On Fri 2014-07-18 16:28:04, Alex Elder wrote:
> If a log record has LOG_PREFIX set, its predecessor record should be
> terminated if it was marked LOG_CONT.
>
> In devkmsg_read(), this condition was being ignored, which would
> lead to such records showing up combined when reading /dev/kmsg.
> Fix this oversight.
>
> We should similarly insert a newline in msg_print_text() in this
> case, to avoid formatted records getting merged.
>
> Suggested-by: Petr Mládek <pmla...@suse.cz>
> Signed-off-by: Alex Elder <el...@linaro.org>
> ---
> kernel/printk/printk.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index e9f0632..a5ad81c 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -575,6 +575,7 @@ static ssize_t devkmsg_read(struct file *file, char
> __user *buf,
> char cont;
> size_t len;
> ssize_t ret;
> + bool insert_newline;
>
> if (!user)
> return -EBADF;
> @@ -626,7 +627,10 @@ static ssize_t devkmsg_read(struct file *file, char
> __user *buf,
> else
> cont = '-';
>
> - len = sprintf(user->buf, "%u,%llu,%llu,%c;",
> + /* Insert a newline if the previous line was not terminated properly */
> + insert_newline = (user->prev & LOG_CONT) && (msg->flags & LOG_PREFIX);
> + len = sprintf(user->buf, "%s%u,%llu,%llu,%c;",
> + insert_newline ? "\n" : "",
> (msg->facility << 3) | msg->level,
> user->seq, ts_usec, cont);
> user->prev = msg->flags;
> @@ -999,10 +1003,12 @@ static size_t msg_print_text(const struct printk_log
> *msg, enum log_flags prev,
> {
> const char *text = log_text(msg);
> size_t text_size = msg->text_len;
> + size_t len = 0;
> + bool insert_newline;
> bool prefix = true;
> bool newline = true;
> - size_t len = 0;
>
> + insert_newline = (prev & LOG_CONT) && (msg->flags & LOG_PREFIX);
> if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
> prefix = false;
>
> @@ -1023,9 +1029,13 @@ static size_t msg_print_text(const struct printk_log
> *msg, enum log_flags prev,
>
> if (buf) {
> if (print_prefix(msg, syslog, NULL) +
> - text_len + 1 >= size - len)
> + text_len + 2 >= size - len)
It counts the '\n' even when it is not used.
I think that it is even wrong that it calculates prefix when it is not used.
> break;
>
> + if (insert_newline) {
> + insert_newline = false;
> + buf[len++] = '\n';
> + }
> if (prefix)
> len += print_prefix(msg, syslog, buf + len);
> memcpy(buf + len, text, text_len);
> @@ -1034,6 +1044,8 @@ static size_t msg_print_text(const struct printk_log
> *msg, enum log_flags prev,
> buf[len++] = '\n';
> } else {
> /* SYSLOG_ACTION_* buffer size only calculation */
> + if (insert_newline)
> + len++;
You forgot "insert_newline = false" here.
> if (prefix)
> len += print_prefix(msg, syslog, NULL);
> len += text_len;
It is just matter of personal style but I would suggest to do this
before the do-while cycle:
/* Force newline if the previous text was not properly finished */
if ((prev & LOG_CONT) && (msg->flags & LOG_PREFIX) && (len < size)) {
if (buf)
buf[len++] = '\n';
else
len++;
}
IMHO, it is more clear. The do-while cycle already is complex enough.
BTW: This is relared to the first patch. I would either patch all
three locations in one patch or better split it into three patches.
Best Regards,
Petr
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