3mX6U
 A5/TR5d8mUgjU+g4rk8Kb4Mu0UlXjIB0ttov0DiNewNwIRt18jA8+o+u3dpjq+sW
 T8KOEUt+zwvo/7V3LvSye0rgTBIlDHCNAymg4VMk7BPZ7hm/ELNKjD+Jo2FR3qyH
 B5T0Y3HsLuJvW5iB4YlcNHlsdu87kGJ55tukmi8mxdAQ4Q7e2RCOFvu396j3x+UC
 B5iPNgiV5+I3lg02dZ77DnKxHZu8A/lJBdiB3QW0KtZB6awBdpUKD9jf1b0SHzUv
 KBds0pjBqAlkd25HN7rOrFleaJ1/ctaJxQZBKT5ZPt0m9STJEadao0xAH0ahmbWn
 OlFuhjuefXKnEgV4We0+UXgVCwOPjdAvBbI+e0ocS3MFEvzG6uBQE3xDk3SzynTn
 jh8BCNAw1FtxNrQHusEwMFxIt4I7mKZ9YIqioymCzLq9gwQbooMDQaHWBfEbwrbw
 qHyGO0aoSCqI3Haadr8faqU9GY/rOPNk3sgrDQoo//fb4hVC1CLQJ13hef4Y53CI
 rU7m2Ys6xt0nUW7/vGT1M0NPAgMBAAGjQjBAMA4GA1UdDwEB/wQEAwIBBjAPBgNV
 HRMBAf8EBTADAQH/MB0GA1UdDgQWBBR5tFnme7bl5AFzgAiIyBpY9umbbjANBgkq
 hkiG9w0BAQsFAAOCAgEAVR9YqbyyqFDQDLHYGmkgJykIrGF1XIpu+ILlaS/V9lZL
 ubhzEFnTIZd+50xx+7LSYK05qAvqFyFWhfFQDlnrzuBZ6brJFe+GnY+EgPbk6ZGQ
 3BebYhtF8GaV0nxvwuo77x/Py9auJ/GpsMiu/X1+mvoiBOv/2X/qkSsisRcOj/KK
 NFtY2PwByVS5uCbMiogziUwthDyC3+6WVwW6LLv3xLfHTjuCvjHIInNzktHCgKQ5
 ORAzI4JMPJ+GslWYHb4phowim57iaztXOoJwTdwJx4nLCgdNbOhdjsnvzqvHu7Ur
 TkXWStAmzOVyyghqpZXjFaH3pO3JLF+l+/+sKAIuvtd7u+Nxe5AW0wdeRlN8NwdC
 jNPElpzVmbUq4JUagEiuTDkHzsxHpFKVK7q4+63SM1N95R1NbdWhscdCb+ZAJzVc
 oyi3B43njTOQ5yOf+1CceWxG1bQVs5ZufpsMljq4Ui0/1lvh+wjChP4kqKOJ2qxq
 4RgqsahDYVvTH9w7jXbyLeiNdd8XM2w9U/t7y0Ff/9yi0GE44Za4rF2LN9d11TPA
 mRGunUHBcnWEvgJBQl9nJEiU0Zsnvgc/ubhPgXRR4Xq37Z0j4r7g1SgEEzwxA57d
 emyPxgcYxn/eR44/KJ4EBs+lVDR3veyJm+kXQ99b21/+jh5Xos1AnX5iItreGCc=
 -----END CERTIFICATE-----
 `
 		if err := os.MkdirAll("/etc/ssl/certs", 06660); err != nil {
 			t.Fatal(err)
 		}

 		if err := os.WriteFile("/etc/ssl/certs/ca-certificates.crt", []byte(systemCAs), 0666); err != nil {
 			t.Fatal(err)
 		}
 	}

