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printk: factor out message formatting from devkmsg_read()

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The extended message formatting used for /dev/kmsg will be used implement
extended consoles.  Factor out msg_print_ext_header() and
msg_print_ext_body() from devkmsg_read().

This is pure restructuring.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: David Miller <davem@davemloft.net>
Cc: Kay Sievers <kay@vrfy.org>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tejun Heo 2015-06-25 15:01:27 -07:00 committed by Linus Torvalds
parent d43ff430f4
commit 0a295e67ec
1 changed files with 80 additions and 66 deletions
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146
kernel/printk/printk.c
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@ -511,6 +511,81 @@ static void append_char(char **pp, char *e, char c)
*(*pp)++ = c;
}
static ssize_t msg_print_ext_header(char *buf, size_t size,
struct printk_log *msg, u64 seq,
enum log_flags prev_flags)
{
u64 ts_usec = msg->ts_nsec;
char cont = '-';
do_div(ts_usec, 1000);
/*
* If we couldn't merge continuation line fragments during the print,
* export the stored flags to allow an optional external merge of the
* records. Merging the records isn't always neccessarily correct, like
* when we hit a race during printing. In most cases though, it produces
* better readable output. 'c' in the record flags mark the first
* fragment of a line, '+' the following.
*/
if (msg->flags & LOG_CONT && !(prev_flags & LOG_CONT))
cont = 'c';
else if ((msg->flags & LOG_CONT) ||
((prev_flags & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
cont = '+';
return scnprintf(buf, size, "%u,%llu,%llu,%c;",
(msg->facility << 3) | msg->level, seq, ts_usec, cont);
}
static ssize_t msg_print_ext_body(char *buf, size_t size,
char *dict, size_t dict_len,
char *text, size_t text_len)
{
char *p = buf, *e = buf + size;
size_t i;
/* escape non-printable characters */
for (i = 0; i < text_len; i++) {
unsigned char c = text[i];
if (c < ' ' || c >= 127 || c == '\\')
p += scnprintf(p, e - p, "\\x%02x", c);
else
append_char(&p, e, c);
}
append_char(&p, e, '\n');
if (dict_len) {
bool line = true;
for (i = 0; i < dict_len; i++) {
unsigned char c = dict[i];
if (line) {
append_char(&p, e, ' ');
line = false;
}
if (c == '\0') {
append_char(&p, e, '\n');
line = true;
continue;
}
if (c < ' ' || c >= 127 || c == '\\') {
p += scnprintf(p, e - p, "\\x%02x", c);
continue;
}
append_char(&p, e, c);
}
append_char(&p, e, '\n');
}
return p - buf;
}
/* /dev/kmsg - userspace message inject/listen interface */
struct devkmsg_user {
u64 seq;
@ -575,19 +650,12 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
{
struct devkmsg_user *user = file->private_data;
struct printk_log *msg;
char *p, *e;
u64 ts_usec;
size_t i;
char cont = '-';
size_t len;
ssize_t ret;
if (!user)
return -EBADF;
p = user->buf;
e = user->buf + sizeof(user->buf);
ret = mutex_lock_interruptible(&user->lock);
if (ret)
return ret;
@ -617,71 +685,17 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
}
msg = log_from_idx(user->idx);
ts_usec = msg->ts_nsec;
do_div(ts_usec, 1000);
len = msg_print_ext_header(user->buf, sizeof(user->buf),
msg, user->seq, user->prev);
len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len,
log_dict(msg), msg->dict_len,
log_text(msg), msg->text_len);
/*
* If we couldn't merge continuation line fragments during the print,
* export the stored flags to allow an optional external merge of the
* records. Merging the records isn't always neccessarily correct, like
* when we hit a race during printing. In most cases though, it produces
* better readable output. 'c' in the record flags mark the first
* fragment of a line, '+' the following.
*/
if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT))
cont = 'c';
else if ((msg->flags & LOG_CONT) ||
((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
cont = '+';
p += scnprintf(p, e - p, "%u,%llu,%llu,%c;",
(msg->facility << 3) | msg->level,
user->seq, ts_usec, cont);
user->prev = msg->flags;
/* escape non-printable characters */
for (i = 0; i < msg->text_len; i++) {
unsigned char c = log_text(msg)[i];
if (c < ' ' || c >= 127 || c == '\\')
p += scnprintf(p, e - p, "\\x%02x", c);
else
append_char(&p, e, c);
}
append_char(&p, e, '\n');
if (msg->dict_len) {
bool line = true;
for (i = 0; i < msg->dict_len; i++) {
unsigned char c = log_dict(msg)[i];
if (line) {
append_char(&p, e, ' ');
line = false;
}
if (c == '\0') {
append_char(&p, e, '\n');
line = true;
continue;
}
if (c < ' ' || c >= 127 || c == '\\') {
p += scnprintf(p, e - p, "\\x%02x", c);
continue;
}
append_char(&p, e, c);
}
append_char(&p, e, '\n');
}
user->idx = log_next(user->idx);
user->seq++;
raw_spin_unlock_irq(&logbuf_lock);
len = p - user->buf;
if (len > count) {
ret = -EINVAL;
goto out;