logger: pass raw libbpf print output

Due to libbpf output being escaped, we should pass the raw output to the
consumer, letting them decide how to format it, since them might want
to, for example, use it in a logger or print directly to stderr.

Reported-by: @yanivagman

logger_cb.go

@@ -8,7 +8,6 @@ import "C"
 import (
 	"fmt"
 	"os"
-	"strings"
 )
 
 // This callback definition needs to be in a different file from where it is declared in C
@@ -19,7 +18,6 @@ import (
 //export loggerCallback
 func loggerCallback(libbpfPrintLevel int, libbpfOutput *C.char) {
 	goOutput := C.GoString(libbpfOutput)
-	goOutput = strings.TrimSuffix(goOutput, "\n")
 
 	for _, fnFilterOut := range callbacks.LogFilters {
 		if fnFilterOut != nil {
@@ -29,6 +27,7 @@ func loggerCallback(libbpfPrintLevel int, libbpfOutput *C.char) {
 		}
 	}
 
+	// pass received output to callback, leaving formatting to consumer
 	callbacks.Log(libbpfPrintLevel, goOutput)
 }
 
@@ -62,9 +61,6 @@ func SetLoggerCbs(cbs Callbacks) {
 
 // logFallback is the default logger callback
 // - level is ignored
-// - output, suffixed with a newline, is printed to stderr
 func logFallback(level int, msg string) {
-	var outMsg = msg + "\n"
-
-	fmt.Fprint(os.Stderr, outMsg)
+	fmt.Fprint(os.Stderr, msg)
 }

logger_cb_test.go

@@ -47,6 +47,6 @@ func TestLogFallback(t *testing.T) {
 		require.NoError(t, err, "failed to copy from read end to buffer")
 
 		// The message should be printed to stderr with a newline
-		assert.Equal(t, tc.message+"\n", buf.String())
+		assert.Equal(t, tc.message, buf.String())
 	}
 }