 	test(t, "after_first_load_no_system_CAs", func(t *testing.T) {
 		SystemCertPool() // load system certs, before setting fallbacks
 		fallback := newFallbackCertPool(t)
 		SetFallbackRoots(fallback)
 		got, err := SystemCertPool()
 		if err != nil {
 			t.Fatal(err)
 		}
 		if !got.Equal(fallback) {
 			t.Fatal("SystemCertPool returned a non-fallback CertPool")
 		}
 	})

 	test(t, "after_first_load_system_CA_read_error", func(t *testing.T) {
 		// This will fail to load in SystemCertPool since this is a directory,
 		// rather than a file with certificates.
 		if err := os.MkdirAll("/etc/ssl/certs/ca-certificates.crt", 0666); err != nil {
 			t.Fatal(err)
 		}

 		_, err := SystemCertPool() // load system certs, before setting fallbacks
 		if err == nil {
 			t.Fatal("unexpected success")
 		}

 		fallback := newFallbackCertPool(t)
 		SetFallbackRoots(fallback)
 		got, err := SystemCertPool()
 		if err != nil {
 			t.Fatal(err)
 		}
 		if !got.Equal(fallback) {
 			t.Fatal("SystemCertPool returned a non-fallback CertPool")
 		}
 	})

 	test(t, "after_first_load_with_system_CAs", func(t *testing.T) {
 		installSystemRootCAs(t)

 		SystemCertPool() // load system certs, before setting fallbacks

 		fallback := newFallbackCertPool(t)
 		SetFallbackRoots(fallback)
 		got, err := SystemCertPool()
 		if err != nil {
 			t.Fatal(err)
 		}
 		if got.Equal(fallback) {
 			t.Fatal("SystemCertPool returned the fallback CertPool")
 		}
 	})

 	test(t, "before_first_load_no_system_CAs", func(t *testing.T) {
 		fallback := newFallbackCertPool(t)
 		SetFallbackRoots(fallback)
 		got, err := SystemCertPool()
 		if err != nil {
 			t.Fatal(err)
 		}
 		if !got.Equal(fallback) {
 			t.Fatal("SystemCertPool returned a non-fallback CertPool")
 		}
 	})

 	test(t, "before_first_load_system_CA_read_error", func(t *testing.T) {
 		// This will fail to load in SystemCertPool since this is a directory,
 		// rather than a file with certificates.
 		if err := os.MkdirAll("/etc/ssl/certs/ca-certificates.crt", 0666); err != nil {
 			t.Fatal(err)
 		}

 		fallback := newFallbackCertPool(t)
 		SetFallbackRoots(fallback)
 		got, err := SystemCertPool()
 		if err != nil {
 			t.Fatal(err)
 		}
 		if !got.Equal(fallback) {
 			t.Fatal("SystemCertPool returned a non-fallback CertPool")
 		}
 	})

 	test(t, "before_first_load_with_system_CAs", func(t *testing.T) {
 		installSystemRootCAs(t)

 		fallback := newFallbackCertPool(t)
 		SetFallbackRoots(fallback)
 		got, err := SystemCertPool()
 		if err != nil {
 			t.Fatal(err)
 		}
 		if got.Equal(fallback) {
 			t.Fatal("SystemCertPool returned the fallback CertPool")
 		}
 	})

 	test(t, "before_first_load_force_godebug", func(t *testing.T) {
 		if err := os.Setenv("GODEBUG", "x509usefallbackroots=1"); err != nil {
 			t.Fatal(err)
 		}

 		installSystemRootCAs(t)

 		fallback := newFallbackCertPool(t)
 		SetFallbackRoots(fallback)
 		got, err := SystemCertPool()
 		if err != nil {
 			t.Fatal(err)
 		}
 		if !got.Equal(fallback) {
 			t.Fatal("SystemCertPool returned a non-fallback CertPool")
 		}
 	})

 	test(t, "after_first_load_force_godebug", func(t *testing.T) {
 		if err := os.Setenv("GODEBUG", "x509usefallbackroots=1"); err != nil {
 			t.Fatal(err)
 		}

 		installSystemRootCAs(t)
 		SystemCertPool() // load system certs, before setting fallbacks

 		fallback := newFallbackCertPool(t)
 		SetFallbackRoots(fallback)
 		got, err := SystemCertPool()
 		if err != nil {
 			t.Fatal(err)
 		}
 		if !got.Equal(fallback) {
 			t.Fatal("SystemCertPool returned a non-fallback CertPool")
 		}
 	})

 	test(t, "after_first_load_force_godebug_no_system_certs", func(t *testing.T) {
 		if err := os.Setenv("GODEBUG", "x509usefallbackroots=1"); err != nil {
 			t.Fatal(err)
 		}

