[PATCH] conf, log: On -h / --help, print usage to stdout, not stderr

[Stefano Brivio <sbrivio@redhat.com>]

Erik suggests that this makes it easier to grep for options, and with
--help we're anyway printing usage information as expected, not as
part of an error report.

Reported-by: Erik Sjölund <erik.sjolund@gmail.com>
Link: https://bugs.passt.top/show_bug.cgi?id=52
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 conf.c | 4 +++-
 log.c  | 8 +++++---
 log.h  | 1 +
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/conf.c b/conf.c
index ffff235..9eb6992 100644
--- a/conf.c
+++ b/conf.c
@@ -1630,8 +1630,10 @@ void conf(struct ctx *c, int argc, char **argv)
 		case 'U':
 			/* Handle these later, once addresses are configured */
 			break;
-		case '?':
 		case 'h':
+			log_to_stdout = 1;
+			/* Falls through */
+		case '?':
 		default:
 			usage(argv[0]);
 			break;
diff --git a/log.c b/log.c
index 3a3d101..63d7801 100644
--- a/log.c
+++ b/log.c
@@ -43,17 +43,19 @@ static char	log_header[BUFSIZ];	/* File header, written back on cuts */
 
 static time_t	log_start;		/* Start timestamp */
 int		log_trace;		/* --trace mode enabled */
+int		log_to_stdout;		/* Print to stdout instead of stderr */
 
 #define BEFORE_DAEMON		(setlogmask(0) == LOG_MASK(LOG_EMERG))
 
 #define logfn(name, level)						\
 void name(const char *format, ...) {					\
+	FILE *out = log_to_stdout ? stdout : stderr;			\
 	struct timespec tp;						\
 	va_list args;							\
 									\
 	if (setlogmask(0) & LOG_MASK(LOG_DEBUG) && log_file == -1) {	\
 		clock_gettime(CLOCK_REALTIME, &tp);			\
-		fprintf(stderr, "%lli.%04lli: ",			\
+		fprintf(out, "%lli.%04lli: ",				\
 			(long long int)tp.tv_sec - log_start,		\
 			(long long int)tp.tv_nsec / (100L * 1000));	\
 	}								\
@@ -70,10 +72,10 @@ void name(const char *format, ...) {					\
 	if ((setlogmask(0) & LOG_MASK(LOG_DEBUG) && log_file == -1) ||	\
 	    (BEFORE_DAEMON && !(log_opt & LOG_PERROR))) {		\
 		va_start(args, format);					\
-		(void)vfprintf(stderr, format, args); 			\
+		(void)vfprintf(out, format, args); 			\
 		va_end(args);						\
 		if (format[strlen(format)] != '\n')			\
-			fprintf(stderr, "\n");				\
+			fprintf(out, "\n");				\
 	}								\
 }
 
diff --git a/log.h b/log.h
index 3aab29d..a17171a 100644
--- a/log.h
+++ b/log.h
@@ -22,6 +22,7 @@ void debug(const char *format, ...);
 	} while (0)
 
 extern int log_trace;
+extern int log_to_stdout;
 void trace_init(int enable);
 #define trace(...)							\
 	do {								\
-- 
@@ -22,6 +22,7 @@ void debug(const char *format, ...);
 	} while (0)
 
 extern int log_trace;
+extern int log_to_stdout;
 void trace_init(int enable);
 #define trace(...)							\
 	do {								\
-- 
2.39.2