shared: Checks or explicitly ignores errors.

Signed-off-by: Mark Laing <mark.laing@canonical.com>

shared/archive.go

@@ -13,7 +13,7 @@ func DetectCompression(fname string) ([]string, string, []string, error) {
 	if err != nil {
 		return nil, "", nil, err
 	}
-	defer f.Close()
+	defer func() { _ = f.Close() }()
 
 	return DetectCompressionFile(f)
 }

shared/cert.go

@@ -259,15 +259,32 @@ func GenCert(certf string, keyf string, certtype bool, addHosts bool) error {
 	if err != nil {
 		return fmt.Errorf("Failed to open %s for writing: %w", certf, err)
 	}
-	certOut.Write(certBytes)
-	certOut.Close()
+
+	_, err = certOut.Write(certBytes)
+	if err != nil {
+		return fmt.Errorf("Failed to write cert file: %w", err)
+	}
+
+	err = certOut.Close()
+	if err != nil {
+		return fmt.Errorf("Failed to close cert file: %w", err)
+	}
 
 	keyOut, err := os.OpenFile(keyf, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
 	if err != nil {
 		return fmt.Errorf("Failed to open %s for writing: %w", keyf, err)
 	}
-	keyOut.Write(keyBytes)
-	keyOut.Close()
+
+	_, err = keyOut.Write(keyBytes)
+	if err != nil {
+		return fmt.Errorf("Failed to write key file: %w", err)
+	}
+
+	err = keyOut.Close()
+	if err != nil {
+		return fmt.Errorf("Failed to close key file: %w", err)
+	}
+
 	return nil
 }
 

shared/cert_test.go

@@ -18,7 +18,7 @@ func TestKeyPairAndCA(t *testing.T) {
 	if err != nil {
 		t.Errorf("failed to create temporary dir: %v", err)
 	}
-	defer os.RemoveAll(dir)
+	defer func() { _ = os.RemoveAll(dir) }()
 
 	info, err := shared.KeyPairAndCA(dir, "test", shared.CertServer, true)
 	if err != nil {

shared/idmap/idmapset_linux.go

@@ -706,7 +706,7 @@ func getFromShadow(fname string, username string) ([][]int64, error) {
 	if err != nil {
 		return nil, err
 	}
-	defer f.Close()
+	defer func() { _ = f.Close() }()
 
 	scanner := bufio.NewScanner(f)
 	for scanner.Scan() {
@@ -756,7 +756,7 @@ func getFromProc(fname string) ([][]int64, error) {
 	if err != nil {
 		return nil, err
 	}
-	defer f.Close()
+	defer func() { _ = f.Close() }()
 
 	scanner := bufio.NewScanner(f)
 	for scanner.Scan() {

shared/idmap/shift_linux.go

@@ -477,8 +477,8 @@ func SupportsVFS3Fscaps(prefix string) bool {
 	if err != nil {
 		return false
 	}
-	tmpfile.Close()
-	defer os.Remove(tmpfile.Name())
+	defer func() { _ = tmpfile.Close() }()
+	defer func() { _ = os.Remove(tmpfile.Name()) }()
 
 	err = os.Chmod(tmpfile.Name(), 0001)
 	if err != nil {

shared/instancewriter/instance_tar_writer.go

@@ -146,7 +146,7 @@ func (ctw *InstanceTarWriter) WriteFile(name string, srcPath string, fi os.FileI
 		if err != nil {
 			return fmt.Errorf("Failed to open file %q: %w", srcPath, err)
 		}
-		defer f.Close()
+		defer func() { _ = f.Close() }()
 
 		r := io.Reader(f)
 		if ignoreGrowth {

shared/netutils/network_linux.go

@@ -23,7 +23,7 @@ func WebsocketExecMirror(conn *websocket.Conn, w io.WriteCloser, r io.ReadCloser
 		for {
 			buf, ok := <-in
 			if !ok {
-				r.Close()
+				_ = r.Close()
 				logger.Debugf("Sending write barrier")
 				err := conn.WriteMessage(websocket.TextMessage, []byte{})
 				if err != nil {
@@ -41,9 +41,9 @@ func WebsocketExecMirror(conn *websocket.Conn, w io.WriteCloser, r io.ReadCloser
 		}
 
 		closeMsg := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
-		conn.WriteMessage(websocket.CloseMessage, closeMsg)
+		_ = conn.WriteMessage(websocket.CloseMessage, closeMsg)
 		readDone <- true
-		r.Close()
+		_ = r.Close()
 	}(conn, r)
 