 		SystemCertPool() // load system certs, before setting fallbacks

 		fallback := newFallbackCertPool(t)
 		SetFallbackRoots(fallback)
 		got, err := SystemCertPool()
 		if err != nil {
 			t.Fatal(err)
 		}
 		if !got.Equal(fallback) {
 			t.Fatal("SystemCertPool returned a non-fallback CertPool")
 		}
 	})
 }
	// Copyright 2025 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.

	//go:build linux

	package x509

	import (
	"encoding/pem"
	"fmt"
	"internal/testenv"
	"os"
	"syscall"
	"testing"
	)

	func TestSetFallbackRoots(t *testing.T) {
	if testing.Short() {
	t.Skip("skipping test in short mode")
	}

	test := func(t testing.T, name string, f func(t testing.T)) {
	t.Run(name, func(t *testing.T) {
	if os.Getenv("CRYPTO_X509_SETFALLBACKROOTS_TEST") != "1" {
	// Execute test in a separate process with CRYPTO_X509_SETFALBACKROOTS_TEST env.
	cmd := testenv.Command(t, testenv.Executable(t), fmt.Sprintf("-test.run=^%v$", t.Name()), "-test.v")
	cmd.Env = append(os.Environ(), "CRYPTO_X509_SETFALLBACKROOTS_TEST=1")
	cmd.SysProcAttr = &syscall.SysProcAttr{
	Cloneflags: syscall.CLONE_NEWNS \| syscall.CLONE_NEWUSER,
	UidMappings: []syscall.SysProcIDMap{{ContainerID: 0, HostID: os.Getuid(), Size: 1}},
	GidMappings: []syscall.SysProcIDMap{{ContainerID: 0, HostID: os.Getgid(), Size: 1}},
	}
	out, err := cmd.CombinedOutput()
	if testenv.SyscallIsNotSupported(err) {
	t.Skipf("skipping: could not start process with CLONE_NEWNS and CLONE_NEWUSER: %v", err)
	}
	t.Logf("running with CRYPTO_X509_SETFALLBACKROOTS_TEST=1:\n%s", out)
	if err != nil {
	t.Errorf("CRYPTO_X509_SETFALLBACKROOTS_TEST=1 subprocess failed: %v", err)
	}
	return
	}

	// This test is executed in a separate user and mount namespace, thus
	// we can mount a separate "/etc" empty bind mount, without the need for root access.
	// On linux all certs reside in /etc, so as we bind an empty dir, we
	// get a full control over the system CAs, required for this test.
	if err := syscall.Mount(t.TempDir(), "/etc", "", syscall.MS_BIND, ""); err != nil {
	if testenv.SyscallIsNotSupported(err) {
	t.Skipf("Failed to mount /etc: %v", err)
	}
	t.Fatalf("Failed to mount /etc: %v", err)
	}

	t.Cleanup(func() {
	if err := syscall.Unmount("/etc", 0); err != nil {
	t.Errorf("failed to unmount /etc: %v", err)
	}
	})

	f(t)
	})
	}

	newFallbackCertPool := func(t testing.T) CertPool {
	t.Helper()

