Merge pull request moby#47999 from thaJeztah/deprecate_pkg_dmesg

pkg/dmesg: deprecate, and use internal utility instead

integration/container/overlayfs_linux_test.go

@@ -8,7 +8,7 @@ import (
 	containertypes "github.com/docker/docker/api/types/container"
 	"github.com/docker/docker/integration/internal/container"
 	"github.com/docker/docker/pkg/archive"
-	"github.com/docker/docker/pkg/dmesg"
+	"golang.org/x/sys/unix"
 	"gotest.tools/v3/assert"
 	"gotest.tools/v3/skip"
 )
@@ -81,9 +81,15 @@ func TestNoOverlayfsWarningsAboutUndefinedBehaviors(t *testing.T) {
 	}
 }
 
-func dmesgLines(bytes int) []string {
-	data := dmesg.Dmesg(bytes)
-	return strings.Split(strings.TrimSpace(string(data)), "\n")
+// dmesgLines returns last messages from the kernel log, up to size bytes,
+// and splits the output by newlines.
+func dmesgLines(size int) []string {
+	data := make([]byte, size)
+	amt, err := unix.Klogctl(unix.SYSLOG_ACTION_READ_ALL, data)
+	if err != nil {
+		return []string{}
+	}
+	return strings.Split(strings.TrimSpace(string(data[:amt])), "\n")
 }
 
 func diffDmesg(prev, next []string) []string {

pkg/dmesg/dmesg_linux.go

@@ -4,11 +4,12 @@ import (
 	"golang.org/x/sys/unix"
 )
 
-// Dmesg returns last messages from the kernel log, up to size bytes
+// Dmesg returns last messages from the kernel log, up to size bytes.
+//
+// Deprecated: the dmesg package is no longer used, and will be removed in the next release.
 func Dmesg(size int) []byte {
-	t := 3 // SYSLOG_ACTION_READ_ALL
 	b := make([]byte, size)
-	amt, err := unix.Klogctl(t, b)
+	amt, err := unix.Klogctl(unix.SYSLOG_ACTION_READ_ALL, b)
 	if err != nil {
 		return []byte{}
 	}