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Subject[PATCH 02/16] printk: factor out message formatting from devkmsg_read()
Date
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: Kay Sievers <kay@vrfy.org>
Cc: Petr Mladek <pmladek@suse.cz>
---
kernel/printk/printk.c | 157 ++++++++++++++++++++++++++-----------------------
1 file changed, 85 insertions(+), 72 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index b6e24af..5ea6709 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -505,6 +505,86 @@ int check_syslog_permissions(int type, bool from_file)
return security_syslog(type);
}

+static void append_char(char **pp, char *e, char c)
+{
+ if (*pp < e)
+ *(*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 {
@@ -565,30 +645,17 @@ static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)
return ret;
}

-static void append_char(char **pp, char *e, char c)
-{
- if (*pp < e)
- *(*pp)++ = c;
-}
-
static ssize_t devkmsg_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
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;
@@ -618,71 +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);
-
- /*
- * 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 = '+';
+ 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);

- 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;
--
2.1.0


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