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-rw-r--r--kernel/printk.c52
1 files changed, 52 insertions, 0 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index b2b5c3a22a3..52493474f0a 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -220,6 +220,58 @@ static inline void boot_delay_msec(void)
#endif
/*
+ * Return the number of unread characters in the log buffer.
+ */
+int log_buf_get_len(void)
+{
+ return logged_chars;
+}
+
+/*
+ * Copy a range of characters from the log buffer.
+ */
+int log_buf_copy(char *dest, int idx, int len)
+{
+ int ret, max;
+ bool took_lock = false;
+
+ if (!oops_in_progress) {
+ spin_lock_irq(&logbuf_lock);
+ took_lock = true;
+ }
+
+ max = log_buf_get_len();
+ if (idx < 0 || idx >= max) {
+ ret = -1;
+ } else {
+ if (len > max)
+ len = max;
+ ret = len;
+ idx += (log_end - max);
+ while (len-- > 0)
+ dest[len] = LOG_BUF(idx + len);
+ }
+
+ if (took_lock)
+ spin_unlock_irq(&logbuf_lock);
+
+ return ret;
+}
+
+/*
+ * Extract a single character from the log buffer.
+ */
+int log_buf_read(int idx)
+{
+ char ret;
+
+ if (log_buf_copy(&ret, idx, 1) == 1)
+ return ret;
+ else
+ return -1;
+}
+
+/*
* Commands to do_syslog:
*
* 0 -- Close the log. Currently a NOP.