 	return readDone, writeDone

shared/netutils/network_linux_cgo.go

@@ -72,7 +72,7 @@ func NetnsGetifaddrs(initPID int32) (map[string]api.InstanceStateNetwork, error)
 		if err != nil {
 			return nil, err
 		}
-		defer f.Close()
+		defer func() { _ = f.Close() }()
 
 		netnsID = C.netns_get_nsid(C.__s32(f.Fd()))
 		if netnsID < 0 {

shared/network.go

@@ -44,8 +44,8 @@ func RFC3493Dialer(network string, address string) (net.Conn, error) {
 		}
 
 		if tc, ok := c.(*net.TCPConn); ok {
-			tc.SetKeepAlive(true)
-			tc.SetKeepAlivePeriod(3 * time.Second)
+			_ = tc.SetKeepAlive(true)
+			_ = tc.SetKeepAlivePeriod(3 * time.Second)
 		}
 
 		return c, nil
@@ -200,7 +200,7 @@ func WebsocketSendStream(conn *websocket.Conn, r io.Reader, bufferSize int) chan
 				break
 			}
 		}
-		conn.WriteMessage(websocket.TextMessage, []byte{})
+		_ = conn.WriteMessage(websocket.TextMessage, []byte{})
 		ch <- true
 	}(conn, r)
 
@@ -269,7 +269,7 @@ func WebsocketProxy(source *websocket.Conn, target *websocket.Conn) chan struct{
 			}
 
 			_, err = io.Copy(w, r)
-			w.Close()
+			_ = w.Close()
 			if err != nil {
 				break
 			}
@@ -293,8 +293,8 @@ func WebsocketProxy(source *websocket.Conn, target *websocket.Conn) chan struct{
 		case <-chRecv:
 		}
 
-		source.Close()
-		target.Close()
+		_ = source.Close()
+		_ = target.Close()
 
 		close(ch)
 	}()
@@ -311,9 +311,9 @@ func defaultReader(conn *websocket.Conn, r io.ReadCloser, readDone chan<- bool)
 	for {
 		buf, ok := <-in
 		if !ok {
-			r.Close()
+			_ = r.Close()
 			logger.Debug("Sending write barrier")
-			conn.WriteMessage(websocket.TextMessage, []byte{})
+			_ = conn.WriteMessage(websocket.TextMessage, []byte{})
 			readDone <- true
 			return
 		}
@@ -325,9 +325,9 @@ func defaultReader(conn *websocket.Conn, r io.ReadCloser, readDone chan<- bool)
 		}
 	}
 	closeMsg := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
-	conn.WriteMessage(websocket.CloseMessage, closeMsg)
+	_ = conn.WriteMessage(websocket.CloseMessage, closeMsg)
 	readDone <- true
-	r.Close()
+	_ = r.Close()
 }
 
 func DefaultWriter(conn *websocket.Conn, w io.WriteCloser, writeDone chan<- bool) {
@@ -364,7 +364,7 @@ func DefaultWriter(conn *websocket.Conn, w io.WriteCloser, writeDone chan<- bool
 		}
 	}
 	writeDone <- true
-	w.Close()
+	_ = w.Close()
 }
 
 // WebsocketIO is a wrapper implementing ReadWriteCloser on top of websocket
@@ -417,14 +417,13 @@ func (w *WebsocketIO) Write(p []byte) (n int, err error) {
 	if err != nil {
 		return -1, err
 	}
-	defer wr.Close()
 
 	n, err = wr.Write(p)
 	if err != nil {
 		return -1, err
 	}
 
-	return n, nil
+	return n, wr.Close()
 }
 
 // Close sends a control message indicating the stream is finished, but it does not actually close
@@ -475,10 +474,10 @@ func WebsocketConsoleMirror(conn *websocket.Conn, w io.WriteCloser, r io.ReadClo
 		for {
 			buf, ok := <-in
 			if !ok {
-				r.Close()
+				_ = r.Close()
 				logger.Debugf("Sending write barrier")
-				conn.WriteMessage(websocket.BinaryMessage, []byte("\r"))
-				conn.WriteMessage(websocket.TextMessage, []byte{})
+				_ = conn.WriteMessage(websocket.BinaryMessage, []byte("\r"))
+				_ = conn.WriteMessage(websocket.TextMessage, []byte{})
 				readDone <- true
 				return
 			}
@@ -491,9 +490,9 @@ func WebsocketConsoleMirror(conn *websocket.Conn, w io.WriteCloser, r io.ReadClo
 		}
 