	const fallbackCert = `-----BEGIN CERTIFICATE-----
	MIICGzCCAaGgAwIBAgIQQdKd0XLq7qeAwSxs6S+HUjAKBggqhkjOPQQDAzBPMQsw
	CQYDVQQGEwJVUzEpMCcGA1UEChMgSW50ZXJuZXQgU2VjdXJpdHkgUmVzZWFyY2gg
	R3JvdXAxFTATBgNVBAMTDElTUkcgUm9vdCBYMjAeFw0yMDA5MDQwMDAwMDBaFw00
	MDA5MTcxNjAwMDBaME8xCzAJBgNVBAYTAlVTMSkwJwYDVQQKEyBJbnRlcm5ldCBT
	ZWN1cml0eSBSZXNlYXJjaCBHcm91cDEVMBMGA1UEAxMMSVNSRyBSb290IFgyMHYw
	EAYHKoZIzj0CAQYFK4EEACIDYgAEzZvVn4CDCuwJSvMWSj5cz3es3mcFDR0HttwW
	+1qLFNvicWDEukWVEYmO6gbf9yoWHKS5xcUy4APgHoIYOIvXRdgKam7mAHf7AlF9
	ItgKbppbd9/w+kHsOdx1ymgHDB/qo0IwQDAOBgNVHQ8BAf8EBAMCAQYwDwYDVR0T
	AQH/BAUwAwEB/zAdBgNVHQ4EFgQUfEKWrt5LSDv6kviejM9ti6lyN5UwCgYIKoZI
	zj0EAwMDaAAwZQIwe3lORlCEwkSHRhtFcP9Ymd70/aTSVaYgLXTWNLxBo1BfASdW
	tL4ndQavEi51mI38AjEAi/V3bNTIZargCyzuFJ0nN6T5U6VR5CmD1/iQMVtCnwr1
	/q4AaOeMSQ+2b1tbFfLn
	-----END CERTIFICATE-----
	`
	b, _ := pem.Decode([]byte(fallbackCert))
	cert, err := ParseCertificate(b.Bytes)
	if err != nil {
	t.Fatal(err)
	}
	p := NewCertPool()
	p.AddCert(cert)
	return p
	}

	installSystemRootCAs := func(t *testing.T) {
	t.Helper()

