> On May 24, 2021, at 9:36 PM, Nick Rosbrook <rosbro...@gmail.com> wrote:
>
> Add some logging methods to Context to provide easy use of the
> Contenxt's xentoollog_logger. These are not exported, but the LogLevel
> type is so that a later commit can allow the Context's log level to be
> configurable.
>
> Becuase cgo does not support calling C functions with variable
> arguments, e.g. xtl_log, add an xtl_log_wrap function to the cgo preamble
> that accepts an already formatted string, and handle the formatting in
> Go.
>
> Signed-off-by: Nick Rosbrook <rosbro...@ainfosec.com>
Looks good. One comment:
> ---
> tools/golang/xenlight/xenlight.go | 45 +++++++++++++++++++++++++++++++
> 1 file changed, 45 insertions(+)
>
> diff --git a/tools/golang/xenlight/xenlight.go
> b/tools/golang/xenlight/xenlight.go
> index fc3eb0bf3f..f68d7b6e97 100644
> --- a/tools/golang/xenlight/xenlight.go
> +++ b/tools/golang/xenlight/xenlight.go
> @@ -32,6 +32,15 @@ static const libxl_childproc_hooks childproc_hooks = {
> .chldowner = libxl_sigchl
> void xenlight_set_chldproc(libxl_ctx *ctx) {
> libxl_childproc_setmode(ctx, &childproc_hooks, NULL);
> }
> +
> +void xtl_log_wrap(struct xentoollog_logger *logger,
> + xentoollog_level level,
> + int errnoval,
> + const char *context,
> + const char *msg)
> +{
> + xtl_log(logger, level, errnoval, context, "%s", msg);
> +}
> */
> import "C"
>
> @@ -192,6 +201,42 @@ func (ctx *Context) Close() error {
> return nil
> }
>
> +// LogLevel represents an xentoollog_level, and can be used to configre the
> log
> +// level of a Context's logger.
> +type LogLevel int
> +
> +const (
> + //LogLevelNone LogLevel = C.XTL_NONE
Why are we not defining this one? Don’t we want to be able to disable logging
entirely?
> + LogLevelDebug LogLevel = C.XTL_DEBUG
> + LogLevelVerbose LogLevel = C.XTL_VERBOSE
> + LogLevelDetail LogLevel = C.XTL_DETAIL
> + LogLevelProgress LogLevel = C.XTL_PROGRESS
> + LogLevelInfo LogLevel = C.XTL_INFO
> + LogLevelNotice LogLevel = C.XTL_NOTICE
> + LogLevelWarn LogLevel = C.XTL_WARN
> + LogLevelError LogLevel = C.XTL_ERROR
> + LogLevelCritical LogLevel = C.XTL_CRITICAL
> + //LogLevelNumLevels LogLevel = C.XTL_NUM_LEVELS
> +)
> +
> +func (ctx *Context) log(lvl LogLevel, errnoval int, format string, a
> ...interface{}) {
> + msg := C.CString(fmt.Sprintf(format, a...))
> + defer C.free(unsafe.Pointer(msg))
> + context := C.CString("xenlight")
> + defer C.free(unsafe.Pointer(context))
Hmm, allocating and freeing a fixed string every time seems pretty wasteful.
Would it make more sense to either use a static C string in the CGo code at the
top instead? Or if not, to make context a global variable we allocate once at
the package level and re-use?
Also, is ‘xenlight’ informative enough? I haven’t looked at the other
“context” strings; would “go-xenlight” or something be better?
> +
> + C.xtl_log_wrap((*C.xentoollog_logger)(unsafe.Pointer(ctx.logger)),
> + C.xentoollog_level(lvl), C.int(errnoval), context, msg)
> +}
I think we want to make it possible long-term to configure your own logger or
have no logger at all; so maybe we should add a `if (ctx.logger == nil)
return;` at then top?
Other than that looks good, thanks!
-George
