From f2616c772c768485de18e7fcb2816bcdcd098339 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Wed, 17 Mar 2021 13:34:35 -0400 Subject: [PATCH] seq_buf: Add seq_buf_terminate() API In the case that the seq_buf buffer needs to be printed directly, add a way to make sure that the buffer is safe to read by forcing a nul terminating character at the end of the string, or the last byte of the buffer if the string has overflowed. Signed-off-by: Steven Rostedt (VMware) --- include/linux/seq_buf.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h index 9d6c28c..5b31c51 100644 --- a/include/linux/seq_buf.h +++ b/include/linux/seq_buf.h @@ -72,6 +72,31 @@ static inline unsigned int seq_buf_used(struct seq_buf *s) } /** + * seq_buf_terminate - Make sure buffer is nul terminated + * @s: the seq_buf descriptor to terminate. + * + * This makes sure that the buffer in @s is nul terminated and + * safe to read as a string. + * + * Note, if this is called when the buffer has overflowed, then + * the last byte of the buffer is zeroed, and the len will still + * point passed it. + * + * After this function is called, s->buffer is safe to use + * in string operations. + */ +static inline void seq_buf_terminate(struct seq_buf *s) +{ + if (WARN_ON(s->size == 0)) + return; + + if (seq_buf_buffer_left(s)) + s->buffer[s->len] = 0; + else + s->buffer[s->size - 1] = 0; +} + +/** * seq_buf_get_buf - get buffer to write arbitrary data to * @s: the seq_buf handle * @bufp: the beginning of the buffer is stored here -- 2.7.4