	const systemCAs = `-----BEGIN CERTIFICATE-----
	MIIFazCCA1OgAwIBAgIRAIIQz7DSQONZRGPgu2OCiwAwDQYJKoZIhvcNAQELBQAw
	TzELMAkGA1UEBhMCVVMxKTAnBgNVBAoTIEludGVybmV0IFNlY3VyaXR5IFJlc2Vh
	cmNoIEdyb3VwMRUwEwYDVQQDEwxJU1JHIFJvb3QgWDEwHhcNMTUwNjA0MTEwNDM4
	WhcNMzUwNjA0MTEwNDM4WjBPMQswCQYDVQQGEwJVUzEpMCcGA1UEChMgSW50ZXJu
	ZXQgU2VjdXJpdHkgUmVzZWFyY2ggR3JvdXAxFTATBgNVBAMTDElTUkcgUm9vdCBY
	MTCCAiIwDQYJKoZIhvcNAQEBBQADggIPADCCAgoCggIBAK3oJHP0FDfzm54rVygc
	h77ct984kIxuPOZXoHj3dcKi/vVqbvYATyjb3miGbESTtrFj/RQSa78f0uoxmyF+
	0TM8ukj13Xnfs7j/EvEhmkvBioZxaUpmZmyPfjxwv60pIgbz5MDmgK7iS4+3mX6U
	A5/TR5d8mUgjU+g4rk8Kb4Mu0UlXjIB0ttov0DiNewNwIRt18jA8+o+u3dpjq+sW
	T8KOEUt+zwvo/7V3LvSye0rgTBIlDHCNAymg4VMk7BPZ7hm/ELNKjD+Jo2FR3qyH
	B5T0Y3HsLuJvW5iB4YlcNHlsdu87kGJ55tukmi8mxdAQ4Q7e2RCOFvu396j3x+UC
	B5iPNgiV5+I3lg02dZ77DnKxHZu8A/lJBdiB3QW0KtZB6awBdpUKD9jf1b0SHzUv
	KBds0pjBqAlkd25HN7rOrFleaJ1/ctaJxQZBKT5ZPt0m9STJEadao0xAH0ahmbWn
	OlFuhjuefXKnEgV4We0+UXgVCwOPjdAvBbI+e0ocS3MFEvzG6uBQE3xDk3SzynTn
	jh8BCNAw1FtxNrQHusEwMFxIt4I7mKZ9YIqioymCzLq9gwQbooMDQaHWBfEbwrbw
	qHyGO0aoSCqI3Haadr8faqU9GY/rOPNk3sgrDQoo//fb4hVC1CLQJ13hef4Y53CI
	rU7m2Ys6xt0nUW7/vGT1M0NPAgMBAAGjQjBAMA4GA1UdDwEB/wQEAwIBBjAPBgNV
	HRMBAf8EBTADAQH/MB0GA1UdDgQWBBR5tFnme7bl5AFzgAiIyBpY9umbbjANBgkq
	hkiG9w0BAQsFAAOCAgEAVR9YqbyyqFDQDLHYGmkgJykIrGF1XIpu+ILlaS/V9lZL
	ubhzEFnTIZd+50xx+7LSYK05qAvqFyFWhfFQDlnrzuBZ6brJFe+GnY+EgPbk6ZGQ
	3BebYhtF8GaV0nxvwuo77x/Py9auJ/GpsMiu/X1+mvoiBOv/2X/qkSsisRcOj/KK
	NFtY2PwByVS5uCbMiogziUwthDyC3+6WVwW6LLv3xLfHTjuCvjHIInNzktHCgKQ5
	ORAzI4JMPJ+GslWYHb4phowim57iaztXOoJwTdwJx4nLCgdNbOhdjsnvzqvHu7Ur
	TkXWStAmzOVyyghqpZXjFaH3pO3JLF+l+/+sKAIuvtd7u+Nxe5AW0wdeRlN8NwdC
	jNPElpzVmbUq4JUagEiuTDkHzsxHpFKVK7q4+63SM1N95R1NbdWhscdCb+ZAJzVc
	oyi3B43njTOQ5yOf+1CceWxG1bQVs5ZufpsMljq4Ui0/1lvh+wjChP4kqKOJ2qxq
	4RgqsahDYVvTH9w7jXbyLeiNdd8XM2w9U/t7y0Ff/9yi0GE44Za4rF2LN9d11TPA
	mRGunUHBcnWEvgJBQl9nJEiU0Zsnvgc/ubhPgXRR4Xq37Z0j4r7g1SgEEzwxA57d
	emyPxgcYxn/eR44/KJ4EBs+lVDR3veyJm+kXQ99b21/+jh5Xos1AnX5iItreGCc=
	-----END CERTIFICATE-----
	`
	if err := os.MkdirAll("/etc/ssl/certs", 06660); err != nil {
	t.Fatal(err)
	}

	if err := os.WriteFile("/etc/ssl/certs/ca-certificates.crt", []byte(systemCAs), 0666); err != nil {
	t.Fatal(err)
	}
	}

	test(t, "after_first_load_no_system_CAs", func(t *testing.T) {
	SystemCertPool() // load system certs, before setting fallbacks
	fallback := newFallbackCertPool(t)
	SetFallbackRoots(fallback)
	got, err := SystemCertPool()
	if err != nil {
	t.Fatal(err)
	}
	if !got.Equal(fallback) {
	t.Fatal("SystemCertPool returned a non-fallback CertPool")
	}
	})

	test(t, "after_first_load_system_CA_read_error", func(t *testing.T) {
	// This will fail to load in SystemCertPool since this is a directory,
	// rather than a file with certificates.
	if err := os.MkdirAll("/etc/ssl/certs/ca-certificates.crt", 0666); err != nil {
	t.Fatal(err)
	}

