printk: factor out message formatting from devkmsg_read()

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>

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index a115490..51ce4f1 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -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;