 		closeMsg := websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")
-		conn.WriteMessage(websocket.CloseMessage, closeMsg)
+		_ = conn.WriteMessage(websocket.CloseMessage, closeMsg)
 		readDone <- true
-		r.Close()
+		_ = r.Close()
 	}(conn, r)
 
 	return readDone, writeDone
@@ -514,6 +513,6 @@ func AllocatePort() (int, error) {
 	if err != nil {
 		return -1, err
 	}
-	defer l.Close()
-	return l.Addr().(*net.TCPAddr).Port, nil
+
+	return l.Addr().(*net.TCPAddr).Port, l.Close()
 }

shared/osarch/tempfile_test.go

@@ -13,11 +13,11 @@ func WriteTempFile(s suite.Suite, dir string, prefix string, content string) (st
 	if err != nil {
 		s.T().Errorf("Failed to create temporary file: %v", err)
 	}
-	defer f.Close()
+	defer func() { _ = f.Close() }()
 
 	_, err = f.WriteString(content)
 	if err != nil {
 		s.T().Errorf("Failed to write string to temp file: %v", err)
 	}
-	return f.Name(), func() { os.Remove(f.Name()) }
+	return f.Name(), func() { _ = os.Remove(f.Name()) }
 }

shared/simplestreams/simplestreams.go

@@ -72,13 +72,13 @@ func (s *SimpleStreams) readCache(path string) ([]byte, bool) {
 
 	fi, err := os.Stat(cacheName)
 	if err != nil {
-		os.Remove(cacheName)
+		_ = os.Remove(cacheName)
 		return nil, false
 	}
 
 	body, err := ioutil.ReadFile(cacheName)
 	if err != nil {
-		os.Remove(cacheName)
+		_ = os.Remove(cacheName)
 		return nil, false
 	}
 
@@ -121,7 +121,7 @@ func (s *SimpleStreams) cachedDownload(path string) ([]byte, error) {
 
 		return nil, err
 	}
-	defer r.Body.Close()
+	defer func() { _ = r.Body.Close() }()
 
 	if r.StatusCode != http.StatusOK {
 		// On local connectivity error, return from cache anyway
@@ -140,8 +140,8 @@ func (s *SimpleStreams) cachedDownload(path string) ([]byte, error) {
 	// Attempt to store in cache
 	if s.cachePath != "" {
 		cacheName := filepath.Join(s.cachePath, fileName)
-		os.Remove(cacheName)
-		ioutil.WriteFile(cacheName, body, 0644)
+		_ = os.Remove(cacheName)
+		_ = ioutil.WriteFile(cacheName, body, 0644)
 	}
 
 	return body, nil

shared/subprocess/bgpm_test.go

@@ -49,7 +49,7 @@ func TestSignalHandling(t *testing.T) {
 	if err != nil {
 		t.Error("Could not open file ", err)
 	}
-	defer file.Close()
+	defer func() { _ = file.Close() }()
 
 	var text = make([]byte, 1024)
 	for {
@@ -159,7 +159,7 @@ func TestProcessStartWaitExit(t *testing.T) {
 	if err != nil {
 		t.Error("Could not open file: ", err)
 	}
-	defer file.Close()
+	defer func() { _ = file.Close() }()
 
 	exp = "hello again\nwaiting now\n"
 	// Read file, line by line

shared/subprocess/proc.go

@@ -143,11 +143,11 @@ func (p *Process) start(fds []*os.File) error {
 	}
 
 	if p.Stdout != nil && p.closeFds {
-		defer p.Stdout.Close()
+		defer func() { _ = p.Stdout.Close() }()
 	}
 
 	if p.Stderr != nil && p.Stderr != p.Stdout && p.closeFds {
-		defer p.Stderr.Close()
+		defer func() { _ = p.Stderr.Close() }()
 	}
 
 	// Start the process.

shared/usbid/load.go

@@ -37,7 +37,7 @@ func Load() {
 		}
 		return
 	}
-	defer usbids.Close()
+	defer func() { _ = usbids.Close() }()
 
 	ids, cls, err := ParseIDs(usbids)
 	if err != nil {

shared/util.go

@@ -8,6 +8,7 @@ import (
 	"encoding/gob"
 	"encoding/hex"
 	"fmt"
+	"github.com/lxc/lxd/lxd/revert"
 	"hash"
 	"io"
 	"io/ioutil"
@@ -76,7 +77,7 @@ func PathIsEmpty(path string) (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	defer f.Close()
+	defer func() { _ = f.Close() }()
 