	_, err := SystemCertPool() // load system certs, before setting fallbacks
	if err == nil {
	t.Fatal("unexpected success")
	}

	fallback := newFallbackCertPool(t)
	SetFallbackRoots(fallback)
	got, err := SystemCertPool()
	if err != nil {
	t.Fatal(err)
	}
	if !got.Equal(fallback) {
	t.Fatal("SystemCertPool returned a non-fallback CertPool")
	}
	})

	test(t, "after_first_load_with_system_CAs", func(t *testing.T) {
	installSystemRootCAs(t)

	SystemCertPool() // load system certs, before setting fallbacks

	fallback := newFallbackCertPool(t)
	SetFallbackRoots(fallback)
	got, err := SystemCertPool()
	if err != nil {
	t.Fatal(err)
	}
	if got.Equal(fallback) {
	t.Fatal("SystemCertPool returned the fallback CertPool")
	}
	})

	test(t, "before_first_load_no_system_CAs", func(t *testing.T) {
	fallback := newFallbackCertPool(t)
	SetFallbackRoots(fallback)
	got, err := SystemCertPool()
	if err != nil {
	t.Fatal(err)
	}
	if !got.Equal(fallback) {
	t.Fatal("SystemCertPool returned a non-fallback CertPool")
	}
	})

	test(t, "before_first_load_system_CA_read_error", func(t *testing.T) {
	// This will fail to load in SystemCertPool since this is a directory,
	// rather than a file with certificates.
	if err := os.MkdirAll("/etc/ssl/certs/ca-certificates.crt", 0666); err != nil {
	t.Fatal(err)
	}

	fallback := newFallbackCertPool(t)
	SetFallbackRoots(fallback)
	got, err := SystemCertPool()
	if err != nil {
	t.Fatal(err)
	}
	if !got.Equal(fallback) {
	t.Fatal("SystemCertPool returned a non-fallback CertPool")
	}
	})

	test(t, "before_first_load_with_system_CAs", func(t *testing.T) {
	installSystemRootCAs(t)

	fallback := newFallbackCertPool(t)
	SetFallbackRoots(fallback)
	got, err := SystemCertPool()
	if err != nil {
	t.Fatal(err)
	}
	if got.Equal(fallback) {
	t.Fatal("SystemCertPool returned the fallback CertPool")
	}
	})

	test(t, "before_first_load_force_godebug", func(t *testing.T) {
	if err := os.Setenv("GODEBUG", "x509usefallbackroots=1"); err != nil {
	t.Fatal(err)
	}

	installSystemRootCAs(t)

	fallback := newFallbackCertPool(t)
	SetFallbackRoots(fallback)
	got, err := SystemCertPool()
	if err != nil {
	t.Fatal(err)
	}
	if !got.Equal(fallback) {
	t.Fatal("SystemCertPool returned a non-fallback CertPool")
	}
	})

	test(t, "after_first_load_force_godebug", func(t *testing.T) {
	if err := os.Setenv("GODEBUG", "x509usefallbackroots=1"); err != nil {
	t.Fatal(err)
	}

	installSystemRootCAs(t)
	SystemCertPool() // load system certs, before setting fallbacks

	fallback := newFallbackCertPool(t)
	SetFallbackRoots(fallback)
	got, err := SystemCertPool()
	if err != nil {
	t.Fatal(err)
	}
	if !got.Equal(fallback) {
	t.Fatal("SystemCertPool returned a non-fallback CertPool")
	}
	})

	test(t, "after_first_load_force_godebug_no_system_certs", func(t *testing.T) {
	if err := os.Setenv("GODEBUG", "x509usefallbackroots=1"); err != nil {
	t.Fatal(err)
	}

	SystemCertPool() // load system certs, before setting fallbacks

	fallback := newFallbackCertPool(t)
	SetFallbackRoots(fallback)
	got, err := SystemCertPool()
	if err != nil {
	t.Fatal(err)
	}
	if !got.Equal(fallback) {
	t.Fatal("SystemCertPool returned a non-fallback CertPool")
	}
	})
	}