log: Don't prefix log file messages with time and severity if they're continuations

In fecb1b65b1ac ("log: Don't prefix message with timestamp on --debug
if it's a continuation"), I fixed this for --debug on standard error,
but not for log files: if messages are continuations, they shouldn't
be prefixed by timestamp and severity.

Otherwise, we'll print stuff like this:

  0.0028: ERROR:   Receive error on guest connection, reset0.0028:  ERROR:   : Bad file descriptor

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 9 insertions, 5 deletions

diff --git a/log.c b/log.c
index 433b552..a61468e 100644
--- a/log.c
+++ b/log.c
@@ -224,19 +224,23 @@ static int logfile_rotate(int fd, const struct timespec *now)
 /**
  * logfile_write() - Write entry to log file, trigger rotation if full
  * @newline:	Append newline at the end of the message, if missing
+ * @cont:	Continuation of a previous message, on the same line
  * @pri:	Facility and level map, same as priority for vsyslog()
  * @now:	Timestamp
  * @format:	Same as vsyslog() format
  * @ap:		Same as vsyslog() ap
  */
-static void logfile_write(bool newline, int pri, const struct timespec *now,
+static void logfile_write(bool newline, bool cont, int pri,
+			  const struct timespec *now,
 			  const char *format, va_list ap)
 {
 	char buf[BUFSIZ];
-	int n;
+	int n = 0;
 
-	n  = logtime_fmt(buf, BUFSIZ, now);
-	n += snprintf(buf + n, BUFSIZ - n, ": %s", logfile_prefix[pri]);
+	if (!cont) {
+		n += logtime_fmt(buf, BUFSIZ, now);
+		n += snprintf(buf + n, BUFSIZ - n, ": %s", logfile_prefix[pri]);
+	}
 
 	n += vsnprintf(buf + n, BUFSIZ - n, format, ap);
 
@@ -278,7 +282,7 @@ void vlogmsg(bool newline, bool cont, int pri, const char *format, va_list ap)
 
 		va_copy(ap2, ap); /* Don't clobber ap, we need it again */
 		if (log_file != -1)
-			logfile_write(newline, pri, now, format, ap2);
+			logfile_write(newline, cont, pri, now, format, ap2);
 		else if (!(log_mask & LOG_MASK(LOG_DEBUG)))
 			passt_vsyslog(newline, pri, format, ap2);