 	// read in ONLY one file
 	_, err = f.Readdir(1)
@@ -404,7 +405,7 @@ func FileMove(oldPath string, newPath string) error {
 		return err
 	}
 
-	os.Remove(oldPath)
+	_ = os.Remove(oldPath)
 
 	return nil
 }
@@ -447,7 +448,7 @@ func FileCopy(source string, dest string) error {
 	if err != nil {
 		return err
 	}
-	defer s.Close()
+	defer func() { _ = s.Close() }()
 
 	d, err := os.Create(dest)
 	if err != nil {
@@ -460,7 +461,6 @@ func FileCopy(source string, dest string) error {
 			return err
 		}
 	}
-	defer d.Close()
 
 	_, err = io.Copy(d, s)
 	if err != nil {
@@ -469,10 +469,13 @@ func FileCopy(source string, dest string) error {
 
 	/* chown not supported on windows */
 	if runtime.GOOS != "windows" {
-		return d.Chown(uid, gid)
+		err = d.Chown(uid, gid)
+		if err != nil {
+			return err
+		}
 	}
 
-	return nil
+	return d.Close()
 }
 
 // DirCopy copies a directory recursively, overwriting the target if it exists.
@@ -743,7 +746,7 @@ func RunningInUserNS() bool {
 	if err != nil {
 		return false
 	}
-	defer file.Close()
+	defer func() { _ = file.Close() }()
 
 	buf := bufio.NewReader(file)
 	l, _, err := buf.ReadLine()
@@ -753,7 +756,7 @@ func RunningInUserNS() bool {
 
 	line := string(l)
 	var a, b, c int64
-	fmt.Sscanf(line, "%d %d %d", &a, &b, &c)
+	_, _ = fmt.Sscanf(line, "%d %d %d", &a, &b, &c)
 	if a == 0 && b == 0 && c == 4294967295 {
 		return false
 	}
@@ -790,20 +793,34 @@ func TextEditor(inPath string, inContent []byte) ([]byte, error) {
 		if err != nil {
 			return []byte{}, err
 		}
+		reverter := revert.New()
+		defer reverter.Fail()
+		reverter.Add(func() { _ = f.Close() })
+		reverter.Add(func() { _ = os.Remove(f.Name()) })
 
 		err = os.Chmod(f.Name(), 0600)
 		if err != nil {
-			f.Close()
-			os.Remove(f.Name())
 			return []byte{}, err
 		}
 
-		f.Write(inContent)
-		f.Close()
+		_, err = f.Write(inContent)
+		if err != nil {
+			return []byte{}, err
+		}
+
+		err = f.Close()
+		if err != nil {
+			return []byte{}, err
+		}
 
 		path = fmt.Sprintf("%s.yaml", f.Name())
-		os.Rename(f.Name(), path)
-		defer os.Remove(path)
+		err = os.Rename(f.Name(), path)
+		if err != nil {
+			return []byte{}, err
+		}
+
+		reverter.Success()
+		reverter.Add(func() { _ = os.Remove(path) })
 	} else {
 		path = inPath
 	}
@@ -1027,7 +1044,7 @@ func SetProgressMetadata(metadata map[string]any, stage, displayPrefix string, p
 
 func DownloadFileHash(ctx context.Context, httpClient *http.Client, useragent string, progress func(progress ioprogress.ProgressData), canceler *cancel.HTTPRequestCanceller, filename string, url string, hash string, hashFunc hash.Hash, target io.WriteSeeker) (int64, error) {
 	// Always seek to the beginning
-	target.Seek(0, 0)
+	_, _ = target.Seek(0, 0)
 
 	var req *http.Request
 	var err error
@@ -1051,7 +1068,7 @@ func DownloadFileHash(ctx context.Context, httpClient *http.Client, useragent st
 	if err != nil {
 		return -1, err
 	}
-	defer r.Body.Close()
+	defer func() { _ = r.Body.Close() }()
 	defer close(doneCh)
 
 	if r.StatusCode != http.StatusOK {
@@ -1103,7 +1120,7 @@ func ParseNumberFromFile(file string) (int64, error) {
 	if err != nil {
 		return int64(0), err
 	}
-	defer f.Close()
+	defer func() { _ = f.Close() }()
 
 	buf := make([]byte, 4096)
 	n, err := f.Read(buf)

shared/util_linux.go

@@ -17,6 +17,7 @@ import (
 
 	"golang.org/x/sys/unix"
 
