kmsg-export-flags.patch

---
 kernel/printk.c |   42 +++++++++++++++++++++++++++---------------
 1 file changed, 27 insertions(+), 15 deletions(-)

--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -356,10 +356,28 @@ static void log_store(int facility, int
 	log_next_seq++;
 }
 
+static bool msg_wants_prefix(const struct log *msg, enum log_flags prev)
+{
+	if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
+		return false;
+	if ((msg->flags & LOG_CONT) && (prev & LOG_CONT) &&
+	    !(prev & LOG_NEWLINE))
+		return false;
+	return true;
+}
+
+static bool msg_wants_newline(const struct log *msg, enum log_flags prev)
+{
+	if ((msg->flags & LOG_CONT) && !(msg->flags & LOG_NEWLINE))
+		return false;
+	return true;
+}
+
 /* /dev/kmsg - userspace message inject/listen interface */
 struct devkmsg_user {
 	u64 seq;
 	u32 idx;
+	enum log_flags prev;
 	struct mutex lock;
 	char buf[8192];
 };
@@ -424,6 +442,7 @@ static ssize_t devkmsg_read(struct file
 	struct devkmsg_user *user = file->private_data;
 	struct log *msg;
 	u64 ts_usec;
+	char flag = '-';
 	size_t i;
 	size_t len;
 	ssize_t ret;
@@ -462,8 +481,12 @@ static ssize_t devkmsg_read(struct file
 	msg = log_from_idx(user->idx);
 	ts_usec = msg->ts_nsec;
 	do_div(ts_usec, 1000);
-	len = sprintf(user->buf, "%u,%llu,%llu;",
-		      (msg->facility << 3) | msg->level, user->seq, ts_usec);
+	if (!msg_wants_prefix(msg, user->prev) ||
+	    !msg_wants_newline(msg, user->prev))
+		flag = '+';
+	len = sprintf(user->buf,
+		      "%u,%llu,%llu,%c;", (msg->facility << 3) | msg->level,
+		      user->seq, ts_usec, flag);
 
 	/* escape non-printable characters */
 	for (i = 0; i < msg->text_len; i++) {
@@ -847,21 +870,10 @@ static size_t msg_print_text(const struc
 {
 	const char *text = log_text(msg);
 	size_t text_size = msg->text_len;
-	bool prefix = true;
-	bool newline = true;
+	bool prefix = msg_wants_prefix(msg, prev);
+	bool newline = msg_wants_newline(msg, prev);
 	size_t len = 0;
 
-	if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
-		prefix = false;
-
-	if (msg->flags & LOG_CONT) {
-		if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
-			prefix = false;
-
-		if (!(msg->flags & LOG_NEWLINE))
-			newline = false;
-	}
-
 	do {
 		const char *next = memchr(text, '\n', text_size);
 		size_t text_len;