+	"github.com/lxc/lxd/lxd/revert"
 	"github.com/lxc/lxd/shared/logger"
 	"github.com/lxc/lxd/shared/units"
 )
@@ -294,7 +295,7 @@ func DeviceTotalMemory() (int64, error) {
 	if err != nil {
 		return -1, err
 	}
-	defer f.Close()
+	defer func() { _ = f.Close() }()
 
 	// Read it line by line
 	scan := bufio.NewScanner(f)
@@ -324,7 +325,8 @@ func DeviceTotalMemory() (int64, error) {
 
 // OpenPtyInDevpts creates a new PTS pair, configures them and returns them.
 func OpenPtyInDevpts(devpts_fd int, uid, gid int64) (*os.File, *os.File, error) {
-	revert := true
+	reverter := revert.New()
+	defer reverter.Fail()
 	var fd int
 	var ptx *os.File
 	var err error
@@ -339,11 +341,7 @@ func OpenPtyInDevpts(devpts_fd int, uid, gid int64) (*os.File, *os.File, error)
 		return nil, nil, err
 	}
 	ptx = os.NewFile(uintptr(fd), "/dev/pts/ptmx")
-	defer func() {
-		if revert {
-			ptx.Close()
-		}
-	}()
+	reverter.Add(func() { _ = ptx.Close() })
 
 	// Unlock the ptx and pty.
 	val := 0
@@ -382,11 +380,7 @@ func OpenPtyInDevpts(devpts_fd int, uid, gid int64) (*os.File, *os.File, error)
 			return nil, nil, err
 		}
 	}
-	defer func() {
-		if revert {
-			pty.Close()
-		}
-	}()
+	reverter.Add(func() { _ = pty.Close() })
 
 	// Configure both sides
 	for _, entry := range []*os.File{ptx, pty} {
@@ -433,7 +427,7 @@ func OpenPtyInDevpts(devpts_fd int, uid, gid int64) (*os.File, *os.File, error)
 		return nil, nil, err
 	}
 
-	revert = false
+	reverter.Success()
 	return ptx, pty, nil
 }
 

shared/util_linux_test.go

@@ -22,15 +22,15 @@ func TestGetAllXattr(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	defer os.Remove(xattrFile.Name())
-	xattrFile.Close()
+	defer func() { _ = os.Remove(xattrFile.Name()) }()
+	_ = xattrFile.Close()
 
 	xattrDir, err := ioutil.TempDir("", "")
 	if err != nil {
 		t.Error(err)
 		return
 	}
-	defer os.Remove(xattrDir)
+	defer func() { _ = os.Remove(xattrDir) }()
 
 	for k, v := range testxattr {
 		err = unix.Setxattr(xattrFile.Name(), k, []byte(v), 0)

shared/util_test.go

@@ -47,22 +47,22 @@ func TestFileCopy(t *testing.T) {
 		t.Error(err)
 		return
 	}
-	defer os.Remove(source.Name())
+	defer func() { _ = os.Remove(source.Name()) }()
 
 	if err := WriteAll(source, helloWorld); err != nil {
-		source.Close()
+		_ = source.Close()
 		t.Error(err)
 		return
 	}
-	source.Close()
+	_ = source.Close()
 
 	dest, err := ioutil.TempFile("", "")
-	defer os.Remove(dest.Name())
+	defer func() { _ = os.Remove(dest.Name()) }()
 	if err != nil {
 		t.Error(err)
 		return
 	}
-	dest.Close()
+	_ = dest.Close()
 
 	if err := FileCopy(source.Name(), dest.Name()); err != nil {
 		t.Error(err)
@@ -90,7 +90,7 @@ func TestFileCopy(t *testing.T) {
 func TestDirCopy(t *testing.T) {
 	dir, err := ioutil.TempDir("", "lxd-shared-util-")
 	require.NoError(t, err)
-	defer os.RemoveAll(dir)
+	defer func() { _ = os.RemoveAll(dir) }()
 
 	source := filepath.Join(dir, "source")
 	dest := filepath.Join(dir, "dest")
@@ -127,7 +127,7 @@ func TestDirCopy(t *testing.T) {
 
 func TestReaderToChannel(t *testing.T) {
 	buf := make([]byte, 1*1024*1024)
-	rand.Read(buf)
+	_, _ = rand.Read(buf)
 
 	offset := 0
 	finished := false